Impact of bisphenol A, F, AF, C, and S on rumen ecology: an exploratory in vitro screening

Ruminants consume significant quantities of biomass, representing a primary pathway for xenobiotic exposure due to pollutant accumulation in plants. This exploratory in vitro screening aimed to evaluate the short-term impact of bisphenol A (BIS_A) and its analogues bisphenol F (BIS_F), bisphenol AF (BIS_AF), bisphenol C (BIS_C), and bisphenol S (BIS_S), on the rumen bacterial community and metabolic profile. A total of 36 fermenters (n = 6 fermentation replicates per treatment) were used: six control vessels without bisphenol addition (CON) and six vessels for each treatment containing 0.6225 mg/mL of individual bisphenols. Fermentations were conducted in a thermostatic chamber for 72 h. Rumen liquors were analysed for fatty acid profile and bacterial community composition. Fatty acid biohydrogenation processes appeared to be markedly reduced across treatments, suggesting a potential perturbation of rumen ecology under these in vitro conditions (lower production of C18:0, p < 0.0001). Analysis of bacterial genera with relative abundances exceeding 0.1% revealed shifts in specific taxa: Advenella (p = 0.0268) exhibited increased relative abundances in BIS_F fermenters, while Comamonas expanded in BIS_F and BIS_C fermenters (p = 0.0136), representing over 40% of the bacterial community. Overall, within this specific single-inoculum setup, bisphenols appeared to exert a selective pressure that modulated rumen fermentation, nitrogen metabolism, and fatty acid biohydrogenation. Given the exploratory design based on fermentation replicates, these findings provide preliminary evidence of microbial sensitivity to bisphenols, laying the groundwork for future multi-donor and in vivo validations.