Biochemical insights into enhanced lipid production by a microalga under combined stress of salinity and arsenic

Abstract

The contamination of water bodies and depleting fuel resources are the two major global concerns. Such a scenario demands a coherent approach of production of green fuels by utilizing the waste/brackish waters for a sustainable economy. Therefore, the current study investigated the adaptive response of Scenedesmus sp. IITRIND2, a halotolerant microalga under combined stress of osmolarity along with arsenic (As (III), As (V)) toxicity. The algal cells efficiently mitigated 75–89 % of As (III) and As (V) from artificial seawater (ASW) having 80 ppm of initial concentration. The ∼ 2-fold higher biosorption of As in ASW cultivated cells was mediated due to the remarkable changes in the cell size as compared to fresh water (FW) grown cells. Though uptake of As in cells significantly inhibited the growth and photosynthetic activity but the cells remodeled their biochemical pools to maintain the overall proportion of lipids (50 % of the dry cell weight). Elevated levels of superoxide dismutase, glutathione, and glutathione reductase aided major stress responsive adaptation in cells under co-toxicity of salinity and As. Further, As spiked cells grown in ASW media improved the oxidative stability and cetane number of the derived fuel. This research sheds light on the possible utilization of a halotolerant microalga, paving a viable and eco-friendly biorefinery framework to remediate As, produce green fuels while desalinating the abundant seawater for further municipal usage.