The emulsification index values of the partially purified biosurfactant
were also measured at different temperatures and pH
values. Biosurfactant An6 showed emulsification activity at temperature
ranging from 20 to 100 C. The retention of over 80%
emulsification activity at 100 C suggested that the biosurfactant
An6 might be useful in extreme environments. Biosurfactant An6
was also found to be active in a wide range of pH from 3.0 to 10.0.
The highest emulsification index (80%) was observed at pH between
5.0 and 9.0, while lower pH reduced the emulsifying activity.
Indeed, there was a 36 and 28% decrease in activity at pH 3.0 and
4.0, respectively (data not shown).