Algicidal metabolites produced by Bacillus sp. strain B1 against Phaeocystis globosa.

The bloom of Phaeocystis globosa has broken out frequently in the coastal areas of China in recent years, which has led to substantial economic losses. This study shows that Bacillus sp. strain B1, which was previously identified by our group, is effective in regulating P. globosa by excreting active metabolites. Heat stability, pH stability and molecular weight range of the algicidal compounds from strain B1 were measured and the results demonstrated that the algicidal activities of these compounds were not affected by pH or temperature variation. The algicidal compounds extracted with methanol were isolated and purified by ODS-A column chromatography and HPLC. The algicidal compounds corresponding to peaks 2-5 eluted from HPLC were further analysed by quadrupole time-of-flight mass spectrometry (Q-TOF-MS). PeakView™ Software determined the compounds corresponding to peaks 2-5 to be L-histidine, o-tyrosine, N-acetylhistamine and urocanic acid on the basis of the accurate mass information, the isotopic pattern and MS-MS spectra. Furthermore, these compounds were also able to eliminate Skeletonema costatum, Prorocentrum donghaiense and Heterosigma akashiwo. This is the first report of bacteria-derived algicidal compounds being identified only by Q-TOF-MS and PeakView™ Software, and these compounds may be used as the constituents of algicides in the future.