TABLE 2.
Effects of temperatures on biosurfactant production after growth of B. subtilis C-1 for 48 h in minimal medium
| Growth temp (°C) | Surface tension (dynes/cm) | Dry biomass concn (g/100 ml) | Biosurfactant concn (mg/100 ml)a | E24 (%)b |
|---|---|---|---|---|
| 25 | 29.44 | 0.182 | 30.6 | 0 |
| 30 | 28.98 | 0.330 | 54.7 | 65 |
| 45 | 30.36 | 0.092 | 24.6 | 0 |
a
Precipitates obtained after acidification of 100-ml portions of the culture filtrates were redissolved in 20 ml of double-distilled water (pH 7.4) and lyophilized.
b
Four milliliters of the culture filtrate was mixed with 6 ml of kerosine oil and vortexed for 3 to 5 min. E24 was calculated as follows: [(height of the emulsion layer stable for 24 h)/(total height)] × 100.