Isolation and identification of amino acids secreted by Bacillus amyloliquefaciens T1 with anti-cyanobacterial effect against cyanobacterium Microcystis aeruginosa

Eutrophication caused by harmful cyanobacteria is becoming more and more serious all over the world. Biological control of harmful cyanobacterial blooms (HCBs) such as anti-cyanobacterial microorganism is considered to be a safe, economical and effective method as its environmental friendly characteristics and species specificity. Bacillus amyloliquefaciens T1, which isolated from a a eutrophic pond in Wuhan, China, shows remarkable anti-cyanobacterial activity against bloom-forming cyanobacterium Microcystis aeruginosa 905. In the current study, the anti-cyanobacterial action mode of strain T1 is investigated, and the anti-cyanobacterial compounds secreted by T1 are purified after extraction with organic solvents. Additionally, the anti-cyanobacterial compounds are further analyzed using Fourier-transform infrared spectroscopy (FTIR) and identified with high-performance liquid chromatography-mass spectrometry (HPLC-MS). Results indicate that the anti-cyanobacterial active components are existed in the cell-free filtrate of B. amyloliquefaciens T1 and the anti-cyanobacterial activity on M. aeruginosa is achieved by indirect interactions. The FTIR absorption spectra reveals that the O-H, -C=C-, C-C, C-O bonds and the aliphatic chains are existed in fraction A2. The purified anti-cyanobacterial active compounds are identified as Lys and Phe with HPLC-MS. The anti-cyanobacterial activity assay indicates the purified amino acids have good anti-cyanobacterial effects against M. aeruginosa with the inhibition efficiency of 94.1% +/- 3.5% and 80.8% +/- 4.3% for Lys and Phe, respectively. It is speculated that amino acids secreted by B. amyloliquefaciens T1 may be used as a biological agent and are potentially useful for controlling HCBs.

Automated summary

The anti-cyanobacterial microorganism Bacillus amyloliquefaciens T1 produces amino acids Lys and Phe which have been purified and shown to have good anti-cyanobacterial effects with inhibition efficiencies of 94.1% and 80.8% respectively against Microcystis aeruginosa. These amino acids secreted by T1 could potentially be used as a biological agent to control harmful cyanobacterial blooms.