The role of horizontal gene transfer in the spread of Snowflake Forming Collagen Binding Aggregation Factors in bacteria

Snowflake Forming Collagen Binding Aggregation Factors (SFCBAF) are unique surface proteins originally described in lactic acid bacteria. These proteins determine the autoaggregation phenotype and are likely to be involved in biofilm formation and adhesion processes., which may serve as one of the mechanisms facilitating bacterial survival and dissemination in the environment. To date, only five collagen-binding aggregation factors of this type have been characterized in detail: AggL from Lactococcus lactis, AggE from Enterococcus faecium, AggLb from Lacticaseibacillus paracasei, AggLr from Lactococcus raffinolactis, and AggA from Tetragenococcus halophilus. In our research group, we have bioinformatically predicted and characterized new potential representatives of collagen-binding aggregation factors in phylogenetically diverse bacteria, including species beyond lactic acid bacteria, suggesting a possible role of horizontal gene transfer in their dissemination. In this study, we analyzed the genomic context of all genes encoding the predicted collagen-binding aggregation factors within a ±7000 nucleotide window from the borders of the predicted gene sequence. This analysis revealed potential genetic elements that may participate in the mobility of these factors. In the majority of analyzed sequences, genes encoding transposases, integrases, or other proteins associated with mobile genetic elements were detected in the immediate vicinity of the aggregation factor genes. These findings emphasize the important role of horizontal gene transfer in the formation and dissemination of collagen-binding aggregation factors among bacteria of various genera and ecological niches, facilitating the spread of adaptive genes and enhancing bacterial plasticity in changing environments.