Fig. 2. Surface tension on actinomycetes isolates growing on glycerol, n-hexane and molase substrate media

The resulting free cell supernatant is measured by its surface tension value using a Du Nouy tensiometer at room temperature. The results of surface tension measurements and a decrease in the value of the surface tension to the control can be seen in Fig 2. The value of the surface tension measured at day 0 (control) and day 7). The decrease in surface tension is caused by the presence of biosurfactants in the supernatant produced by bacterial isolates during the growth process.

将所得无细胞上清液于室温下采用杜诺伊（Du Nouy）表面张力仪测定其表面张力值。表面张力测定结果以及相较于对照组的表面张力降幅详见图2。分别记录第0天（对照组）与第7天测得的表面张力值。表面张力的降低源于细菌分离株在生长过程中所产生的上清液中存在生物表面活性剂。