Crosstalk of AsA/DHA and GSH/GSSG ratios' role in growth-phase dependent antioxidative defense in euryhaline and freshwater microalgae: explored for the first time

The cooperative role of vital components of the antioxidative defense pathway in addition to redox couples was studied in a growth-phase dependent manner at 20, 30, and 40 days after subculturing (DAS) in five different euryhaline microalgal strains (EMS) Scenedesmus MKB (B-S), Spirulina subsalsa (B-6), Anabaena sp. (B-7), Chlorella sp. (B-8), and Chlorosarcinopsis eremi (B-18) collected from waterlogged areas of Punjab, India and in two freshwater microalgal strains (FMS). EMS surpasses to maintain a high redox couple's ratio ascorbic acid/dehydroascorbate (AsA/DHA), and reduced glutathione/oxidized glutathione (GSH/GSSG) through a close-knit pattern of antioxidative enzymes including high specific activities of ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), glutathione reductase (GR), dehydroascorbate reductase (DHAR) and less specific activity of glutathione peroxidase (GPX). While FMS struggled for the same irrespective of near similar total glutathione and higher specific activity of GPX might be answerable for the lesser redox ratio than EMS. However, high specific activity of catalase (CAT) might be sought to compensate for the less increase of APX in FMS. The fact significantly less H2O2, and malondialdehyde (MDA) with DAS in EMS than in FMS and higher redox ratios exquisitely elevate their tolerance ability making EMS a captivating prospect for cultivation in waterlogged areas. Additionally, their abundance of potent antioxidants further highlights the potential of EMS as an excellent source of these beneficial compounds.