Typing and evaluating heat resistance of Bacillus cereus sensu stricto isolated from the processing environment of powdered infant formula

Zhuang, Kejin, Li, Hongfu, Zhang, Ziwei, Wu, Shuang, Zhang, Yashuo, Fox, Edward M., Man, Chaoxin and Jiang, Yujun (2019) Typing and evaluating heat resistance of Bacillus cereus sensu stricto isolated from the processing environment of powdered infant formula. Journal of Dairy Science, 102 (9). pp. 7781-7793. ISSN 0022-0302

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Official URL: https://doi.org/10.3168/jds.2019-16392

Abstract

Bacillus cereus sensu lato is one of the most harmful bacterial groups affecting the quality and safety of powdered infant formula (PIF). In this study, samples were collected from the raw materials and processing environments of PIF. A total of 84 isolates were identified as Bacillus cereus sensu stricto (B. cereus s. s.) by 16S rRNA analysis, molecular typing technology, and physiological and biochemical tests. The 84 B. cereus s. s. strains were assigned to panC group II, group III, and group IV. Then, the 7 housekeeping genes glpF, gmk, ilvD, pta, pur, pycA, and tpi were selected for multilocus sequence typing. Results showed that the 84 isolates were clustered into 24 sequence types (ST), and 14 novel ST were detected. Among the 24 ST, ST999 (19/84, 22.62%) and ST1343 (13/84, 15.48%) predominated. The correlation between processing areas and ST showed that the processing environments of the production and packing areas were the most susceptible to contamination by B. cereus s. s. Spores of these ST showed different heat resistance phenotypes evaluated by the analysis of DT (time in minutes of spore decimal reduction at each temperature) and Z values (temperature increase required to reduce the DT value to one-tenth of the original). Spores from group III according to panC gene analysis were the most heat resistant. These findings will help us to better understand B. cereus s. s. contamination and control in PIF processing environments.

Item Type: Article
Uncontrolled Keywords: powdered infant formula, Bacillus cereus sensu stricto, processing environment, sheat resistance
Subjects: C400 Genetics
D400 Agriculture
D600 Food and Beverage studies
D700 Agricultural Sciences
D900 Others in Veterinary Sciences, Agriculture and related subjects
Department: Faculties > Health and Life Sciences > Applied Sciences
Depositing User: Elena Carlaw
Date Deposited: 08 Jul 2019 12:17
Last Modified: 21 Aug 2019 10:33
URI: http://nrl.northumbria.ac.uk/id/eprint/39892

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