269
production in microalgae. Transcriptomic regulation of hydrogen production by C.
reinhardtii under sulphur deprivation revealed cellular reorganization of the photosynthetic apparatus and the differential abundance of transcripts coding for genes
essential for energy-dependent quenching. These studies were complemented with
functional gene knockouts, resulting in mutants with enhanced hydrogen production (Nguyen et al. 2008; Ghirardi et al. 2007; Mus et al. 2007). Sulphur-starved C.
reinhardtii also exhibited increases in transcripts coding for genes involved in stress
response and detoxification along with metabolic remodelling to generate increased
reducing equivalents (Toepel et al. 2013).
Proteomic data provide information about peptide sequences, which can support
incomplete genome annotation and network gap analysis. A recent study employed
proteomic analyses to determine the effect of a dark stress on lipid biosynthesis in P.
tricornutum (Bai et al. 2016) and reported induced expression of proteins in the
biochemical pathways of glycolysis and the synthesis of fatty acids, potentially
using excess carbon and nitrogen produced from protein breakdown, which resulted
into 2.3-folds increase in total lipid content. Nguyen et al. (2011) reported proteomic
profiling of oil bodies from C. reinhardtii, with focus on proteins involved in lipid
metabolism, which can be used for further studies related to genetic engineering of
the oil synthetic pathways of the strain. A sub-proteome analysis of Chlamydomonas
(Terashima et al. 2010) has revealed the presence of proteins in the chloroplast
exhibiting similarity to proteins found in the organisms that don’t perform photosynthesis, thus suggesting the role of chloroplast enzymes in the capability of the cell to
survive under heterotrophic conditions. Approximately 42 chloroplast proteins with
unknown function were identified and showed that they do not have any similarity
with other proteins from land plants and may be specific in microalgae species
(Terashima et al. 2010). Proteomic approaches have also been used to evaluate the
changes in protein abundance during photoautotrophic and mixotrophic growth of
Chlamydomonas. The data supported the presence of carbonic anhydrases (Cah) in
the microalgae being Cah1, Cah2, Cah3, Cah4 and Cah9 all detected during autotrophic growth, while only Cah1, Cah3 and Cah4 were detected during mixotrophic
growth (Wienkoop et al. 2010). Proteomic approach was also used to study response
of H. pluvialis to oxidative stress (Wang et al. 2004a) and to study the molecular
basis of salinity tolerance in D. salina (Liska et al. 2004).
Metabolites are the end products of cellular regulatory processes, and their levels
can be used as the ultimate response of cell to environmental changes (Jamers et al.
2009). Metabolomics is defined as the comprehensive and quantitative analysis of
all (or a subset) metabolites in a biological system at a specific time point, reflecting
a snapshot of all the regulatory events responding to the external environmental
conditions (Kumar et al. 2016). Metabolomics produce a large compound set which
can provide information about missing metabolic pathways in the organism. It shares
distinct advantages with proteomics in terms of elucidating gene function, i.e. the
total complement of proteins or metabolites changes according to the physiological,
developmental or pathological state of a cell; unlike transcript analysis, proteins and
metabolites are functional entities within the cell (Raamsdonk et al. 2001). Further,
there are fewer metabolites than genes or gene products to be studied. Most of the
13 Oxidative Stress-Induced Bioprospecting of Microalgae
production in microalgae. Transcriptomic regulation of hydrogen production by C.
reinhardtii under sulphur deprivation revealed cellular reorganization of the photosynthetic apparatus and the differential abundance of transcripts coding for genes
essential for energy-dependent quenching. These studies were complemented with
functional gene knockouts, resulting in mutants with enhanced hydrogen production (Nguyen et al. 2008; Ghirardi et al. 2007; Mus et al. 2007). Sulphur-starved C.
reinhardtii also exhibited increases in transcripts coding for genes involved in stress
response and detoxification along with metabolic remodelling to generate increased
reducing equivalents (Toepel et al. 2013).
Proteomic data provide information about peptide sequences, which can support
incomplete genome annotation and network gap analysis. A recent study employed
proteomic analyses to determine the effect of a dark stress on lipid biosynthesis in P.
tricornutum (Bai et al. 2016) and reported induced expression of proteins in the
biochemical pathways of glycolysis and the synthesis of fatty acids, potentially
using excess carbon and nitrogen produced from protein breakdown, which resulted
into 2.3-folds increase in total lipid content. Nguyen et al. (2011) reported proteomic
profiling of oil bodies from C. reinhardtii, with focus on proteins involved in lipid
metabolism, which can be used for further studies related to genetic engineering of
the oil synthetic pathways of the strain. A sub-proteome analysis of Chlamydomonas
(Terashima et al. 2010) has revealed the presence of proteins in the chloroplast
exhibiting similarity to proteins found in the organisms that don’t perform photosynthesis, thus suggesting the role of chloroplast enzymes in the capability of the cell to
survive under heterotrophic conditions. Approximately 42 chloroplast proteins with
unknown function were identified and showed that they do not have any similarity
with other proteins from land plants and may be specific in microalgae species
(Terashima et al. 2010). Proteomic approaches have also been used to evaluate the
changes in protein abundance during photoautotrophic and mixotrophic growth of
Chlamydomonas. The data supported the presence of carbonic anhydrases (Cah) in
the microalgae being Cah1, Cah2, Cah3, Cah4 and Cah9 all detected during autotrophic growth, while only Cah1, Cah3 and Cah4 were detected during mixotrophic
growth (Wienkoop et al. 2010). Proteomic approach was also used to study response
of H. pluvialis to oxidative stress (Wang et al. 2004a) and to study the molecular
basis of salinity tolerance in D. salina (Liska et al. 2004).
Metabolites are the end products of cellular regulatory processes, and their levels
can be used as the ultimate response of cell to environmental changes (Jamers et al.
2009). Metabolomics is defined as the comprehensive and quantitative analysis of
all (or a subset) metabolites in a biological system at a specific time point, reflecting
a snapshot of all the regulatory events responding to the external environmental
conditions (Kumar et al. 2016). Metabolomics produce a large compound set which
can provide information about missing metabolic pathways in the organism. It shares
distinct advantages with proteomics in terms of elucidating gene function, i.e. the
total complement of proteins or metabolites changes according to the physiological,
developmental or pathological state of a cell; unlike transcript analysis, proteins and
metabolites are functional entities within the cell (Raamsdonk et al. 2001). Further,
there are fewer metabolites than genes or gene products to be studied. Most of the
13 Oxidative Stress-Induced Bioprospecting of Microalgae