Characterization of lipase-producing halophilic bacteria and partial purification of lipase from Virgibacillus halodenitrificans SKP5-4

Abstract

Aims: The aim of this research was to isolate and characterize lipase-producing halophilic strains and partially purify lipase from Virgibacillus halodenitrificans SKP5-4. Methodology and results: Eighteen strains of moderately halophilic bacteria were isolated from shrimp paste (Ka-pi) in Thailand. Based on the phenotypic and genotypic characteristics, ten lipase-producing halophilic bacteria were identified as Bacillus amyloliquefaciens subsp. plantarum (SKP1-4), Bacillus salacetis (SKP7-4), Thalassobacillus hwangdonensis (SKP1-5), Staphylococcus saprophyticus subsp. bovis (SKP2-1 and SKP2-3), Oceanobacillus manasiensis (SKP5-5), Allobacillus halotolerans (SKP2-8), Allobacillus salarius (SKP4-8), Allobacillus saliphilus (SKP8-2), and V. halodenitrificans (SKP5-4). Strain SKP5-4 exhibited high lipase production and was selected for partial purification using Hitrap^TM DEAE FF anion exchange chromatography and 40-60% cold acetone precipitation. The molecular mass of the protein was estimated at 12, 30, 43 and 50 kDa based on Native-PAGE (10% w/v). Optimal conditions for enzyme activity were pH 7.0, temperature 40 °C and 2% (w/v) NaCl. Additionally, the halophilic lipase showed higher activity at low ionic strength and maintained 80% relative activity at 3-9% (w/v) NaCl. Conclusion, significance and impact of study: This study characterized ten moderate halophiles and demonstrated the secretion of halophilic lipases from V. halodenitrificans SKP5-4. The halophilic lipase identified may contribute to the production of volatile fatty acids in shrimp paste, enhancing flavour and aroma.