Microorganisms play pivotal roles in shaping ecosystems and biogeochemical cycles. Their intricat... more Microorganisms play pivotal roles in shaping ecosystems and biogeochemical cycles. Their intricate interactions involve complex biochemical processes. Fourier Transform-Infrared (FT-IR) spectroscopy is a powerful tool for monitoring these interactions, revealing microorganism composition and responses to the environment. This review explores the diversity of applications of FT-IR spectroscopy within the field of microbiology, highlighting its specific utility in microbial cell biology and environmental microbiology. It emphasizes key applications such as microbial identification, process monitoring, cell wall analysis, biofilm examination, stress response assessment, and environmental interaction investigation, showcasing the crucial role of FT-IR in advancing our understanding of microbial systems. Furthermore, we address challenges including sample complexity, data interpretation nuances, and the need for integration with complementary techniques. Future prospects for FT-IR in environmental microbiology include a wide range of transformative applications and advancements. These include the development of comprehensive and standardized FT-IR libraries for precise microbial identification, the integration of advanced analytical techniques, the adoption of high-throughput and single-cell analysis, real-time environmental monitoring using portable FT-IR systems and the incorporation of FT-IR data into ecological modeling for predictive insights into microbial responses to environmental changes. These innovative avenues promise to significantly advance our understanding of microorganisms and their complex interactions within various ecosystems.
High representation by ammonia-oxidizing archaea (AOA) in marine systems is consistent with their... more High representation by ammonia-oxidizing archaea (AOA) in marine systems is consistent with their high affinity for ammonia, efficient carbon fixation, and copper (Cu)-centric respiratory system. However, little is known about their response to nutrient stress. We therefore used global transcriptional and proteomic analyses to characterize the response of a model AOA, Nitrosopumilus maritimus SCM1, to ammonia starvation, Cu limitation and Cu excess. Most predicted protein-coding genes were transcribed in exponentially growing cells, and of~74% detected in the proteome,~6% were modified by N-terminal acetylation. The general response to ammonia starvation and Cu stress was downregulation of genes for energy generation and biosynthesis. Cells rapidly depleted transcripts for the A and B subunits of ammonia monooxygenase (AMO) in response to ammonia starvation, yet retained relatively high levels of transcripts for the C subunit. Thus, similar to ammonia-oxidizing bacteria, selective retention of amoC transcripts during starvation appears important for subsequent recovery, and also suggests that AMO subunit transcript ratios could be used to assess the physiological status of marine populations. Unexpectedly, cobalamin biosynthesis was upregulated in response to both ammonia starvation and Cu stress, indicating the importance of this cofactor in retaining functional integrity during times of stress.
Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair R... more Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair River sediments on two enrichment media with increasing concentrations of Pb (NO 3) 2. Bacterial strains that grew at 1.25 or 1.5 g L −1 of Pb (NO 3) 2 L −1) were purified and selected for further study. Ninety-seven Pb-resistant strains were screened for the ability to produce bioflocculants. The majority of the Pb-resistant strains demonstrated moderate to high flocculation activity. Metal removal assays demonstrated that the higher is the flocculation activity, the higher is the efficiency of metal removal. In the multi-metal solutions, the bacterial strain with the highest flocculation activity (R19) had the highest metal removing capability (six out of eight metals) and the highest metal removal efficiency. The highly selective affinity towards Pb 2+ observed for strain R19 suggests its use for the recovery of Pb 2+ from multiple metal solutions. Because they are well adapted to unfavorable conditions due to their resistance to metals (e.g., Pb) and antibiotics, these characteristics may help in developing an effective process for wastewater treatment using these strains.
Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair R... more Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair River sediments on two enrichment media with increasing concentrations of Pb (NO 3) 2. Bacterial strains that grew at 1.25 or 1.5 g L −1 of Pb (NO 3) 2 L −1) were purified and selected for further study. Ninety-seven Pb-resistant strains were screened for the ability to produce bioflocculants. The majority of the Pb-resistant strains demonstrated moderate to high flocculation activity. Metal removal assays demonstrated that the higher is the flocculation activity, the higher is the efficiency of metal removal. In the multi-metal solutions, the bacterial strain with the highest flocculation activity (R19) had the highest metal removing capability (six out of eight metals) and the highest metal removal efficiency. The highly selective affinity towards Pb 2+ observed for strain R19 suggests its use for the recovery of Pb 2+ from multiple metal solutions. Because they are well adapted to unfavorable conditions due to their resistance to metals (e.g., Pb) and antibiotics, these characteristics may help in developing an effective process for wastewater treatment using these strains.
Bacteria exhibit a number of metabolism-dependent and metabolism-independent processes for the up... more Bacteria exhibit a number of metabolism-dependent and metabolism-independent processes for the uptake and accumulation of toxic metals. The removal of these metals from environmental sources such as soil, sludge, and wastewaters using microbe-based technologies provide an alternative for their recovery and remediation. Lead (Pb) is a pervasive metal in the environment that adversely affects all living organisms. Many aspects of metal-microbe interactions remain unexploited in biotechnology and further development and application is necessary, particularly to the problem of Pb release into the environment. Thus, this review provides a synopsis of the most important bacterial phenotypes and biochemical attributes that are instrumental in lead bioremediation, along with what is known of their genetic background that can be exploited or improved through genetic engineering. This review also highlights the potential of Pb-resistant bacteria in bringing about detoxification of Pb-contaminated terrestrial and aquatic systems in a highly sustainable and environmental friendly manner, and the existing challenges that still lie in the path to in situ and large-scale bioremediation.
Waters draining into a lake carry with them much of the suspended sediment that is transported by... more Waters draining into a lake carry with them much of the suspended sediment that is transported by rivers and streams from the local drainage basin. The organic matter processing in the sediments is executed by heterotrophic microbial communities, whose activities may vary spatially and temporally. Thus, to capture and evaluate some of these variabilities in the sediments, we sampled six sites: three from the St. Clair River and three from Lake St. Clair in spring, summer, fall, and winter of 2016. At all sites and dates, we investigated the spatial and temporal variations in 19 extracellular enzyme activities using API ZYM. Our results indicated that a broad range of enzymes were found to be active in the sediments. Phosphatases, lipases, and esterases were synthesized most intensively by the sediment microbial communities. No consistent difference was found between the lake and sediment samples. Differences were more obvious between sites and seasons. Sites with the highest metabolic (enzyme) diversity reflected the capacity of the sediment microbial communities to breakdown a broader range of substrates and may be linked to differences in river and lake water quality. The seasonal variability of the enzymes activities was governed by the variations of environmental factors caused by anthropogenic and terrestrial inputs, and provides information for a better understanding of the dynamics of sediment organic matter of the river and lake ecosystems. The experimental results suggest that API ZYM is a simple and rapid enzyme assay procedure to evaluate natural processes in ecosystems and their changes.
Electricity generation in a microbial fuel cell (MFC) using carbon monoxide (CO) or synthesis gas... more Electricity generation in a microbial fuel cell (MFC) using carbon monoxide (CO) or synthesis gas (syngas) as a carbon source has been demonstrated recently. While the majority of MFCs have been tested at ambient or mesophilic temperatures, thermophilic systems warrant evaluation because of the potential for increased microbial activity rates on the anode. It has been indicated that thermophilic MFCs, which are operated at thermophilic temperatures (>50°C), are potentially superior to mesophilic MFCs operated at mesophilic temperatures (30–40°C) in terms of performance, reaction activity, durability and substrate range. Considering that the syngas temperature at the exit of the gasification process could be in a range of 45 to 55°C, the operation of the MFC at thermophilic temperatures might be preferable because it eliminates the need for syngas cooling and might lead to a higher biocatalytic activity. A thermophilic MFC-based process of syngas conversion to electricity might offer several advantages, such as high Coulombic efficiency and biocatalytic activity in the presence of carbon monoxide and sulfur components. This article reviews the thermophilic microorganisms (carboxydotrohs and exoelectrogens) involved in the generation of electricity in CO/syngas-fed MFC and the design considerations to overcome the practical challenges for operating an MFC on syngas at thermophilic temperatures.
Rapid industrialization and urbanization have led to widespread metal contamination in aquatic ec... more Rapid industrialization and urbanization have led to widespread metal contamination in aquatic ecosystems. This study explores the metal tolerance and biosorption characteristics of four bacterial strains (Serratia sp. L2, Raoultella sp. L30, Klebsiella sp. R3, and Klebsiella sp. R19) isolated from Saint Clair River sediments. These strains effectively removed various metal cations (As 3+ , Pb 2+ , Cu 2+ , Mn 2+ , Zn 2+ , Cd 2+ , Cr 6+ , and Ni 2+) in single and multi-metal solutions. Minimum inhibitory concentration (MIC) assays revealed strain-specific variations in metal tolerance, with L2 and L30 exhibiting higher tolerance. Surprisingly, R3 and R19, despite lower tolerance, demonstrated superior metal removal efficiency, challenging the notion that tolerance dictates removal efficacy. In single-metal solutions, R3 and R19 excelled at extracting various metal ions, while competitive binding in multi-metal solutions hindered removal. However, R3 and R19 retained higher removal efficiencies, possibly due to enhanced flocculation activities facilitating metal-ion contact. Comprehensive Fourier-transform infrared (FTIR) analysis highlighted the strains' metal-binding capabilities, with novel peaks emerging after metal exposure, indicative of extracellular polymeric substance (EPS) production. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed metal accumulation on bacterial surfaces and within cytoplasmic regions and revealed morphological changes and metal adsorption patterns, emphasizing the strains' ability to adapt to metal stress. Scanning transmission microscopy (STEM) and EDX analysis uncovered metal accumulation within bacterial cells, underscoring the complexity of microbialmetal interactions. This study also confirms that the simultaneous presence of an aqueous solution may cause a mutual inhibition in the adsorption of each metal to the EPS resulting in reduced metal uptake, which emphasizes the need to select specific bacterial strains for a given metal-containing effluent. The differences in metal distribution patterns between Klebsiella sp. R19 and Raoultella sp. L30 suggest species-specific metal accumulation strategies driven by environmental conditions and metal availability. The heavy metal-removing capabilities and the ability to grow over a wide range of metal concentrations of the strains used in this study may offer an advantage to employ these organisms for metal remediation in bioreactors or in situ.
High representation by ammonia-oxidizing archaea (AOA) in marine systems is consistent with their... more High representation by ammonia-oxidizing archaea (AOA) in marine systems is consistent with their high affinity for ammonia, efficient carbon fixation, and copper (Cu)-centric respiratory system. However, little is known about their response to nutrient stress. We therefore used global transcriptional and proteomic analyses to characterize the response of a model AOA, Nitrosopumilus maritimus SCM1, to ammonia starvation, Cu limitation and Cu excess. Most predicted protein-coding genes were transcribed in exponentially growing cells, and of ~ 74% detected in the proteome, ~ 6% were modified by N-terminal acetylation. The general response to ammonia starvation and Cu stress was downregulation of genes for energy generation and biosynthesis. Cells rapidly depleted transcripts for the A and B subunits of ammonia monooxygenase (AMO) in response to ammonia starvation, yet retained relatively high levels of transcripts for the C subunit. Thus, similar to ammonia-oxidizing bacteria, selective retention of amoC transcripts during starvation appears important for subsequent recovery, and also suggests that AMO subunit transcript ratios could be used to assess the physiological status of marine populations. Unexpectedly, cobalamin biosynth-esis was upregulated in response to both ammonia starvation and Cu stress, indicating the importance of this cofactor in retaining functional integrity during times of stress.
Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair R... more Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair River sediments on two enrichment media with increasing concentrations of Pb (NO 3) 2. Bacterial strains that grew at 1.25 or 1.5 g L −1 of Pb (NO 3) 2 L −1) were purified and selected for further study. Ninety-seven Pb-resistant strains were screened for the ability to produce bioflocculants. The majority of the Pb-resistant strains demonstrated moderate to high flocculation activity. Metal removal assays demonstrated that the higher is the flocculation activity, the higher is the efficiency of metal removal. In the multi-metal solutions, the bacterial strain with the highest flocculation activity (R19) had the highest metal removing capability (six out of eight metals) and the highest metal removal efficiency. The highly selective affinity towards Pb 2+ observed for strain R19 suggests its use for the recovery of Pb 2+ from multiple metal solutions. Because they are well adapted to unfavorable conditions due to their resistance to metals (e.g., Pb) and antibiotics, these characteristics may help in developing an effective process for wastewater treatment using these strains.
Some thermophiles and psychrophiles have developed the ability to resort to specific defense mech... more Some thermophiles and psychrophiles have developed the ability to resort to specific defense mechanisms to quell stresses like toxicity of heavy metal ions or metals. Some of them could survive and grow even at high metal ion concentrations and are capable of binding large quantities of metallic cations. Moreover, some of these microorganisms are able to synthesize nanoparticles. The remarkable ability of these group of microbes to reduce heavy metal ions make them one of the best candidates for nanoparticle synthesis. In this chapter, ther-mophilic and psychrophilic microorganisms used in nanoparticle biosynthesis are presented. The aim of chapter is to make a reflection on the current state and future prospects and especially the possibilities and limitations of the use of extremophiles in bio-based technique for industries.
Microorganisms capable of synthesizing nanoparticles are prevalent microflora of the terrestrial ... more Microorganisms capable of synthesizing nanoparticles are prevalent microflora of the terrestrial and marine ecosystems. These microorganisms are involved in biogeochemical cycling of metals in processes such as precipitation (biomineralization), decomposition (bioweathering), and degradation (biocorro-sion). The biosynthesis of metal NPs by microbes is a function of heavy metal toxicity resistance mechanisms. Resistance mechanisms range from redox enzymes that convert toxic metal ions to inert forms, structural proteins that bind protein, or through the use of efflux proteins that transport metal ions by proton motive force, chemiosmotic gradients, or ATP hydrolysis, which work together to coordinate synthesis nanoparticle synthesis. This chapter focuses on the biological systems; bacteria, fungi, actinomycetes, and algae for utilization in nanotechnology, especially in the development of a reliable and eco-friendly processes for the synthesis of metallic nanoparticles. The rich microbial diversity points to their innate potential for acting as potential biofactories for nanoparticles synthesis.
Halophiles are salt loving organisms that flourish in saline environments such as marine and estu... more Halophiles are salt loving organisms that flourish in saline environments such as marine and estuarine environments, solar salterns, salt lakes, brines and saline soils. They offer potential applications in various fields of biotechnology. They can be used as a source of metabolites, compatible solutes and other compounds of industrial value. The biodegradation of organic pollutants in hypersaline environments and treatment of saline effluents contaminated with organic by halophiles have been investigated. Some halophiles are a potential source of extracellular hydrolases like proteases with a wide array of industrial applications. These enzymes exhibit stability over a range of saline conditions and harsh conditions of pH or/and ionic strength. Recently, they are being explored as potential sources of metal tolerant microorganisms with the ability to synthesize metallic nanoparticles. This chapter covers the various halophilic organisms and their by-products that have been exploited for nanomaterial synthesis, the mechanisms that may be involved in the nanomaterial fabrication and the possible applications of the fabricated nanoparticles.
In this chapter we discuss the applications of bionanoparticles (BNP) in biomedical and environme... more In this chapter we discuss the applications of bionanoparticles (BNP) in biomedical and environmental fields. In the biomedical field, these nanoparticles have been investigated for antimicrobial applications, biosensing, imaging, and drug delivery. In the environmental field, nanoparticles have been investigated for applications in bioremediation of diverse contaminants, water treatment, and production of clean energy. Overall, the BNP have attracted the attention of diverse researchers because their syntheses are more environmentally friendly, produces more homogeneously distributed nanoparticles and some of them can be easily biodegradable. Although there are several studies investigating the application of BNP, these nanomaterials are still way less studied than synthetic nanoparticles, since researchers are still identifying the microbiological synthetic pathways of these BNP. It is expected that with the advancement of the understanding of BNP synthesis pathways, the application of BNP will expand to many more fields than biomedical and environmental and will be potentially applied in diverse nan-otechnological industries.
Acidophiles and alkaliphiles have been exploited for the synthesis of nanoparticles. The nanomate... more Acidophiles and alkaliphiles have been exploited for the synthesis of nanoparticles. The nanomaterial synthesizing biocomponents of these microorganisms have an added advantage of providing excellent stability to the nanoma-terial being synthesized. Some produce biomolecules such as proteins, peptides and a special class of metal-binding molecules referred to as phytochelatins that are used for the in vitro stabilization of synthesized nanomaterials. This chapter provides an overview of the many acidophilic and alkalophilic microorganisms capable of synthesizing nanoparticles.
Carboxydotrophic bacteria (carboxydotrophs) have the ability to uptake carbon monoxide (CO) and s... more Carboxydotrophic bacteria (carboxydotrophs) have the ability to uptake carbon monoxide (CO) and synthesize butanol. The aims of this study were to determine the butanol tolerance and biological production of butanol carboxydotrophic strains. In this study, 11 carboxydotrophic strains were exposed to increasing n-butanol concentrations (1–3% vol/vol) to determine their effect on growth. Butanol production by the strains was quantified and the identity of the strains was elucidated using 16S rRNA sequencing. The carboxydotrophic strains possessed inherent tolerance to butanol and tolerated up to 3% n-butanol. Among the 11 strains, T1-16, M2-32 and M3-28 were the most tolerant to butanol. The 16S rRNA gene sequence of these strains was similar (99% nucleotide similarity) to the butanol-tolerant strains Bacillus licheniformis YP1A, Pediococcus acidilacti IMUA20068 and Enterococcus faecium IMAU60169, respectively. The carboxydotrophic strains screened in this study have two distinct features: (1) high tolerance to butanol and (2) natural production of low concentration of butanol from CO, which distinguish them from other screened butanol-tolerant strains. The butanol tolerance of these carboxydotrophic strains makes them ideal for genetic studies, particularly the molecular mechanisms that enable them to survive such hostile environmental conditions and the identification of genes that confer tolerance to butanol.
Microorganisms play pivotal roles in shaping ecosystems and biogeochemical cycles. Their intricat... more Microorganisms play pivotal roles in shaping ecosystems and biogeochemical cycles. Their intricate interactions involve complex biochemical processes. Fourier Transform-Infrared (FT-IR) spectroscopy is a powerful tool for monitoring these interactions, revealing microorganism composition and responses to the environment. This review explores the diversity of applications of FT-IR spectroscopy within the field of microbiology, highlighting its specific utility in microbial cell biology and environmental microbiology. It emphasizes key applications such as microbial identification, process monitoring, cell wall analysis, biofilm examination, stress response assessment, and environmental interaction investigation, showcasing the crucial role of FT-IR in advancing our understanding of microbial systems. Furthermore, we address challenges including sample complexity, data interpretation nuances, and the need for integration with complementary techniques. Future prospects for FT-IR in environmental microbiology include a wide range of transformative applications and advancements. These include the development of comprehensive and standardized FT-IR libraries for precise microbial identification, the integration of advanced analytical techniques, the adoption of high-throughput and single-cell analysis, real-time environmental monitoring using portable FT-IR systems and the incorporation of FT-IR data into ecological modeling for predictive insights into microbial responses to environmental changes. These innovative avenues promise to significantly advance our understanding of microorganisms and their complex interactions within various ecosystems.
High representation by ammonia-oxidizing archaea (AOA) in marine systems is consistent with their... more High representation by ammonia-oxidizing archaea (AOA) in marine systems is consistent with their high affinity for ammonia, efficient carbon fixation, and copper (Cu)-centric respiratory system. However, little is known about their response to nutrient stress. We therefore used global transcriptional and proteomic analyses to characterize the response of a model AOA, Nitrosopumilus maritimus SCM1, to ammonia starvation, Cu limitation and Cu excess. Most predicted protein-coding genes were transcribed in exponentially growing cells, and of~74% detected in the proteome,~6% were modified by N-terminal acetylation. The general response to ammonia starvation and Cu stress was downregulation of genes for energy generation and biosynthesis. Cells rapidly depleted transcripts for the A and B subunits of ammonia monooxygenase (AMO) in response to ammonia starvation, yet retained relatively high levels of transcripts for the C subunit. Thus, similar to ammonia-oxidizing bacteria, selective retention of amoC transcripts during starvation appears important for subsequent recovery, and also suggests that AMO subunit transcript ratios could be used to assess the physiological status of marine populations. Unexpectedly, cobalamin biosynthesis was upregulated in response to both ammonia starvation and Cu stress, indicating the importance of this cofactor in retaining functional integrity during times of stress.
Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair R... more Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair River sediments on two enrichment media with increasing concentrations of Pb (NO 3) 2. Bacterial strains that grew at 1.25 or 1.5 g L −1 of Pb (NO 3) 2 L −1) were purified and selected for further study. Ninety-seven Pb-resistant strains were screened for the ability to produce bioflocculants. The majority of the Pb-resistant strains demonstrated moderate to high flocculation activity. Metal removal assays demonstrated that the higher is the flocculation activity, the higher is the efficiency of metal removal. In the multi-metal solutions, the bacterial strain with the highest flocculation activity (R19) had the highest metal removing capability (six out of eight metals) and the highest metal removal efficiency. The highly selective affinity towards Pb 2+ observed for strain R19 suggests its use for the recovery of Pb 2+ from multiple metal solutions. Because they are well adapted to unfavorable conditions due to their resistance to metals (e.g., Pb) and antibiotics, these characteristics may help in developing an effective process for wastewater treatment using these strains.
Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair R... more Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair River sediments on two enrichment media with increasing concentrations of Pb (NO 3) 2. Bacterial strains that grew at 1.25 or 1.5 g L −1 of Pb (NO 3) 2 L −1) were purified and selected for further study. Ninety-seven Pb-resistant strains were screened for the ability to produce bioflocculants. The majority of the Pb-resistant strains demonstrated moderate to high flocculation activity. Metal removal assays demonstrated that the higher is the flocculation activity, the higher is the efficiency of metal removal. In the multi-metal solutions, the bacterial strain with the highest flocculation activity (R19) had the highest metal removing capability (six out of eight metals) and the highest metal removal efficiency. The highly selective affinity towards Pb 2+ observed for strain R19 suggests its use for the recovery of Pb 2+ from multiple metal solutions. Because they are well adapted to unfavorable conditions due to their resistance to metals (e.g., Pb) and antibiotics, these characteristics may help in developing an effective process for wastewater treatment using these strains.
Bacteria exhibit a number of metabolism-dependent and metabolism-independent processes for the up... more Bacteria exhibit a number of metabolism-dependent and metabolism-independent processes for the uptake and accumulation of toxic metals. The removal of these metals from environmental sources such as soil, sludge, and wastewaters using microbe-based technologies provide an alternative for their recovery and remediation. Lead (Pb) is a pervasive metal in the environment that adversely affects all living organisms. Many aspects of metal-microbe interactions remain unexploited in biotechnology and further development and application is necessary, particularly to the problem of Pb release into the environment. Thus, this review provides a synopsis of the most important bacterial phenotypes and biochemical attributes that are instrumental in lead bioremediation, along with what is known of their genetic background that can be exploited or improved through genetic engineering. This review also highlights the potential of Pb-resistant bacteria in bringing about detoxification of Pb-contaminated terrestrial and aquatic systems in a highly sustainable and environmental friendly manner, and the existing challenges that still lie in the path to in situ and large-scale bioremediation.
Waters draining into a lake carry with them much of the suspended sediment that is transported by... more Waters draining into a lake carry with them much of the suspended sediment that is transported by rivers and streams from the local drainage basin. The organic matter processing in the sediments is executed by heterotrophic microbial communities, whose activities may vary spatially and temporally. Thus, to capture and evaluate some of these variabilities in the sediments, we sampled six sites: three from the St. Clair River and three from Lake St. Clair in spring, summer, fall, and winter of 2016. At all sites and dates, we investigated the spatial and temporal variations in 19 extracellular enzyme activities using API ZYM. Our results indicated that a broad range of enzymes were found to be active in the sediments. Phosphatases, lipases, and esterases were synthesized most intensively by the sediment microbial communities. No consistent difference was found between the lake and sediment samples. Differences were more obvious between sites and seasons. Sites with the highest metabolic (enzyme) diversity reflected the capacity of the sediment microbial communities to breakdown a broader range of substrates and may be linked to differences in river and lake water quality. The seasonal variability of the enzymes activities was governed by the variations of environmental factors caused by anthropogenic and terrestrial inputs, and provides information for a better understanding of the dynamics of sediment organic matter of the river and lake ecosystems. The experimental results suggest that API ZYM is a simple and rapid enzyme assay procedure to evaluate natural processes in ecosystems and their changes.
Electricity generation in a microbial fuel cell (MFC) using carbon monoxide (CO) or synthesis gas... more Electricity generation in a microbial fuel cell (MFC) using carbon monoxide (CO) or synthesis gas (syngas) as a carbon source has been demonstrated recently. While the majority of MFCs have been tested at ambient or mesophilic temperatures, thermophilic systems warrant evaluation because of the potential for increased microbial activity rates on the anode. It has been indicated that thermophilic MFCs, which are operated at thermophilic temperatures (>50°C), are potentially superior to mesophilic MFCs operated at mesophilic temperatures (30–40°C) in terms of performance, reaction activity, durability and substrate range. Considering that the syngas temperature at the exit of the gasification process could be in a range of 45 to 55°C, the operation of the MFC at thermophilic temperatures might be preferable because it eliminates the need for syngas cooling and might lead to a higher biocatalytic activity. A thermophilic MFC-based process of syngas conversion to electricity might offer several advantages, such as high Coulombic efficiency and biocatalytic activity in the presence of carbon monoxide and sulfur components. This article reviews the thermophilic microorganisms (carboxydotrohs and exoelectrogens) involved in the generation of electricity in CO/syngas-fed MFC and the design considerations to overcome the practical challenges for operating an MFC on syngas at thermophilic temperatures.
Rapid industrialization and urbanization have led to widespread metal contamination in aquatic ec... more Rapid industrialization and urbanization have led to widespread metal contamination in aquatic ecosystems. This study explores the metal tolerance and biosorption characteristics of four bacterial strains (Serratia sp. L2, Raoultella sp. L30, Klebsiella sp. R3, and Klebsiella sp. R19) isolated from Saint Clair River sediments. These strains effectively removed various metal cations (As 3+ , Pb 2+ , Cu 2+ , Mn 2+ , Zn 2+ , Cd 2+ , Cr 6+ , and Ni 2+) in single and multi-metal solutions. Minimum inhibitory concentration (MIC) assays revealed strain-specific variations in metal tolerance, with L2 and L30 exhibiting higher tolerance. Surprisingly, R3 and R19, despite lower tolerance, demonstrated superior metal removal efficiency, challenging the notion that tolerance dictates removal efficacy. In single-metal solutions, R3 and R19 excelled at extracting various metal ions, while competitive binding in multi-metal solutions hindered removal. However, R3 and R19 retained higher removal efficiencies, possibly due to enhanced flocculation activities facilitating metal-ion contact. Comprehensive Fourier-transform infrared (FTIR) analysis highlighted the strains' metal-binding capabilities, with novel peaks emerging after metal exposure, indicative of extracellular polymeric substance (EPS) production. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed metal accumulation on bacterial surfaces and within cytoplasmic regions and revealed morphological changes and metal adsorption patterns, emphasizing the strains' ability to adapt to metal stress. Scanning transmission microscopy (STEM) and EDX analysis uncovered metal accumulation within bacterial cells, underscoring the complexity of microbialmetal interactions. This study also confirms that the simultaneous presence of an aqueous solution may cause a mutual inhibition in the adsorption of each metal to the EPS resulting in reduced metal uptake, which emphasizes the need to select specific bacterial strains for a given metal-containing effluent. The differences in metal distribution patterns between Klebsiella sp. R19 and Raoultella sp. L30 suggest species-specific metal accumulation strategies driven by environmental conditions and metal availability. The heavy metal-removing capabilities and the ability to grow over a wide range of metal concentrations of the strains used in this study may offer an advantage to employ these organisms for metal remediation in bioreactors or in situ.
High representation by ammonia-oxidizing archaea (AOA) in marine systems is consistent with their... more High representation by ammonia-oxidizing archaea (AOA) in marine systems is consistent with their high affinity for ammonia, efficient carbon fixation, and copper (Cu)-centric respiratory system. However, little is known about their response to nutrient stress. We therefore used global transcriptional and proteomic analyses to characterize the response of a model AOA, Nitrosopumilus maritimus SCM1, to ammonia starvation, Cu limitation and Cu excess. Most predicted protein-coding genes were transcribed in exponentially growing cells, and of ~ 74% detected in the proteome, ~ 6% were modified by N-terminal acetylation. The general response to ammonia starvation and Cu stress was downregulation of genes for energy generation and biosynthesis. Cells rapidly depleted transcripts for the A and B subunits of ammonia monooxygenase (AMO) in response to ammonia starvation, yet retained relatively high levels of transcripts for the C subunit. Thus, similar to ammonia-oxidizing bacteria, selective retention of amoC transcripts during starvation appears important for subsequent recovery, and also suggests that AMO subunit transcript ratios could be used to assess the physiological status of marine populations. Unexpectedly, cobalamin biosynth-esis was upregulated in response to both ammonia starvation and Cu stress, indicating the importance of this cofactor in retaining functional integrity during times of stress.
Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair R... more Lead is an extensive contaminant. Pb-resistant bacterial strains were isolated from Saint Clair River sediments on two enrichment media with increasing concentrations of Pb (NO 3) 2. Bacterial strains that grew at 1.25 or 1.5 g L −1 of Pb (NO 3) 2 L −1) were purified and selected for further study. Ninety-seven Pb-resistant strains were screened for the ability to produce bioflocculants. The majority of the Pb-resistant strains demonstrated moderate to high flocculation activity. Metal removal assays demonstrated that the higher is the flocculation activity, the higher is the efficiency of metal removal. In the multi-metal solutions, the bacterial strain with the highest flocculation activity (R19) had the highest metal removing capability (six out of eight metals) and the highest metal removal efficiency. The highly selective affinity towards Pb 2+ observed for strain R19 suggests its use for the recovery of Pb 2+ from multiple metal solutions. Because they are well adapted to unfavorable conditions due to their resistance to metals (e.g., Pb) and antibiotics, these characteristics may help in developing an effective process for wastewater treatment using these strains.
Some thermophiles and psychrophiles have developed the ability to resort to specific defense mech... more Some thermophiles and psychrophiles have developed the ability to resort to specific defense mechanisms to quell stresses like toxicity of heavy metal ions or metals. Some of them could survive and grow even at high metal ion concentrations and are capable of binding large quantities of metallic cations. Moreover, some of these microorganisms are able to synthesize nanoparticles. The remarkable ability of these group of microbes to reduce heavy metal ions make them one of the best candidates for nanoparticle synthesis. In this chapter, ther-mophilic and psychrophilic microorganisms used in nanoparticle biosynthesis are presented. The aim of chapter is to make a reflection on the current state and future prospects and especially the possibilities and limitations of the use of extremophiles in bio-based technique for industries.
Microorganisms capable of synthesizing nanoparticles are prevalent microflora of the terrestrial ... more Microorganisms capable of synthesizing nanoparticles are prevalent microflora of the terrestrial and marine ecosystems. These microorganisms are involved in biogeochemical cycling of metals in processes such as precipitation (biomineralization), decomposition (bioweathering), and degradation (biocorro-sion). The biosynthesis of metal NPs by microbes is a function of heavy metal toxicity resistance mechanisms. Resistance mechanisms range from redox enzymes that convert toxic metal ions to inert forms, structural proteins that bind protein, or through the use of efflux proteins that transport metal ions by proton motive force, chemiosmotic gradients, or ATP hydrolysis, which work together to coordinate synthesis nanoparticle synthesis. This chapter focuses on the biological systems; bacteria, fungi, actinomycetes, and algae for utilization in nanotechnology, especially in the development of a reliable and eco-friendly processes for the synthesis of metallic nanoparticles. The rich microbial diversity points to their innate potential for acting as potential biofactories for nanoparticles synthesis.
Halophiles are salt loving organisms that flourish in saline environments such as marine and estu... more Halophiles are salt loving organisms that flourish in saline environments such as marine and estuarine environments, solar salterns, salt lakes, brines and saline soils. They offer potential applications in various fields of biotechnology. They can be used as a source of metabolites, compatible solutes and other compounds of industrial value. The biodegradation of organic pollutants in hypersaline environments and treatment of saline effluents contaminated with organic by halophiles have been investigated. Some halophiles are a potential source of extracellular hydrolases like proteases with a wide array of industrial applications. These enzymes exhibit stability over a range of saline conditions and harsh conditions of pH or/and ionic strength. Recently, they are being explored as potential sources of metal tolerant microorganisms with the ability to synthesize metallic nanoparticles. This chapter covers the various halophilic organisms and their by-products that have been exploited for nanomaterial synthesis, the mechanisms that may be involved in the nanomaterial fabrication and the possible applications of the fabricated nanoparticles.
In this chapter we discuss the applications of bionanoparticles (BNP) in biomedical and environme... more In this chapter we discuss the applications of bionanoparticles (BNP) in biomedical and environmental fields. In the biomedical field, these nanoparticles have been investigated for antimicrobial applications, biosensing, imaging, and drug delivery. In the environmental field, nanoparticles have been investigated for applications in bioremediation of diverse contaminants, water treatment, and production of clean energy. Overall, the BNP have attracted the attention of diverse researchers because their syntheses are more environmentally friendly, produces more homogeneously distributed nanoparticles and some of them can be easily biodegradable. Although there are several studies investigating the application of BNP, these nanomaterials are still way less studied than synthetic nanoparticles, since researchers are still identifying the microbiological synthetic pathways of these BNP. It is expected that with the advancement of the understanding of BNP synthesis pathways, the application of BNP will expand to many more fields than biomedical and environmental and will be potentially applied in diverse nan-otechnological industries.
Acidophiles and alkaliphiles have been exploited for the synthesis of nanoparticles. The nanomate... more Acidophiles and alkaliphiles have been exploited for the synthesis of nanoparticles. The nanomaterial synthesizing biocomponents of these microorganisms have an added advantage of providing excellent stability to the nanoma-terial being synthesized. Some produce biomolecules such as proteins, peptides and a special class of metal-binding molecules referred to as phytochelatins that are used for the in vitro stabilization of synthesized nanomaterials. This chapter provides an overview of the many acidophilic and alkalophilic microorganisms capable of synthesizing nanoparticles.
Carboxydotrophic bacteria (carboxydotrophs) have the ability to uptake carbon monoxide (CO) and s... more Carboxydotrophic bacteria (carboxydotrophs) have the ability to uptake carbon monoxide (CO) and synthesize butanol. The aims of this study were to determine the butanol tolerance and biological production of butanol carboxydotrophic strains. In this study, 11 carboxydotrophic strains were exposed to increasing n-butanol concentrations (1–3% vol/vol) to determine their effect on growth. Butanol production by the strains was quantified and the identity of the strains was elucidated using 16S rRNA sequencing. The carboxydotrophic strains possessed inherent tolerance to butanol and tolerated up to 3% n-butanol. Among the 11 strains, T1-16, M2-32 and M3-28 were the most tolerant to butanol. The 16S rRNA gene sequence of these strains was similar (99% nucleotide similarity) to the butanol-tolerant strains Bacillus licheniformis YP1A, Pediococcus acidilacti IMUA20068 and Enterococcus faecium IMAU60169, respectively. The carboxydotrophic strains screened in this study have two distinct features: (1) high tolerance to butanol and (2) natural production of low concentration of butanol from CO, which distinguish them from other screened butanol-tolerant strains. The butanol tolerance of these carboxydotrophic strains makes them ideal for genetic studies, particularly the molecular mechanisms that enable them to survive such hostile environmental conditions and the identification of genes that confer tolerance to butanol.
This book encompasses the most updated and recent account of research and implementation of Micro... more This book encompasses the most updated and recent account of research and implementation of Microbial Electrochemical Technologies (METs) from pioneers and experienced researchers in the field who have been working on the interface between electrochemistry and microbiology/biotechnology for many years. It provides a holistic view of the METs, detailing the functional mechanisms, operational configurations, influencing factors governing the reaction process and integration strategies. The book not only provides historical perspectives of the technology and its evolution over the years but also the most recent examples of up-scaling and near future commercialization, making it a must-read for researchers, students, industry practitioners and science enthusiasts.
This book provides an extensive overview of the current research worldwide on the use of extremop... more This book provides an extensive overview of the current research worldwide on the use of extremophiles in the biosynthesis of metal nanoparticles and their applications. In view of the tremendous industrial potential of producing nanoparticles from extremophiles, the chapter will shed light in the specifics of fermentation media and recovery of nanoparticles from microbiological process using standard microorganisms. Discussions on limitations and challenges further outline the future of extremophilic-mediated technology.
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outline the future of extremophilic-mediated technology.