Newly isolated native microalgal strains producing polyhydroxybutyrate and energy storage precursors simultaneously: Targeting microalgal biorefinery

Abstract

With escalating urbanization and ever-increasing population, plastic pollution has become the problem of hour. Owing to its deep roots in our daily life, it is imperative to find an alternative. Sustainable production of poly hydroxy butyrate (PHB) can be our way out from this soup of plastic pollution. Microalgae, being photoautotrophs, helps in bioremediation and can metabolize the waste products into biodiesel, bioethanol, protein, and also bioplastics in the form of PHB. The present study reports the accumulation of PHB in Coelastrella sp., Ettlia texensis and Pecatinodesmus sp. isolated from nearby regions of Indore under nutrient stress and mixotrophic conditions. The individual effect of nutrients was studied, and concluded that under mixotrophic cultivation, Coelastrella sp. can accumulate up to 151.8 ± 12.1 μg/mg dry cell weight (DCW) of PHB under N1.5P0.04Ga10 supplementation in 72 h of cultivation. A two-stage cultivation strategy enabled the accumulation of high PHB content in microalgae without compromising the microalgal growth, which was noted in terms of chlorophyll and biomass accumulation. Principle component analysis (PCA) revealed close relation between biomass and poly hydroxybutyrate (PHB) accumulation with organic carbon presence having a great impact. These results pave the way for sustainable PHA/PHB production using three microalgal species.