获得性抗生素抗性基因在蔬菜发酵过程中的水平转移规律与分子机制研究

Recently, the acquired antibiotic resistance genes (AARGs), a new type diffused pollution, are increasing global concern and their horizontal transfers is a new research topic in the food safety. For scientific understanding and preventing the food safe risks of AARGs, it is an important to clarify their horizontal transfer law and molecular mechanisms in the food processing. The fermentation food industry is an important parts of Chinese food industries, while its fermentation processing, which is mediated by complex microorganisms, provides a better ecological court for the AARGs transfer and dissemination among the microorganisms. Unfortunately, in the fermentation processing, the systemic research were carried out till now. In this project, the molecular elements, the horizontal transfer laws, the transfer molecular mechanisms and the affecting transfer factors will be systematically investigated in the lactic acid bacteria of Sichuan pickle vegetable materials, fermentation environments and fermentation process. The AARGs horizontal transfer laws, molecular mechanisms and important factors affected on the horizontal transfer among the same species and different species lactic acid bacteria throughout the fermentation process will be revealed by the analysis of horizontal transfer element category, candidate gene clone, bacteriophage transduction, the DNA sequence homology of horizontal transfer elements, and the relevance between the horizontal transfer frequency and the fermentation factors. This result will provide the scientific base to evaluate food safety and to design the effective strategies to control AARGs horizontal transfer in vegetable fermentation process.

作为全球关注的新型面源污染之一，获得性抗生素抗性基因（AARGs）的水平转移成为了食品安全领域近年来研究的新课题。AARGs在食品加工过程中的水平转移规律与分子机制的阐明对科学认识和防控AARGs的食品安全风险具有极为重要的意义。发酵食品是我国食品产业的重要组成部分，其发酵过程多样化的微生物参与为AARGs水平转移提供了高风险的生态场所，但目前缺乏系统深入研究。项目以中国发酵蔬菜的典型代表-四川泡菜为材料，在考察蔬菜原料和发酵环境AARGs污染的基础上，重点研究发酵过程中乳酸菌的AARGs水平转移元件、转移规律、分子机制以及影响转移的因素，通过对转移元件类型、候选基因、转移元件同源性、转移频率与发酵因子的相关性和噬菌体转导的分析，揭示蔬菜发酵过程中AARGs的水平转移规律与分子机制，阐明影响AARGs水平转移的重要因素，为正确评估发酵蔬菜AARGs的安全风险和制定相关防控策略提供科学依据。

获得性抗生素抗性基因（AARGs）导致的潜在食品风险成为了近年来食品领域研究的新课题。发酵蔬菜中多样化的微生物参与为AARGs水平转移提供了高风险。项目重点研究了四川泡菜原料和发酵过程中乳酸菌、ARGs和AARGs水平转移元件、转移规律、分子机制以及影响转移的因素等，结果表明：①不同蔬菜附生的优势乳酸菌群落结构不同，其中Weissella属常被检出；蔬菜中四环素和链霉素的耐药菌株比例相对较高，其中tetB、tetC、strB检出频率最高；菌株耐药性高低与耐药基因种类和数量无相关性。② 发酵过程中，ARGs浓度与细菌总量显著正相关；发酵乳酸菌中检出了tetD的水平转移元件I类整合子基因int I1；食窦魏斯氏菌W5检出质粒水平转移元件pA010，该质粒上的II型毒素-抗毒素系统能够赋予宿主多种抗生素耐药性；融合魏斯氏菌Q10检出了能够转移多种AARGs的水平转移元件ISCR1。③菌株耐药性不一定是抗性基因引起，其它抗逆系统转移也可以导致菌株产生抗生素耐药性。④发酵过程中，喹诺酮类和青霉素类抗性基因能够通过ISCR1，以7.47-7.98×10-4向食窦魏斯氏菌、戊糖乳杆菌、植物乳杆菌和肠膜明串珠菌水平转移。⑤蔬菜原料抗生素残留和含抗菌性的香辛料能够能够促进AARGs转移。上述结果为正确评估发酵蔬菜AARGs的安全风险和制定相关防控策略提供了科学依据。