Biological control of zebra mussels by indigenous pathogenic bacteria and their extracellular products

Abstract

摘要 无脊椎动物斑马贝(Dreissena polymorpha) 的生物污损造成了巨大的经济损失，而应用从斑马贝体内分离出的土著菌株及其体外代谢产物对它进行生物防治是一种经济效益显著且对环境友好的方法.本文主要报导从斑马贝体内分离的土著菌株中筛选出致病菌并研究该细菌及其代谢产物对它的控制作用.在三十多种土著菌株中，中间气单胞菌（ Aeromonas media），维罗纳气单胞菌（A. veronii），杀鲑气单胞菌杀鲑亚种（A. salmonicida subsp. salmonicida）和腐败希瓦氏菌（Shewanella putrefaciens）是幼体斑马贝的致命致病菌.当接种量为每只斑马贝107 个细菌时，接种中间气单胞菌、杀鲑气单胞菌杀鲑亚种和腐败希瓦氏菌的5 d 死亡率为100%，而维罗纳气单胞菌为65%.通过扫描电镜(SEM)发现，垂死的斑马贝肌肉组织被破坏并含有大量的细菌.4种细菌代谢产物的不同组分表现出对斑马贝不同的致死效果，在所研究的3种不同Mr组分中（Mr<5×103,5×10310×103及>10×103），>10 ×103组分具有最高致死率.这些结果为控制贝类无脊椎动物的生物污损提供了新方法. 图4 参24 Abstract Biofouling agent zebra mussel (Dreissena polymorpha) has caused enormous economic losses. Application of biological control method using indigenous microorganisms isolated from zebra mussels or extracellular materials extracted from these bacteria is economically significant and environmentally favored. The objectives of this study were to screen virulent bacterial species from isolated indigenous microorganisms of zebra mussels and to elucidate the function of microbial products in controlling the zebra mussels infestation. Among more than 30 bacteria isolated from temperature stressed mussels, Aeromonas media, A. veronii, A. salmonicida subsp. salmonicida, and Shewanella putrefaciens were virulent pathogens to juvenile zebra mussels. Inoculation of A. media, A. salmonicida subsp. salmonicida and S. putrefaciens resulted in 100% mortality within 5 d at 107 cells per zebra mussel, and 65% for A. veroni. On the mussel tissue a dense microbial population was evident from the moribund mussels viewed with Scanning Electron Microscopy (SEM). Bacterial metabolites, fractionated and concentrated from stationaryphase cultural supernatants (cell free) of the four bacterial isolates, displayed varying degrees of antagonistic effects on zebra mussels. Among the three size fractions examined, Mr<5×103, 5×10310×103,and>10×103, the most lethal fraction seems to be>10×103 for three of the four isolates tested. The results suggest that both selective indigenous microorganisms and their extracellular metabolites may provide novel strategies for control of biofouling invertebrates. Fig 4, Ref 24