Enhanced biomass production of Synechocystis sp. PCC 6803 by two associated bacteria Paenibacillus camelliae and Curtobacterium ammoniigenes.

Synechocystis sp. PCC 6803 grown continuously in a 5-L photo-bioreactor for 20 months was found to have associated consortia with heterotrophic microorganisms. Two strains of bacteria were isolated from the long-term cultures of cyanobacteria with the aim to test whether their presence affects cyanobacterial growth and metabolism. The two strains were phylogenetically identified as Paenibacillus camelliae and Curtobacterium ammoniigenes, respectively. Co-culturing the Synechocystis sp. with either of the isolates under photoautotrophic and photoheterotrophic conditions exerted a statistically significant growth enhancement effect on cyanobacteria. Under co-culture experiments, the addition of P. camelliae resulted in a four-fold higher biomass yield with a considerable decrease in the stationary period. The growth was more pronounced on the addition of acetate to the culture media. Growth-enhancing factors like indole acetic acid (IAA) and siderophores were detected in the co-culture conditions which proved to be the main driving force in boosting cyanobacterial growth. Thus, the cyanobacteria-bacteria consortia can be very useful for augmenting biomass production by circumventing the time factor which can be further exploited for various biotechnological applications.