OPTIMIZATION OF CULTURE CONDITIONS AND PARTIAL PURIFICATION OF PHYTASE ENZYME ISOLATED FROM BACTERIAL ISOLATES

Abstract

Background: Phytic acid is an anti-nutritional agent in cereal foods, creating nutritional and health problems in human and animals by chelating minerals thereby causing their reduced uptake by the intestine. This study investigates the effects of culture conditions on the phytase enzyme production by three bacterial strains.

Methods: The three bacterial strains were isolated from traditional fermented foods and confirmed by molecular techniques as Lactococcus lactis LAC460, Lactobacillus fermentum SBC0035 and Lysinibacillus macroides DSM54. The phytase-producing bacterial strains were isolated using a phytase screening agar medium. To optimize the culture conditions for optimal production of phytase from the bacterial strains, different factors were studied.

Results: All the isolates attained maximum growth after 36 h of fermentation, and the absorbance was 0.85, 0.88 and 0.84 at 700 nm for Lactococcus lactis LAC460, Lactobacillus fermentum SCB0035 and Lysinibacillus macroides DSM54 respectively. The combination of 0.75% mannose plus 0.75% sucrose and yeast extract were the most efficient carbon and nitrogen sources for phytase production by all the strains isolated while corn starch and soybean meal were the most efficient alternative carbon and nitrogen sources for phytase production. The optimum pH range and temperature for the activity of phytase were found to be 6.5 - 7.5 and 40-60? respectively for all the strains. The partially purified enzyme from Lactobacillus fermentum SCB0035 was 50% stable for 1 h at 80°C. CuSO₄ and FeSO₄ showed an inhibitory effect on the phytase activity as the effect was dose dependent while CaCl₂ and MgSO₄ showed an increase in phytase activity in a dose dependent manner.

Conclusion: This study suggests that the phytase enzyme obtained from the bacterial strains used in this study most especially Lactobacillus fermentum SCB0035 can be exploited in upgrading the nutritional status of feed in animal diet and in the reduction of phosphorus pollution problem in livestock production.