Lindsay D, Brözel V S, Von Holy A
School of Molecular and Cell Biology, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa.
J Food Prot. 2006 May;69(5):1168-72. doi: 10.4315/0362-028x-69.5.1168.
This study aimed to trace the dynamics of biofilm formation by vegetative cells and endospores of Bacillus cereus DL5 and Bacillus subtilis 168. Counts of B. cereus DL5 and B. subtilis 168 vegetative cells and spores either attached to glass wool or, correspondingly, planktonic cells were determined by standard plate-counting methods. Results from this study highlighted the biofilm-forming potential of both spores and vegetative cells of two different Bacillus species. It was shown that once Bacillus spores had attached to a surface, the spores germinated under favorable (B. cereus DL5) and even unfavorable (B. subtilis 168) nutrient conditions, resulting in biofilms containing both spores and vegetative populations. Furthermore, it was suggested that vegetative B. cereus DL5 cells exhibited a low propensity for spore formation in attached and planktonic growth forms in nutrient-limited growth medium. By contrast, vegetative B. subtilis 168 cells readily formed spores in planktonic and attached microcosms when exposed to nutrient-limited growth conditions. Sporulation in attached Bacillus populations is an important practical consideration for many food industries, such as dairy processing, where bacilli are routinely isolated from populations attached to processing-equipment surfaces.
本研究旨在追踪蜡样芽孢杆菌DL5和枯草芽孢杆菌168的营养细胞和芽孢形成生物膜的动态过程。通过标准平板计数法测定附着在玻璃棉上的蜡样芽孢杆菌DL5和枯草芽孢杆菌168的营养细胞和芽孢数量，以及相应的浮游细胞数量。本研究结果突出了两种不同芽孢杆菌的芽孢和营养细胞形成生物膜的潜力。结果表明，一旦芽孢杆菌的芽孢附着在表面，在有利（蜡样芽孢杆菌DL5）甚至不利（枯草芽孢杆菌168）的营养条件下芽孢都会萌发，从而形成包含芽孢和营养群体的生物膜。此外，研究表明，在营养受限的生长培养基中，附着生长和浮游生长形式的蜡样芽孢杆菌DL5营养细胞形成芽孢的倾向较低。相比之下，当暴露于营养受限的生长条件时，枯草芽孢杆菌168的营养细胞在浮游和附着的微观环境中很容易形成芽孢。对于许多食品行业，如乳制品加工行业，附着的芽孢杆菌群体中的芽孢形成是一个重要的实际考虑因素，在这些行业中，经常从附着在加工设备表面的群体中分离出芽孢杆菌。
