Co-cultivation of Isochrysis galbana and Marinobacter sp. can enhance algal growth and docosahexaenoic acid production

Isochrysis galbana, an important diet microalgal species, is widely used in aquaculture and rich in docosahexaenoic acid (DHA). Currently, no efficient strategies are available to steadily enhance the production of its biomass and DHA. It has been reported that algae-associated bacteria can affect the yield of algae and the production of high-value compounds. Here, we identified a growth-promoting bacterial strain Marinobacter sp., which could enhance the growth, the content of chlorophyll a, the maximal photochemical efficiency of PS II (F-v/F-m), and soluble protein content of I. galbana when they were co-cultured, while superoxide dismutase (SOD) activity was decreased. Besides, Marinobacter sp. promoted the production of DHA and up-regulated the expressions of genes involved in DHA synthesis pathway of I. galbana. Our study clearly suggested that co-cultivation of I. galbana and Marinobacter sp. could effectively enhance the quality and quantity of microalgae, showing promising applications in improving productivity and sustainability of aquaculture algal rearing systems.