title: Influence of Nutrient Availability and Quorum Sensing on the Formation of Metabolically Inactive Microcolonies Within Structurally Heterogeneous Bacterial Biofilms: An Individual-Based 3D Cellular Automata Model.
abstract: The resistance of bacterial biofilms to antibiotic treatment has been attributed to the emergence of structurally heterogeneous microenvironments containing metabolically inactive cell populations. In this study, we use a three-dimensional individual-based cellular automata model to investigate the influence of nutrient availability and quorum sensing on microbial heterogeneity in growing biofilms. Mature biofilms exhibited at least three structurally distinct strata: a high-volume, homogeneous region sandwiched between two compact sections of high heterogeneity. Cell death occurred preferentially in layers in close proximity to the substratum, resulting in increased heterogeneity in this section of the biofilm; the thickness and heterogeneity of this lowermost layer increased with time, ultimately leading to sloughing. The model predicted the formation of metabolically dormant cellular microniches embedded within faster-growing cell clusters. Biofilms utilizing quorum sensing were more heterogeneous compared to their non-quorum sensing counterparts, and resisted sloughing, featuring a cell-devoid layer of EPS atop the substratum upon which the remainder of the biofilm developed. Overall, our study provides a computational framework to analyze metabolic diversity and heterogeneity of biofilm-associated microorganisms and may pave the way toward gaining further insights into the biophysical mechanisms of antibiotic resistance.
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana, 502285, India.
authors.forename: Lakshmi
authors.initials: L
authors.lastname: Machineni
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana, 502285, India.
authors.forename: Anil
authors.initials: A
authors.lastname: Rajapantul
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana, 502285, India.
authors.forename: Vandana
authors.initials: V
authors.lastname: Nandamuri
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology Hyderabad, Kandi, Sangareddy, Telangana, 502285, India. parag@iith.ac.in.
authors.forename: Parag D
authors.initials: PD
authors.lastname: Pawar
mesh_terms: D018407:Bacterial Physiological Phenomena; D018441:Biofilms / Q000187:drug effects / Q000254:growth & development*; D018533:Biomass; D003198:Computer Simulation; D003470:Culture Media; D024881:Drug Resistance, Bacterial / Q000502:physiology; D005110:Extracellular Space / Q000378:metabolism; D055641:Mathematical Concepts; D008954:Models, Biological; D053038:Quorum Sensing / Q000502:physiology*
chemical_list: D003470:Culture Media
keywords: Autoinducer; Biofilms; Extracellular polymeric substances; Heterogeneity; Metabolic diversity; Quorum sensing