Jeong So-Yeon, Cho Kyung-Suk, Kim Tae Gwan
Department of Microbiology, Pusan National University, Pusan 46241, Republic of Korea.
Department of Environmental Science and Engineering, Ewha Womans University, Seoul 03760, Republic of Korea.
J Microbiol Biotechnol. 2018 Oct 28;28(10):1706-1715. doi: 10.4014/jmb.1804.04015.
Several non-methylotrophic bacteria have been reported to improve the growth and activity of methanotrophs; however, their interactions remain to be elucidated. We investigated the interaction between sp. M6 and sp. NM2. A batch co-culture experiment showed that NM2 markedly increased the biomass and methane removal of M6. qPCR analysis revealed that NM2 enhanced both the growth and methane-monooxygenase gene expression of M6. A fed-batch experiment showed that co-culture was more efficient in removing methane than M6 alone (28.4 18.8 μmol·l·d), although the biomass levels were similar. A starvation experiment for 21 days showed that M6 population remained stable while NM2 population decreased by 66% in co-culture, but the results were opposite in pure cultures, indicating that M6 may cross-feed growth substrates from NM2. These results indicate that M6 apparently had no negative effect on NM2 when M6 actively proliferated with methane. Interestingly, a batch experiment involving a dialysis membrane indicates that physical proximity between NM2 and M6 is required for such biomass and methane removal enhancement. Collectively, the observed interaction is beneficial to the methanotroph but adversely affects the non-methylotroph; moreover, it requires physical proximity, suggesting a tight association between methanotrophs and non-methylotrophs in natural environments.
据报道，几种非甲基营养型细菌可促进甲烷营养菌的生长和活性；然而，它们之间的相互作用仍有待阐明。我们研究了菌株M6和菌株NM2之间的相互作用。分批共培养实验表明，NM2显著增加了M6的生物量和甲烷去除量。定量聚合酶链反应（qPCR）分析显示，NM2增强了M6的生长以及甲烷单加氧酶基因的表达。补料分批实验表明，尽管生物量水平相似，但共培养在去除甲烷方面比单独培养M6更有效（28.4±18.8 μmol·l·d）。一项为期21天的饥饿实验表明，在共培养中，M6的数量保持稳定，而NM2的数量减少了66%，但在纯培养中结果相反，这表明M6可能从NM2获取交叉营养生长底物。这些结果表明，当M6以甲烷为底物积极增殖时，对NM2显然没有负面影响。有趣的是，一项涉及透析膜的分批实验表明，NM2和M6之间的物理接近对于这种生物量和甲烷去除的增强是必要的。总体而言，观察到的这种相互作用对甲烷营养菌有益，但对非甲基营养菌有不利影响；此外，它需要物理接近，这表明在自然环境中甲烷营养菌和非甲基营养菌之间存在紧密的联系。
