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Articles by Shoaib Hamid
Total Records ( 2 ) for Shoaib Hamid
  Shoaib Hamid and G. Sibi
  Background and Objective: Reactive oxygen species (ROS) are produced due to imbalance between cellular ROS production and elimination leading to oxidative stress. Antioxidants are known to involve in protecting cells from oxidative stress induced by various stresses in micro-algae. This study was carried out with the objective of determining the antioxidant system responses in micro-algae grown under nutrient stress conditions. Materials and Methods: Chlorococcopsis minuta was cultivated in nitrogen and phosphorous reprieve and deprived conditions and enzymatic (superoxide dismutase, catalase, ascorbate peroxidase) and non-enzymatic (Hydrogen peroxide, proline, polyphenol content and lipid per-oxidation level) antioxidants were analyzed. Results: Activities of antioxidant enzymes in C. minuta during nutrient stress showed that the activities of SOD, CAT and APX were increased in nutrient stress cultures when compared to nutrient fulfilled conditions. There was a 33% increase in lipid per-oxidation N-P- media than N-P+ media. Proline content increased with nutrient stress and reached 8 folds higher in nitrogen and phosphorous deprived media than the control. Total phenolic content was greater in N-P- indicating the nutrient stress triggered antioxidant system in the micro-algae. Conclusion: Nitrogen deprivation with phosphorous depletion condition demonstrated the oxidative stress and enhanced activation of enzymatic and non-enzymatic antioxidant systems at various levels.
  Shoaib Hamid and G. Sibi
  Background and Objectives: Physiological response in micro-algae triggered by nutrient stress to induce triacylglycerol accumulation is a promising solution to produce micro-algae based biofuel. The main objective of the study was to determine the response of micro-algae to nutrient stress by means of lipid accumulation. Materials and Methods: This study investigated the effect of nitrogen sufficient and nitrogen deficient conditions (N+ and N-) in micro-algal biomass and lipid productivity to determine the response to nutrient stress by micro-algae. A micro-alga was isolated from fresh water lake and amplification of 18S rDNA genes with the primers NS1 and NS4 resulted in 1300 bp fragments. The 18s rDNA sequences obtained were compared against sequences in the GenBank nucleotide collection through the Basic Local Alignment Search Tool (BLAST). Results: The micro-algae were identified as Chlorococcopsis minuta based on sequence similarities. In the case of micro-algae grown in nutrient limited conditions (N- media), the biomass content was lower with the yield of 8.4 g L1, however, there was a 62.5% increase in the total lipid content (11.7%) compared to nutrient sufficient conditions. Confocal imaging of lipid droplets stained by Nile red showed that lipid droplets was increased in N deficient (N-) conditions when compared to N sufficient (N+) conditions. Conclusion: Increase in lipid content of C. minuta was confirmed by accumulation of more lipid droplets under nutrient stress conditions.
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