摘要:
固氮微生物菌种选育是固氮微生物肥料生产应用的基础。本研究从玉米根际土壤分离到1株高效固氮菌株GD542, 菌体短杆状, 0.4 μm×1.0~1.5 μm, 革兰氏阴性; 固氮酶活性为5.046 nmol (C2H4)·h-1·mg-1(蛋白); 利用碳源较广泛, 抗逆性较强, 既可在4 ℃低温生长, 也可以在37 ℃下生长, 耐盐性高达10%。16 S rDNA序列分析结果表明, 该菌株与鞘氨醇单孢菌Sphingomonas azotifigens的16 S rDNA序列有高达96%的同源性, 结合形态特征和生理生化特征等, 将其初步鉴定为鞘氨醇单孢菌Sphingomonas sp.。接种小白菜的温室盆栽试验表明, 菌株GD542具有很好的固氮效能, 与无氮对照相比, 接种GD542处理植株干重增加206%, 含氮量增加230%, 达到统计学显著差异水平, 开发应用前景较好。
Abstract:
Breeding of nitrogen-fixing bacteria is the basis for nitrogen-fixing microbial fertilization. A high efficiency nitrogen-fixing bacteria Sphingomonas GD542 was isolated from maize rhizosphere — a short rod of 0.4 mm×1.0~1.5 mm, G-, with 5.046 nmol (C2H4)·h-1·mg-1(protein) nitrogenase activity, that can grow from 4 ℃ to 37 ℃ and resistant to 10% NaCl. Phylogeny based on 16 S rDNA sequence shows that GD542 shares 96% DNA homology with S. azotifigens. Based on the analysis results of morphology, physiology, chemical property, and 16 S rDNA sequencing, strain GD542 is identified as Sphingomonas sp. Green house test shows a statistically significant increase in dry weight and nitrogen content in pakchoi inoculated with GD542 strain, indicating high nitrogen fixing ability of GD542 strain. There is 206% increase in dry weight and 230% increase in plant nitrogen content of pakochoi compared with the control. Hence GD542 strain holds a good prospect for future applications.
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