School of Biological Sciences, Universiti Sains Malaysia, Gelugor, Malaysia.
Biotechnology Research Institute, Universiti Malaysia Sabah, Kota Kinabalu, Malaysia.
Lett Appl Microbiol. 2021 May;72(5):610-618. doi: 10.1111/lam.13455. Epub 2021 Feb 18.
Paenibacillus durus strain ATCC 35681 is a Gram-positive diazotroph that displayed capability of fixing nitrogen even in the presence of nitrate or ammonium. However, the nitrogen fixation activity was detected only at day 1 of growth when cultured in liquid nitrogen-enriched medium. The transcripts of all the nifH homologues were present throughout the 9-day study. When grown in nitrogen-depleted medium, nitrogenase activities occurred from day 1 until day 6 and the nifH transcripts were also present during the course of the study albeit at different levels. In both studies, the absence of nitrogen fixation activity regardless of the presence of the nifH transcripts raised the possibility of a post-transcriptional or post-translational regulation of the system. A putative SigA box sequence was found upstream of the transcription start site of nifB1, the first gene in the major nitrogen fixation cluster. The upstream region of nifB2 showed a promoter recognizable by SigE, a sigma factor normally involved in sporulation.
坚韧芽胞杆菌（Paenibacillus durus）菌株 ATCC 35681 是一种革兰氏阳性固氮菌，即使在存在硝酸盐或铵盐的情况下，也表现出固氮能力。然而，当在富含氮的液体培养基中培养时，仅在生长的第 1 天检测到氮固定活性。在整个 9 天的研究中，所有 nifH 同源物的转录本都存在。当在氮缺乏的培养基中生长时，固氮酶活性从第 1 天持续到第 6 天，并且在研究过程中也存在 nifH 转录本，尽管水平不同。在这两项研究中，无论是否存在 nifH 转录本，氮固定活性的缺失都提出了该系统可能受到转录后或翻译后调控的可能性。在主要氮固定簇的第一个基因 nifB1 的转录起始位点上游发现了一个假定的 SigA 框序列。nifB2 的上游区域显示出可被 SigE 识别的启动子，SigE 是一种通常参与孢子形成的 sigma 因子。
