Natural aggregation of Lactobacillus: Mechanisms and influencing factors

Lactobacillus aggregation is a bacterial behavior, in which Lactobacillus cells adhere to each other or other strains to form aggregates. Substantial evidence indicates that Lactobacillus aggregation is closely related to biofilm formation, adhesion, colonization, and host physiological functions. Current reviews on Lactobacillus aggregation are often limited to a few aspects, or serve as a single step to address other related problems. In this paper, we review the current state and characteristics of self- and co-aggregations, including aggregation percentages, influencing factors, molecular mechanisms, and functions. Lactobacillus aggregation is a strain-specific behavior, rather than a species-specific one, and the characteristics of both aggregations are similar. The same species of Lactobacillus exhibits a relatively broad range of aggregation percentage, and involved in different influencing factors and mechanisms. Moreover, the same factors and mechanisms also participate in different Lactobacillus aggregations. This is mainly because of the complexity of aggregations. Meanwhile, we also summarize the functions of aggregation, including enhancing bacterial survival, promoting biofilm formation and involving in host physiological regulation.