Isolation and characterization of an algicidal bacterium indigenous to lake Taihu with a red pigment able to lyse microcystis aeruginosa / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To isolate and characterize indigenous algicidal bacteria and their algae-lysing compounds active against Microcystis aeruginosa, strains TH1, TH2, and FACHB 905.</p><p><b>METHODS</b>The bacteria were identified using the Biolog automated microbial identification system and 16S rDNA sequence analysis. The algae-lysing compounds were isolated and purified by silica gel column chromatography and reverse-phase high performance liquid chromatography. Their structures were confirmed by Nuclear Magnetic Resonance (NMR) and Fourier Transform Infrared (FT-IR) spectroscopy. Algae-lysing activity was observed using microscopy.</p><p><b>RESULTS</b>The algae-lysing bacterium LTH-2 isolated from Lake Taihu was identified as Serratia marcescens. Strain LTH-2 secreted a red pigment identified as prodigiosin (C20H25N3O), which showed strong lytic activity with algal strains M. aeruginosa TH1, TH2, and FACHB 905 in a concentration-dependent manner. The 50% inhibitory concentration (IC50) of prodigiosin with the algal strains was 4.8 (± 0.4)× 10⁻² μg/mL, 8.9 (± 1.1)× 10⁻² μg/mL, and 1.7 (± 0.1)× 10⁻¹ μg/mL in 24 h, respectively.</p><p><b>CONCLUSION</b>The bacterium LTH-2 and its pigment had strong Microcystis-lysing activity probably related to damage of cell membranes. The bacterium LTH-2 and its red pigment are potentially useful for regulating blooms of harmful M. aeruginosa.</p>

Enrichment and Molecular Characterization of a Bacterial Culture Involved in Lysis of Microcystis aeruginosa / 微生物学通报

An enrichment culture showing specific algae-lysing activity was isolated from the mixtures of different samples and Microcystis aeruginosa. The process of algal lysis was monitored by chlorophyll measurement, PCR, and denaturing gradient gel electrophoresis (DGGE). The result showed that the enrichment culture had still high algicidal activity against M. aeruginosa after 1/100000 dilution. Rubritepida sp. C1, Pseudomonas sp. C2 and Sphingomonas sp. C3, as accompanying bacteria, existed in M.aeruginosa. The bacterial community in M. aeruginosa showed significant change after adding the enrichment culture, where uncultured Flavorbacterium sp. A2, Sphingomonas sp. C3 and Hydrogenophaga sp. A3 were observed, and A2 became a dominant species. The obvious correlation can be seen between change of bacterial population and extinction of M. aeruginosa. Compared identification of pure bacterium with sequencing of DGGE band, it was inferred that uncultured bacteria were probably play an important role in controlling the growth and abundance of M. aeruginosa.

ADVANCES ON ALGICIDAL SUBSTANCES PRODUCED BY ALGICIDAL BACTERIA / 微生物学通报

In recent years,more and more researchers have realized the possibility that algicidal bacteria could be a useful tool in reducing the impact of harmful algae blooms. In this review, the ecological roles of algicidal substances was briefly discussed, then special emphasis placed on the categories and extract methods of algicidal substances which have been reported. Some ideas for the further studies on algicidal substances were also proposed.