Mutualistic interactions of green microalga Chlorella sp. with bacterial quorum sensing degrader Bacillus spp isolated from biofloc and freswater prawn Macrobrachium rosenbergii

Abstract

Aim: Bacterial quorum sensing degrader isolated from biofloc and giant freshwater prawn, Macrobrachium rosenbergii were investigated for mutual interaction with green microalga, Chlorella sp. for potential use of disease control in aquatic environment. Methodology: Two potential strains of quorum sensing (QS) degrader were successfully isolated from biofloc and giant freshwater prawn, Macrobrachium rosenbergii. Meanwhile, Chlorella sp. was made axenic using 13 to 500 ppm of different antibiotic mixtures (chloramphenicol, tetracycline, enrofloxacin, kanamycin, and neomycin), where interaction of algae with different QS degrader strains, different microbial communities and pathogenic bacterium Aeromonas hydrophila were investigated. Results: The QS degrader strains were identified as Bacillus subtilis, BP-BFT/1b and Bacillus cereus, BP-MBRG/1b. Growth of Chlorella sp. added with Bacillus subtilis, BP-BFT/1b was higher compared to Bacillus cereus, BP-MBRG/1b. The results showed that the growth of axenic Chlorella sp. improved ine i n t h e p r e s e n c e o f b a c t e r i a, i n c l u d i n g bacterial QS degraders. Interpretation: There is a potential to incorporate b o t h B . s u b t i l i s BPBFT/1b and B. cereus B P M B R G / 1 b i n aquaculture systems to overcome invasion of p a t h o g e n i c b a c t e r i a u s i n g b a c t e r i a l Q S degrading mechanism.