Department of Marine Biology, Microbiology and Biochemistry, School of Marine Sciences, Cochin University of Science and Technology, Cochin, Kerala, India.
School of Environmental Sciences, Mahatma Gandhi University, Kottayam, Kerala, India.
J Basic Microbiol. 2017 Nov;57(11):922-932. doi: 10.1002/jobm.201700072. Epub 2017 Aug 8.
In the present study, we report the nitrogen fixing potential of heterotrophic diazotrophs isolated from a tropical estuary and adjacent coastal sea. Results of the study revealed that most of the species that are capable of fixing nitrogen in the study area belongs to the genus Bacillus. The isolates from the estuary showed maximum homology with Bacillus megaterium, B. cereus, B. safencis, B. licheniformis, B. aerophilus, B. oceanisediminis, B. flexus, B. aquimaris, B. vietnamensis, and B. subterraneaus, whereas the diazotrophic isolates from coastal samples were closely related to B. subtilis, B. megaterium, B. circulans, B. aerophilus, B. flexus, and B. oceanisediminis. Experimental studies to determine the nitrogen fixation potential of isolates revealed considerable variation among different strains and the highest nitrogen fixing potential was recorded in B. megaterium (210.05 ± 7.0 nmol C H /mg protein/day) followed by B. flexus (108.76 ± 3.66 nmol C H /mg protein/day) and B. circulans (98.28 ± 4.32 nmol C H /mg protein/day). Molecular basis of nitrogen fixation by these heterotrophic Bacillus strains has been explored in terms of the presence of nifH gene in them. We observed that heterotrophic Bacillus sp. have potential ability to fix nitrogen.
在本研究中，我们报告了从热带河口和相邻沿海水域分离的异养固氮菌的固氮潜力。研究结果表明，在研究区域中能够固氮的大多数物种属于芽孢杆菌属。来自河口的分离物与巨大芽孢杆菌、蜡样芽孢杆菌、苏云金芽孢杆菌、地衣芽孢杆菌、嗜气芽孢杆菌、海洋解氮芽孢杆菌、弯曲芽孢杆菌、水生芽孢杆菌、越橘芽孢杆菌和深层芽孢杆菌的同源性最高，而来自沿海样本的固氮分离物与枯草芽孢杆菌、巨大芽孢杆菌、环状芽孢杆菌、嗜气芽孢杆菌、弯曲芽孢杆菌和海洋解氮芽孢杆菌密切相关。确定分离物固氮潜力的实验研究表明，不同菌株之间存在相当大的差异，最大固氮潜力记录在巨大芽孢杆菌（210.05±7.0 nmol C H /mg 蛋白/天），其次是弯曲芽孢杆菌（108.76±3.66 nmol C H /mg 蛋白/天）和环状芽孢杆菌（98.28±4.32 nmol C H /mg 蛋白/天）。从这些异养芽孢杆菌菌株的氮固定的分子基础方面探讨了 nifH 基因的存在。我们观察到异养芽孢杆菌具有固氮的潜在能力。
