摘要
      抗生素耐药性细菌（ARB）和抗生素耐药性基因（ARGs）是对人类健康构成风险的新兴污染物。为了研究致病性ARB和通过细胞外ARG（eARGs）和细胞内ARG（iARGs）的水平基因转移（HGT），建立了体外消化模拟系统来监测通过人工消化道的ARB和ARG。结果表明，ARB主要受胃液酸度的影响，约99%的ARB（总种群为2.45×109–2.54×109）在pH 2.0时被杀死，并严重损伤细菌细胞膜。然而，当胃液的pH值为3.0及以上时，超过80%的ARB（总人口为2.71×109–3.90×109）在挑战中存活下来。大多数ARB死于高酸度，但可以检测到其ARGs、intI1和16S rRNA。eARGs（占总基因的0.03~24.56%）明显少于iARGs。eARGs显示出比iARGs更大的HGT潜力，这表明转化比结合更容易发生。转移潜能依次为tet（100%）>sul（75%）>bla（58%），与intI1与tetA和sul2的高度相关性有关（p<0.01）。此外，与对照相比，pH 1.0的胃液可以将ARGs的转移频率降低2-3个数量级，但仍对人类健康构成潜在风险。在消化液的处理下，ARGs表现出较高的基因水平转移潜力，这表明食源性ARGs对ARGs向肠道细菌的水平转移具有很大的风险。
Abstract
Antibiotic resistance bacteria (ARB) and antibiotic resistance genes (ARGs) are emerging contaminants posing risk to human health. To investigate the pathogenic ARBs and the horizontal gene transfer (HGT) via both extracellular ARGs (eARGs) and intracellular ARGs (iARGs), an in vitro digestion simulation system was established to monitoring the ARB and ARGs passing through the artificial digestive tract. The results showed that ARB was mostly affected by the acidity of the gastric fluid with about 99% ARB (total population of 2.45 × 109–2.54 × 109) killed at pH 2.0 and severe damage of bacterial cell membrane. However, more than 80% ARB (total population of 2.71 × 109–3.90 × 109) survived the challenge when the pH of the gastric fluid was 3.0 and above. Most ARB died from the high acidity, but its ARGs, intI1 and 16 S rRNA could be detected. The eARGs (accounting for 0.03–24.56% of total genes) were less than iARGs obviously. The eARGs showed greater HGT potential than that of iARGs, suggesting that transformation occurred more easily than conjugation. The transferring potential followed: tet (100%) > sul (75%) > bla (58%), related to the high correlation of intI1 with tetA and sul2 (p < 0.01). Moreover, gastric juice of pH 1.0 could decrease the transfer frequency of ARGs by 2–3 order of magnitude compared to the control, but still posing potential risks to human health. Under the treatment of digestive fluid, ARGs showed high gene horizontal transfer potential, suggesting that food-borne ARBs pose a great risk of horizontal transfer of ARGs to intestinal bacteria.

https://www.sciencedirect.com/science/article/pii/S0147651322010879