Coexistence facilitates interspecific biofilm formation in complex microbial communities

Abstract

Social interactions in which bacteria respond to one another by modifying their phenotype are central determinants of microbial communities. It is known that interspecific interactions influence the biofilm phenotype of bacteria; a phenotype that is central to the fitness of bacteria. However, the underlying role of fundamental ecological factors, specifically coexistence and phylogenetic history, in biofilm formation remains unclear. This study examines how social interactions affect biofilm formation in multi-species co-cultures from five diverse environments. We found prevalence of increased biofilm formation among co-cultured bacteria that have coexisted in their original environment. Conversely, when randomly co-culturing bacteria across these five consortia, we found less biofilm induction and a prevalence of biofilm reduction. Reduction in biofilm formation was even more predominant when co-culturing bacteria from environments where long-term coexistence was unlikely to have occurred. Phylogenetic diversity was not found to be a strong underlying factor but a relation between biofilm induction and phylogenetic history was found. The data indicates that biofilm reduction is typically correlated with an increase in planktonic cell numbers, thus implying a behavioral response rather than mere growth competition. Our findings suggest that an increase in biofilm formation is a common adaptive response to long-term coexistence.

Ecological insights into the underlying evolutionary patterns of biofilm formation from biological wastewater treatment systems: Red or Black Queen Hypothesis?

“…Based on growth preference, biological wastewater treatment takes full advantage of microbial aggregates in engineered ecosystems (Ahmed, Tian, & Delatolla, 2019; Bagheri & Mirbagheri, 2018; Mahendran, Lishman, & Liss, 2012). When coexisting with other species in the same environment, microorganisms could coevolve with others via interspecies interactions (Madsen et al, 2016). The principles of microbial ecology suggest that the evolutionary processes of coexisting multispecies were critical for the resistance and functions of microbial communities (Burmølle, Ren, Bjarnsholt, & Sørensen, 2014; Hua, Joyce, Fong, & Palsson, 2006; Madsen et al, 2016).…”

“…When coexisting with other species in the same environment, microorganisms could coevolve with others via interspecies interactions (Madsen et al, 2016). The principles of microbial ecology suggest that the evolutionary processes of coexisting multispecies were critical for the resistance and functions of microbial communities (Burmølle, Ren, Bjarnsholt, & Sørensen, 2014; Hua, Joyce, Fong, & Palsson, 2006; Madsen et al, 2016). As one ubiquitous survival form, biofilms can be formed as microbial aggregates in biological treatment processes (moving bed biofilm reactor [MBBR] or floc‐based membrane bioreactor [MBR]), causing either beneficial or detrimental effects on the reactor performance (Guo et al, 2019; Meng et al, 2009).…”

“…Foster and Bell (2012) also proposed that the typical result of adaptation was competition rather than cooperation among cocultures from a tree rainwater pool. These previous studies focusing on natural environments or pure bacteria provide fundamental clues for the understanding of biofilm formation in engineered systems (Foster & Bell, 2012; Madsen et al, 2016).…”

“…Because cooperation in multispecies communities could result in “emerging community properties,” such as enhanced biofilm biomass, biofilm phenotypes have been applied to reveal the underlying interspecies interactions (Liu et al, 2019; Ren, Madsen, Sorensen, & Burmolle, 2015). By evaluating the gains/losses of biofilm biomass (Burmolle et al, 2006; Ren et al, 2015), it is possible to construct a more nuanced and strict multiregime biofilm classification scheme, enabling the identification of the underlying interspecies interactions of cocultures from natural environment (Madsen et al, 2016). Based on the study of 1,235 cocultures, Madsen et al (2016) showed the practicality of such a scheme for processing a large number of samples.…”

“…By evaluating the gains/losses of biofilm biomass (Burmolle et al, 2006; Ren et al, 2015), it is possible to construct a more nuanced and strict multiregime biofilm classification scheme, enabling the identification of the underlying interspecies interactions of cocultures from natural environment (Madsen et al, 2016). Based on the study of 1,235 cocultures, Madsen et al (2016) showed the practicality of such a scheme for processing a large number of samples. Thus, this biofilm classification scheme could be promising for the unbiased and detailed investigation of interspecies interactions in wastewater treatment systems.…”