Isolation, identification and characterization of enzyme-producing lactic acid bacteria from traditional fermented foods

Industrialization processes are prone to produce various forms of waste which can be utilized to produce silage. These wastes can be treated by using lactic acid bacteria (LAB), which are known to be potential enzyme producers. Seven strains of LAB were isolated from traditional fermented food, 'tapai pulut', 'tempeh', 'tempoyak' and 'fu yu' and were screened for amylase, cellulase and protease production in order to select for strains that could potentially be used industrially in silage production. All seven LAB isolates exhibited high protease production, and two of them also exhibited high amylase and cellulase production. The two isolates exhibiting high amylase and cellulase production were selected and identified as Pediococcus acidilactici FY2 and Enterococcus durans FY3 via biochemical profiling (API 50 CHL) and 16 s rDNA sequencing. E. durans was found to have the highest amylase (Vmax: 5.51 μmol/mL/min; Km: 0.300 g/100 mL) and cellulase (Vmax: 3.50 μmol/mL/min; Km: 0.006 g/100 mL) production, while exhibiting strong protease production (Vmax: 0.51 μmol/mL/min; Km: −0.287 g/100 mL). P. acidilactici was found to have strong amylase (Vmax: 4.43 μmol/mL/min; Km: 0.433 g/100 mL) and cellulase (Vmax: 2.66 μmol/mL/min; Km: 0.002 g/100 mL) production while exhibiting the highest protease production (Vmax: 2.14 μmol/mL/min; Km: −0.348 g/100 mL). These results suggest that E. durans is a better candidate for future industrial application as overall it has a higher enzyme reaction velocity when compared to P. acidilactici. Further studies should be carried out to confirm the Km value for protease production, to purify and characterize all three enzymes produced and to optimize the growth conditions of E. durans.