Differential Adaptive Response and Survival of Salmonella enterica Serovar Enteritidis Planktonic and Biofilm Cells Exposed to Benzalkonium Chloride

Abstract

This study examined the adaptive response and survival of planktonic and biofilm phenotypes of Salmonella enterica serovar Enteritidis adapted to benzalkonium chloride (BC). Planktonic cells and biofilms were continuously exposed to 1 g ml ؊1 of BC for 144 h. The proportion of BC-adapted biofilm cells able to survive a lethal BC treatment (30 g ml ؊1 ) was significantly higher (4.6-fold) than that of BC-adapted planktonic cells. Similarly, there were 18.3-fold more survivors among the BC-adapted biofilm cells than among their nonadapted (i.e., without prior BC exposure) cell counterparts at the lethal BC concentration, and this value was significantly higher than the value for BC-adapted planktonic cells versus nonadapted cells (3.2-fold). A significantly higher (P < 0.05) proportion of surviving cells was noticed among BC-adapted biofilm cells relative to BC-adapted planktonic cells following a 10-min heat shock at 55°C. Fatty acid composition was significantly influenced by phenotype (planktonic cells or biofilm) and BC adaptation. Cell surface roughness of biofilm cells was also significantly greater (P < 0.05) than that of planktonic cells. Key proteins upregulated in BC-adapted planktonic and biofilm cells included CspA, TrxA, Tsf, YjgF, and a probable peroxidase, STY0440. Nine and 17 unique proteins were upregulated in BC-adapted planktonic and biofilm cells, respectively. These results suggest that enhanced biofilm-specific upregulation of 17 unique proteins, along with the increased expression of CspA, TrxA, Tsf, YjgF, and a probable peroxidase, phenotype-specific alterations in cell surface roughness, and a shift in fatty acid composition conferred enhanced survival to the BC-adapted biofilm cell population relative to their BC-adapted planktonic cell counterparts.

ZnO Nanoparticles Impose a Panmetabolic Toxic Effect Along with Strong Necrosis, Inducing Activation of the Envelope Stress Response in Salmonella enterica Serovar Enteritidis

“…Biofilms of Salmonella serovar Enteritidis were grown in polycarbonate multichannel flow cells. Prior to inoculation, the channels of the flow cell device were sterilized by flushing with 10% (wt/vol) sodium hypochlorite solution for 10 min (15). Then, sterile nutrient medium (10% strength TSB) was pumped through the flow cells via silicone tubing using a Watson-Marlow peristaltic pump operated at a bulk flow rate of 25 ml per hour and a laminar flow velocity of 0.07 cm per second per channel.…”

Adaptive response of single and binary Pseudomonas aeruginosa and Escherichia coli biofilms to benzalkonium chloride

“…Biofilm tolerance to disinfectants may result from (i) slow microbial growth rates that are attributable to nutrient depletion within biofilms, (ii) binding of the biocide to EPS, (iii) neutralization or degradation of the biocide, as well as (iv) the expression of biofilm-specific phenotypes [2,12,14]. There are evidences that proteins involved in oxidative stress response, cell envelope synthesis, and EPS synthesis are up-regulated in biofilms, indicating that these altered phenotypes might contribute to cell survival, persistence, and growth in a biofilm community [15,16]. Moreover, biofilms usually comprise more than one microbial species, and can harbour strains with less ability to develop a biofilm, contributing to their survival and persistence.…”

Critical review on biofilm methods

“…It has also proven useful for quantitative biofilm analysis, especially to confirm findings obtained by quantitative (viable count, CV staining) or other imaging (light microscopy, SEM) techniques (Ansari et al, 2013;Chatterjee et al, 2014;Li et al, 2015;Salunke et al, 2014). Among the characteristics of the sample surface examined, height and roughness analyses from AFM images allow quantification of biofilm biomass in terms of thickness and EPS amount, respectively (Ansari et al, 2013;Chatterjee et al, 2014;Danin et al, 2015;Li et al, 2015;Mangalappalli-Illathu et al, 2008;Nandakumar et al, 2004;Qin et al, 2009;Sharma et al, 2010).…”