Removing contaminants and enhancing mutualism bacteria in Arthrospira (Spirulina) platensis mass culture using salinity adjustment and Azadirachta indica biopesticide.

Arthrospira (Spirulina) platensis is a multicellular photosynthetic prokaryote that contains high amounts of protein, vitamins, and minerals. Thus, A. platensis is recognized as a nutritious food by the United Nations World Food Conference and is referred to "Super Food" that has good economic prospects. However, the mass cultivation system is not free from contaminants, so it is necessary to modify the culture conditions. A. platensis has an optimum salinity of 15 ppt and salinity modification can be used to deal with contaminants. In addition, biopesticide is also capable of reducing microalgae culture contaminants in a short time without reducing the performance of microalgae. Therefore, it is important to study the effect of salinity and biopesticide on reducing bacterial contaminants in A. platensis mass culture. The study was carried out using a salinity of 15 ppt (S15B) with the addition of 0.5 ml/L Azadirachta indica biopesticide. Bacterial diversity was determined by Next Generation Sequencing. The results showed that the S15BD7 treatment was the most effective treatment for reducing bacterial contamination, in which several genera of pathogenic bacteria, including Vibrio, Pseudomonas, and Enterobacter, decreased drastically. In addition, the relationship between bacteria and microalgae can also be mutualism. The S15BD7 treatment had the highest mutualism symbiosis with E. coli, Halomonas sp., and Marinobacter salsuginis species. Thus, adjustment of salinity and application of biopesticide can be used as a novel approach to reduce bacterial contamination and enhance bacterial mutualism. [ABSTRACT FROM AUTHOR]