Isolation and characterization of lipase producing bacteria for potential application in piglet feed

Abstract

The objectives of this study were to screen the most effective lipase producing microorganism suitable for triacylglycerols containing medium chain fatty acid degradation. The isolates were characterized for their potential of lipase activity, stability in pig's digestive tract, feed pelleting temperature, and antimicrobial activity under simulated pig gastric conditions. Microorganisms were isolated from samples of coconut milk, palm, bamboo seed, fermented soybean, and hot spring soil. The total of 235 isolates were screened on agar medium containing coconut oil. Using p-nitrophenyl laurate as substrate, MHS- 4 showed maximum lipase activity of 630 U/ml and most stable under digestive tract conditions and feed pelleting temperature (85°C). Besides lipase activity, the crude enzyme expressed amylase, cellulase, xylanase, and protease activities. The enzyme product was not toxic to rat intestine epithelial cell and mouse subcutaneous connective tissue. Isolate MHS-4 was identified as Bacillus licheniformis MHS-4 based on the 16S rRNA sequences. Moreover, coconut oil emulsion with exogenous lipase from B. licheniformis MHS-4 exhibited inhibition zone on agar plates against Escherichia coli, Staphylococcus aureus, Salmonella choleraesuis, and Clostridium butyricum. The combination also revealed a significant (P < 0.05) depressive effect on piglet small intestinal and hindgut microbiota. The lactic acid and volatile fatty acids indicating the fermentation activity of the microbiota was lowered (P < 0.05). Therefore, the results indicated that addition of coconut oil with exogenous lipase of B. licheniformis MHS-4 could be used in the diet of weaned piglets to promote the growth.