Fine resolution analysis of bacterial communities associated with Neochloris oleoabundans culture and insights into terpenes as contamination control agents

Biological contamination is one of the main bottlenecks in microalgae production, reducing quality and productivity and sometimes leading to the complete loss of the cultures. Selecting terpenes can be a pathway toward eco-friendly contamination control in microalgae cultures. This work evaluated the presence of bacterial contaminants in N. oleoabundans cultures through HTS and 16 S analysis and their susceptibility to six natural terpenes (α-pinene, β-pinene, limonene, trans-cinnamaldehyde, linalool, and eugenol). The principal phyla identified were Proteobacteria, Bacteroidetes, and Actinobacteria, and based on these data, 89 bacterial isolates of seven genera were obtained (36 Aureimonas sp., 27 Microbacterium sp., 5 Pseudomonas sp., 9 Bacillus sp., 14 Shinella sp., 1 Brevundimonas sp., and 1 Exiguobacterium sp.) at 25ºC in the presence of light. It was possible to observe that Beta-pinene 50 mg L^{- 1} only inhibited Bacillus sp. In contrast, Alpha-pinene, Linalool, and Trans-cinnamaldehyde, at a concentration of 6.25 mg L^{- 1} efficiently inhibited most isolates. The inhibition percentages found were 79-99%.