Fig. 5

Matrix protects biofilm cells under elevated chloride ion stress. 0 h is the CFU of cells before chlorine treatment and 1 h is the CFU post chlorine treatment. Three different concentrations of sodium hypochlorite (a 200, b 400, c 500 p.p.m) were used. a At 200 p.p.m, WT, and co-culture showed a similar pattern of CFU reduction there was less reduction in CFU than ∆csgD mutant. b There was no significant CFU reduction in WT at 400 p.p.m. c At 500 p.p.m there was a complete reduction in CFU of the ∆csgD mutant and in co-culture where both cellulose and curli are produced to complement each other and protect itself from chlorine stress. n = 3 biological replicates, Paired t-test, 95% CI, P value < 0.05