Zhao Xingchen, Höfte Monica, Spanoghe Pieter, Rajkovic Andreja, Uyttendaele Mieke
Food Microbiology and Food Preservation Research Unit, Department of Food Technology, Safety and Health, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium; Research Group for Food Microbiology and Hygiene, National Food Institute, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark.
Laboratory of Phytopathology, Department of Plants and Crops, Faculty of Bioscience Engineering, Ghent University, 9000 Ghent, Belgium.
J Food Prot. 2024 Aug;87(8):100321. doi: 10.1016/j.jfp.2024.100321. Epub 2024 Jun 25.
Bacillus thuringiensis-based commercial products as a biopesticide have been used for more than 60 years in agriculture. However, as one of the species in B. cereus group, B. thuringiensis has been considered as an emerging hazard with the potential to cause food toxico-infections. The present study aimed to evaluate the biofilm-forming ability of B. thuringiensis biopesticide strains and their attachment on spinach, compared to foodborne B. cereus strains. Biofilm formations of tested strains were found to be strain-specific and affected by the nutrient conditions more than the incubation time. Nutrient starvation conditions generally reduced the biofilm formation of tested B. thuringiensis and B. cereus strains, particularly B. thuringiensis ABTS-1857 strain was found as the nonbiofilm former in starvation conditions. It is worth mentioning that B. thuringiensis SA-11 strain showed stronger biofilm-forming ability with more air-liquid interface biofilm than the other two B. thuringiensis biopesticide strains, but no such higher attachment of B. thuringiensis SA-11 to spinach was observed. These results indicate that B. thuringiensis SA-11 strain can enter the food processing lines by the attachment on spinach leaves, and it has the potential to form biofilms throughout the processing lines or the production environment when sufficient nutrients are available. However, more biofilm tests of B. thuringiensis biopesticide strains in the vegetable production chain should be performed. The dry formulation of commercial B. thuringiensis biopesticides enhanced their adhesion on spinach leaves, whereas the strength of adhesion was not improved by the formulation. In addition, 1-2 log reductions of spores after the intensive washing of spinach leaves in the lab were detected. However, the log reduction due to the actual washing done by the food processing companies in large-volume washing baths or by consumers at home would be limited and less than this lab simulation.
基于苏云金芽孢杆菌的商业产品作为生物农药已在农业中使用了60多年。然而，作为蜡样芽孢杆菌属的一个物种，苏云金芽孢杆菌被认为是一种新出现的危害，有可能导致食源性中毒感染。本研究旨在评估苏云金芽孢杆菌生物农药菌株的生物膜形成能力及其在菠菜上的附着情况，并与食源性蜡样芽孢杆菌菌株进行比较。发现受试菌株的生物膜形成具有菌株特异性，且受营养条件的影响大于培养时间。营养饥饿条件通常会降低受试苏云金芽孢杆菌和蜡样芽孢杆菌菌株的生物膜形成，特别是发现苏云金芽孢杆菌ABTS - 1857菌株在饥饿条件下不形成生物膜。值得一提的是，苏云金芽孢杆菌SA - 11菌株表现出比其他两种苏云金芽孢杆菌生物农药菌株更强的生物膜形成能力，且气液界面生物膜更多，但未观察到苏云金芽孢杆菌SA - 11对菠菜有更高的附着。这些结果表明，苏云金芽孢杆菌SA - 11菌株可通过附着在菠菜叶上进入食品加工生产线，并且在有足够营养时有可能在整个生产线或生产环境中形成生物膜。然而，应在蔬菜生产链中对苏云金芽孢杆菌生物农药菌株进行更多的生物膜测试。商业苏云金芽孢杆菌生物农药的干制剂增强了它们在菠菜叶上的附着力，而制剂并未提高附着力强度。此外，在实验室中对菠菜叶进行强化清洗后，检测到孢子减少了1 - 2个对数级。然而，食品加工公司在大容量清洗槽中实际清洗或消费者在家中清洗导致的对数减少将是有限的，且低于此实验室模拟结果。
