Microorganisms: Pure cultures, Alcaligenes euthophus (TISTR 1095), Alcaligenes faecalis
(TISTR 038) and Pseudomonas oleovorans (TISTR 1097) were purchased from Thailand Institute
of Scientific and Technological Research (TISTR). Five loops of pure culture colony on nutrient
agar (NA) incubated at 30°C for 48 h were transferred to 5 mL nutrient broth (NB). After
incubation at 30°C for 48 h, 5 mL of cell suspension was secondly transferred into 95 mL and
incubated in 200 rpm shaking incubator (JSSI-l00C, KOREA) until the bacterial growth reached
log phase (16 h incubation). Cell suspension was centrifuged and cell pellet was washed with
distilled water twice and was re-suspended in NB prior to use.