不同土壤中紫花苜蓿根瘤菌抗逆性的比较

Stress Resistence of Alfalfa Rhizobium from Different Soil Types

为准确评价紫花苜蓿(Medicago sativa L.)根瘤菌的抗盐性,采用GGE双标图对来自盐碱土和黑土的6个紫花苜蓿根瘤菌(Rhizobium)菌株分别进行耐盐性、耐酸碱及其泌酸碱能力的评价研究。结果表明:黑土土壤紫花苜蓿根瘤菌株Hmx-c耐盐性极强,在10%NaCl培养基上生长正常;盐碱土壤紫花苜蓿根瘤菌株Lmx-a和黑土土壤紫花苜蓿根瘤菌株Hmx-b耐酸性最强,能在pH 4.0的培养基上正常生长;耐碱性最强的是盐碱土壤菌株Hmx-c,可以在pH 12.0的培养基上正常生长。进一步试验表明,菌株Hmx-a既能抗pH 4.0的酸逆境,又能抗pH 11.0的碱逆境。根瘤菌菌株耐碱性的强弱与其泌酸能力相关。

Six rhizobia strains were isolated from the alfalfa root of two soil types in Heilongjiang province. The salt-resistant, acid-alkali resistant and acid-alkali secreting ability of each strain were studied using GGE method. Result showed that alfalfa rhizobia strain numbered as Hmx-c from black soil type had the strongest salt-resistant ability, and regularly grew in 10% NaC1 medium. Alfalfa rhizobia strain numbered as Lmx-a from saline-alkali soil type and Hmx-b from black soil type had the strongest acid-resistant abili- ty, and regularly grew in medium with pH value of 4.0. The strain numbered as Hmx-c from saline-alkali soil type possessed the strongest alkali-resistant ability, and regularly grew in medium with pH value of 12.0. A further experiment indicated that strain numbered as Hmx-a resisted both acid stress with pH val- ue of 4.0 and alkali stress with pH value of 11.0. Meanwhile, the ability of alkali resistance was interre- lated to the ability of acid secreting.