Diversity of aromatic compound-degrading genes in relation to soil capacity to protect from pollution

发展地球上的可持续农业是不可或缺的。要实现可持续农业，必须发展保护土壤肥力不受农药和单季种植等各种胁迫的技术，并保持土壤微生物多样性。本研究调查了土壤微生物的结构和多样性及其与土壤抗化学胁迫能力的关系，并对土壤DNA的提取方法进行了优化。利用通用引物和内切酶对16SrDNA进行了扩增，结果表明，不同施肥措施下的土壤中16SrDNA呈现出特定的限制性片段长度多态。融合点测定表明，施入农家肥的土壤中高G+C DNA含量增加。并与其他分析土壤微生物群落结构的方法进行了比较：磷脂脂肪酸组成、呼吸苯二酚谱、Biolog；&lt；；证实了高G+C DNA的增加。通过测定土壤中五氯酚(PCP)和2，4，5，6-四氯间苯二甲腈(TPN)的降解速率，考察了土壤对化学胁迫的保护能力。接受农家肥的土壤对它们的降解速度更快。主要降解菌为五氯苯酚革兰氏阴性杆菌和多种真菌(尤其是镰刀菌)。对于TPN，活性微生物群的降解能力与土壤中总微生物群落结构的变化趋势不一致。用聚合酶链式反应扩增方法对BPHC等加氧酶基因进行了检测。

It is indispensable to develop the sustainable agriculture on the earth. To realize the sustainable agriculture, it is essential to develop the technology to protect the soil fertility from various stresses such as pesticides and mono-cropping, and keep the soil microbial diversity. In this study, we investigate the structure and diversity of soil microorganisms and ita relation wity the capacity of soil to protect from the chemical stresses.The extraction method of soil DNA was optimized. The PCR amplifications of16SrDNA using universal primet sets and endonuclease digestion showed specific patterns of restriction fragment length polymorphism in the soils recieving different fertilizing practices. Melitng point measurement revealed the increase in high G+C DNA in the soil receiving farmyard manure. This results were compared with other methods to anaiyze the microbial community structure in soil : phospholipid fatty acids composition, respiratory quinone profile, Biolog^<<encircledR>> plate substrate assimilation test. The increase in the high G+C DNA was comfirmed. The soil capacity to protect from chemical stresses was examined by measuring the degradation rate of pentachlorophenol (PCP) and 2,4,5,6-tetrachl oroisophthalonitrile (TPN) in soil. The soil receiving farmyard manure degraded them faster. The major degrading microorganisms were a Gram-negative rod for PCP and various fungi (especialy Fusarium spp.) for TPN.The active microhial gropus for the degradation capacity did not admit with the tendency of total microbial community structure in soil. The detestion of oxgenase genes such as bphc was also tried by PCR amplification method.