Department of Food Science and Technology, Laboratory of Microbiology and Biotechnology of Foods, Agricultural University of Athens, Athens, Greece.
Appl Environ Microbiol. 2012 Apr;78(8):2586-95. doi: 10.1128/AEM.07099-11. Epub 2012 Feb 3.
This study aimed to investigate the possible influence of bacterial intra- and interspecies interactions on the ability of Listeria monocytogenes and Salmonella enterica to develop mixed-culture biofilms on an abiotic substratum, as well as on the subsequent resistance of sessile cells to chemical disinfection. Initially, three strains from each species were selected and left to attach and form biofilms on stainless steel (SS) coupons incubated at 15°C for 144 h, in periodically renewable tryptone soy broth (TSB), under either monoculture or mixed-culture (mono-/dual-species) conditions. Following biofilm formation, mixed-culture sessile communities were subjected to 6-min disinfection treatments with (i) benzalkonium chloride (50 ppm), (ii) sodium hypochlorite (10 ppm), (iii) peracetic acid (10 ppm), and (iv) a mixture of hydrogen peroxide (5 ppm) and peracetic acid (5 ppm). Results revealed that both species reached similar biofilm counts (ca. 10(5) CFU cm(-2)) and that, in general, interspecies interactions did not have any significant effect either on the biofilm-forming ability (as this was assessed by agar plating enumeration of the mechanically detached biofilm bacteria) or on the antimicrobial resistance of each individual species. Interestingly, pulsed-field gel electrophoresis (PFGE) analysis clearly showed that the three L. monocytogenes strains did not contribute at the same level either to the formation of mixed-culture sessile communities (mono-/dual species) or to their antimicrobial recalcitrance. Additionally, the simultaneous existence inside the biofilm structure of S. enterica cells seemed to influence the occurrence and resistance pattern of L. monocytogenes strains. In sum, this study highlights the impact of microbial interactions taking place inside a mixed-culture sessile community on both its population dynamics and disinfection resistance.
本研究旨在探究细菌种内和种间相互作用对李斯特菌和肠炎沙门氏菌在非生物基质上形成混合培养生物膜的能力以及固定细胞随后对化学消毒的抗性的可能影响。最初，从每个种中选择了三个菌株，并将其留在不锈钢（SS）优惠券上附着并形成生物膜，在 15°C 下孵育 144 小时，在周期性可再生的胰蛋白胨大豆肉汤（TSB）中，无论是在单培养还是混合培养（单-/双物种）条件下。形成生物膜后，将混合培养的固定群落用（i）苯扎氯铵（50 ppm）、（ii）次氯酸钠（10 ppm）、（iii）过氧乙酸（10 ppm）和（iv）过氧化氢（5 ppm）和过氧乙酸（5 ppm）的混合物进行 6 分钟的消毒处理。结果表明，两种菌都达到了相似的生物膜计数（约 10(5) CFU cm(-2))，并且一般来说，种间相互作用对生物膜形成能力（通过机械去除生物膜细菌的琼脂平板计数来评估）或对每种单独物种的抗微生物抗性都没有任何显著影响。有趣的是，脉冲场凝胶电泳（PFGE）分析清楚地表明，三种李斯特菌菌株既没有以相同的水平促进混合培养固定群落（单-/双物种）的形成，也没有促进其对抗微生物剂的抗性。此外，肠沙门氏菌细胞同时存在于生物膜结构内似乎会影响李斯特菌菌株的发生和抗性模式。总之，本研究强调了混合培养固定群落中发生的微生物相互作用对其种群动态和消毒抗性的影响。
