Enhanced Biofilm Formation and Increased Resistance to Antimicrobial Agents and Bacterial Invasion Are Caused by Synergistic Interactions in Multispecies Biofilms

Abstract

Most biofilms in their natural environments are likely to consist of consortia of species that influence each other in synergistic and antagonistic manners. However, few reports specifically address interactions within multispecies biofilms. In this study, 17 epiphytic bacterial strains, isolated from the surface of the marine alga Ulva australis, were screened for synergistic interactions within biofilms when present together in different combinations. Four isolates, Microbacterium phyllosphaerae, Shewanella japonica, Dokdonia donghaensis, and Acinetobacter lwoffii, were found to interact synergistically in biofilms formed in 96-well microtiter plates: biofilm biomass was observed to increase by >167% in biofilms formed by the four strains compared to biofilms composed of single strains. When exposed to the antibacterial agent hydrogen peroxide or tetracycline, the relative activity (exposed versus nonexposed biofilms) of the four-species biofilm was markedly higher than that in any of the single-species biofilms. Moreover, in biofilms established on glass surfaces in flow cells and subjected to invasion by the antibacterial protein-producing Pseudoalteromonas tunicata, the four-species biofilms resisted invasion to a greater extent than did the biofilms formed by the single species. Replacement of each strain by its cell-free culture supernatant suggested that synergy was dependent both on species-specific physical interactions between cells and on extracellular secreted factors or less specific interactions. In summary, our data strongly indicate that synergistic effects promote biofilm biomass and resistance of the biofilm to antimicrobial agents and bacterial invasion in multispecies biofilms.

Synergistic interactions in mixed-species biofilms of pathogenic bacteria from the respiratory tract

“…Thus, in a niche with a specifi ed number of cells, the presence of different species of bacteria can result in a greater quantity of biofi lm, as has been reported previously 12,13 .…”

Enzymatic approaches in paper industry for pulp refining and biofilm control

“…This configuration explains that bacteria in biofilm show greater resistance to biocides compared to their planktonic forms. Established biofilms can tolerate antimicrobial agents at concentrations of 10-100 times higher than those needed to kill genetically equivalent planktonic bacteria, making biofilms extremely difficult to eradicate (Burmolle 2006, Jefferson 2004, Stoodley 2002.…”

Next‐generation studies of microbial biofilm communities

“…For example, Burmolle et al . (2006) showed that a mixed species biofilm achieves significantly more biomass than the monospecies biofilms (Ren et al ., 2015), without the need to input more nutrients. Further, we and others have observed that such mixed communities have heightened tolerance to antimicrobials, chemical stress and predation (Burmolle et al ., 2006; Lee et al ., 2014; Kumar and Ting, 2015).…”