Isolation, identification and characterization of phytoplankton-lytic bacterium CH-22 against Microcystis aeruginosa

Abstract

a b s t r a c tA bacterial strain named CH-22 showing phytoplankton-lytic activity against bloom-forming cyanobacterium Microcystis aeruginosa was isolated from Lake Chaohu of Anhui Province, China. The isolated strain was identified as Pseudomonas putida by morphology and homology research based on 16S rDNA. The phytoplankton-lytic activity was confirmed by reduction in cell number and chlorophyll a concentration of M. aeruginosa in an infected culture for a defined period. The initial bacterial and M. aeruginosa densities affected the phytoplankton-lytic activity significantly. When the 15% (150 mL/mL) concentration of bacterial cultures was infected, the highest phytoplankton-lytic activity reached to 98.8% after 7 days. When the initial M. aeruginosa density was less than 3 Â 10 6 cells/mL, about 90.0% of chlorophyll a was removed. Obvious reduction in phycocyanin concentration in the treated M. aeruginosa suggests that isolated strain may possibly inhibit the synthesis of photosynthetic apparatus. Supernatants of bacterial cultures showed higher phytoplankton-lytic activity, suggesting that phytoplankton-lytic bacterium P. putida indirectly attacked M. aeruginosa cells by secretion of extracellular antialgal substances, which is characterized as anti-heat shock. The isolated P. putida also showed effective phytoplankton-lytic activity against a wide range of phytoplankton. These results suggest that indigenous bacteria isolated from eutrophic lake may be employed to regulate the ecological balance between the phytoplankton and bacteria, and consequently, to reduce the occurrence of cyanobacterial blooms in freshwaters.

Factors affecting the virulence of Ralstonia solanacearum and its colonization on tobacco roots

“…The genomic DNA was extracted using a genomic DNA purification kit (AxyPrep). The 16S rRNA gene was amplified by PCR, performed as described by Zhang et al (2011) using the universal primers 27F (5 0 -GAGAGTTT-GATCCTGGCTCAG-3 0 ) and 1541R (5 0 -AAGGAGGTGATC-CAGCCGCA-3 0 ) (Hsiao & Kirby, 2008). The PCR product was purified and sequenced by Takara Biotechnology (Dalian) Co. Ltd. A comparison of the nucleotide sequence and relative nucleotide sequences in the NCBI database was carried out using BLAST.…”

Cyanobactericidal Effect of Streptomyces sp. HJC-D1 on Microcystis auruginosa

“…Similar to our results, Hua et al [4] found that Streptomyces strain NT0401 caused a significant reduction in live M. aeruginosa cells at 5% (v/v) treatment level. The cyanobactericidal activity of microorganisms towards many kinds of cyanobacteria have also been published in other recent studies [5], [7], [30], and the effective removal efficiencies of Chl a were reported as approximately 50%–98% at a suitable bacterial density for more than 6 d [30], [31]. However, cell viability was restored after treatment for a period of time [10].…”

Isolation and Characterization of Algicidal Bacterium against the Toxic Cyanobacterium Microcystis Aeruginosa

“…The micro-morphological observations were carried out using light microscope and scanning electron microscope (SEM). Under light microscope, the bacterium was observed by gram staining [12]. For SEM observation, the bacterium was cultured for 14 days on agar medium and then fixed overnight with osmium tetroxide vapor, freeze-dried, mounted on the stub, sputter-coated with gold palladium and examined under a scanning electron microscope.…”