Characterization and lipolytic activity of lactic acid bacteria isolated from Thai fermented meat.

Twenty six strains of lactic acid bacteria (LAB) were isolated from Thai fermented meat products, including 7 samples of Nham (fermented pork), 7 Sai-krog-prieo (fermented sausage) and one Mum (fermented beef). The isolates were identified as Lactobacillus pentosus (5 isolates), Lactobacillus sp. (11 isolates), Pediococcus pentosaceus (5 isolates) and each isolate of Pediococcus lolii, Leuconostoc fallax, Weissella thailandensis, W. cibaria, and W. paramesenteroides based on their phenotypic characteristics and 16S rRNA gene sequence similarities (99.8-100 %). The isolates were primary screened for their lipolytic activity on agar plates. The rodshaped isolates showed 0.031±0.030-0.938±0.127 U/ml of lipase activity in broth supplemented with Tween 20, Tween 40, Tween 60 or Tween 80. The isolate SS50-1 identified as Lactobacillus pentosus showed the highest activity in Tween 80 (0.938±0.127 U/ml). The coccal isolates showed lipase activity ranged from 0.029±0.006- 1.090±0.033 U/ml when Tween 20, Tween 40, Tween 60 or Tween 80 was used as a substrate. The isolate SS48-4 identified as Pediococcus lolii showed the highest activity in Tween 80 (1.090±0.033 U/ml).

Identification and characterization of lipolytic bacteria from Thai fermented foods

Aims: Gram-positive spore forming rod-shaped bacteria from Thai fermented foods were isolated, identified and screened for lipolytic activity. Methodology and results: Bacterial strains were isolated from Thai fermented foods by the standard dilution technique using Tryptic soy agar. Seven isolates which belong to the genus Bacillus and one isolate which belongs to Paenibacillus were characterized based on their phenotypic characteristics and 16S rRNA gene sequence analyses. Isolates NM8-1 (Group 1), PR9-2 (Group 2), PR11-1 (Group 3), KM15-1 and SS49-4 (Group 4), SS48-5 (Group 5) and SS503 (Group 6), were closely related to Bacillus methylotropicus, B. pumilus, B. flexus, B. cereus, B. subtilis and B. anthracis, based on 99.90-100% similarities, respectively. Isolate NM45-3 (Group 7) was closely related to Paenibacillus pasadenensis based on 99.55% similarity. All the isolates were susceptible to amikacin, chloramphenicol, clindamycin, erythromycin, gentamicin, imipenem, kanamycin, levofoxacin, novobiocin, streptomycin, tetracycline and vancomycin. Their lipase production in nutrient broth with Tween 20, Tween 40, Tween 60 or Tween 80 ranged from 0.014±0.129 - 3.231±0.087 U/mL. Bacillus subtilis SS48-5 exhibited highest lipase production when cultured with Tween 80 at pH 7.5 for 24 h. The optimum lipase production of this strain was at 40 °C after incubated for 30 h. Conclusion, significance and impact of study: The characterization and evaluation of the lipolytic activity of Bacillus and Paenibacillus strains isolated from Thai fermented foods will be useful for the species diversity, food fermentation and the lipase production.