Fast-growing과 Slow-growing Rhizobium japonicum의 생화학적 특성

Biochemical Characterization of Fast-and Slow-Growing Rhizobium japonicum

국내에서 분리된 대두근류균을 생육속도에 따라서 2.4시간의 평균세대시간을 가지는 fast-grower와 13.1시간의 평균세대시간을 가지는 slow-grower로 나눌 수 있었다. Fest-grower는 6-phosogluconate dehydrogenase 효소역가가 slow-grower 보다 높았으며 sucrose를 탄소원으로 이용하였다. Fest-grower 중에서 특히 R4, R278은 NaCl 0.5M농 도에서도 생육하였으며 시험한 대두 근류균은 모두 pH 4.5 이하에서 생육이 저지되었다. 또한 식물배양기 조건하에서 접종실험을 한 결과 시험된 모든 대두품종에 양호하게 근류를 형성하였으며 L-259 (NRRL) 균주에 비해서 0.1-2배의 질소고정력을 나타내었다.

Rhizobium japonicum isolates from all around Korea could be classified into two groups, i.e., acid producing fast-growers with 2.4 hour mean generation time and non-acid producing slow-growers in yeast extract-mannitol medium with 13.1 hour mean generation time. Tested fast-growers were higher in 6-phosphogluconate dehydrogenase activity than slow-growers were and used sucrose as carbon source whereas slow-growers did not. Fast-grower R4, R257, R278, showed tolerance even in 0.5M NaCl or above and the growth of all the strains tested were inhibited at below pH 4.5. Relative symbiotic activities of nitrogen fixation for these isolated with Glycine max cv. Jangyeobkong (commercial soybean cultivar mostly cultivated in Korea) ranged 0.1 to 2.0 comparing to that of R. japonicum L-259 (NRRL), without regard to their growth rate.