The prevalence and characterization of Bacillus cereus isolated from raw and pasteurized buffalo milk in southwestern China

Abstract

Bacillus cereus is an important food-borne pathogenic bacteria and a putrid microorganism in the dairy industry. Raw and pasteurized buffalo milk play important roles in the dairy market in southwestern China. However, the reports on the prevalence and characterization of B. cereus strains isolated from the above sources are lacking. In this study, 150 raw buffalo milk samples and 300 pasteurized buffalo milk samples were collected from 3 provinces in southwestern China. The genotype, virulence gene distribution, antibiotic resistance, and biofilm-forming ability of isolates were analyzed. Ninety-six B. cereus strains were isolated and identified: 50 isolates (33.3%) from buffalo raw milk and 46 isolates (15.3%) from pasteurized buffalo milk. These strains were classified into 41 sequence types (ST) and 5 groups, of which ST857 was the predominant ST. The detection rates of virulence genes nheABC cluster, hblACD cluster, cytK, bceT, entFM, hlyII, and cesB were 89.6%, 13.5%, 64.6%, 71.9%, 84.4%, 62.5%, and 6.25%, respectively. The antimicrobial susceptibility testing showed that more than 90% of the isolates were susceptible to gentamicin, chloramphenicol, ciprofloxacin, erythromycin, vancomycin, and tetracycline, as well as resistant to ampicillin, cefepime, oxacillin, and rifampin. The results of biomass biofilm evaluation of the isolates on the stainless-steel tube showed that the optical density values at a wavelength of 595 nm of all strains in group I were greater than 1, with the strongest overall biofilm-forming ability among 5 groups, and the overall biofilm-forming ability of group III was the weakest. There was a relationship between the biofilm-forming ability and phylogenetic relation-ship of B. cereus strains. Taken together, our findings are the first to report the contamination situation and characterization of B. cereus isolated from raw and pasteurized buffalo milk in southwestern China as well as indicate the potential risk posed by this pathogen to dairy industry and public health.

Characterization and spoilage potential of Bacillus cereus isolated from farm environment and raw milk

“…In this study, 47 strains of B. cereus sl were classified into 14 STs. Similarly, Fei et al ( 2019 ) divided 54 B. cereus isolates into 18 STs, Zhuang et al ( 2019 ) clustered 84 isolates into 24 STs, Zhao et al ( 2020 ) divided 54 isolates into 24 STs, and Chang et al ( 2021 ) classified 96 B. cereus isolates into 41 STs, illustrating that B. cereus sl from raw milk and farm environment has a high genetic diversity. We found ST1150 was the main ST of B. cereus sl among samples.…”

The prevalence, antibiotic resistance and multilocus sequence typing of colistin‐resistant bacteria isolated from Penaeus vannamei farms in earthen ponds and HDPE film‐lined ponds in China

“…ST26 (56%, 37/66) was the most prevalent ST, consistent with previous reports (Yu et al, 2020). ST26 has also been found in many other types of food, such as ready‐to‐eat food, infant formula and milk (Chang et al, 2021; Yang et al, 2021; Zhang et al, 2020). Notably, it has been reported that ST26 is a known ST associated with food poisoning, which can cause vomiting (Priest et al, 2004).…”

Evaluation of Antibiofilm Activity of Nigella sativa and Olive Oils’ Nanoemulsions against Bacillus cereus from Dairy Processing Plants

“…This agrees with Mugadza et al [24] who isolated B. cereus from raw milk, pasteurized milk, and filler nozzles. In addition, Chang et al [8] isolated B. cereus at 33.3% from buffalo raw milk and 15.3% from pasteurized buffalo milk from three provinces in China. Kariesh cheese had the highest B. cereus isolation rates and counts compared with ice cream, and pasteurized milk.…”

“…In agreement with recorded results, Radmehr et al [27] found that 53.7% of the isolated B. cereus from pasteurized milk had the ability to form biofilm. Furthermore, Chang et al [8] isolated biofilm-producing B. cereus with multidrug resistance from raw and pasteurized buffalo milk retailed in China. Besides, Fei et al [7] recorded biofilm formation at both the phenotypic and genotypic levels among B. cereus isolated from powdered milk sold in China.…”

“…The elimination of B. cereus from different food matrices, particularly dairy products is considered as a challenging issue in the food industry. In this context, B. cereus was frequently isolated from dairy products such as soft cheese and yoghurt in Ghana [5], artisan cheeses made in Mexico [6], powdered infant formula in China [7], raw and pasteurized milk in China [8]. However, the prevalence of B. cereus in dairy products such as kariesh cheese, ice cream, and milk retailed in Egypt, as well as in their contact surfaces in the dairy plants had received less attention.…”