Draft genome analysis, poly-phasic study and lipid biosynthesis pathway of Scenedesmus sp. SVMIICT1.

A comprehensive polyphasic evaluation of a microalgal isolate Scenedesmus sp. SVMIICT1 through morphological, biochemical, photosynthetic characterization, next-generation sequencing and lipid pathway analysis was reported. The strain was cultivated photo-autotrophically, where the maximum photosynthetic yield (FV/FM) of 0.75 was observed on the 4th day with optimal PSII photochemical efficiency. Enhanced electron transport rate (ETR(I)) with inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) resulted in cyclic electron flow. A fair share of carbohydrate content (36 µg/mg) was ascribed to the presence of pyrenoid towards higher CO2 sequestration pursuant to carbon concentrating mechanism (CCM). Denovo sequencing of the genome was assembled, annotated for the prediction of gene and protein. KEGG automatic annotation server (KAAS) analysis depicted the presence of genes accompanying the biosynthesis of the glycerophospholipid pathway. Fatty acid profile represented a higher fraction of palmitic acid (C16:0; 41.6%) followed by alpha-linolenic acid (C18:3; 44.5%).

Lutein and ß-carotene biosynthesis in Scenedesmus sp. SVMIICT1 through differential light intensities.

The study evaluated the biosynthesis of lutein and ß-carotene by Scenedesmus sp. SVMIICT1 under five different light intensities (50, 250, 500, 750 and 1000 µE/m2/s). Liquid chromatography/mass spectrometry (LC/MS) was used to determine relative quantities of lutein and ß-carotene. Relatively, high lutein content of 1.43 ± 0.04 and 0.70 ± 0.02 mg/g was found with 50 and 500 µE/m2/s conditions respectively. ß-Carotene content was quantified as 0.15 ± 0.01, 0.1 ± 0.01 and 0.12 ± 0.02 mg/g with 50, 250 and 500 µE/m2/s conditions respectively. The light intensities altered photosystem II and photosystem I. At 50 µE intensity, high chlorophyll content and high photosystem II quantum efficiency (FV/FM) was observed. Low FV/FM ratio of around 0.3 was detected in high light intensities (750 µE and 1000 µE) due to photoinhibition. Lipid fraction increased with increasing light intensity and the fatty acid profiles were similar in all five conditions.

Algal biorefinery models with self-sustainable closed loop approach: Trends and prospective for blue-bioeconomy.

Microalgae due to its metabolic versatility have received a focal attention in the biorefinery and bioeconomy context. Microalgae products have broad and promising application potential in the domain of renewable fuels/energy, nutraceutical, pharmaceuticals and cosmetics. Biorefining of microalgal biomass in a circular loop with an aim to maximize resource recovery is being considered as one of the sustainable option that will have both economical and environmental viability. The expansive scope of microalgae cultivation with self-sustainability approach was discussed in this communication in the framework of blue-bioeconomy. Microalgae based primary products, cultivation strategies, valorization of microalgae biomass for secondary products and integrated biorefinery models for the production of multi-based products were discussed. The need and prospect of self-sustainable models in closed loop format was also elaborated.

Non-lethal nitrate supplementation enhances photosystem II efficiency in mixotrophic microalgae towards the synthesis of proteins and lipids.

The current study is aimed at understanding the effect of two different concentrations of nitrate (NaNO3) i.e., 2.94 mM (1X) and 8.82 mM (3X) on the productivity of Scenedesmus sp. in terms photosynthetic efficiency, growth, biomass and protein/lipid synthesis. The experiments were conducted by growing the microalgae in mixotrophic mode with a fixed dissolved organic carbon (110 mM). Chlorophyll a fluorescence fast kinetics parameter such as FV/FM, FM/FO, Pi_Abs, TRo/RC and ABS/RC depicted an improved PSII efficiency in 3X conditions. Higher nitrate concentration in BBM medium favored better assimilation of chlorophyll pigments, carbohydrates (160 mg/g), proteins (524 mg/g) and total lipids along with higher biomass (11.4 g/L). The microalgae cell growth, biomass and biochemical composition are significantly influenced by excess nitrates supplementation in the growth medium.

Regulatory effect of Fe-EDTA on mixotrophic cultivation of Chlorella sp. towards biomass growth and metabolite production.

The study examined the effect of varying concentrations of iron in the form of ethylene diamine tetra-acetic acid ferric sodium salt (Fe-EDTA) for cultivation of Chlorella sp. under mixotrophic condition to evaluate biomass growth and metabolites production. The experimental data depicted enhanced biomass production along with lipids, carbohydrates and proteins at an optimal iron concentration (8mg/L). Relatively higher biomass production (5.4g/L; 96h) with simultaneous total chlorophyll (5mg/mL (Chl a/b: 3.7/1.3mg/mL)), carbohydrates (105mg/g) and proteins (593mg/g) was observed with 8 mg/L Fe-EDTA. Total and neutral lipid content of 38% and 15.6% was observed under nutrient deprived conditions. The presence of iron showed distinct influence on the saturated fraction of FAME and increment in oleic acid (omega fatty acids; edible oil). Higher concentrations of Fe-EDTA (10/12mg/L) depicted incremental fraction of oleic acid.