Exploring the dynamics of algae-associated microbiome during the scale-up process of Tetraselmis sp. microalgae: A metagenomics approach.

[Display omitted] • Microbial profiling of large-scale algal culture was conducted using metagenomics. • Bacterial invaders increased gradually throughout Tetraselmis upscaling stages. • Balneola , Roseovarius , and Marinobacter had algae growth-promoting properties. • Ulvibacter , Aestuariicoccus and Defluviimonas demoted Tetraselmis growth. Microalgae have become a key source of valuable compounds, promoting commercial scale applications. However, biological contamination is one of the most critical problems associated with large scale algal production, especially in open systems such as raceway ponds. The current research is the first to assess the effectiveness of open raceway ponds in maintaining a pure culture of Tetraselmis sp. , starting from 20 L culture up to 10,000 L culture. Microbial profiling of each successive stage revealed lower abundance of eukaryotic organisms, whereas bacterial abundance increased notably resulting in a significant decrease in Tetraselmis sp. abundance. Furthermore , s everal bacteria with algae growth-promoting properties were found throughout the various culture stages including Balneola, Roseovarius, and Marinobacter. However, some algae-suppressive bacteria were evidenced at later stages such as Ulvibacter, Aestuariicoccus , and Defluviimonas. Overall, due to the increasing bacterial concentration, considerations limiting bacterial contamination need to be taken. [ABSTRACT FROM AUTHOR]