Glutathione‐Gated Potassium Efflux as a Mechanism of Active Biofilm Detachment

Abstract

Biofilm detachment often has detrimental effects such as pipe obstruction and infection, yet the detachment mechanisms underlying dispersal remain largely unknown. In this study, a stress response mechanism known as glutathione‐gated potassium efflux (GGKE) was evaluated as an active detachment mechanism in the dispersal of Pseudomonas aeruginosa biofilms. N‐ethylmaleimide (NEM) was used to activate potassium efflux proteins (Kef) associated with the GGKE pathway. This stress response mechanism was hypothesized to lead to altered cation concentration, which can potentially affect polymer bridging in biofilms, and ultimately cause biofilm detachment. Results showed the activation of GGKE by NEM exposure caused biofilm detachment without inducing a measurable change in viability, and detached biomass concentration and composition were dependent on NEM concentration. More detached biomass was observed with higher concentrations of NEM, with a trend of increasing polymer detachment. The detachment was likely resulting from a weakened biofilm structural integrity induced by bridge denaturing from GGKE activation. This study is important in understanding biofilm detachment from engineered systems such as membrane aerated bioreactors.

Pseudomonas aeruginosa glutathione biosynthesis genes play multiple roles in stress protection, bacterial virulence and biofilm formation

“…NEM also activates P . aeruginosa glutathione-gated potassium efflux (GGKE), which leads to K + and Ca 2+ efflux and H + influx, and alters biofilms to result in detachment [ 22 ]. GSH and its intermediates may provide general thiol-buffering effects to protect bacteria against the thiol-depleting agent NEM.…”

Pseudomonas aeruginosa gshA Mutant Is Defective in Biofilm Formation, Swarming, and Pyocyanin Production

“…As GSH has been shown to be important for potassium transport in biofilms ( 18 ) and GSH biosynthesis genes are upregulated in biofilms of Candida albicans ( 19 ), we assessed whether GSH deficiency could alter biofilm formation in P. aeruginosa . Strains were grown for 24 h in minimal media in a 96-well plate after which biofilm biomass was assayed using crystal violet.…”

Emergence of a novel Enterobacter kobei clone carrying chromosomal-encoded CTX-M-12 with diversified pathogenicity in northeast China

“…Intriguingly, ECC3018 could form four- to ten-fold more biofilm (24 h 0.12 ± 0.02; 48 h 0.18 ± 0.04) than the other two (24 h 0.012 ± 0.003, 0.011 ± 0.002; 48 h 0.048 ± 0.03, 0.037 ± 0.02) (p <0.05) at 37°C. The discrepancy could be explained by multiple non-synonymous SNPs identified in the genes involved in biofilm formation (see Supplementary material, Table S1 ), including barA encoding a sensory histidine kinase [10] , kefA encoding a potassium efflux system [11] and malT encoding a transcriptional activator of maltose regulon [12] . Additionally, more non-synonymous SNPs than synonymous ones (36 versus 12) were identified in the clone frequently associated with genes involved in metabolism, membrane and pathogenicity.…”