| Water blooms caused by bule-green algae broke out frequently all over the world, which led to serious environmental problems. Salvaging and dealing with the blue-green algae from polluted water timely could avoid the deterioration of water body caused by the rotting of algae in the water. However, the secondary pollution would be caused by the rotting of salvaged algae if they were stacked simply and were not treated timely and effectively. How to deal with the Taihu lake algae effectively and promptly is one of key questions in the course of solving Tailu Lake algae Pollution.In this paper, an algae-lysing bacterium with a strong algicidal effect was isolated from Taihu Lake. Through making cyanobacteria cells broken, the strain could make water contained in algal cells be released quickly. At the same time, microcystin (MC) degradation bacteria was isolated from Taihu Lake. Microcystins of salvage blue algae were degradated quickly and efficiently by solid state fermentation technology. This would provide theoretical and technical support for resource utilization of salvage blue algae in Taihu Lake.An algae-lysing bacterium CA with a strong algicidal effect to Microcystis aeruginosa was isolated from Taihu Lake was identified as Aquimonas sp. by morphological features, physiological and biochemical characteristics, as well as phylogenetic analysis of C16S rDNA sequences. The degradation rate of CA against Microcystis aeruginosa cells and chlorophyll a were100%and83.9%in ten days respectively. Algicidal effect of CA was positively correlated with the concentration of bacterial suspensions, while negatively correlated with algal concentration. The bacterium body of CA had no algicidal effect, but their sterile filtrate could lyse Microcystis aeruginosa significantly, which indicated that CA lysed Microcystis aeruginosa in an indirect way through excreting algae-lysing substance. The CA cells showed algicidal effect when adding a small amount of beef extract, glucose or urea to algal liquid culture.CA filtrate had algicidal effect. Microcystis aeruginosa cells and chlorophyll a decreased after ten days. At the same time, phycocyanin and allophycocyanin decreased dramatically, and the MDA content also decreased. Through the study of algicidal substances activity, it was found that algicidal substances were nonprotein substances, and the algicidal substances had well thermal stability which had algicidal effect even under the treatment of dealing with2h at121℃. Furthermore the algicidal substances had a strong pH stability under alkaline conditions, but there would be a little part of the loss of algicidal activity in the acidic conditions. Through the organic reagent extraction, it was found that algicidal substance had strong polarity. At the same time, CA fermentation broth had algicidal effect for rich algal water and algal mud in Taihu Lake.A MC-RR degradation bacterium CM1was isolated from Taihu Lake. The CM1was identified as Lysinibacillus boronitolerans by morphological features, physiological and biochemical characteristics, as well as phylogenetic analysis of16S rDNA sequences. The effects of the temperature and pH on the biodegradation activity of MC-RR by strain CM1were investigated. MC-RR was degraded from12.8μg/mL to1.7μg/mL in60h with the degradation rate of86.9%. The optimal temperature and pH for biodegradation of MC-RR were37℃and7.0, respectively. Based on the research of MC-RR degradation by the extracellular and intracellular substances, both of them could degrade MC-RR, furthermore, intracellular substance had a stronger degradation activity, and MC-RR of7.3ug/mL could be completely degradated in12h.After the algae muds were broken by algicidal strain CA fermentation broth, the broken algae mud water was mixed with rapeseed cakes, and the protein degrading bacteria and microcystins degrading bacteria were added, then the mixtrue was aerobically composted. During the composting process, organic matter in the pile was decreased, while the total nitrogen tended to increase. Carbon to nitrogen ratio also showed a decreasing trend. The results of33days cyanobacteria compost showed that the cyanobacteria compost could be finished after a month based on the determination of the pH, temperature, organic matter, the total nutrient and seed germination index of the compost. After33days of fermentation, microcystins in the cyanobacteria compost were significantly reduced from6.8μg/kg at the beginning to0.6μg/ml at the end, in which the degradation rate of microcystins reached by90.71%. |
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