Utilization of atmospheric ammonia by an extremely oligotrophic bacterium, Rhodococcus erythropolis N9T-4
Utilization of atmospheric ammonia by an extremely oligotrophic bacterium, Rhodococcus erythropolis N9T-4
复制标题
DOI：
10.1016/j.jbiosc.2013.06.005
复制
发表时间：
2014-01-01
影响因子：
2.8
通讯作者：
Takagi, Hiroshi
中科院分区：
文献类型：
--
作者：
Yoshida, Nobuyuki;Inaba, Satoshi;Takagi, Hiroshi
红球红球菌N9T-4表现出极少营养生长，需要二氧化碳才能生长。本文对N9T-4寡营养生长的氮源进行了研究。与大多数其他细菌一样，N9T-4在无碳源的无机最低限度培养基上更喜欢将铵盐作为氮源。有趣的是，N9T-4也能在没有碳源和氮源的琼脂糖或硅胶固化的最小培养基上生长，这表明该细菌对氮也是寡养的。由于在细胞中未检测到固氮酶活性，在N9T-4基因组中也没有发现编码固氮酶的基因，因此可以排除该细菌进行重氮化生长的可能性。DNA芯片分析表明，其中一个氨转运蛋白基因(AmtB)在寡营养条件下的上调幅度是异养条件下的40-50倍。在氮素限制条件下，amtB基因的中断导致了生长缺陷。此外，在无氮源的最低限度的密闭培养体系中，添加氨蒸气能促进N9T-4的生长。这些结果表明，N9T-4利用微量大气氨作为氮源。(C)2013年，日本生物技术学会。版权所有。
Rhodococcus erythropolis N9T-4 shows extremely oligotrophic growth and requires CO2 for its growth. In this report, nitrogen sources for the oligotrophic growth of N9T-4 were examined. As is true for most other bacteria, N9T-4 preferred ammonium salt to nitrate as the nitrogen source on an inorganic minimum medium without carbon sources. Interestingly, N9T-4 could also grow on the minimal medium solidified by agarose or silica gel without carbon and nitrogen sources, suggesting that this bacterium is also oligotrophic for nitrogen. We can rule out the possibility of diazotrophic growth of this bacterium, because nitrogenase activity was not detected in the cells and the putative gene encoding nitrogenase was not found in N9T-4 genome. DNA microarray analysis revealed that one of the ammonium transporter genes (amtB) was strongly upregulated 40-50 fold higher under oligotrophic conditions than under heterotrophic conditions. Disruption of amtB led to a growth defect under nitrogen-limiting conditions. Furthermore, additional ammonia vapor enhanced the growth of N9T-4 on the minimum medium without nitrogen sources in a closed culture system. These results suggest that N9T-4 utilizes the trace amount of atmospheric ammonia as the nitrogen source. (C) 2013, The Society for Biotechnology, Japan. All rights reserved.