Increasing microbial risks under co-contamination: View from virulence factor genes

Abstract

The coexistence of virulence factor genes (VFGs) and antibiotic resistance genes (ARGs) in environmental microbial communities poses an escalating threat to public health, particularly under pollutant-induced selective pressures. While non-antibiotic pollutants have been shown to promote ARG dissemination, their effects on VFGs remain poorly understood. Soil pH can simultaneously affect pollutant bioavailability and microbial community composition, thereby altering selective pressures and modulating the dynamics of both ARGs and VFGs. Here, we assessed the influence of arsenic (As) and triclocarban (TCC), alone and in combination, on soil VFG profiles across a pH gradient. Co-contamination significantly increased VFG abundance, with near-neutral pH intensifying this effect through enhanced pollutant bioavailability. VFG enrichment was primarily driven by pollutant-induced shifts in microbial community composition. In particular, neutral pH conditions promoted the proliferation of γ-Proteobacteria, which may serve as dominant VFG hosts. In addition, the co-contamination enhanced the co-occurrence of VFGs and ARGs, suggesting a potential expansion of pathogenic and antibiotic-resistant bacterial populations and elevating the risk of virulence trait dissemination. These findings underscore the need to evaluate microbial risks from the perspective of VFGs, particularly under co-contamination scenarios, to better anticipate emerging public health threats within a One Health framework.

Graphical abstract

Keywords

virulence factor genes / combined pollution / co-selective / microbial risk

Highlight

	● Co-contamination enhanced VFG dissemination compared to single pollutants.
	● Arsenic and triclocarban elevated VFG abundance, especially at neutral pH.
	● Co-contamination enriched γ-Proteobacteria as key potential hosts of VFGs.
	● Co-contamination increased PARBs, amplifying ecological and public health risks.

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