FIG 8.

Arginine deiminase contributes to long-term (5-day) static biofilm survival. Overnight cultures were diluted in TSB supplemented with 35 mM glucose and 5 mM arginine to an OD₆₀₀ of 0.100 and incubated statically in 24-well plates at 37°C. (A and B) Cell-free supernatant was collected for measurement of pH (A) and ammonia (B). (C) Representative wells were scraped, and the cells were resuspended and dilution plated for enumeration. Plasmids pNF232 and pNF233 contain the native (arcA1B1D1R1) and acquired (arcA2D2R2B2C2) ADI operons, respectively. Data were analyzed using the Student t test (n = 3; **, significant difference from strain 1457 with P < 0.05).