Persister cells in a biofilm treated with a biocide

Abstract

This study investigated the physiology and behaviour following treatment with ortho-phthalaldehyde (OPA), of Pseudomonas fluorescens in both the planktonic and sessile states. Steady-state biofilms and planktonic cells were collected from a bioreactor and their extracellular polymeric substances (EPS) were extracted using a method that did not destroy the cells. Cell structure and physiology after EPS extraction were compared in terms of respiratory activity, morphology, cell protein and polysaccharide content, and expression of the outer membrane proteins (OMP). Significant differences were found between the physiological parameters analysed. Planktonic cells were more metabolically active, and contained greater amounts of proteins and polysaccharides than biofilm cells. Moreover, biofilm formation promoted the expression of distinct OMP. Additional experiments were performed with cells after EPS extraction in order to compare the susceptibility of planktonic and biofilm cells to OPA. Cells were completely inactivated after exposure to the biocide (minimum bactericidal concentration, MBC = 0.55 ± 0.20 mM for planktonic cells; MBC = 1.7 ± 0.30 mM for biofilm cells). After treatment, the potential of inactivated cells to recover from antimicrobial exposure was evaluated over time. Planktonic cells remained inactive over 48 h while cells from biofilms recovered 24 h after exposure to OPA, and the number of viable and culturable cells increased over time. The MBC of the recovered biofilm cells after a second exposure to OPA was 0.58 ± 0.40 mM, a concentration similar to the MBC of planktonic cells. This study demonstrates that persister cells may survive in biocide-treated biofilms, even in the absence of EPS.

Development and Control of Bacterial Biofilms on Dairy Processing Membranes

“…If not controlled early, the biofilm formation on membrane surfaces will impair their performance (Maxcy 1969;Mattila and others 1990). It is challenging to eliminate biofilms from all dairy/food processing equipment, because of their high resistance to antimicrobials (Simões andothers 2006, 2010;Simões and Vieira 2009). Studies on cleaning of polyamide composite membranes indicate that fluid components and cleaning chemicals alter the surface properties of polyamide RO membrane.…”

“…Biofilms have also been reported to be a source of pathogens such as Listeria monocytogenes, Yersinia enterocolitica, Campylobacter jejuni, Salmonella spp., Staphylococcus spp., and even Escherichia coli 0157:H7 (Somers and others 1994;Kumar and Anand 1998;Wong 1998;Sharma and Anand 2002b). The presence of pathogens in biofilm matrices has a direct impact on food safety (Simões and Vieira 2009;Simões and others 2010). The presence of biofilms also results in lowering the shelf-life of the product (Zottoia 1994).…”

Evaluation antibacterial and antibiofilm activity of the antimicrobial peptide P34 against Staphylococcus aureus and Enterococcus faecalis

“…There are many advantages to an organism forming a biofilm, since these structures are more resistant to adverse environmental conditions compared to planktonic cells. Biofilms are resistance with makes their elimination from food processing environment a big challenge (Simões et al 2006, Simões andVieira 2009).…”

“…Most outbreaks whose etiologic agents are transmitted by food seems to be associated with biofilms. In recent years, there have been a significant number of reports correlating the persistence of foodborne pathogens on food contact surfaces and the occurrence of biofilms (Simões and Vieira 2009, Yaron and Römling 2015, Bridier et al 2015. Enterococcus spp.…”

Biological Applications of Plants and Algae Lectins: An Overview

“…They act as mediators of the binding between bacteria and the surface that will serve as substrate for biofilm formation [155], as well as site of interaction between microorganisms to form cell aggregates [156,157]. Furthermore, through EPS matrix, maintains the biofilm attached in the surface, conferring a greater resistance to antimicrobial agents in general [158,159].…”