Utilization of waste peel extract for cultivation of microalgal isolates: a study of lipid productivity and growth kinetics

The excessive price of nutrients needed for microalgal cultivation is a vital constraint, although mass production is essential for attaining economically viable production of algal fuels and value-added products. Increasing energy demand has prompted the world to look for alternative oil resources. There is a crucial demand for sustainable and economically viable source of energy due to the reduction in conventional fossil fuel supplies. In this study, potato peel and sweet lime peels were exploited in place of conventional growth mediums for the cultivation of microalgal cells. These wastes are zero-value material, which contains vital nutrients and elements for the cultivation of oleaginous microorganisms like microalgae. The growth of the isolated strains Chlorella sorokiniana KMBM_K and KMBM_I in the pretreated peel hydrolysates was investigated. The biomass and lipid extracted can be further investigated for potential applications in biofuel, feed, and food additives. A new insight can be obtained with this study as it integrates the concept of lipid extracted microalgal biomass utilization (LEMB) approach along with waste disposal, thereby serving in the management of these agricultural wastes. While performing the optimization studies, pH 7 and 25% and 40% dilution, respectively, for potato peel and sweet lime were found to support more biomass and lipid yield. The highest biomass yield of 2.1 g L-1 and highest lipid productivity of 49.93 mg L-1 day(-1) are obtained in Chlorella sorokiniana KMBM_K when cultivated in potato peel extract. This study showed that these agricultural wastes can be used as a natural, cost effective, ecofriendly, efficient, and affordable substrate for the cultivation of the microalgal isolates.