Spore-Forming Bacteria in Plant-Based Milk Alternatives: Isolation, Identification, and Molecular Detection of Virulence and Heat Resistance Genes

This is the authors' abstract. We don't add key points for this paper.

The growing popularity and rapid expansion of plant-based milk alternatives (PBMAs) in Brazil highlight the importance of assessing their microbiological quality and potential safety risks. This study aimed to evaluate the commercial sterility of 111 PBMA samples marketed in Brazil, isolate spore-forming bacteria, identify the recovered strains using MALDI-TOF MS, and detect nine virulence genes and six heat resistance genes in Bacillus cereus isolates. In 82 samples, the commercial sterility test indicated mesophilic (35 °C) or thermophilic (55 °C) growth, as evidenced by positive reactions in the culture media recommended by the analytical protocol. A total of 139 aerobic isolates were obtained, of which 99 were mesophilic and 40 thermophilic. Mesophilic isolates included Bacillus cereus , Bacillus siralis , Bacillus pumilus , Lysinibacillus fusiformis , Bacillus coagulans , and Paenibacillus lactis , while thermophilic isolates comprised Geobacillus stearothermophilus , Anoxybacillus flavithermus , and Aeribacillus pallidus . The virulence and heat resistance profiles of 15 B. cereus isolates revealed the presence of the virulence genes cytK , bceT , entFM , nheA , nheB , nheC , and hblC in 73.3%, 66.6%, 26.6%, 100%, 86.6%, 86.6%, and 93.3% of isolates, respectively, and the heat resistance gene cdnL in all isolates. Overall, the present study contributes to a better understanding of the microbiological risks associated with PBMAs. Ensuring effective inactivation of spore-forming microorganisms, particularly toxin-producing B. cereus strains, is essential, as the composition of these products may favor both the persistence and proliferation of such bacteria.