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

在地球上发展可持续农业是必不可少的。为了实现农业的可持续发展，必须发展保护土壤肥力的技术，使其免受农药和单一作物等各种胁迫，并保持土壤微生物的多样性。在本研究中，我们研究了土壤微生物的结构和多样性及其与土壤抵御化学胁迫能力的关系。优化了土壤DNA的提取方法。利用通用引物集和酶切酶切对16srdna进行PCR扩增，发现不同施肥条件下土壤中限制性内切片段长度多态性的特定模式。熔点测定结果显示，接受农家肥的土壤中高G+C DNA含量增加。该结果与其他分析土壤微生物群落结构的方法（磷脂脂肪酸组成、呼吸醌谱、Biolog^<<encircledR>>板底物同化试验）进行了比较。高G+C DNA的增加得到证实。通过测定土壤中五氯酚（PCP）和2,4,5,6-四烷基或二苯二腈（TPN）的降解速率，考察了土壤对化学胁迫的保护能力。接受了农家肥的土壤降解得更快。PCP的主要降解微生物为革兰氏阴性棒，TPN的主要降解微生物为各种真菌（尤其是镰刀菌）。活性微生物群的降解能力与土壤微生物群落结构的总体趋势不一致。用PCR扩增法检测氧化酶基因，如bphc。

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.