不同基模势下luxAB标记的弗氏中华根瘤菌在土壤中的存活能力

经接合转移将luxAB基因插入弗氏中华根瘤菌（Rhizobium fredii)染色体，取可高效结瘤固氮的R fredii lux3菌株用于分子生态学研究，在不同基模势下，研究了lux3在土壤中的存活，基模势为－30和－750kPa时，lux3在灭菌土中的存活能力明显（P＜0．05）高于未灭菌土，当基模势为－1500kPa时，土壤是否灭菌对lux3的存活影响没有差异，不同基模势对lux3活性影响显著，在－1500kPa的未灭菌土中随着饥饿时间的延长，可恢复活性的细菌数量显著下降，比较了测定微生物活性的3种方法（即脱氢酶活性，生物发光和微生物呼吸），发光值变化与活细胞密度变化一致。

SURVIVAL POTENTIAL OF luxAB MARKED RHIZOBIUM FREDII IN SOIL AT DIFFERENT MATRIC POTENTIAL

The lux AB gene is a convenient and useful marker for Rhizobium fredii . The lux AB gene was inserted into the chromosome of R. fredii by conjugation. R.fredii lux 3 which could nodulate and fix nitrogen efficiently was used in studying on molecular ecology of R. fredii . The survival and activity of R.fredii lux 3 were studied following inoculation into soil microcosms at different matric potentials. Survival potential of lux 3 was significantly ( P <0.05) greater in sterile than non sterile soil at -30 and -750 kPa, but it was not affected by autoclaving of soil at -1 500 kPa. The activity of R. fredii lux 3 in soil were influenced significantly by different matric potential. Reactivation decreased greatly with prolonged starvation in non sterile soil at -1 500 kPa. Population activity was measured by dehydrogenase activity, bio luminecence and respiration.Metabolic activity measured by luminescence decreased significantly with time ( P <0.05). Fig 4, Tab 2, Ref 8