Glyphosate Effects on Growth and Biofilm Formation in Bee Gut Symbionts and Diverse Associated Bacteria

Biofilm formation is a common adaptation enabling bacteria to thrive in various environments and to withstand external pressures. In the context of host-microbe interactions, biofilms play vital roles in establishing microbiomes associated with animals and plants and are used by opportunistic microbes to facilitate proliferation within hosts. Investigating biofilm dynamics, composition, and responses to environmental stressors is crucial for understanding microbial community assembly and biofilm regulation in health and disease. In this study, we explore the independent gut colonization and in vitro biofilm formation abilities of core members of the honey bee ( Apis mellifera ) gut microbiota. Additionally, we assess the impact of glyphosate, a widely used herbicide with antimicrobial properties, and a glyphosate-based formulation on growth and biofilm formation in bee gut symbionts as well as in other biofilm-forming bacteria associated with diverse animals and plants. Our results demonstrate that several strains of core bee gut bacterial species can independently colonize the bee gut, which probably depends on their ability to form biofilms. Furthermore, glyphosate exposure has varying effects on bacterial growth and biofilm formation. These findings imply specific impacts of environmental stressors on microbial biofilms with both ecological and host health-related implications.

Importance

Biofilms are essential for microbial communities to establish and thrive in diverse environments. In the honey bee gut, the core microbiota member Snodgrassella alvi forms biofilms, potentially aiding the establishment of other members and promoting interactions with the host. In this study, we show that specific strains of other core members, including Bifidobacterium , Bombilactobacillus , Gilliamella , and Lactobacillus , also form biofilms. We then examine the impact of glyphosate, a widely used herbicide that disrupts the bee microbiota, on their growth and biofilm formation. Our findings demonstrate diverse effects of glyphosate on biofilm formation, ranging from inhibition to enhancement, reflecting observations in other beneficial or pathogenic bacteria associated with animals and plants. Thus, glyphosate exposure may influence bacterial growth and biofilm formation, potentially shaping microbial establishment on host surfaces and impacting health outcomes.