An Introduction to Bacterial Biofilms and Their Proteases, and Their Roles in Host Infection and Immune Evasion

Abstract

Bacterial biofilms represent multicellular communities embedded in a matrix of extracellular polymeric substances, conveying increased resistance against environmental stress factors but also antibiotics. They are shaped by secreted enzymes such as proteases, which can aid pathogenicity by degrading host proteins of the connective tissue or the immune system. Importantly, both secreted proteases and the capability of biofilm formation are considered key virulence factors. In this review, we focus on the basic aspects of proteolysis and protein secretion, and highlight various secreted bacterial proteases involved in biofilm establishment and dispersal, and how they aid bacteria in immune evasion by degrading immunoglobulins and components of the complement system. Thus, secreted proteases represent not only prominent antimicrobial targets but also enzymes that can be used for dedicated applications in biotechnology and biomedicine, including their use as laundry detergents, in mass spectrometry for the glycoprofiling of antibodies, and the desensitization of donor organs intended for positive crossmatch patients.

The RNA Chaperone Protein Hfq Regulates the Characteristic Sporulation and Insecticidal Activity of Bacillus thuringiensis

“…In this study, we found that when hfq was deleted, the expression of many enterotoxin genes in bacteria, such as nheA , nheB , entFM , entD 1, entD 2, and hbl C, was significantly increased at the transcriptional level ( Figure 6B ), which to some extent enhanced bacterial virulence ( de Maagd et al, 2003 ). In addition, the deletion of hfq also led to a significant increase in the amount of bacterial biofilm formation ( Figure 3B ), and the ability to form biofilms is also considered to be a key virulence factor in a variety of bacteria ( Ramírez-Larrota and Eckhard, 2022 ). Environmental adaptability can help bacteria resist antibiotics and the host’s immune system, which facilitates bacterial survival and infection in the host, ultimately leading to host death ( Al Safadi et al, 2012 ; Giaouris et al, 2015 ).…”

Essential role of ascO for virulence of Aeromonas veronii and inducing apoptosis

“…The decrease in biofilm formation ability after the mutation of ascO gene in this experiment needs further investigation. Studies have shown that the ability to form biofilms is considered to be a key virulence factor for a variety of bacteria (Ramirez‐Larrota & Eckhard, 2022). We hypothesized that the decreased biofilm formation ability of the mutant strain ∆ ascO was one of the factors contributing to its decreased virulence.…”

Colonization and Infection of Indwelling Medical Devices by Staphylococcus aureus with an Emphasis on Orthopedic Implants

“…After attachment to the plasma protein-covered device is accomplished, bacteria grow by proliferation and produce polymeric molecules to form a scaffolding extracellular matrix ( Figure 1 ). Biofilm polymers include polysaccharides, proteins, extracellular DNA (eDNA), teichoic acids and other molecules on the whole constituting an aqueous gel-like material with proper mechanical properties and resistance to external shocks [ 91 ].…”