Abiotic stress-induced enhanced pigment production and its multifaceted process optimization in fast-growing Synechococcus sp. PCC 11901

Abstract

Carotenoids, valued for their antioxidant properties and industrial applications, are witnessing rapidly accelerating market demands. Meanwhile, cyanobacteria with rapid growth and simple nutrient needs are extensively employed for the production of bioactive compounds in an environmentally sustainable manner. To address the limited application of cyanobacterial species in large-scale carotenoid production, our study investigated the effects of nutrients (NaNO₃ and KH₂PO₄), as well as salt (NaCl), metal (CuSO₄.5H₂O), and oxidative (H₂O₂) stress conditions, on carotenoid biosynthesis in the recently discovered fast-growing Synechococcus sp. PCC 11901. In our study, the RSM model (R² value of 0.9373) based medium optimization has enhanced carotenoid and chlorophyll a production in PCC 11901 by 1.99- and 1.74-fold, respectively, under mild deficiencies of NaCl, NaNO₃, and KH₂PO₄. Furthermore, exposure to low Cu (40 µM) and moderate H₂O₂ stress (3 mM) elevated carotenoid production by 1.74- and 1.53-fold, respectively, on the eighth day. In comparison, previous optimization studies in cyanobacteria have reported up to a 2.52-fold (9.78 µg ml⁻¹) and a 1.52-fold (0.369 µg ml⁻¹) increase in carotenoid yields. Additionally, the increased Cu accumulation of 0.76 µg/mg dry biomass under 40 µM Cu stress indicates PCC 11901 potential in metal pollution bioremediation. In addition to the observed radical scavenging potential of the carotenoids, Cu and NaCl stress induced the highest ascorbate peroxidase and catalase antioxidant enzymatic activities in PCC 11901, respectively, compared to control and other stress conditions. The study revealed the potential of fast-growing Synechococcus sp. PCC 11901 in carotenoid production under abiotic stress conditions for environmentally safe and sustainable bio-manufacturing.

Keywords

Carotenoid / Fast-growing cyanobacteria / Synechococcus sp. PCC 11901 / Multifaceted process optimization / Abiotic stress

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Funding

Science and Engineering Research Board(CRG/2021/001206)

RIGHTS & PERMISSIONS

Jiangnan University