Isolation and characterization of biosurfactants-producing bacteria isolated from palm oil industry and evaluation for biosurfactants production using low-cost substrates

Biosurfactants-producing bacteria were isolated from various palm oil refinery industrial sites in the south of Thailand.

Isolates were screened for biosurfactant production by using low-cost, agro-industrial by-products or wastes

as a substrate. Based on drop collapsing test and emulsification activity, 25 isolates were selected. All the selected

isolates reduced the growth medium surface tension to 40 mN/m and produced emulsions with xylene. Twenty

isolates exhibited high emulsion-stabilizing capacity, maintaining more than 50% of the original emulsion volume

for 24 h. The phylogenetic position of these 25 isolates was evaluated by 16S rRNA gene sequence analysis.The

production of biosurfactants was determined for strains representative of 15 different bacterial genera, six of them

(Azorhizobium, Buttiauxella, Comamonas, Halopenitus, Haloplanus and Sinorhizobium ) have been for the first time

reported in this study as biosurfactant-producing strains. Additionally, Sinorhizobium meliloti AS91 and Marinobacter

hydrocarbonoclasticus AS51 produced extracellular biosurfactant which exhibited the lowest surface tension

(32 mN/m) and emulsification activity (69%) when cashew apple juice and used vegetable oil were used as the carbon

source, respectively. Overall, this is the first study of a phylogenetic analysis of biosurfactant-producing bacteria

from palm oil refinery industry site and their ability to produce biosurfactant on renewable substrates.