Microalgae mixotrophic cultivation for β-galactosidase production

Abstract

Microalgae present unexplored biotechnological potential and the ability to use different carbon sources in mixotrophic cultivation. Considering the need for efficient and low-cost industrial processes, the aim of this work was to evaluate the ability of microalgae and cyanobacteria to produce intra- and extracellular β-galactosidase. Eight species of Chlorophyta and Cyanophyta were cultivated in mixotrophic conditions with lactose as a carbon source. Dunaliella tertiolecta, Chlorella minutissima, and Nannochloropsis oculata were able to grow under mixotrophic conditions showing biomass production and growth rates higher than those of photoautotrophic cultures. β-Galactosidase extracellular production was 33.5 U L−1 on the 11th cultivation day for D. tertiolecta. For N. oculata and C. minutissima, the values were 29.6 and 11.02 U L−1 on the 14th and the 7th cultivation days, respectively. This study demonstrates the ability of microalgae to hydrolyze lactose under a mixotrophic regime and to outstanding great potential in the production of biomass and β-galactosidase.