This study aimed to examine the potential link between Bacillus cereus biofilm formation, virulence, and pathogenicity. The biofilm formation abilities of nine B. cereus strains isolated from food and two reference strains (ATCC 10876 and ATCC 25621) were measured using a crystal violet assay. Among the tested strains, three strains (GIHE 617-5, GIHE 86-09, and GIHE 728-17) and both reference strains were capable of biofilm formation. A positive correlation was obtained for higher cell surface hydrophobicity and increased biofilm formation. In contrast, HPLC analysis for elevated autoinducer-2 (Al-2) production revealed a negative impact on biofilm formation. PCR data indicated that all tested strains were capable of producing common B. cereus enterotoxins, including Hbl—A, C, and D, CytK, Nhe—B and C, EntFM, and BceT, but were negative for production of the emetic toxin cereulide and the pore-forming toxin Hly II. Meanwhile, RT-PCR data revealed a close correlation between high biofilm formation and the upregulation of several tested virulence genes for selected strains. However, elevated upregulation of virulence genes was not consistent in all of the higher biofilm-forming strains. Cytotoxicity analysis revealed higher virulence characteristics compared to those of low biofilm-forming strains.

中文翻译：

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蜡样芽孢杆菌生物膜形成行为在毒力和致病特征中的作用


本研究旨在探讨蜡样芽孢杆菌生物膜形成、毒力和致病性之间的潜在联系。使用结晶紫测定法测量从食品中分离的九种蜡样芽孢杆菌菌株和两种参考菌株（ATCC 10876 和 ATCC 25621）的生物膜形成能力。在测试的菌株中，三个菌株（GIHE 617-5、GIHE 86-09 和 GIHE 728-17）和两个参考菌株能够形成生物膜。较高的细胞表面疏水性和增加的生物膜形成呈正相关。相比之下，自诱导剂 2 (Al-2) 产量升高的 HPLC 分析揭示了对生物膜形成的负面影响。 PCR数据表明，所有测试菌株均能够产生常见的蜡样芽孢杆菌肠毒素，包括Hbl-A、C和D、CytK、Nhe-B和C、EntFM和BceT，但不产生催吐毒素蜡状芽胞杆菌肠毒素和成孔毒素 Hly II。同时，RT-PCR 数据揭示了高生物膜形成与选定菌株的几个测试毒力基因的上调之间的密切相关性。然而，毒力基因上调的升高在所有较高生物膜形成菌株中并不一致。细胞毒性分析显示与低生物膜形成菌株相比具有更高的毒力特征。