# Genomic and phenotypic diversities among Bacillus cereus isolates from cosmetics

## TL;DR

This study compares the genetic and phenotypic traits of Bacillus cereus strains from cosmetics and other sources to understand their survival and resistance capabilities.

## Contribution

The study reveals no unique traits in cosmetic isolates and highlights that antimicrobial resistance depends on both genetic factors and antibiotic concentration.

## Key findings

- Cosmetic and non-cosmetic B. cereus isolates showed no distinguishing traits in growth or resistance.
- Antimicrobial resistance varied based on both the strain's genetic profile and antibiotic concentration.
- B. cereus 3 A ES was the most resistant strain, while B. pumilus ATCC 7061 was the least resistant.

## Abstract

As Bacillus cereus species can negatively affect the safety and quality of both food and non-food products, it would be useful to describe among the selected strains traits supporting survival in specific matrices. We recently characterized the genome of 3 A ES, a B. cereus isolated from eye shadow, revealing multiple genes predicted to support the adaptation of this strain to harsh environmental conditions. Here, we compared the genotypic and phenotypic relative sensitivity/ resistance of B. cereus 3 A ES with two additional B. cereus cosmetic isolates: an eye shadow isolate, 7 C ES, a baby wipe isolate, 1 L BW, as well as clinical strain American Type Culture Collection (ATCC) 49,063, an emetic strain from unknown origin F60006, the ATCC 14,579 reference type strain, and a non-cereus strain, B. pumilus ATCC 7061. An additional eye shadow isolate, 8 A ES, was only tested phenotypically.

BTyper, the B. cereus subtyping tool within the FDA HFP GalaxyTrakr bioinformatic platform, separated the strains in three phylogenetic groups, with B. pumilus as an outlier. Four strains were identified as B. cereus sensu stricto (s.s.), group IV: 3 A ES, ATCC strains 14,579 and 49,063, with 7 C ES additionally identified as B. cereus s.s. biovar Thuringiensis. F60006 was recognized as B. mosaicus subsp. cereus Emeticus s.s., in group III. Isolate 1 L BW was identified as B. cytotoxicus, group VII. Analyses of these genomic sequences using the Pathosystems Resource Integration Center (BV-BRC - PATRIC) revealed genes predicting resistance for diverse antibiotic groups and biocides. B. cereus strains displayed resistance to most of the compounds tested with Vitek® 2 Compact system and phenotype microarrays™. No differences were found between the overall average growth that correlates with the respiration response between the isolates from cosmetics and non-cosmetics (p = 0.56). However, there was a significant difference (p < 0.001) in the overall sensitivity/resistance phenotypes of the strains: the non-cereus ATCC 7061 was the least resistant strain and 3 A ES, the most resistant.

Although these B. cereus strains exhibited a range of genotypic and phenotypic profiles, there were no traits distinguishing isolates from cosmetics from the isolates from non-cosmetics tested. Further, antimicrobial resistance was not only dependent on the arsenal carried by a given strain but also on the concentration of each antibiotic.

The online version contains supplementary material available at 10.1186/s12866-025-04311-x.