Abstract Cronobacter spp. is a conditioned pathogen found mainly in milk powder; it can seriously harm infant health. We investigated biofilm formation in eight strains of Cronobacter spp. and found that DSM 18707 had the strongest capacity to form biofilm. Biofilm-related genes bcsA, bcsG, flgJ, and flhE were selected for qRT-PCR detection. Expression of bcsG in Cronobacter spp. was associated with the ability to form biofilm. Knockout of bcsG in DSM 18707 was associated with markedly reduced biofilm formation and exopolysaccharide content relative to the wild type. Moreover, fluorescence microscopy revealed that the knockout mutants had comparatively lower biofilm density. In the knockout mutants, bcsA, flgJ, and flhE were up-regulated in the first three days but down-regulated by days 4 and 5. Hence, the expression levels of bacterial biofilm-related genes may change with biofilm production; moreover, bcsG positively regulates the formation of exopolysaccharides and biofilm in Cronobacter spp.

中文翻译：

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胞外多糖相关基因 bcsG 影响克罗诺杆菌属的生物膜形成。

摘要 Cronobacter spp。是一种主要存在于奶粉中的条件病原体；它会严重危害婴儿的健康。我们研究了八株克罗诺杆菌属的生物膜形成。并发现 DSM 18707 形成生物膜的能力最强。选择生物膜相关基因 bcsA、bcsG、flgJ 和 flhE 进行 qRT-PCR 检测。bcsG 在 Cronobacter spp 中的表达。与形成生物膜的能力有关。与野生型相比，DSM 18707 中 bcsG 的敲除与生物膜形成和胞外多糖含量显着减少有关。此外，荧光显微镜显示敲除突变体具有相对较低的生物膜密度。在敲除突变体中，bcsA、flgJ 和 flhE 在前三天上调，但在第 4 天和第 5 天下调。因此，细菌生物膜相关基因的表达水平可能随着生物膜的产生而变化；此外，bcsG 积极调节克罗诺杆菌属中胞外多糖和生物膜的形成。