Co-culture of Chlorella and Scenedesmus could enhance total lipid production under bacteria quorum sensing molecule stress

Abstract

When coupling wastewater treatment and biofuel production, bacteria inevitably compete with microalgae for nutrients and habitat resources. Yet, microalgae utilize symbiotic relationships to mediate adverse effects in unfavorable environments. We hypothesized microalgal co-culture strategy could be a feasible approach to resist the quorum-sensing molecule stress from bacteria. Here, we used two model microalgae taxa, Chlorella and Scenedesmus, to compare cell growth and lipid production in mono- and co-culture conditions under the stress of a representative bacterial signal, C6-HSL. Co-culture cultivation reduced growth inhibition (by 50 % for Chlorella and 35 % for Scenedesmus) induced by C6-HSL. Antioxidant enzymes and mitochondrial activities were inhibited by C6-HSL stress in monoculture, but they were negligibly affected using the co-culture strategy. The maximum lipid productivity and production of the co-culture system were 0.12 g/(L d) and 0.71 g/L, respectively, and lipid production was 20–79 % higher than that of Chlorella and Scenedesmus monocultures. We found that the co-culture strategy could efficiently limit bacterial-induced competition stress and thus improve microalgae lipid production.