Gao Yuqian, Zhang Qi, Chen Yuannan, Yang Yanqing, Zhou Chenxiao, Yu Jiayang, Li Yanan, Qiu Liyou
Key Laboratory of Enzyme Engineering of Agricultural Microbiology, Ministry of Agriculture and Rural Affairs, College of Life Sciences, Henan Agricultural University, Zhengzhou 450046, China.
Microorganisms. 2024 Dec 30;13(1):43. doi: 10.3390/microorganisms13010043.
Nitrogen fertilizers in agriculture often suffer losses. Ammonia-assimilating bacteria can immobilize ammonia and reduce these losses, but they have not been used in agriculture. This study identified an ammonia-assimilating strain, sp. B12, which assimilated ammonia via the glutamate dehydrogenase (GDH) pathway at low levels (5 mM) and the glutamine synthetase (GS)-glutamine-2-oxoglutarate aminotransferase (GOGAT) pathway at high levels (10 mM). Inoculating wheat with B12 increased seedling dry weight, nitrogen accumulation, rhizosphere soil nitrogen content, and root enzyme activities, including GDH, superoxide dismutase (SOD), catalase (CAT), and peroxidase (POD), under both conditions. However, root GS, GOGAT enzyme activities, and ammonia assimilation-related gene expressions were lower than the controls. The results suggest that the ammonia-assimilating bacterium promotes wheat growth, nitrogen accumulation, and soil nitrogen immobilization by establishing an ammonia and amino acid exchange with roots and enhancing root antioxidant capacity, making it a potential plant growth-promoting rhizobacteria (PGPR).
农业中的氮肥经常会出现损失。氨同化细菌可以固定氨并减少这些损失，但尚未在农业中得到应用。本研究鉴定出一株氨同化菌株，即 sp. B12，其在低水平（5 mM）时通过谷氨酸脱氢酶（GDH）途径同化氨，在高水平（10 mM）时通过谷氨酰胺合成酶（GS）-谷氨酰胺-2-酮戊二酸氨基转移酶（GOGAT）途径同化氨。在这两种条件下，用B12接种小麦均增加了幼苗干重、氮积累、根际土壤氮含量以及根酶活性，包括GDH、超氧化物歧化酶（SOD）、过氧化氢酶（CAT）和过氧化物酶（POD）。然而，根GS、GOGAT酶活性以及氨同化相关基因表达低于对照。结果表明，该氨同化细菌通过与根建立氨和氨基酸交换并增强根抗氧化能力来促进小麦生长、氮积累和土壤氮固定，使其成为一种潜在的植物促生根际细菌（PGPR）。
