Abiotic stress effects on polyunsaturated fatty acid biosynthesis in Chlorococcum oleofaciens and Leptolyngbya sp.

Microalgae play a crucial role in the biogenesis of polyunsaturated fatty acids (PUFAs), essential bioactive molecules widely used in the pharmaceutical industry for their therapeutic efficacy and health-enhancing benefits. These microorganisms, due to their rapid growth and resilient nature, make an efficient source for PUFA production. The biogenesis of PUFAs in microalgae involves a series of enzymatic reactions catalyzed by elongases and desaturases that convert precursor fatty acids into PUFAs, including omega-6 and omega-3. This study explores cost-effective, and environmentally friendly strategies to enhance PUFA production in microalgae for use in the food and feed industries. The present studyevaluates the influences of salinity, pH, and low temperature on the nutraceutical properties of Chlorococcum oleofaciens and Leptolyngbya sp., with a focus on PUFA production. Among the conditions tested, 10 mM NaCl yielded in the highest specific growth rates for Chlorococcum oleofaciens and Leptolyngbya sp., reaching 0.142 ± 0.0010, 0.122 ± 0.0016 day^-1, respectively. Under the same conditions, biomass yields peaked at 6.89 ± 0.22, 7.06 ± 0.35 g/L. The highest PUFA content of linolenic acid (29, 7.7%), eicosapentaenoic acid (47, 41%), and docosahexaenoic acid (56, 47%) was recorded at 15 °C. The activities of superoxide dismutase and malondialdehyde increased in response to elevated salinity, low temperature, and pH, indicating oxidative stress adaptation. In conclusion, low temperature had a significant effect on the enhancement of PUFA content in Chlorococcum oleofaciens and Leptolyngbya sp., making these microalgae potential strains for PUFA production. These findings offer valuable insights for optimizing cultivation practices and enhancing the productivity of these economically important microalgae. KEY POINTS: • Chlorococcum oleofaciens and Leptolyngbya sp. were studied for PUFA production. • Salinity, pH, and low temperature have a marked effects on the PUFA profile of microalgae. • The highest specific growth rate occurred at 10 mM NaCl. • The highest PUFA content was observed at 15 °C.