Table 2.
Comparison of culturable and viable biofilm bacteria after batch disinfection with 2 mg l−1 NH2Cl for 5 or 24 h.
| NH2Cl (mg l−1), | Culturable bacteria | Esterase activity | Intact membranes | BacLight™ Total |
|---|---|---|---|---|
| Time (h) | (Log10 CFU cm−2) | (Log10 cells cm−2) | (Log10 cells cm−2) | direct count (Log10 cells cm−2) |
| 0 mg l−1, 5 h | 6.26 (0.00) | 6.06 (0.13) | 6.07 (0.14) | 6.16 (0.15) |
| 2 mg l−1, 5 h | 5.56 (0.23)* | 5.87 (0.14) | 5.88 (0.07) | 6.08 (0.04) |
| LR | 0.7 | 0.19 | 0.19 | 0.08 |
| 0 mg l−1, 24h | 6.00 (0.09) | 5.89 (0.15) | 5.89 (0.09) | 5.96 (0.07) |
| 2 mg l−1, 24 h | 5.30 (0.13)* | 5.73 (0.09) | 5.76 (0.14) | 6.05 (0.12) |
| LR | 0.7 | 0.16 | 0.13 | −0.09 |
Note: Direct viability was quantified by detection of esterase activity and cell membrane integrity (n = 3 coupons; SD in parentheses; LR = log reduction). Total direct count of bacteria was calculated as the sum of viable and nonviable cells after BacLight™ staining (green and red cells).
*
= a statistically significant reduction from the untreated control (p < 0.01).