Surface colonization allows diatoms, a dominant group of phytoplankton inoceans, to adapt to hars... more Surface colonization allows diatoms, a dominant group of phytoplankton inoceans, to adapt to harsh marine environments while mediating biofoulings to hu-man-made underwater facilities. The regulatory pathways underlying diatom sur-face colonization, which involves morphotype switching in some species, remainmostly unknown. Here, we describe the identification of 61 signaling genes,including G-protein-coupled receptors (GPCRs) and protein kinases, which aredifferentially regulated during surface colonization in the model diatom species,Phaeodactylum tricornutum. We show that the transformation ofP.tricornutumwith constructs expressing individualGPCRgenes induces cells to adopt the sur-face colonization morphology.P.tricornutumcells transformed to expressGPCR1Adisplay 30% more resistance to UV light exposure than their non-biofouling wild-type counterparts, consistent with increased silicification of cellwalls associated with the oval biofouling morphotype. Our results provide amechanistic definition of morphological shifts during surface colonization andidentify candidate target proteins for the screening of eco-friendly, anti-biofouling molecules.
Background Diatoms, which can accumulate large amounts of carotenoids, are a major group of micro... more Background Diatoms, which can accumulate large amounts of carotenoids, are a major group of microalgae and the dominant primary producer in marine environments. Phaeodactylum tricornutum, a model diatom species, acquires little silicon for its growth although silicon is known to contribute to gene regulation and play an important role in diatom intracellular metabolism. In this study, we explored the effects of artificial high-silicate medium (i.e. 3.0 mM sodium metasilicate) and LED illumination conditions on the growth rate and pigment accumulation in P. tricornutum, which is the only known species so far that can grow without silicate. It’s well known that light-emitting diodes (LEDs) as novel illuminants are emerging to be superior monochromatic light sources for algal cultivation with defined and efficient red and blue lights. Results Firstly, we cultivated P. tricornutum in a synthetic medium supplemented with either 0.3 mM or 3.0 mM silicate. The morphology and size of diatom...
Microalgae have been investigated for the photosynthetic production of natural products with indu... more Microalgae have been investigated for the photosynthetic production of natural products with industrial and biomedical applications. Their rapid growth offers an advantage over higher plants, while their complex metabolic capacities allow for the production of various molecules. Despite their potentials, molecular techniques are underdeveloped in microalgae compared to higher plants, fungi, and bacteria. However, recent advances in genome sequencing, strain development, and genome editing technologies, are providing thrust to enhance research on microalgal species that have branched out from several focal model organisms to encompass a great diversity of species. In this review, we highlight the recent, significant advances in microalgal research, with a focus on the development of new resources that can enhance work on model and non-model species.
Diatoms, considered as one of the most diverse and largest groups of algae, can provide the means... more Diatoms, considered as one of the most diverse and largest groups of algae, can provide the means to reach a sustainable production of petrochemical substitutes and bioactive compounds. However, a prerequisite to achieving this goal is to increase the solar-to-biomass conversion efficiency of photosynthesis, which generally remains less than 5% for most photosynthetic organisms. We have developed and implemented a rapid and effective approach, herein referred to as intracellular spectral recompositioning (ISR) of light, which, through absorption of excess blue light and its intracellular emission in the green spectral band, can improve light utilization. We demonstrate that ISR can be used chemogenically, by using lipophilic fluorophores, or biogenically, through the expression of an enhanced green fluorescent protein (eGFP) in the model diatom Phaeodactylum tricornutum. Engineered P. tricornutum cells expressing eGFP achieved 28% higher efficiency in photosynthesis than the parenta...
With the advent of modern biotechnology, microorganisms from diverse lineages have been used to p... more With the advent of modern biotechnology, microorganisms from diverse lineages have been used to produce bio-based feedstocks and bioactive compounds. Many of these compounds are currently commodities of interest, in a variety of markets and their utility warrants investigation into improving their production through strain development. In this review, we address the issue of strain improvement in a group of organisms with strong potential to be productive "cell factories": the photosynthetic microalgae. Microalgae are a diverse group of phytoplankton, involving polyphyletic lineage such as green algae and diatoms that are commonly used in the industry. The photosynthetic microalgae have been under intense investigation recently for their ability to produce commercial compounds using only light, CO₂, and basic nutrients. However, their strain improvement is still a relatively recent area of work that is under development. Importantly, it is only through appropriate engineer...
Through iterative cycles of selection, amplification, and mutagenesis, in vitro selection provide... more Through iterative cycles of selection, amplification, and mutagenesis, in vitro selection provides the ability to isolate molecules of desired properties and function from large pools (libraries) of random molecules with as many as 10(16) distinct species. This review, in recognition of a quarter of century of scientific discoveries made through in vitro selection, starts with a brief overview of the method and its history. It further covers recent developments in in vitro selection with a focus on tools that enhance the capabilities of in vitro selection and its expansion from being purely a nucleic acids selection to that of polypeptides and proteins. In addition, we cover how next generation sequencing and modern biological computational tools are being used to complement in vitro selection experiments. On the very least, sequencing and computational tools can translate the large volume of information associated with in vitro selection experiments to manageable, analyzable, and exploitable information. Finally, in vivo selection is briefly compared and contrasted to in vitro selection to highlight the unique capabilities of each method.
Marine diatoms have recently gained much attention as they are expected to be a promising resourc... more Marine diatoms have recently gained much attention as they are expected to be a promising resource for sustainable production of bioactive compounds such as carotenoids and biofuels as a future clean energy solution. To develop photosynthetic cell factories, it is important to improve diatoms for value-added products. In this study, we utilized UVC radiation to induce mutations in the marine diatom Phaeodactylum tricornutum and screened strains with enhanced accumulation of neutral lipids and carotenoids. Adaptive laboratory evolution (ALE) was also used in parallel to develop altered phenotypic and biological functions in P. tricornutum and it was reported for the first time that ALE was successfully applied on diatoms for the enhancement of growth performance and productivity of value-added carotenoids to date. Liquid chromatography-mass spectrometry (LC-MS) was utilized to study the composition of major pigments in the wild type P. tricornutum, UV mutants and ALE strains. UVC rad...
As a major primary producer in marine environments, diatoms have been considered as promising fee... more As a major primary producer in marine environments, diatoms have been considered as promising feedstocks for their applications in functional foods, bioactive pharmaceuticals, and cosmetics. This review focusses on the biotechnology potential of diatoms for value-added products like carotenoids. The impact of abiotic environmental stresses, such as intensity and quality of incident light, nutrient deficiency and silicon depletion, on diatoms has been examined to determine key factors that affect the growth performance and the accumulation of valuable compounds. Previous studies suggested that adaptive evolution could be an efficient method to improve the diatom productivity of valuable compounds. Light emitting diode (LED)-based photobioreactors were introduced and proposed as a promising new technology for producing quality products from diatoms. Currently available molecular biology tools were also summarized and discussed in relation to their application in the production of caro...
We recently evaluated the relationship between abiotic environmental stresses and lutein biosynth... more We recently evaluated the relationship between abiotic environmental stresses and lutein biosynthesis in the green microalga Dunaliella salina and suggested a rational design of stress-driven adaptive evolution experiments for carotenoids production in microalgae. Here, we summarize our recent findings regarding the biotechnological production of carotenoids from microalgae and outline emerging technology in this field. Carotenoid metabolic pathways are characterized in several representative algal species as they pave the way for biotechnology development. The adaptive evolution strategy is highlighted in connection with enhanced growth rate and carotenoid metabolism. In addition, available genetic modification tools are described, with emphasis on model species. A brief discussion on the role of lights as limiting factors in carotenoid production in microalgae is also included. Overall, our analysis suggests that light-driven metabolism and the photosynthetic efficiency of microal...
ABSTRACT There is a particularly high interest to derive carotenoids such as b-carotene and lutei... more ABSTRACT There is a particularly high interest to derive carotenoids such as b-carotene and lutein from higher plants and algae for the global market. It’s well known that b-carotene can be overproduced in Dunaliella salina in response to stressful light conditions. How- ever, little is known about the effects of light quality on caroten- oid metabolism, e.g. red light and/or blue light with narrow spectra. We have studied the effect of red LED lighting on growth rate and biomass yield and identified the optimal photon flux for D. salina growth. We found that the major carotenoids changed in parallel to the chlorophyll b content and that increas- ing the photon stress of red light alone was not capable of up-regulating carotenoid accumulation due to serious photoda- maging. A pathway proposed based on LC/MS data is consistent with the one proposed for caorotenoid metabolism in Chlamydo- monas reinhardtii. We have found that combining red LED (75%) with blue LED (25%) allowed growth at a higher total photon flux. Long-term iterative stress with additional blue light led to increased b-carotene and lutein accumulation. This appli- cation of adaptive laboratory evolution (ALE) yielded adapted strains of D. salina with increased accumulation of carotenoids under combined blue and red light condition.
Surface colonization allows diatoms, a dominant group of phytoplankton inoceans, to adapt to hars... more Surface colonization allows diatoms, a dominant group of phytoplankton inoceans, to adapt to harsh marine environments while mediating biofoulings to hu-man-made underwater facilities. The regulatory pathways underlying diatom sur-face colonization, which involves morphotype switching in some species, remainmostly unknown. Here, we describe the identification of 61 signaling genes,including G-protein-coupled receptors (GPCRs) and protein kinases, which aredifferentially regulated during surface colonization in the model diatom species,Phaeodactylum tricornutum. We show that the transformation ofP.tricornutumwith constructs expressing individualGPCRgenes induces cells to adopt the sur-face colonization morphology.P.tricornutumcells transformed to expressGPCR1Adisplay 30% more resistance to UV light exposure than their non-biofouling wild-type counterparts, consistent with increased silicification of cellwalls associated with the oval biofouling morphotype. Our results provide amechanistic definition of morphological shifts during surface colonization andidentify candidate target proteins for the screening of eco-friendly, anti-biofouling molecules.
Background Diatoms, which can accumulate large amounts of carotenoids, are a major group of micro... more Background Diatoms, which can accumulate large amounts of carotenoids, are a major group of microalgae and the dominant primary producer in marine environments. Phaeodactylum tricornutum, a model diatom species, acquires little silicon for its growth although silicon is known to contribute to gene regulation and play an important role in diatom intracellular metabolism. In this study, we explored the effects of artificial high-silicate medium (i.e. 3.0 mM sodium metasilicate) and LED illumination conditions on the growth rate and pigment accumulation in P. tricornutum, which is the only known species so far that can grow without silicate. It’s well known that light-emitting diodes (LEDs) as novel illuminants are emerging to be superior monochromatic light sources for algal cultivation with defined and efficient red and blue lights. Results Firstly, we cultivated P. tricornutum in a synthetic medium supplemented with either 0.3 mM or 3.0 mM silicate. The morphology and size of diatom...
Microalgae have been investigated for the photosynthetic production of natural products with indu... more Microalgae have been investigated for the photosynthetic production of natural products with industrial and biomedical applications. Their rapid growth offers an advantage over higher plants, while their complex metabolic capacities allow for the production of various molecules. Despite their potentials, molecular techniques are underdeveloped in microalgae compared to higher plants, fungi, and bacteria. However, recent advances in genome sequencing, strain development, and genome editing technologies, are providing thrust to enhance research on microalgal species that have branched out from several focal model organisms to encompass a great diversity of species. In this review, we highlight the recent, significant advances in microalgal research, with a focus on the development of new resources that can enhance work on model and non-model species.
Diatoms, considered as one of the most diverse and largest groups of algae, can provide the means... more Diatoms, considered as one of the most diverse and largest groups of algae, can provide the means to reach a sustainable production of petrochemical substitutes and bioactive compounds. However, a prerequisite to achieving this goal is to increase the solar-to-biomass conversion efficiency of photosynthesis, which generally remains less than 5% for most photosynthetic organisms. We have developed and implemented a rapid and effective approach, herein referred to as intracellular spectral recompositioning (ISR) of light, which, through absorption of excess blue light and its intracellular emission in the green spectral band, can improve light utilization. We demonstrate that ISR can be used chemogenically, by using lipophilic fluorophores, or biogenically, through the expression of an enhanced green fluorescent protein (eGFP) in the model diatom Phaeodactylum tricornutum. Engineered P. tricornutum cells expressing eGFP achieved 28% higher efficiency in photosynthesis than the parenta...
With the advent of modern biotechnology, microorganisms from diverse lineages have been used to p... more With the advent of modern biotechnology, microorganisms from diverse lineages have been used to produce bio-based feedstocks and bioactive compounds. Many of these compounds are currently commodities of interest, in a variety of markets and their utility warrants investigation into improving their production through strain development. In this review, we address the issue of strain improvement in a group of organisms with strong potential to be productive "cell factories": the photosynthetic microalgae. Microalgae are a diverse group of phytoplankton, involving polyphyletic lineage such as green algae and diatoms that are commonly used in the industry. The photosynthetic microalgae have been under intense investigation recently for their ability to produce commercial compounds using only light, CO₂, and basic nutrients. However, their strain improvement is still a relatively recent area of work that is under development. Importantly, it is only through appropriate engineer...
Through iterative cycles of selection, amplification, and mutagenesis, in vitro selection provide... more Through iterative cycles of selection, amplification, and mutagenesis, in vitro selection provides the ability to isolate molecules of desired properties and function from large pools (libraries) of random molecules with as many as 10(16) distinct species. This review, in recognition of a quarter of century of scientific discoveries made through in vitro selection, starts with a brief overview of the method and its history. It further covers recent developments in in vitro selection with a focus on tools that enhance the capabilities of in vitro selection and its expansion from being purely a nucleic acids selection to that of polypeptides and proteins. In addition, we cover how next generation sequencing and modern biological computational tools are being used to complement in vitro selection experiments. On the very least, sequencing and computational tools can translate the large volume of information associated with in vitro selection experiments to manageable, analyzable, and exploitable information. Finally, in vivo selection is briefly compared and contrasted to in vitro selection to highlight the unique capabilities of each method.
Marine diatoms have recently gained much attention as they are expected to be a promising resourc... more Marine diatoms have recently gained much attention as they are expected to be a promising resource for sustainable production of bioactive compounds such as carotenoids and biofuels as a future clean energy solution. To develop photosynthetic cell factories, it is important to improve diatoms for value-added products. In this study, we utilized UVC radiation to induce mutations in the marine diatom Phaeodactylum tricornutum and screened strains with enhanced accumulation of neutral lipids and carotenoids. Adaptive laboratory evolution (ALE) was also used in parallel to develop altered phenotypic and biological functions in P. tricornutum and it was reported for the first time that ALE was successfully applied on diatoms for the enhancement of growth performance and productivity of value-added carotenoids to date. Liquid chromatography-mass spectrometry (LC-MS) was utilized to study the composition of major pigments in the wild type P. tricornutum, UV mutants and ALE strains. UVC rad...
As a major primary producer in marine environments, diatoms have been considered as promising fee... more As a major primary producer in marine environments, diatoms have been considered as promising feedstocks for their applications in functional foods, bioactive pharmaceuticals, and cosmetics. This review focusses on the biotechnology potential of diatoms for value-added products like carotenoids. The impact of abiotic environmental stresses, such as intensity and quality of incident light, nutrient deficiency and silicon depletion, on diatoms has been examined to determine key factors that affect the growth performance and the accumulation of valuable compounds. Previous studies suggested that adaptive evolution could be an efficient method to improve the diatom productivity of valuable compounds. Light emitting diode (LED)-based photobioreactors were introduced and proposed as a promising new technology for producing quality products from diatoms. Currently available molecular biology tools were also summarized and discussed in relation to their application in the production of caro...
We recently evaluated the relationship between abiotic environmental stresses and lutein biosynth... more We recently evaluated the relationship between abiotic environmental stresses and lutein biosynthesis in the green microalga Dunaliella salina and suggested a rational design of stress-driven adaptive evolution experiments for carotenoids production in microalgae. Here, we summarize our recent findings regarding the biotechnological production of carotenoids from microalgae and outline emerging technology in this field. Carotenoid metabolic pathways are characterized in several representative algal species as they pave the way for biotechnology development. The adaptive evolution strategy is highlighted in connection with enhanced growth rate and carotenoid metabolism. In addition, available genetic modification tools are described, with emphasis on model species. A brief discussion on the role of lights as limiting factors in carotenoid production in microalgae is also included. Overall, our analysis suggests that light-driven metabolism and the photosynthetic efficiency of microal...
ABSTRACT There is a particularly high interest to derive carotenoids such as b-carotene and lutei... more ABSTRACT There is a particularly high interest to derive carotenoids such as b-carotene and lutein from higher plants and algae for the global market. It’s well known that b-carotene can be overproduced in Dunaliella salina in response to stressful light conditions. How- ever, little is known about the effects of light quality on caroten- oid metabolism, e.g. red light and/or blue light with narrow spectra. We have studied the effect of red LED lighting on growth rate and biomass yield and identified the optimal photon flux for D. salina growth. We found that the major carotenoids changed in parallel to the chlorophyll b content and that increas- ing the photon stress of red light alone was not capable of up-regulating carotenoid accumulation due to serious photoda- maging. A pathway proposed based on LC/MS data is consistent with the one proposed for caorotenoid metabolism in Chlamydo- monas reinhardtii. We have found that combining red LED (75%) with blue LED (25%) allowed growth at a higher total photon flux. Long-term iterative stress with additional blue light led to increased b-carotene and lutein accumulation. This appli- cation of adaptive laboratory evolution (ALE) yielded adapted strains of D. salina with increased accumulation of carotenoids under combined blue and red light condition.
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