Inhibition of Microcystis aeruginosa by Bacillus subtilis fmb60 non-ribosome peptide metabolites

Abstract:

Microcystis aeruginosa, a type of algal bloom microalgae, is widely distributed in water, causing serious deteriorated effects on humans and the ecological environment. As a biocontrol microorganism, Bacillus subtilis can synthesize various bioactive substances through non-ribosomal peptide synthetase, to inhibit the growth of M. aeruginosa. Thus, it is imperative to investigate the non-ribosomal peptide (NRP) metabolites of B. subtilis fmb60. Three NRP metabolites from B. subtilis fmb60 including bacillibactin, surfactin and fengycin were extracted and identified by genome mining technology. The growth inhibition of M. aeruginosa was studied by adding various concentrations of NRP metabolites. The half-effect concentration value (EC50.4 d) of M. aeruginosa was 26.5 mg/L after incubation for 4 days. With the increasing concentration, the inhibitory effects of NRP metabolites of B. subtilis fmb60 on M. aeruginosa was enhanced significantly. Compared with the control group, with the addition of 50 mg/L NRP metabolites to the M. aeruginosa, the content of Fv/Fm, Fv/Fo and Yield parameter after cultured for 4 days were decreased by 2.8%, 1.7% and 2.0%, respectively. Those findings indicate that the NRP metabolites of B. subtilis fmb60 can significantly inhibit the photosynthesis and metabolism of M. aeruginosa, which provides a theoretical foundation for the development of biological algae inhibitor of B. subtilis.