玉米根际高效固氮菌Sphingomonas sp. GD542的分离鉴定及接种效果初步研究

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,0.4μm×1.0～1.5μm,革兰氏阴性;固氮酶活性为5.046nmol(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%。16SrDNA序列分析结果表明,该菌株与鞘氨醇单孢菌Sphingomonas azotifigens的16SrDNA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。

Isolation, identification and inoculation effect of nitrogen-fixing bacteria Sphingomonas GD542 from maize rhizosphere

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 _2H_4)·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.