Browsing by Author "Priyanka Maurya"

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A Study on Dunaliella salina Under Selected Nutrient Manipulation with Reference to the Biomass, Lipid Content Along with Expression of ACCase and RuBisCO Genes
(Springer, 2023) Sk Riyazat Khadim; Abhishek Mohanta; Prabhakar Singh; Priyanka Maurya; Ankit Kumar Singh; Arvind Kumar Singh; Ravi Kumar Asthana
Energy crises and climate change attracted less-explored microalgae as renewable resources. Deficiencies of nitrogen and phosphorus are the most effective inducers of lipid accumulation in microalgae but at the cost of biomass productivity. Therefore, nitrogen, phosphorus, and carbon manipulation of the culture medium was adopted for maximizing lipid as well as biomass production in Dunaliella salina. Phosphate deficiency in combination with 1.25 mM KNO3 (1/8 of the basal) resulted in higher lipid content (341.1 mg g−1 dry cell weight, DCW), but lower biomass (13.12 mgL−1d−1 DCW). The addition of 10.00 mM NaHCO3 to such cultures enhanced not only lipid content to 1.17-fold but also biomass productivity to 2.25-fold. The increase in biomass may be correlated with the stress-ameliorating effects of bicarbonate augmentation which helped in maintaining the health of the cells, as reflected by robust photosynthetic performance. The two important enzymes, RuBisCO and ACCase were also monitored for their expressions. RuBisCO possesses large and small subunits (rbcL and rbcS) responsible for incorporation of CO2, and beta carboxyl transferase (accD) of the heteromeric ACCase is associated with the first and committed step of fatty acid biosynthesis. Enhanced biomass and lipid content in D. salina cells after NaHCO3 augmentation may be ascribed to 6.23-fold increase in the expression of accD and > 2.16-fold increase in rbcL and rbcS genes. Thus, the present work recommends a threshold level of nitrogen and bicarbonate in phosphate deficient D. salina cultures for simultaneously maximizing the biomass and lipid content. © 2022, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
Bioaccumulation of selenium in halotolerant microalga Dunaliella salina and its impact on photosynthesis, reactive oxygen species, antioxidative enzymes, and neutral lipids
(Elsevier Ltd, 2023) Prabhakar Singh; Sakshi Singh; Priyanka Maurya; Abhishek Mohanta; Hardik Dubey; Sk. Riyazat Khadim; Ankit K. Singh; Adarsh K. Pandey; Arvind K. Singh; Ravi K. Asthana
Selenium (Se) is an essential element for living systems, however, toxic at higher levels. In the present study, Dunaliella salina cells were exposed to different Se concentrations for their growth (EC50 195 mg L−1) as well as Se accumulation. The cells exposed to 50 mg L−1 Se showed photoautotrophic growth parallel to control and accumulated 65 μg Se g−1 DW. A decrease in photosynthetic quantum yield, chlorophyll content, and the increase in intracellular reactive oxygen species, proline content, and lipid peroxidation accompanied by higher neutral lipid accumulation, were recorded at higher Se level. The enzymes superoxide dismutase and catalase played a pivotal role in antioxidative defense. Heterogeneity in accumulated carotenoids at varying concentrations of selenium was prevalent. The cells exposed to 200 mg L−1 Se resulted in the disorganization of organelles. Thus, the Se enriched biomass obtained at 50 mg L−1 may be explored for bio-fortification of food and feed. © 2023 Elsevier Ltd
Biochemical and physiological characterization of a halotolerant Dunaliella salina isolated from hypersaline Sambhar Lake, India
(Blackwell Publishing Inc., 2019) Prabhakar Singh; Riyazat Khadim; Ankit K. Singh; Urmilesh Singh; Priyanka Maurya; Anupam Tiwari; Ravi K. Asthana
The objective of the present study was to characterize intrinsic physiological and biochemical properties of the wall-less unicellular cholorophyte Dunaliella salina isolated from a hypersaline Sambhar Lake. The strain grew optimally at 0.5 M NaCl and 16:8 h L:D photoperiod along with maintaining low level of intracellular Na + even at higher salinity, emphasizing special features of its cell membranes. It was observed that the cells experienced stress beyond 2 M NaCl as evidenced by increased intracellular reactive oxygen species and antioxidative enzymes, nevertheless proline and malondialdehyde content declined sharply accompanied by higher neutral lipid accumulation. Salinity exceeding 2 M resulted decrease in photosynthetic quantum yield (Fv/Fm) and enhanced glycerol synthesis accompanied by leakage. Super oxide dismutase seemed to play a pivotal role in antioxidative defense as eight isoforms were expressed differentially while catalase and glutathione peroxidase showing no significant change in their expression at higher salinity. The ability of D. salina to grow in range of salinities by sustaining healthy photosynthetic apparatus along with accumulation of valuable products made this alga an ideal organism that can be exploited as resource for biofuel and commercial products. © 2018 Phycological Society of America
Strategies for increased production of lipids and fine chemicals from commercially important microalgae
(Elsevier, 2020) Sk Riyazat Khadim; Abhishek Mohanta; Priyanka Maurya; Prabhakar Singh; Ravi K. Asthana
There is an increase in the human population worldwide, land holdings per capita decrease, and crop productivity is stabile. Energy consumption is increasing, but fossil fuel reserves decrease. Therefore, catering the huge population and continuous supply of the energy demand makes the microalgal system a treasure for human beings. Industrialization leads to an increase of greenhouse gases in the environment and resulting climate change. Microalgae are the source of polyunsaturated fatty acids, antioxidants, hormones, natural colorants (in the form of pigments), and natural lipids. Microalgae do not require large land areas; they may be cultivated in bioreactors occupying small space even on the roof top and grow on simple inexpensive inorganic compounds, water, and sunlight. They have a short generation time and can be easily manipulated for increased production of desired chemicals in a bioreactor. However, the knowledge of genome sequences, proteomics, and bioinformatics has to be combined to create a system biology to understand higher production strategies. This chapter summarizes the screening of the desired strains of microalgae, their mass cultivation, and constraints in production on an industrial scale. © 2021 Elsevier Inc.