甲烷氧化菌素的产生和铜捕获作用

Production and Copper Acquisition Ability of Methanobactin

甲烷氧化菌素(mb)是由甲烷氧化菌产生的与铜捕获和吸收有关的生物螯合剂。采用NMS/CAS-Cu劈半平板法检测发现甲基弯菌Methylosinus trichosporium IMV3011在以甲烷和甲醇为碳源时均具有向外界分泌mb的能力。甲基弯菌Methylosinus trichosporium IMV3011在限铜胁迫下能够在培养介质中积累mb,甲醇为碳源时mb的积累量明显高于甲烷为碳源时mb的积累量,推测mb的合成与细胞中NADH含量有关。mb的专一性研究发现从甲基弯菌Methylos inustrichosporium IMV3011发酵上清液中分离到的mb能够提高其它3种甲烷氧化菌由无铜培养基向含铜培养基转移时的pMMO活性的表达,并明显缩短它们由无铜培养基转移到含铜培养基时生长的延滞期,提高生长速度。表明其它3种甲烷氧化菌同样能够吸收来自于甲基弯菌Methylosinus trichosporium IMV3011的mb捕获的铜。

Methanobactin（mb）is biochelator that appears to function as an agent for copper acquisition and uptake in methanotrophs.The production of mb during growth of Methylosinus trichosporium IMV 3011 on methane and methanol was determined by split nitrate mineral salts/CAS-Cu（chrome azurol S）plates.mb was found to be accumulated in the spent medium of Methylosinus trichosporium IMV 3011 under copper-limited condition.The mb production ability of methanol-grown cells were obviously higher than that of methane-grown cells.It has been speculated that methanol can act as the electron-donating substrate to regenerate the NADH and drive mb synthesis.The effect of mb from Methylosinus trichosporium IMV3011 on the growth lag,growth rate and whole-cell pMMO（particles Methane Monooxygenase）activity of other methanotrophs were measured respectively to assess the specifity of mb.It has been shown that mb from Methylosinus trichosporium IMV 3011 can accelerate the expression of whole cell pMMO activity of other methanotrophs when cultures are exposed to elevatory copper concentration.Also,mb from Methylosinus trichosporium IMV 3011 can shorten the growth lag and increase the growth rate of other methanotrophs either in elevatory or constant copper concentration.The results suggested that other methanotroph may take delivery of copper from mb released by Methylosinus trichosporium IMV 3011.