球形棕囊藻溶藻菌的分离鉴定及溶藻作用研究

【目的】从广西北部湾海域分离筛选和鉴定针对球形棕囊藻的溶藻细菌，研究其溶藻特性。【方法】采用梯度稀释和平板划线法从海水水样中分离纯化溶藻菌，菌藻共培养后，通过观察颜色和测定叶绿素a含量筛选溶藻菌，形态观察和细菌16S rDNA测序鉴定溶藻菌；通过光学显微镜观察溶藻菌的溶藻过程，测定溶藻菌菌液、菌体重悬液、无菌滤液的溶藻率，分析其主要溶藻方式，通过测定菌藻共培养后藻液的叶绿素a含量，研究溶藻菌的生长时期、菌液添加量、球形棕囊藻的生长阶段、光照等对溶藻效果的影响。【结果】分离筛选出一株具有高效溶藻作用的溶藻菌PG47，鉴定为高地芽孢杆菌。PG47间接抑藻，溶藻活性物质可以破坏藻细胞的细胞壁和细胞膜。对数期以后的菌液均具有较好的溶藻活性，且当菌液与藻液体积比达到5%以后，溶藻率就高达80%，对处于延迟期、对数期、平台期的球形棕囊藻均具有高效的溶藻效果，在不同光照条件下，溶藻率均维持在60%以上，适用性广。【结论】筛选得到高地芽孢杆菌PG47是一株高效溶球形棕囊藻菌，为治理球形棕囊藻赤潮提供了一种新思路。

Isolation, Identification and Algicidal Characteristics of algicidal bacteria on Phaeocystis globosa

Objective] To isolate, screen and identify algicidal bacteria on Phaeocystis globosa from Beibu Gulf of Guangxi and study its algicidal activity. Method] Algicidal bacteria were isolated and purified by 10-fold serial dilution and plate streaking method. Algicidal bacteria were screened by observing color and determining chlorophyll a content after co-culture of bacteria and algae. Algicidal bacteria were identified by morphological observation and 16SrDNA sequences analysis. The algicidal progress was observed with light microscope. The main algicidal way were analyzed by measuring the algicidal rate of bacterial culture, washed bacteria and sterile filtrate. The algae-lysing effects of culture time, inoculum, growth stage of Phaeocystis globosa and light conditions were studied by measuring the content of chlorophyll after co-culture of bacteria and algae. Results] An algicidal bacterium (PG47) with high-efficiency algicidal activity was isolated and identified as Bacillus altitudinis from Beibu Gulf. The algicidal mode of the strain PG47 was indirect that its extracellular secretions could destroy the cell wall and cell membrane. The bacterial suspension during log, stationary and decline phase all show significant algicidal activity. The algicidal rate can achieve 80% when the bacterial / algal suspension volume ratio is more than 5%. It has algicidal effect on Phaeocystis globosa in each culture stage and keep above 60% under different light conditions. Conclusion] The isolated Bacillus altitudinis PG47 has high-efficiency algicidal activity showing potential for the control of Phaeocystis globosa red tide.