Growth and extracellular enzyme production by microorganisms isolated from Ugba - an indigenous Nigerian fermented condiment

Abstract

Studies were conducted to isolate and identify the fermenting microorganisms of ‘Ugba’, an indigenous Nigerian fermented food condiment. The isolated microorganisms were screened for amylase, protease and lipase production, the activity and specific activity of the enzymes were also determined. The effect of pH and temperature on the activity of the enzymes was also studied. The following groups of organisms were identified as among the major fermenting organisms isolated from fermenting ‘Ugba’; Bacillus species, Proteus species, Staphylococcus species, Micrococcus species and Pseudomonas species. Bacillus, Staphylococcus and Proteus were positive for amylase production. Bacillus subtilis, B. licheniformis and Staphylococcus species exhibited the highest potential for amylase production. Maximal amylase activity was achieved within the pH range of 6 to 7, while the optimum temperature range for the enzyme activity was between 50 to 60°C. Twelve isolates identified as Bacillus subtilis (Bs₁, Bs₂, Bs₃, Bs₄, Bs₅, Bs₆ and Bs₇) and Bacillus lichenformis (Bl1, Bl2, Bl3, Bl4 and Bl5) were identified as among the major fermenting organisms. These isolates tested positive for protease enzyme production with the highest protease activity shown by Bs₃ (18.48 ul/ml) and the least by Bl₂ (4.21ul/ml) and Bl₃ (4.28 ul/ml). Highest protease activity (18.48 ul/ml) was recorded at the end of the third day of incubation. The optimum temperature for protease activity was observed to be within 35 to 40°C, while the optimum pH range for the enzyme activity was recorded at pH 7 to 8. Screening of the isolated organisms for lipase production revealed that Micrococcus species, Pseudomonas species and a strain of Bacillus subtilis (Bs₂) were able to produce lipase enzyme. The study evaluated the potential of the strains in starter culture development for fermentation of African foods.

Keywords: Ugba, fermentation, amylase, protease, lipase, enzyme activity

African Journal of Biotechnology Vol. 12(26), pp. 4158-4167