Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, 510070, China.
Guangdong Provincial Key Laboratory of Microbial Culture Collection and Application, State Key Laboratory of Applied Microbiology Southern China, Guangdong Institute of Microbiology, Guangdong Academy of Sciences, Guangzhou, 510070, China.
Environ Pollut. 2021 Feb 1;270:116261. doi: 10.1016/j.envpol.2020.116261. Epub 2020 Dec 15.
Antibiotics are frequently used for clinical treatment and by the farming industry, and most of these are eventually released into the surrounding environment. The impact of these antibiotic pollutants on environmental microorganisms is a concern. The present study showed that after Pseudomonas putida entered the logarithmic growth phase, tetracycline strongly stimulated its biofilm formation in a dose-dependent manner. This was supported by the increased expression of the key adhesin gene lapA in response to tetracycline treatment. Tetracycline treatment also changed the expression levels of the exopolysaccharide gene clusters alg, bcs and pea and the adhesin gene lapF. However, these genes did not participate in the tetracycline-induced biofilm formation. When a biofilm had been established, the P. putida population became more tolerant to tetracycline. Confocal laser scanning microscopic images showed that the interior of the biofilm provided favorable conditions that protected bacterial cells from tetracycline. Besides, biofilm formation of P. putida was also promoted by several other antibiotics, including oxytetracycline, fluoroquinolones, rifampicin, and imipenem, but not aminoglycosides. Susceptibility tests suggested that biofilm conferred a higher tolerance on P. putida cells to specific antibiotics (e.g., tetracyclines and fluoroquinolones). These antibiotics exerted a stronger inducing effect on biofilm formation. Together, our results indicate that P. putida actively forms robust biofilms in response to antibiotic stress, and the biofilms improve the survival of bacterial population under such stress.
抗生素常被用于临床治疗和农业领域，其中大部分最终会释放到周围环境中。这些抗生素污染物对环境微生物的影响令人担忧。本研究表明，在恶臭假单胞菌进入对数生长期后，四环素以剂量依赖的方式强烈刺激其生物膜形成。这一现象得到了 lapA 关键黏附素基因表达增加的支持，而 lapA 基因对四环素处理有反应。四环素处理还改变了 alg、bcs 和 pea 外多糖基因簇和黏附素基因 lapF 的表达水平。然而，这些基因并未参与四环素诱导的生物膜形成。当生物膜形成后，恶臭假单胞菌种群对四环素的耐受性增加。共聚焦激光扫描显微镜图像显示，生物膜内部为细菌细胞提供了有利于保护其免受四环素影响的条件。此外，其他几种抗生素，包括土霉素、氟喹诺酮类、利福平、亚胺培南，也能促进恶臭假单胞菌的生物膜形成，但不能促进氨基糖苷类抗生素的生物膜形成。药敏试验表明，生物膜使恶臭假单胞菌细胞对特定抗生素（如四环素类和氟喹诺酮类）具有更高的耐受性。这些抗生素对生物膜形成具有更强的诱导作用。总之，我们的研究结果表明，恶臭假单胞菌会积极响应抗生素压力形成坚固的生物膜，而生物膜能提高细菌种群在这种压力下的生存能力。
