一株耐酸野生葛藤(Pueraria lobata)根瘤菌的筛选与耐酸机理初步研究

Primary study on acid tolerance mechanism of a wild aciduric Rhizobium strain isolated from Pueraria lobata

从重庆市北碚区缙云山酸性黄壤（pH4．6）上生长的葛藤根瘤中分离到一株耐酸葛藤根瘤菌PR389，能在pH4．3的YMA培养基上正常生长，而一般根瘤菌最适生长pH值为6．5—7．5，说明PR389为一株耐酸葛藤根瘤菌。通过质子通量试验发现，与不耐酸的菌株相比，PR389的细胞膜能阻止过量的H^＋进入细胞，表明PR389具有某种能力使之在低酸性环境下不受伤害。在耐酸性试验中，PR389在加氯霉素的强酸性（pH3．8）YMA培养液中表现出来的耐酸性被氯霉素抑制。推测胞内特异蛋白质的诱导合成是PR389具有耐酸性的原因。

An aciduric Rhizobium strain, named as PR389 , was isolated from the nodule of wild Pueraria Iobata which grew in yellow soil （pH4.6） on the Jin-yun Mountain in Bei-bei, Chong-qing city. The isolated strain, which could grow under pH 4.6 distinct from the optimal pH 6.5 - 7.5 for rhizobium, showed some typical features of aciduric rhizobium. This was also confirmed by the proton flux assay. Compared to the acid-sensitive Rhizobium strain PR21, the cell membrane of PR389 could hold back excessive H^＋ entering cell. This feature can protect PR389 from harm of acid. In the test of acid tolerance, the aciduric ability of strain PR389 under low acidic（pH3.8） was restrained by antibiotic chloramphenicol. It was speculated that special proteins in the cells of PR389 could be induced and synthesized in acidic environment.