Correlation of Mutations in the hblA Gene with Bacillus cereus Disease Isolated from Loungwila, a Traditional Fermented Beverages in Republic of Congo

Abstract

Bacillus cereus is a pathogenic bacterium recognized for triggering foodborne illnesses, particularly through its enterotoxins, which are linked to various gastroenteritis outbreaks. This study explores the relationship between mutations in the hblA gene, which encodes for the haemolysin BL toxin, and B. cereus strains isolated from Lougwila, a traditional fermented beverage in the Republic of Congo. A total of 145 B. cereus strains were obtained from Lougwila samples, and their hblA gene sequences were analyzed for mutations by using PCR, sequencing and in silico translation. In the hblA region 100-230, we identified deletion mutations of amino acids, as follows: HblA-S23∆KN, ∆YYE, ∆KEG, S28-∆KKQL, ∆QQNQ, and ∆ESD. Substitution mutations as follows:  HblA-S23-A103K, N103R, S28-N222Q, Y223L, Y224E, K225S, Q226D, S52-Q169A, Q165Y, K212L S62-K112R, K114R, Q169A, Q170A, , S2-E174N, and Y224A. In the hblA region 250-330, we identified three substitution mutations in B. cereus S2, comprising: E290D, Q269L, and E265D. The results revealed a significant correlation between specific mutations in HblA 3D structures. This study underscores the need for further investigation into the genetic diversity of B. cereus strains in fermented foods, as well as the implementation of safety measures to mitigate foodborne outbreaks.