Biofilms: Architecture, Resistance, Quorum Sensing and Control Mechanisms

Abstract

Biofilm is a mode of living employed by many pathogenic and environmental microbes to proliferate as multicellular aggregates on inert inanimate or biological substrates. Several microbial diseases are associated with biofilms that pose challenges in treatment with antibiotics targeting individual cells. Bacteria in biofilms secrete exopolymeric substances that contribute to architectural stability and provide a secure niche to inhabiting cells. Quorum sensing (QS) plays essential roles in biofilm development. Pathogenic bacteria in biofilms utilize QS mechanisms to activate virulence and develop antibiotic resistance. This review is a brief overview of biofilm research and provides updates on recent understandings on biofilm development, antibiotic resistance and transmission, and importance of QS mechanisms. Strategies to combat biofilm associated diseases including anti-biofilm substances, quorum quenching molecules, bio-surfactants and competitive inhibitors are briefly discussed. The review concludes with updates on recent approaches utilized for biofilm inhibition and provides perspectives for further research in the field.

Prevalence and Therapies of Antibiotic-Resistance in Staphylococcus aureus

“…Bacterial biofilm is an extracellular complex structure composed of a microbial population attached to the surface of the substrate, and its internal microorganisms are surrounded by a highly hydrated extracellular polymer matrix produced by itself, which is a protective way of survival for bacteria to adapt to their surroundings (Craft et al, 2019;Saxena et al, 2019). Moreover, the vast majority of bacteria in nature exist in the form of biofilms, and the most prominent feature of bacterial biofilms is their strong adhesion and drug resistance, which allowing bacteria to resist host immune responses and evade antibiotic killing (Kanwar et al, 2017).…”

“…Their resistance to antibacterial drugs can increase to 1,000 times that of plankton. At present, domestic and foreign anti-biofilm treatments mainly focus on the continuous development of new antibacterial drugs, but antibiotics and chemical synthetic drugs used in clinical medicine have certain toxic effects (Saxena et al, 2019). Biofilm bacteria are prone to resistance to these conventional drugs, and resistant strains presented an increasing trend (Craft et al, 2019).…”

Quorum-Sensing Regulation of Antimicrobial Resistance in Bacteria

“…The formation of bacterial biofilms is closely related to the development of drug resistance. It is generally believed that bacterial biofilms can lead to bacterial drug resistance through penetration restriction mechanisms, nutrition restriction mechanisms, and drug resistance phenotypic mechanisms [82]. The molecular barrier and charge barrier (mostly negatively charged) formed by the polysaccharides in the biofilm can prevent or delay the penetration of certain antibiotics, which is the main mechanism of limiting permeability [76].…”

Competitive and/or Cooperative Interactions of Listeria monocytogenes With Bacillus cereus in Dual-Species Biofilm Formation

“…Biofilms are a complex form of microbial ecosystem that allows a high level of interaction among different organisms (Saxena et al, 2019;Yuan et al, 2019). These interactions can influence both the temporal and spatial properties of biofilms.…”

“…In the cooperative bacterial interactions, the benefit on biofilm formations occurs by facilitating adhesion, growth, and protection against biocides. Competitive interactions may occur in the dispute for space, nutrients, and energy sources (exploitative competition), or due to the production of secondary compounds such as bacteriocins, enzymes, hydrogen peroxide, and organic acids (interference competition), favoring competitive exclusion (Elias and Banin, 2012;Knight, 2015;Saxena et al, 2019;Yuan et al, 2019).…”