热液贻贝共附生群体感应细菌的筛选及功能初探

Screening and Function Study of Quorum Sensing Bacteria Associated with Hydrothermal Mussels

为了探究热液贻贝共附生微生物中是否存在群体感应(Quorum sensing, QS)细菌及若存在会拥有的功能,本研究对西南印度洋天成热液区贻贝鳃中可培养共附生细菌进行分离、鉴定,并从中筛选群体感应细菌,对群体感应细菌的信号分子种类,以及成膜和二甲基巯基丙酸(DMSP)利用能力进行探究。结果显示:从热液贻贝鳃中分离共附生细菌96株,根据16S rRNA基因序列确定了25株不同菌株,它们分属于4个门、5个纲、14个属。其中:变形菌门(Proteobacteria)是优势菌群,占比64%;玫瑰杆菌类群占20%。筛选出群体感应细菌3株(Sulfitobacter pontiacus TCYB15、Sulfitobacter pontiacus TCYB21和Roseivivax marinus TCYB24),它们具有产生C8-HSL、C6-HSL两种AHLs信号分子的能力,且都具有成膜和利用DMSP的潜力。本研究证实热液贻贝共附生微生物中存在群体感应细菌,推测它们可在鳃中形成生物膜并在与贻贝共附生过程中参与硫的循环。

The deep-sea hydrothermal area is an extreme environment with huge temperature variation, high toxicity, and low oxygen concentration. However, numerous mussels still existed in deep-sea hydrothermal area and were symbiotic with a large number of microorganisms. It is not clear whether there are quorum sensing(QS) bacteria in these microorganisms. In this study, cultivable associated bacteria from mussel gills in the southwest Indian Ocean hydrothermal area named Tianchen were isolated and identified. Quorum sensing bacteria were screened and the types of AHL signal molecules were analyzed. The abilities to form biofilm and utilize dimethylsulfoniopropionate(DMSP) of quorum sensing bacteria were assessed. The results showed that 96 strains of cultivable associated bacteria were isolated from the mussel gills. According to the 16 S rRNA gene sequence, 25 different strains were identified and belonged to 4 phyla, 5 classes, 14 genera. Among them, Proteobacteria is the dominant flora, accounting for 64%, and the Roseobacter group accounts for 20%. Three strains of quorum sensing bacteria(Sulfitobacter pontiacus TCYB15,Sulfitobacter pontiacus TCYB21 and Roseivivax marinus TCYB24) were screened out. They produced two AHLs signaling molecules(C8-HSL and C6-HSL) and had the functions of forming biofilm and utilizing DMSP. This study confirmed the existence of quorum sensing bacteria in the associated microorganisms of hydrothermal mussels. It is speculated that they can form biofilm in the gills and participate in the sulfur cycle in the process of symbiosis with mussels.