Enhanced lipid productivity of an oleaginous microalgal mutant strain Scenedesmus sp. Z-4 and the underlying differences responsible for its superior lipid accumulation over wild strain Scenedesmus sp. MC-1

Abstract

In this work, the lipid productivity of an oleaginous microalgal mutant strain Scenedesmus sp. Z-4 was improved to a maximum of 204.2 mg L−1 d−1 by single factor optimization, when 10 g L−1 glucose, 0.8 g L−1 NaNO3, 0.04 g L−1 K2HPO4 and initial pH of 7.0 were used in batch culture. Furthermore, multi-scale comparisons between mutant strain Z-4 and wild strain MC-1 were made, including cell surface elements and functional groups, biomass production, lipid accumulation and intracellular component percentages. The total EPS (extracellular polymeric substances) content of mutant strain Z-4 was 42.1% higher than that of wild strain MC-1, mainly due to the increase of extracellular protein and polysaccharide. Remarkable decrease of intracellular polysaccharide was found in the cells of mutant strain Z-4, implying the reallocation of carbon fluxes. These findings may be beneficial to understand the superior lipid production of mutant strain Scenedesmus sp. Z-4.