Kanokrat Saisa-ard, Atipan Saimmai, and Suppasil Maneerat

pp. 163 - 175

Abstract

Biosurfactant-producing bacteria were isolated from 89 different soil samples contaminated with palm oil in 35 palm
oil industry sites in the south of Thailand. The phylogenetic diversity of the isolates was evaluated by 16S rRNA gene
analysis. Among 1,324 colonies obtained, 134 isolates released extracellular biosurfactant when grown on low-cost substrates
by a drop collapsing test. Among these, the 53 isolates that showed the highest biosurfactant production on different
substrates were found to belong to 42 different bacterial genera. Among these sixteen (Caryophanon; Castellaniella;
Filibacter; Geminicoccus; Georgenia; Luteimonas; Mesorhizobium; Mucilaginibacter; Nubsella; Paracoccus; Pedobacter;
Psychrobacter; Rahnella; Sphingobium; Sphingopyxis and Sporosarcina) were first reported as biosurfactant-producing
strains. By using low-cost, agro-industrial by-products or wastes, Azorhizobium doebereinerae AS54 and Geminicoccus
roseus AS73 produced extracellular biosurfactant, which exhibited the lowest surface tension reduction (25.5 mN/m) and
highest emulsification activity (69.0%) when palm oil decanter cake and used palm oil was used as a carbon sources, 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.