Nitrogen fixation in Rhodopseudomonas palustris co-cultured with Bacillus subtilis in the presence of air
Nitrogen fixation in Rhodopseudomonas palustris co-cultured with Bacillus subtilis in the presence of air
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DOI：
10.1016/j.jbiosc.2018.10.010
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发表时间：
2019-05-01
影响因子：
2.8
通讯作者：
Maeda, Isamu
中科院分区：
文献类型：
--
作者：
Arashida, Haruka;Kugenuma, Takumi;Maeda, Isamu
紫色非硫细菌（PNSB）在好氧条件下培养时，即使在无氮培养基中也不发生固氮作用。假设PNSB可能不具有足够的能力来保护其蜂窝组件免于暴露于空气（20.95体积%）。氧气）。因此，本研究将枯草芽孢杆菌与紫色非硫细菌沼泽红球藻一起接种在无氮培养基中，以检测Rps是否固氮。当共培养物暴露于20.95体积%时，发生沼泽化氧气Rps.沼泽藻只有与B一起接种时才能生长并形成生物膜。枯草杆菌。当在共培养物中形成的生物膜接种在无N培养基中时，在连续传代培养中观察到固氮生长。在与Rps共培养的条件下，nifH基因的表达、固氮酶活性的解除、总氮的增加和C/N的降低均得到了明显的改善。palustris和B.枯草芽孢杆菌证明了在有氧条件下固氮的发生。在密封培养容器中，较低的培养基与空气比抑制了固氮菌的生长，B的生长也受到抑制。枯草芽孢杆菌先于Rps生长。palustris在共培养。这些结果表明，B.枯草芽孢杆菌的生长通常伴随着耗氧，这可能导致培养基中溶解氧浓度的降低，从而有助于固氮酶活性的产生。沼泽(C)2018年，日本生物技术学会。All rights reserved.
Nitrogen fixation in purple non-sulfur bacteria (PNSB) does not take place even in N-free medium when they are cultured under aerobic conditions. It is assumed that PNSB might possess inadequate capability to protect their cellular components from exposure to air (20.95 vol.% oxygen). In this study, therefore, Bacillus subtilis was inoculated together with a purple non-sulfur bacterium Rhodopseudomonas palustris in N-free medium in order to examine whether nitrogen fixation in Rps. palustris takes place when the co-culture is exposed to 20.95 vol.% oxygen. Rps. palustris grew and formed biofilm only when it was inoculated together with B. subtilis. When the biofilm formed in the co-culture was inoculated in N-free medium, diazotrophic growth was observed in the sequential subcultures. Expression of nifH gene, derepression of nitrogenase activity, an increase of total nitrogen, and a decrease of C/N in the co-culture of Rps. palustris and B. subtilis demonstrated the occurrence of nitrogen fixation under aerobic conditions. The diazotrophic growth was suppressed at a lower medium-to-air ratio in a sealed culture vessel, and growth of B. subtilis preceded growth of Rps. palustris in the co-culture. These results suggest that growth of B. subtilis, which is usually accompanied with oxygen consumption, might cause a decrease of dissolve oxygen concentration in medium and contribute to the occurrence of nitrogenase activity in Rps. palustris. (C) 2018, The Society for Biotechnology, Japan. All rights reserved.