喹啉降解反应器菌群内整合子检测和菌株耐药性分析

Detection of integron and antibiotic resistance analysis in a lab-scale quinoline degrading microbial community

摘要:

本文运用PCR技术及克隆文库方法, 对一个实验室规模的喹啉降解反应器生物膜系统中的整合子进行了分析。结果表明, 在该反硝化喹啉降解反应器的生物膜群落中, 整合子携带着丰富多样的基因盒。主要为编码与抗生素耐药性相关的基因盒, 如氨基糖苷类耐药基因(aadA基因等), 也带有与工业废水环境发现的整合子中可能与芳香族化合物降解有关的基因(如FldF基因)。还有一些功能未知的基因。鉴于耐药性相关基因的广泛存在, 对该反应器中分离的优势菌株进行了耐药性分析。结果表明, 44.1%的菌株存在耐药性, 29.4%的菌株有多重耐药性。它们对4种抗生素的耐药率分别为: 氨苄青霉素29.4%、卡那霉素23.5%、氯霉素20.6%、链霉素23.5%。不存在抗生素选择压力环境的微生物群落中分离的群落优势菌株普遍具有抗生素耐药性, 而且群落基因组的整合子中携带多种抗生素抗性基因的基因盒。这一现象还未曾见报道, 其成因值得进一步研究。

Abstract:

In this study, PCR and clone library methods were used to analyze the composition and potential functions of integrons in the ecosystem of a lab-scale quinoline-degrading bioreactor. The results showed that the integrons carried gene cassettes of sizes between 200 bp and 1 000 bp. Some gene cassettes could not find any analogue in database. But some of them are similar with the sequences of integrons previously found in industrial wastewater, such as FldF gene, which might be related to degradation of aromatic compounds. Many cassettes had aminoglycoside resistance genes, such as aadA gene, which might encode antibiotic-resistance protein. To verify this result, we measured the antibiotic resistance pattern of 34 isolated strains, which were dominant in the quinoline-degrading bioreactor. Results indicated 44.1% of the isolates were resistant to antibiotics, and the incidence of multiple antibiotic resistances was 29.4%. The ratio of resistance to ampicillin, kanamycin, chloromycetin, streptomycin of the isolates were 29.4%, 23.5%, 20.6%, 23.5%, respectively. There barely exists antibiotic stress in the quinoline wastewater bioreactor and the environment where seed sludge came from. However, the dominant bacterial strains were generally resistant to antibiotic and many integrons carried resistance gene in first gene cassette. This phenomenon so far has not been reported and its mechanism needs further study.