The Depletion Mechanism Actuates Bacterial Aggregation by Exopolysaccharides and Determines Species Distribution & Composition in Bacterial Aggregates

• DOI: 10.3389/fcimb.2022.869736
• Publication Date: 2022-06-16T04:52:10Z
• Authors: Patrick R. Secor; Lia A. Michaels; DeAnna C. Bublitz; Laura K. Jennings; Pradeep K. Singh
• Keywords: 0301 basic medicine; Staphylococcus aureus; Burkholderia; Polymers; quorum sensing; Microbiology; biofilm; QR1-502; Anti-Bacterial Agents; 03 medical and health sciences; aggregate; Cellular and Infection Microbiology; Biofilms; Pseudomonas aeruginosa; Staphylococcus Aureus

Bacteria in natural environments and infections are often found cell aggregates suspended polymer-rich solutions, aggregation can promote bacterial survival stress resistance. One mechanism, called depletion aggregation, is driven by physical forces between bacteria high concentrations of polymers the environment rather than activity per se. As such, aggregated mechanism will disperse when polymer fall unless other adhesion mechanisms supervene. Here we investigated whether actuate aggregating effects Pseudomonas aeruginosa exopolysaccharides for (i.e. not surface attached) bacteria, how affects inter-species interactions. We that cells overexpressing Pel Psl remained after short periods whereas wild-type mucoid P. did not. In co-culture, had contrasting on aeruginosa's interactions with coccus- rod-shaped bacteria. Depletion caused S. aureus (cocci) (rods) to segregate from each resist secreted antimicrobial factors resulting species co-existence. contrast, Burkholderia sp. (both rods) intermix, enhancing type VI secretion inhibition aeruginosa, leading dominance. These results show addition being a primary cause suspensions, inherent some self-produced determine distribution composition communities.