TABLE 6.
Comparison of specific levels of enterotoxin production between the fnr mutant and its parent strain, B. cereus F4430/73a
| Growth conditions | Amt of enterotoxin (U g−1 [dry weight] of cells)
|
|||
|---|---|---|---|---|
| Hbl
|
Nhe
|
|||
| WT | fnr | WT | fnr | |
| Aerobic | ||||
| Glucose | 1.0 ± 0.2 | NZ | 1.5 ± 0.3 | NZ |
| Anaerobic | ||||
| Glucose | 12.0 ± 2.0 | NG | 8.0 ± 1.0 | NG |
| Glucose and 20 mM fumarate | 10.0 ± 2.0 | NG | 5.5 ± 0.5 | NG |
| Glucose and 20 mM nitrate | 1.0 ± 0.2 | NZ | 2.1 ± 0.2 | NZ |
| Glycerol and 20 mM nitrate | 0.16 ± 0.03 | NZ | 0.37 ± 0.03 | NZ |
| Glycerol and 60 mM nitrate | NZ | NZ | NZ | NZ |
a
Hbl and Nhe levels were measured in culture supernatants at the end points for pH-regulated batch cultures. Cells were grown under aerobiosis or anaerobiosis on MOD medium supplemented with glucose (30 mM) or glycerol (60 mM) as a carbon source and with or without an external electron acceptor (nitrate or fumarate). Values are means ± standard deviations of three independent measurements. WT, wild type (B. cereus F4430/73); fnr, fnr mutant; NG, no growth; NZ, yield near zero or below 0.01.