基模势对luxAB标记的快生型大豆根瘤菌在土壤中存活的影响

经接合转移将luxAB基因插入快生型大豆根瘤菌 (Rhizobiumfredii)染色体 ,取可高效结瘤固氮的R .frediilux3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在灭菌土中的生存能力明显 (P<0 .0 5)高于未灭菌土 ,当基模势为 - 1 50 0kPa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 - 1 50 0kPa的未灭菌土中 ,随着饥饿时间延长 ,可恢复活性的细菌数量显著下降 .同时比较了测定微生物活性的 3种方法 (即生物发光、脱氢酶活性和微生物呼吸 ) ,发光值变化与活细胞密度变化一致 ,PLf值 (即潜在发光 ,Potentialluminescence)反映了可恢复活性的饥饿种群密度 .luxAB基因是一种比较简便而实用的标记

Effect of matric potential on the survival of luxAB marked Rhizobium fredii in soil.

The luxAB gene were inserted into the chromosome of Rhizobium fredii by conjugation.R.fredii lux3 which could nodulate soybean and fix nitrogen efficiently was used in studying on molecular ecology of R. fredii. The survival and activity of R.fredii lux3 were studied following inoculation into soil microcosms at different matric potentials.Survival were significantly (P<0.05) greater in sterile soil at -30 and -750 kPa than that in nonsterile soil.Survival at - 1500 kPa was not affected by autoclaving of soil.The activity of R. fredii lux3 in soil were influenced significantly by different matric potentials.Reactivation decreased greately with prolonged starvation.Population activity was measured by liquid scillination, dehydrogenase activity and respiration.Metabolic activity measured by luminescence decreased significantly with time (P<0.05).Luminescence following amendment with substrates ( potential luminescence,PLf) demonstrated the time required for activation of the starved inoculum.Therefore,luxAB gene was a convenient and useful marker for R.fredii.