马铃薯内生固氮菌的分离及其促生特性研究

内生固氮菌是一类重要的植物促生菌,占据着植物组织内有利于营养供应和微环境适宜的生态位,能更好的发挥促生功能,促生机制包括固氮、解磷、产植物生长素、产ACC脱氨酶、产铁载体及拮抗病害等。本文从连作3年马铃薯根筛选获得8株内生固氮菌,其中短芽孢杆菌属(Brevibacterium)3株,芽孢杆菌属(Bacillus)3株和泛菌属(Pantoea)2株。促生特性研究发现:菌株Brevibacterium sp.GWR4具有较高固氮酶活性16.206nmol C2H4/(mg蛋白质·h)],与圆褐固氮菌的固氮酶活性具有极显著性差异(P0.01);菌株Pantoea spp.GWR2、GWR3具有极高的产IAA能力,分别为186.07、162.21μg/m L,GWR2兼具产ACC脱氨酶活性3.74μmol/(mg蛋白质·h)],GWR3兼具溶解无机磷的能力;菌株Brevibacterium sp.GWR5可以拮抗尖孢镰刀菌MLSOF(Fusarium xysporum)和茄病镰刀菌MLS-QB(Fusarium solani),兼具溶解有机磷和产IAA能力;Bacillus spp.GWR7、GWR8兼具固氮和产IAA能力。盆栽试验显示,分别接种Pantoea sp.GWR3,Brevibacterium spp.GWR4、GWR5和Bacillus spp.GWR7、GWR8后小白菜鲜重显著高于未接菌对照处理。可见,这5株菌兼具多种促生特性且对小白菜具有较好的促生效果,有望进一步研究开发成为微生物肥料生产菌种。

Isolation and functional characterizations of potato endogenous nitrogen-fixing bacteria

Endogenous nitrogen-fixing bacteria is one of important plant promoting growth bacteria and occupies the plant tissue which is conductive to nutrient supply and suitable micro ecological environment and can better promote growth. The promoting plant growth mechanisms includes nitrogen fixation, phosphate solubilization, phytohormone production, ACC-deaminase pro-duction and suppression of pathogens. In this study, eight endogenous nitrogen-fixing bacteria were isolated from the root of po-tato and were identified as Brevibacterium ( 3 ) , Bacillus ( 3 ) , and Pantoea ( 2 ) . The results of functional characterizations showed that the nitrogenase activity of Brevibacterium sp. GWR4 was 16. 206 nmol C2 H4/( mg protein·h) , which was signifi-cantly higher (P<0. 01) than that of Azotobacter charoococcum. Pantoea spp. GWR2 with ACC-deaminase activity and GWR3 with solubilization of inorganic phosphate had high capacities of IAA-production with 186. 07 μg/mL and 162. 21 μg/mL, re-spectively. Brevibacterium sp. GWR5, with solubilization of organic phosphate and production of IAA, had the capability to antagonize the growth of Fusarium solani MLS-QB and Fusarium xysporum MLS-OF. Bacillus spp. GWR7 and GWR8 had the nitrogenase activities and produced IAA. The pot trial showed that the fresh weights of Chinese cabbage inoculated with GWR3, GWR4, GWR5, GWR7, GWR8 were significantly higher than that with no inoculation control, respectively. The five bacte-ria with functional characterizations should have good application prospect.