甲烷古菌群感效应信号分子的检测

竹节状甲烷鬃菌(Methanosaeta harundinacea)6Ac是本实验室分离自厌氧颗粒污泥中的甲烷古菌新种。该菌具有短杆(3μm-5μm)和长链状(>200μm)两种细胞形态,且与细胞密度相关,暗示该菌可能存在群感效应调控的细胞形态变化。【目的】验证该菌存在群感效应信号分子并与细胞形态变化相关。【方法】用高丝氨酸内酯指示菌Agrobacterium tumefaciens NTL4检测菌株6Ac的培养液,并用购买的高丝氨酸内酯标准品加入短杆菌株6Ac检测形态变化。【结果】菌株6Ac的培养液中含有高丝氨酸内酯类物质。实验证明化学合成的高丝氨酸内酯N-(β-酮基)辛酰高丝氨酸内酯能够促进竹节状甲烷鬃菌的长链细胞形成。而且在马氏甲烷八叠球菌(Methanosarcina mazei)、热自养甲烷杆菌(Methanothermobacter thermautotrophicus)和甲酸甲烷杆菌(Methanobacterium formicicum)的培养液中也检测到了高丝氨酸内酯。【结论】多种甲烷古菌可以产生高丝氨酸内酯类物质,并可能以此类物质作为群感效应的信号分子。

Detection of the quorum sensing signals in methanogenic Archaea

Methanosaeta harundinacea 6Ac displayed a cell-density dependent cell morphology transition between short rods(3 μm-5 μm) and filaments(>200μm),implying a quorum sensing system in this archaeon.Objective] This study aimed to confirm that cell morphology related quorum sensing exists in Methanosaeta harundinacea.Methods] By using the bioassay of Agrobacterium tumefaciens NTL4,we determined the presence of acyl homoserine lactones(AHLs) in the spent cultures of Methanosaeta harundinacea 6Ac and other three methanogens.A chemical synthetic AHL,N-(β-Ketooctanoyl)-L-homoserine lactone was added into the culture of short rods to detect the morphology change.Results] We determined that AHLs were produced by Methanosaeta harundinacea,Methanosarcina mazei,Methanothermobacter thermautotrophicus and Methanobacterium formicicum.Addition of N-(β-Ketooctanoyl)-L-homoserine lactone into the culture of Methanosaeta harundinacea 6Ac stimulated the formation of filamentous cells.Conclusion] This study indicates that AHL-based quorum sensing may be used by several species of methanogenic Archaea.