Madhaiyan M, Poonguzhali S, Senthilkumar M, Sundaram Sp, Sa Tongmin
Department of Agricultural Chemistry, Chungbuk National University, 48 Gaesin-dong, Cheongju, Chungbuk 361-763, Republic of Korea.
Microbiol Res. 2009;164(1):114-20. doi: 10.1016/j.micres.2006.08.009. Epub 2006 Oct 30.
The nitrogen fixing methylotrophic bacteria were isolated from the nodules of tropical legumes. Two isolates CMCJ317 and CMSA322 isolated from Crotalaria juncea and Sesbania aculeata possessing high nitrogenase activities under pure culture conditions and able to form nodules under inoculated conditions were further characterized. The biochemical characteristics revealed their close relationship with Methylobacterium nodulans type strain ORS2060. The PCR amplification of nodA and mxaF genes showed the expected 584 and 555 bp products, respectively, similar to M. nodulans ORS2060 and digestion with restriction enzymes revealed that the two isolates differed. The strains showed significantly higher nitrogenase activity and also improved nodulation and shoot nitrogen of the plants when inoculated to Macroptilum atropurpureum. CMCJ317 and CMSA322 formed nodules on C. juncea and M. atropurpureum under green house conditions and also significantly increased the nitrogen concentration in shoots. These findings show that the ability to establish symbiosis with legumes is more widespread in Methylobacterium.
固氮甲基营养菌是从热带豆科植物的根瘤中分离得到的。从菽麻和刺田菁中分离出的两株菌株CMCJ317和CMSA322，在纯培养条件下具有较高的固氮酶活性，且在接种条件下能够形成根瘤，对其进行了进一步的特性研究。生化特性表明它们与结瘤甲基杆菌模式菌株ORS2060关系密切。对nodA和mxaF基因进行PCR扩增，分别得到了预期的584 bp和555 bp产物，与结瘤甲基杆菌ORS2060相似，用限制性内切酶消化后发现这两株分离菌株存在差异。当接种到大翼豆上时，这些菌株表现出显著更高的固氮酶活性，同时也改善了植株的结瘤情况和地上部氮含量。CMCJ317和CMSA322在温室条件下能在菽麻和大翼豆上形成根瘤，还显著提高了地上部的氮浓度。这些发现表明，甲基杆菌与豆科植物建立共生关系的能力更为普遍。
