巨菌草一株内生固氮菌的分子鉴定及生物学特性

Molecular Characterization and Biological Characteristics of Endophytic Nitrogen-fixing Bacteria in JUNCAO

菌草(JUNCAO)是可作为栽培食用菌、药用菌的草本植物。内生固氮菌具有生物固氮的功能,可以促进植物生长,提高植物对病原菌的拮抗作用。采用无氮培养基、乙炔还原法等方法从巨菌草根中分离纯化到1株具有较强固氮酶活性的菌株,固氮酶活性值为270.20 nmolC2H4/(mL·h)。通过16S rDNA序列分析,进一步确定该菌株属于变栖克雷伯氏菌(Klebsiella variicola)。内生固氮菌株fjg102对稻瘟病菌Guy11和Ku70的抑菌率分别为40.25%和44.30%,具有一定的抑制病原菌的作用。菌株fjg102革兰氏染色阳性,具有溶磷作用、触酶反应为阳性、明胶液化为阳性等生理生化特性。盆栽试验结果表明,接种fjg102菌株后对大麦有明显的促生作用。其中叶长增加37.26%,根长增长9.40%,根重增加66.16%,鲜重增加96.40%,干重增加80%。可见,该内生固氮菌株具有生物固氮和促生的效果,可进一步研究开发成为微生物肥料生产菌种。

JUNCAO are herbaceous plants that can be used as the substrate for edible and medicinal fungi cultivation.Endophytic nitrogen-fixing bacteria have the function of biological nitrogen fixation,which can promote plant growth and enhance the antagonism of plants against pathogenic bacteria.In this study,one strain with strong nitrogenase activity was isolated and purified from the roots of JUNCAO by nitrogen-free medium and acetylene reduction method and was identified as Klebsiella variicola by16 S r DNA sequence.The nitrogenase activity of Klebsiella variicola fjg102 was 278.22 nmol/(m L·h).fjg102 strain has antifungi activity against Magnaporthe oryzae Guy11 and Ku70,with the inhibitory rate of 40.25%and 44.30%.It was found that the strain fjg102 was Gram-positive,and has phosphorus solubilization,catalase-positive and gelatin liquefaction positive.When inoculated on barely,fjg102 strain show obvious promoting effects.Among them,the length of leaves increased by 37.26%,the root length increased by 9.40%,the root weight increased by 66.16%,the fresh weight increased by 96.40%,and the dry weight increased by 80%.In summary,The Klebsiella variicola fjg102 isolated from JUNCAO should has good application prospect.