Abstract
The production of extracellular polymeric substance (EPS) is important for the survival of biofilms. However, EPS production is costly for bacteria and the bacterial strains that produce EPS (EPS+) grow in the same environment as non-producers (EPS−) leading to competition between these strains for nutrients and space. The outcome of this competition is likely to be dependent on factors such as initial attachment, EPS production rate, ambient nutrient levels and quorum sensing. We use an Individual-based Model (IbM) to study the competition between EPS+ and EPS− strains by varying the nature of initial colonizers which can either be in the form of single cells or multicellular aggregates. The microbes with EPS+ characteristics obtain a competitive advantage if they initially colonize the surface as smaller aggregates and are widely spread-out between the cells of EPS−, when both are deposited on the substratum. Furthermore, the results show that quorum sensing-regulated EPS production may significantly reduce the fitness of EPS producers when they initially deposit as aggregates. The results provide insights into how the distribution of bacterial aggregates during initial colonization could be a deciding factor in the competition among different strains in biofilms.
Highlights
Biofilms are surface associated communities of bacteria that are surrounded by adhesive extracellular polymeric substance (EPS) (Davey and O’toole, 2000) which provides them with mechanical integrity and allows resistance against attack from foreign entities
Microbial competition between two bacterial strains with differing EPS producing characteristics (EPS+/quorum sensing (QS)+/QS− vs. EPS−), has been studied using an Individual-based Model (IbM), with one strain initially deposited on the substratum as aggregate(s) and the other as individual cells
The results show that when there is no quorum sensing and if EPS− cells attach as relatively large aggregates; the EPS+ cells gain the maximum competitive advantage if they attach on the substratum as single cells
Summary
Biofilms are surface associated communities of bacteria that are surrounded by adhesive extracellular polymeric substance (EPS) (Davey and O’toole, 2000) which provides them with mechanical integrity and allows resistance against attack from foreign entities. Understanding the dynamics of growth and competition between several microbial species in a biofilm is crucial for our understanding of chronic diseases such as cystic fibrosis, infection in medical devices, biofouling and various processes used in wastewater treatment. Mathematical models such as Cellular Automaton (CA) and Individual-based Models (IbMs) (Kreft et al, 2001; Picioreanu et al, 2004; Xavier et al, 2005; Nadell et al, 2008; Lardon et al, 2011; Jayathilake et al, 2017) have been instrumental in providing insights into the spatiotemporal growth and competition of microbes under varying conditions. As Ib modeling leads to more realistic biofilm structures (Kreft et al, 2001), it has been widely used to study social evolution in biofilms (Kreft, 2004; Xavier and Foster, 2007; Nadell et al, 2008; Mitri et al, 2011)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
