Ashraf Essa
Fayoum University, Botany, Faculty Member
- Ashraf Essa is a Professor of Microbiology at Fayoum University (Egypt) where he has been a faculty member since 1991... moreAshraf Essa is a Professor of Microbiology at Fayoum University (Egypt) where he has been a faculty member since 1991. At the moment, he is Associate Professor of Microbiology at Jazan University (Saudi Arabia) since 2013. Dr. Essa completed his Ph.D. at Birmingham University (United Kingdom) and his M.Sc at Cairo University (Egypt). He has supervised 2 PhD students and 7 MSc students at Fayoum University (Egypt) meanwhile he is supervising 2 MSc students at Jazan University (Saudi Arabia). He has over 45 scientific papers and projects either presented or published. Dr. Essa is an internationally recognized expert in many areas including molecular microbiology, environmental microbiology, heavy metals bioremediation and biological treatment of wastewater. His research interests lie in the area of plant microbe interaction where plant growth promoting rhizobacteria are used to ameliorate the biotic and abiotic stress on plants.edit
Cyanobacteria are a diverse group of prokaryotes that are spread worldwide. They improve the growth and development of the plants they share their vicinity via releasing various biologically active substances. The effect of the exudates... more
Cyanobacteria are a diverse group of prokaryotes that are spread worldwide. They improve the growth and development of the plants they share their vicinity via releasing various biologically active substances. The effect of the exudates of the cyanobacterial strains; Anabaena oryzae, Nostoc ellipsosporum and Synechococcus sp. on the percent of seed germination and the seedling growth criteria of Sorghum durra and Helianthus annuus was investigated in this study. A marked promotion in the seed germination of Sorghum durra was recorded with Anabaena oryzae and Synechococcus sp. while the three culture filtrates demonstrated a negative consequence with Helianthus annuus. At the same time, the seedling growth criteria of the treated plants were highly significantly enhanced especially with Anabaena oryzae. Also, A clear augmentation in the activity of the antioxidant enzymes; catalase, peroxidase and polyphenol oxidase was recorded in the treated plants. Analysis of Anabaena oryzae exud...
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Domestic wastewater is considered a favorable environment for the survival of broad arrays of microorganisms. The current study aimed to characterize the bacteria isolated from two domestic wastewater treatment plants in Jazan, KSA.... more
Domestic wastewater is considered a favorable environment for the survival of broad arrays of microorganisms. The current study aimed to characterize the bacteria isolated from two domestic wastewater treatment plants in Jazan, KSA. Morphological and biochemical tests were used to identify the bacterial isolates. Moreover, the antibiotic susceptibility pattern of the bacteria isolates was studied using disc diffusion method. The enteric Gram-negative Enterobacteriaceae were identified as Citrobacter freundii, Pantoea sp., Serratia liquefaciens, Serratia odorifera, Proteus vulgaris, Rahnella aquatilis, Enterobacter sp., Escherichia coli, and Enterobacter cloacae. Simultaneously, non-enteric Gram-negative bacilli were identified as Sphingomonas paucimobilis, Pseudomonas putida, Pseudomonas aeruginosa, Aeromonas sobria, Chryseomonas luteola, and Pasteurella aerogenes. Also, the Gram-positive isolates were identified as Staphylococcus xylosus, Kocuria kristinae and Staphylococcus epidermidis. At the same time, a high level of resistance against Ampicillin/Sulbactam (94.5%) was observed while the recorded percentage of resistance against trimethoprime/sulphamethoxoazole, ticarcillin, imipenen, piperacillin, colistin, cefoxitin and cefepime were 67%, 62%, 22.2%, 33.3%, 22.2%, 83.3% and 38.9% respectively. This study highlighted the existence of multiple antibiotic resistant strains in the tested sewage wastewater that could be attributed to the disproportionate use of antibiotics for human and animal diseases.
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Microorganisms can modify the chemical and physical characters of metals leading to an alteration in their speciation, mobility, and toxicity. Aqueous heavy metals solutions (Hg, Cd, Pb, Ag, Cu, and Zn) were treated with the volatile... more
Microorganisms can modify the chemical and physical characters of metals leading to an alteration in their speciation, mobility, and toxicity. Aqueous heavy metals solutions (Hg, Cd, Pb, Ag, Cu, and Zn) were treated with the volatile metabolic products (VMPs) of Escherichia coli Z3 for 24 h using aerobic bioreactor. The effect of the metals treated with VMPs in comparison to the untreated metals on the growth of E. coli S1 and Staphylococcus aureus S2 (local isolates) was examined. Moreover, the toxic properties of the treated and untreated metals were monitored using minimum inhibitory concentration assay. A marked reduction of the treated metals toxicity was recorded in comparison to the untreated metals. Scanning electron microscopy and energy dispersive X-ray analysis revealed the formation of metal particles in the treated metal solutions. In addition to heavy metals at variable ratios, these particles consisted of carbon, oxygen, sulfur, nitrogen elements. The inhibition of me...
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Soil salinity has a great impact on decreasing yield potentials of the cultivated crops. The effect of presoaking Zea mays grains in the crude extract of the halotolerant alga Dunaliella bardawil on growth and some metabolic activities of... more
Soil salinity has a great impact on decreasing yield potentials of the cultivated crops. The effect of presoaking Zea mays grains in the crude extract of the halotolerant alga Dunaliella bardawil on growth and some metabolic activities of salinized plants was investigated in this study. The Pre-soaking treatment demonstrated a highly significant enhancement in the percentage of seed germination. Moreover, the growth parameters of the pretreated plants were improved at hyposalinity stress conditions comparing with untreated ones. A huge augmentation in the soluble carbohydrates, polyols, free amino acids and proline contents was recorded with the pretreated plants at hypersaline stress conditions. GC-MS analysis identified some bioactive molecules in the algal extract such as nicotinamide, xanthine, dihydroxyphenylglycol and linalool that could potentially participate in the alleviation of the salinity stress. Abstract Asian Journal of Biological and Life Sciences Original Research
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ABSTRACT Abstract The inhabitation of microorganisms and their subsequent interaction with mineral matrix of the stone substrate under varied environmental conditions encourages deterioration of stones leading to the loss of strength,... more
ABSTRACT Abstract The inhabitation of microorganisms and their subsequent interaction with mineral matrix of the stone substrate under varied environmental conditions encourages deterioration of stones leading to the loss of strength, durability and aesthetic. This study highlighted the synthesis of nanosilver particles (AgNPs) using the biogenic volatiles of the bacterial strain Nesterenkonia halobia. The antimicrobial activities of AgNPs were evaluated against the gram positive bacterial strain Streptomyces parvullus and fungal strain Apergillus niger. Furthermore, the silver particles were mixed with two types of consolidation polymers and were used to coat the external surfaces of sandstone and limestone blocks. The stones treated with silicon polymer loaded with AgNPs showed an elevated antimicrobial potentiality against A. niger and S. parvullus. Scan electron microscope (SEM) and electron dispersive X-ray spectroscopy (EDX) analysis of treated stones demonstrated the existence of nano-composite structures containing the elemental silver. Polymers functionalized with AgNPs can be used not only as potent biocides but also for the consolidation of the historic monuments and artifacts. Keywords Biogenic volatiles; Nanosilver; Antibacterial; Antifungal; Polymers
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This study investigated the effect of some cyanobacterial exudates on the level of sex hormones in a mammalian model and to identify the molecules that could act as endocrine disruptor. In this study, the cytotoxicity of purified exudates... more
This study investigated the effect of some cyanobacterial exudates on the level of sex hormones in a mammalian model and to identify the molecules that could act as endocrine disruptor. In this study, the cytotoxicity of purified exudates of some axenic cyanobacterial cultures (Nostoc ellipsosporum, Nostoc muscorum, Anabaena oryzae & Anabaena. sp.) was evaluated against normal melanocyte cell line (HFB4). The intraperitoneal injection of the cyanobacterial exudates demonstrated a marked disturbance in the serum level of testosterone, progesterone, follicular stimulating hormone (FSH) and luteinizing hormone (LH) of male mice. GC-MS and LC-MS/MS analysis showed the presence of some sterol-like compounds in the cyanobacterial filtrates. This work demonstrated that the nontoxic cyanobacterial species have the ability to produce some bioactive compounds into their surroundings that can disrupt the mammalian reproductive hormones. The cyanobacterial extracellular bioactive molecules can affect on the production of the sex hormones via positive and negative feedback and may be a risk to human beings.
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Resistance to Cr(VI) is usually associated with its cellular exclusion, precluding enrichment techniques for the isolation of organisms accumulating Cr(VI) via bioreduction to insoluble Cr(III). A technique was developed to screen for... more
Resistance to Cr(VI) is usually associated with its cellular exclusion, precluding enrichment techniques for the isolation of organisms accumulating Cr(VI) via bioreduction to insoluble Cr(III). A technique was developed to screen for potential Cr(VI) reduction in approx. 2000 isolates from a coastal environment, based on the non-specific reduction of selenite and tellurite to Se0 and Te0, and reduction of tetrazolium blue to insoluble blue formazan. The most promising strains were further screened in liquid culture, giving three, which were identified by 16S rRNA sequence analysis as Bacillus pumilus, Exiguobacterium aurantiacum and Pseudomonas synxantha, all of which reduced 100 microM Cr(VI) anaerobically, without growth. The respective removal of Cr(VI) was 90% and 80% by B. pumilus and E. aurantiacum after 48 h and 80% and by P. synxantha after 192 h. With the gram positive strains Cr(VI) promoted loss of flagella and, in the case of B. pumilus, lysis of some cells, but Cr was deposited as an exocellular precipitate which was identified as containing Cr and P using energy dispersive X-ray microanalysis (EDAX). This prompted the testing of Citrobacter sp. N14 (subsequently re-assigned by 16S rRNA sequence analysis and biochemical studies as a strain of Serratia) which bioprecipitates metal cation phosphates via enzymatically-liberated phosphate. This strain reduced Cr(VI) at a rate comparable to that of P. synxantha but Cr(III) was not bioprecipitated where La(III) was removed as LaPO4, even though a similar amount of phosphate was produced in the presence of Cr(III). Since B. pumilus removed most of the Cr(VI), with the formation of cell-bound CrPO4 implicated, this suggests that this strain could have future bioprocess potential.
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Mercury is one of the most toxic heavy metals, and has significant industrial and agricultural uses. These uses have led to severe localized mercury pollution. Mercury volatilization after its reduction to the metallic form by... more
Mercury is one of the most toxic heavy metals, and has significant industrial and agricultural uses. These uses have led to severe localized mercury pollution. Mercury volatilization after its reduction to the metallic form by mercury-resistant bacteria has been reported as a mechanism for mercury bioremediation [Brunke, Deckwer, Frischmuth, Horn, Lunsdorf, Rhode, Rohricht, Timmis and Weppen (1993) FEMS Microbiol. Rev. 11, 145–152; von Canstein, Timmis, Deckwer and Wagner-Dobler (1999) Appl. Environ. Microbiol. 65, 5279–5284]. The reduction/volatilization system requires to be studied further, in order to eliminate the escape of the metallic mercury into the environment. Recently we have demonstrated three different mechanisms for mercury detoxification in one organism, Klebsiella pneumoniae M426, which may increase the capture efficiency of mercury.
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Research Interests: Kinetics, Bioremediation, Biology, Medicine, Multidisciplinary, and 15 moreChemical Kinetics, Biological Sciences, Biodegradation, Insecticides, Soil contamination, Pseudomonas, Sterilization, Soil Microbiology, Contaminated soil, Serratia marcescens, Microbial Activity, Serratia, Diazinon, Carbon Source, and Rate Constant
Biorem ediation of the ne matici de oxa my l by Enterobacter ludwigii isolated from agricultural wa stewater ABSTRACT: O xam yl is an important carbam at e nem aticide that is us ed f or the contr ol of nemat odes i n many economic cr ops... more
Biorem ediation of the ne matici de oxa my l by Enterobacter ludwigii isolated from agricultural wa stewater ABSTRACT: O xam yl is an important carbam at e nem aticide that is us ed f or the contr ol of nemat odes i n many economic cr ops i n Eg ypt. It is char act erized by high ac ut e t oxicit y t o mammals and aq uatic organisms. Microbial degradation is the m ain approac h c ontrolling the environment al cont amination with oxam yl. In t his current s tud y, using e nrichm ent tec hnique, oxam yl degrading bact erium w as isolat ed from agricult ural drainage ditches of oxam yl-tr eat ed fields (Fayoum , Eg ypt). The isolat ed bact erium w as identified as Ent erobact er ludwi gii based on the biochemic al c har act erizati on and 16S rDN A gene s equenci ng. A n axenic cult ure of E. ludwigii was grow n i n mi nimum s alt m edium enric hed wit h oxam yl as s ole carbon and nitrogen sourc e. Mor eov er, t he f act ors aff ecti ng on oxam yl d egradati on wer e inves tigat ed. T he maxim um c apability of oxam yl d egradati on w as ac hiev ed at 200 ppm of oxam yl wit hin 6 days at pH v alue 7.0 and temperatur e 37°C. In c onclusi on, this st ud y clarified t he not able c apabilit y of E. ludwigii for the d egradati on of oxam yl fr om contami nated agricultur al was tew at er.
ABSTRACT Atrazine is one of the most environmentally prevalent s-triazine groups of herbicides that inhibit photosynthesis of broadleaf and grassy weeds. Degradation time of this compound is about 200 days and is frequently found as... more
ABSTRACT Atrazine is one of the most environmentally prevalent s-triazine groups of herbicides that inhibit photosynthesis of broadleaf and grassy weeds. Degradation time of this compound is about 200 days and is frequently found as contaminant in ground water. In the present study, atrazine degrading bacterium was isolated from agricultural drainage ditches (Fayoum, Egypt) by enrichment technique. Based on morphological, biochemical and 16S rDNA gene sequencing, this bacterium was identified as Ochrobactrum oryzae. A pure culture of O. oryzae were grown in minimum media supplemented with atrazine as sole carbon and nitrogen source. The influence of atrazine concentration as well as temperature and pH on the bacterial growth and rate of atrazine degradation was investigated. The maximum capability of atrazine degradation (83.5%) was achieved at concentration 400 ppm of atrazine within 9 days at pH value 9.0 and temperature 30°C. Therefore, O. oryzae can be used efficiently for the environmental cleanup of agricultural wastewater contaminated with high concentrations of atrazine.
Application of cyanobacteria as biofertilizer has a beneficial effect on crop growth and productivity. The extracts of three cyanobacterial isolates (Anabaena oryzae, Nostoc ellipsosporum & Synechococcus sp.) were used to investigate... more
Application of cyanobacteria as biofertilizer has a beneficial effect on crop growth and productivity. The extracts of three cyanobacterial isolates (Anabaena oryzae, Nostoc ellipsosporum & Synechococcus sp.) were used to investigate their effect on the percent of seed germination and the seedling growth criteria of two crop plants (Sorghum durra and Helianthus annus). The application of various concentrations of the cyanobacterial extracts induced a highly significant stimulatory effect on the percentage of seed germination as well as seedling growth parameters of the tested plants. A clear enhancement in the activity of some antioxidant enzymes was recorded. The growth enhancement of the pretreated seeds was attributed to the presence of auxin and gibberellin in cyanobacterial extract.
A mixed cyanobacterial population consisting of Anabaena oryzae, Nostoc ellipsosporum, Calothrix castellii, Tolypothrix ceytonica & Synechococcus sp. was used to study the effect of malathion, an organophosphorus insecticide, on the... more
A mixed cyanobacterial population consisting of Anabaena oryzae, Nostoc ellipsosporum, Calothrix castellii, Tolypothrix ceytonica & Synechococcus sp. was used to study the effect of malathion, an organophosphorus insecticide, on the growth and the diversity of the algal group structure. A sharp decrease in the growth of the algal population was observed by increasing the concentration of malathion. Amongst them A. oryzae tolerated high concentrations of this compound. Moreover, A. oryzae overtopped the other strains even in presence and absence of malathion. The other strains were more sensitive and they completely vanished from the algal population under higher concentrations of the insecticide (300–400 ppm). A unialgal culture of A. oryzae was further subjected to grow under N-limitation and P-limitation in absence and presence of malathion (100 ppm). A marked elevation in the chlorophyll "a", protein contents and the percentage of heterocystous cells of A. oryzae was re...
Atrazine is one of the most environmentally prevalent s-triazine groups of herbicides that inhibit photosynthesis of broadleaf and grassy weeds. Degradation time of this compound is about 200 days and is frequently found as contaminant in... more
Atrazine is one of the most environmentally prevalent s-triazine groups of herbicides that inhibit photosynthesis of broadleaf and grassy weeds. Degradation time of this compound is about 200 days and is frequently found as contaminant in ground water. In the present study, atrazine degrading bacterium was isolated from agricultural drainage ditches (Fayoum, Egypt) by enrichment technique. Based on morphological, biochemical and 16S rDNA gene sequencing, this bacterium was identified as Ochrobactrum oryzae. A pure culture of O. oryzae were grown in minimum media supplemented with atrazine as sole carbon and nitrogen source. The influence of atrazine concentration as well as temperature and pH on the bacterial growth and rate of atrazine degradation was investigated. The maximum capability of atrazine degradation (83.5%) was achieved at concentration 400 ppm of atrazine within 9 days at pH value 9.0 and temperature 30°C. Therefore, O. oryzae can be used efficiently for the environmen...
The biosynthesis of metal nanoparticles has recently drawn a great deal of attention because of the necessity to develop inexpensive, eco-friendly and efficient synthesis techniques. This study highlighted the synthesis of nanocopper... more
The biosynthesis of metal nanoparticles has recently drawn a great deal of attention because of the necessity to develop inexpensive, eco-friendly and efficient synthesis techniques. This study highlighted the synthesis of nanocopper particles (CuNPs) of dimensions 10–50 nm using the headspace gases of the bacterial culture Nesterenkonia halobia. The antimicrobial activities of CuNPs were evaluated against the bacterial strains Bacillus brevis and Staphylococcus aureus and fungal strains Penicillium stolenferum and Apergillus niger. Moreover, the copper particles (60 mg/L) were mixed with consolidation polymers and were used to coat the outer surfaces of sandstone and limestone blocks. The treated stones showed a prominent antimicrobial activity against A. niger and S. parvullus. Scan electron microscope (SEM) and electron dispersive X-ray spectroscopy (EDX) analysis of treated stones demonstrated the existence of nanocomposite structures containing the elemental copper.
Three cyanobacterial isolates (Spirulina platensis, Nostoc muscorum, and Anabaena oryzae) were used individually or as a mixed culture to precipitate some heavy metals (Hg 2+ , Cd 2+ , Cu 2+ and Pb 2+) out of their solutions through using... more
Three cyanobacterial isolates (Spirulina platensis, Nostoc muscorum, and Anabaena oryzae) were used individually or as a mixed culture to precipitate some heavy metals (Hg 2+ , Cd 2+ , Cu 2+ and Pb 2+) out of their solutions through using the culture biogas produced during their aerobic growth in a batch bioreactor. Variable capabilities of metal bioprecipitation were recorded by the three algal isolates. FT-IR studies showed the existence of –OH groups in the metal precipitate produced by the algal isolates while –NH groups were identified only in the metal precipitates produced by N. muscorum, and A. oryzae. In conclusion, this study highlighted a novel approach for heavy metals bioremediation through the transformation of these metals into nitrogen complexes and/or hydroxide complexes via using the culture biogas produced by some cyanobacterial species.
The effect of presoaking maize grains in the algal crude extract of Dunaliella bardawili on growth and some metabolic activities of salinized plants was investigated in this study. Presoaked maize grains in the algal extract had... more
The effect of presoaking maize grains in the algal crude extract of Dunaliella bardawili on growth and some metabolic activities of salinized plants was investigated in this study. Presoaked maize grains in the algal extract had progressively alleviated the repression effect of NaCl stress up to 12 mdSm-1. Moreover the treated plants recorded a highly significant increase in the soluble carbohydrates, polyols, free amino acids and proline contents compared with the untreated plants. The algal extract analysis showed the presence of high concentrations of carotenoids and proline.
Mercury resistance is found in many genera of bacteria. Common amongst enterobacteria are transposons related to Tn21, which is both mercuric ion- and streptomycin-/spectinomycin-and sulphonamide-resistant. Other Tn21-related transposons... more
Mercury resistance is found in many genera of bacteria. Common amongst enterobacteria are transposons related to Tn21, which is both mercuric ion- and streptomycin-/spectinomycin-and sulphonamide-resistant. Other Tn21-related transposons often have different antibiotic resistances compared with Tn21, but share many non-antibiotic-resistance genes with it. In this article we discuss possible mechanisms for the evolution of Tn21 and related genetic elements.
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Excessive exposure to heavy metals is known to induce deleterious effects on health. The monitoring of heavy metals in sewage is important for examining environmental pollution induced by treated sewage effluent (TSE). In the current... more
Excessive exposure to heavy metals is known to induce deleterious effects on health. The monitoring of heavy metals in sewage is important for examining environmental pollution induced by treated sewage effluent (TSE). In the current investigation, heavy metals concentrations of TSE of two sewage treatment plants in the Jazan region of KSA were monitored using a Perkin Elmer Optima 7000 DV inductively coupled plasma optical emission spectrometer (ICP-OES). The heavy metals concentrations were below the permissible limit, according to the Ministry of Water and Electricity (MWE) standards of Saudi authorities, except for magnesium and mercury. TSE from the treatment plants was subjected to additional treatment using the volatile organic compounds (VOCs) of the bacterial strain Citrobacter freundii. A marked reduction of the heavy metals concentrations of the bacterial-treated TSE was recorded. The impact of the bacterial-treated TSE on germination indices of Vigna radiata and Hordeum vulgare was investigated. The seedlings irrigated with the bacterial-treated TSE recorded a clear enhancement of growth parameters. Moreover, the level of accumulated heavy metals in seedlings irrigated with bacterial-treated TSE was reduced compared with those irrigated with untreated TSE. The current study clarified that the level of heavy metals in TSE could be markedly reduced via the application of bacterial VOCs and hence it can be used as a water resource for agricultural purposes.
Microorganisms can modify the chemical and physical characters of metals leading to an alteration in their speciation, mobility, and toxicity. Aqueous heavy metals solutions (Hg, Cd, Pb, Ag, Cu, and Zn) were treated with the volatile... more
Microorganisms can modify the chemical and physical characters of metals leading to an alteration in their speciation, mobility, and toxicity. Aqueous heavy metals solutions (Hg, Cd, Pb, Ag, Cu, and Zn) were treated with the volatile metabolic products (VMPs) of Escherichia coli Z3 for 24 h using aerobic bioreactor. The effect of the metals treated with VMPs in comparison to the untreated metals on the growth of E. coli S1 and Staphylococcus aureus S2 (local isolates) was examined. Moreover, the toxic properties of the treated and untreated metals were monitored using minimum inhibitory concentration assay. A marked reduction of the treated metals toxicity was recorded in comparison to the untreated metals. Scanning electron microscopy and energy dispersive X-ray analysis revealed the formation of metal particles in the treated metal solutions. In addition to heavy metals at variable ratios, these particles consisted of carbon, oxygen, sulfur, nitrogen elements. The inhibition of metal toxicity was attributed to the existence of ammonia, hydrogen sulfide, and carbon dioxide in the VMPs of E. coli Z3 culture that might responsible for the transformation of soluble metal ions into metal complexes. This study clarified the capability of E. coli Z3 for indirect detoxification of heavy metals via the immobilization of metal ions into biologically unavailable species. K E Y W O R D S chelators, detoxification, Escherichia coli, extracellular, heavy metals
Domestic wastewater is considered a favourable environment for the survival of broad arrays of microorganisms. The current study aimed to characterize the bacteria isolated from two domestic wastewater treatment plants in Jazan, KSA.... more
Domestic wastewater is considered a favourable environment for the survival of broad arrays of microorganisms. The current study aimed to characterize the bacteria isolated from two domestic wastewater treatment plants in Jazan, KSA. Morphological and biochemical tests were used to identify the bacterial isolates. Moreover, the antibiotic susceptibility pattern of the bacteria isolates was studied using disc diffusion method. The enteric Gram-negative Enterobacteriaceae isolates were identified as Citrobacter freundii, Pantoea sp., Serratia liquefaciens, Serratia odorifera, Proteus vulgaris, Rahnella aquatilis, Enterobacter sp., Escherichia coli, and Enterobacter cloacae. Simultaneously, non-enteric Gram-negative bacilli were identified as Sphingomonas paucimobilis, Pseudomonas putida, Pseudomonas aeruginosa, Aeromonas sobria, Chryseomonas luteola, and Pasteurella aerogenes. Also, the Gram-positive isolates were identified as Staphylococcus xylosus, Kocuria kristinae and Staphylococcus epidermidis. At the same time, a high level of resistance against Ampicillin/Sulbactam (94.5%) was observed while the recorded percentage of resistance against trimethoprim/sulphamethoxoazole, ticarcillin, imipenen, piperacillin, colistin, cefoxitin and cefepime were 67%, 62%, 22.2%, 33.3%, 22.2%, 83.3%, and 38.9%, respectively. This study highlighted the existence of multiple antibiotic resistant strains in the tested sewage wastewater that could be attributed to the disproportionate use of antibiotics for human and animal diseases.
This study was conducted to screen the antioxidant and antimicrobial activities of the methanolic extracts of ten types of edible seeds that are used commonly as food additives and beverages. Contents of flavonoids, polyphenols and... more
This study was conducted to screen the antioxidant and antimicrobial activities of the methanolic extracts of ten types of edible seeds that are used commonly as food additives and beverages. Contents of flavonoids, polyphenols and ascorbate as well as total antioxidant activity of extracts were analyzed. At the same time, the antimicrobial activities were performed against different bacterial and fungal strains. Extracts of Cuminum cyminum and Pimpinella anisum showed the highest values of polyphenols while elevated levels of flavonoids and ascorbic acid were recorded in Linum usitatissimum, Piper nigrum, Pimpinella anisum and Portulaca oleraceae extracts. The tested extracts demonstrated a high capability to scavenge DPPH free radicals at levels above 89%. Furthermore, seed extracts of Piper nigrum, Brassica alba, recorded a remarkable antibacterial activities against wide range of bacterial strains. Simultaneously, the seed extracts of Coriandrum sativum, Cuminum cyminum, Piper nigrum and Nigella sativa recorded high potentiality to inhibit the growth of various fungal strains. It can be concluded that Cuminum cyminum, Linum usitatissimum, Piper nigrum, Pimpinella anisum, Coriandrum sativum and Nigella sativa seeds could have beneficial impacts on human health as a result of their high antioxidant and antimicrobial activities.
The capability of thermophilic microorganisms to flourish at high temperatures makes their enzyme systems ideal for various biotechnological applications. Based on the proteolytic and amylolytic activities, two thermophilic bacteria were... more
The capability of thermophilic microorganisms to flourish at high temperatures makes their enzyme systems ideal for various biotechnological applications. Based on the proteolytic and amylolytic activities, two thermophilic bacteria were isolated from hot springs in Jazan, Saudi Arabia. The antibiotic and heavy metals susceptibility patterns of the bacterial isolates were performed. According to the metabolic fingerprint, the bacterial isolates were identified as Brevibacterium linens and Bacillus subtilis. Moreover, the impact of temperature, substrate concentration, and some metal ions on the production of proteases and amylases from the bacterial strains was investigated. The maximum protease production was achieved at 50°C while the greatest amylase production was recorded at 30°C for both strains at a constant pH of 7.5. The highest enzyme production was recorded at 5% skimmed milk for protease of B. linens and 10% for B. subtilis while 0.6% starch was the optimum substrate concentration of amylase production of the two strains. Furthermore, Ca 2+ showed a simulative influence on protease production from the two strains whereas Mg 2+ and Mn 2+ demonstrated minor effect. On the other hand, Ca 2+ , Mg 2+ and Mn 2+ demonstrated a positive effect on the amylase production from both strains.
The antifungal potentialities of three endophytic bacterial strains, Stenotrophomonas maltophila H8 (Xanthomonadales: Xanthomonadaceae), Pseudomonas aeruginosa H40 (Pseudomonadales: Pseudomonadaceae) and Bacillus subtilis H18 (Bacillales:... more
The antifungal potentialities of three endophytic bacterial strains, Stenotrophomonas maltophila H8 (Xanthomonadales: Xanthomonadaceae), Pseudomonas aeruginosa H40 (Pseudomonadales: Pseudomonadaceae) and Bacillus subtilis H18 (Bacillales: Bacillaceae) were evaluated against the phytopathogenic fungus Rhizoctonia solani in cotton seedlings under greenhouse conditions. The bacterial strains were applied as a soil drench or talc-based bioformulation in R. solani-infested soil and non-infested soil. Results indicated that the soil drench treatment was more efficient than talc-based bioformulation. A significant increase of seed emergence and seedling survival with a clear reduction of disease severity was achieved with the endophytic bacterial treatments. At the same time, the fresh weight, dry weight, shoot length and root length of the treated plants were markedly enhanced. Moreover, there was an apparent induction of the antioxidant enzymes (peroxidase, polyphenol oxidase and catalase) of the treated seedlings. Gas chromatography-mass spectrometry revealed the presence of various bioactive compounds in the bacterial supernatant. The antagonistic activity of the bacterial strains against R. solani was attributed to their capability to produce a broad spectrum of antifungal compounds in addition to bioactive molecules that can trigger the systemic resistance in the infected seedlings. ARTICLE HISTORY
Biorem ediation of the ne matici de oxa my l by Enterobacter ludwigii isolated from agricultural wa stewater ABSTRACT: O xam yl is an important carbam at e nem aticide that is us ed f or the contr ol of nemat odes i n many economic cr ops... more
Biorem ediation of the ne matici de oxa my l by Enterobacter ludwigii isolated from agricultural wa stewater ABSTRACT: O xam yl is an important carbam at e nem aticide that is us ed f or the contr ol of nemat odes i n many economic cr ops i n Eg ypt. It is char act erized by high ac ut e t oxicit y t o mammals and aq uatic organisms. Microbial degradation is the m ain approac h c ontrolling the environment al cont amination with oxam yl. In t his current s tud y, using e nrichm ent tec hnique, oxam yl degrading bact erium w as isolat ed from agricult ural drainage ditches of oxam yl-tr eat ed fields (Fayoum , Eg ypt). The isolat ed bact erium w as identified as Ent erobact er ludwi gii based on the biochemic al c har act erizati on and 16S rDN A gene s equenci ng. A n axenic cult ure of E. ludwigii was grow n i n mi nimum s alt m edium enric hed wit h oxam yl as s ole carbon and nitrogen sourc e. Mor eov er, t he f act ors aff ecti ng on oxam yl d egradati on wer e inves tigat ed. T he maxim um c apability of oxam yl d egradati on w as ac hiev ed at 200 ppm of oxam yl wit hin 6 days at pH v alue 7.0 and temperatur e 37°C. In c onclusi on, this st ud y clarified t he not able c apabilit y of E. ludwigii for the d egradati on of oxam yl fr om contami nated agricultur al was tew at er.
Background: Biodeterioration of historic monuments and stone works by microorganisms takes place as a result of biofilm production and secretion of organic compounds that negatively affect on the stone matrix. Methods: Copper... more
Background: Biodeterioration of historic monuments and stone works by microorganisms takes place as a result of biofilm production and secretion of organic compounds that negatively affect on the stone matrix. Methods: Copper nanoparticles (CuNPs) were prepared biologically using the headspace gases generated by the bacterial culture Escherichia coli Z1. The antimicrobial activity of CuNPs was evaluated against the bacterial strains Bacillus subtilis, Micrococcus luteus, Streptomyces parvulus, Escherichia coli, Pseudomonas aeruginosa as well as some fungal strains Aspergillus niger, Aspergillus flavus, Penicillium chrysogenum, Fusarium solani and Alternaria solani.
IAZINON is an organophosphorous insecticide that is ……….commonly used to control various agricultural and household pests and is frequently found as contaminant in water bodies. In the present study, a diazinon degrading bacterium was... more
IAZINON is an organophosphorous insecticide that is ……….commonly used to control various agricultural and household pests and is frequently found as contaminant in water bodies. In the present study, a diazinon degrading bacterium was isolated from agricultural drainage ditches (Fayoum, Egypt) by enrichment technique. Based on morphological, biochemical and 16S rDNA gene sequencing, it was identified as Pseudomonas aeruginosa. A pure culture of P. aeruginosa was grown in minimal medium supplemented with diazinon as sole carbon source. The influence of diazinon concentration, temperature and pH on the bacterial growth and rate of diazinon degradation was investigated. The maximum capability of diazinon degradation (83.6 %) was achieved at concentration 400 ppm of diazinon at pH value 7.0 and temperature 30°C within 14 days. Therefore, P. aeruginosa can be used efficiently for the environmental cleanup of agricultural wastewater contaminated with high levels of diazinon.
Active resistance to the mercuric ion is widely distributed in environmental microbes and results from the action of mercuric reductase. Five mercury resistant bacteria: Escherichia coli Z1, E. coli Z3, Pseudomonas putida Z2, Serratia... more
Active resistance to the mercuric ion is widely distributed in environmental microbes and results from the action of mercuric reductase. Five mercury resistant bacteria: Escherichia coli Z1, E. coli Z3, Pseudomonas putida Z2, Serratia marcescens Z4 and Xanthomonas sp. Z5 were isolated and identified from sludge sample. The presence of mercury resistance determinants was screened by polymerase chain reaction (PCR) using merA-specific primers. Based on the analysis of merA amplicons, high similarity was recorded between the merA region of the strains P. putida Z2 and Xanthomonas sp. Z5 with those of Tn5053; while the merA of E. coli Z1 was analogous to those of Tn21. In case of the bacterial strains E. coli Z3 and S. marcescens Z4 a great matching was obtained between their merA and those of Tn5036. The effect of mercury stress upon the structure of mercury reducing biofilm at the species level and the type of mercury resistance determinants was studied in a continuous bioreactor. Community analysis suggested that the bacterial strain E. coli Z3 containing Tn5036-like determinant is well adapted strain that tolerated elevated levels of mercury whereas the other strains showed a less fitness under these extreme conditions.
Heavy metals pollution is nowadays one of the most important environmental concerns. This paper illustrates the employment of the biogenic volatile compounds generated during the aerobic growth of activated sludge on raw domestic... more
Heavy metals pollution is nowadays one of the most important environmental concerns. This paper illustrates the employment of the biogenic volatile compounds generated during the aerobic growth of activated sludge on raw domestic wastewater for heavy metals removal. Most of the tested metals even as individual or mixed metal species (Co, Cu, Cd, Fe, Hg, Ni, Mn, Pb and Zn) were potentially transformed into insoluble precipitates and then separated out of their solutions. The Fourier-transform infrared (FTIR) analysis has identified some organosulfur groups (thiol, disulfide and thiocarbonyl), in addition to amine group in the metal precipitates. This study highlighted the application of the microbial volatile metabolites for heavy metals bioremediation in a powerful, cost effective and eco-friendly bioprocess.
Three cyanobacterial isolates (Spirulina platensis, Nostoc muscorum, and Anabaena oryzae) were used individually or as a mixed culture to precipitate some heavy metals (Hg 2+ , Cd 2+ , Cu 2+ and Pb 2+) out of their solutions through using... more
Three cyanobacterial isolates (Spirulina platensis, Nostoc muscorum, and Anabaena oryzae) were used individually or as a mixed culture to precipitate some heavy metals (Hg 2+ , Cd 2+ , Cu 2+ and Pb 2+) out of their solutions through using the culture biogas produced during their aerobic growth in a batch bioreactor. Variable capabilities of metal bioprecipitation were recorded by the three algal isolates. FT-IR studies showed the existence of-OH groups in the metal precipitate produced by the algal isolates while-NH groups were identified only in the metal precipitates produced by N. muscorum, and A. oryzae. In conclusion, this study highlighted a novel approach for heavy metals bioremediation through the transformation of these metals into nitrogen complexes and/or hydroxide complexes via using the culture biogas produced by some cyanobacterial species.