The efficiency of some proteolytic bacteria isolated from modjo tannery waste for application in leather and detergent industry

Abstract

The extracellular proteases have great commercial value and multiple applications in various industrial sectors since they posses almost all characteristics desired for their biotechnological applications. In Ethiopia, all tanneries use many chemicals, despite the lack of survey on the particular types of optional technology. But enzyme technology serves as an immediate solution for such crucial problems beyond reducing environmental pollution. The objective of this work was to isolate efficient proteolytic bacteria from tannery wastes and production of protease enzyme from them. In this work samples of Leather sludge were collected from Modjo Tannery, South East of Addis Ababa. Five isolates were screened for protease production by culturing on skim milk agar, out of which two isolates showed efficient enzyme production. The bacterial isolates with prominent zone of clearance and showing efficient enzyme production were further characterized to genus level following standard procedures. Moreover, the growth conditions for the highest protease production were optimized with different pH, temperature and NaCl concentration. Enzyme activity was assayed using tyrosine-casein method. The proteases from PMOJ-01 (Micrococcus) and PMOJ-05 (Bacillus) were active at pH 8, pH 7, and temperature of 37 and 35 o C, respectively. The total protein contents of PMOJ-01 and PMOJ-05 was 0.45 μmole and 0.48 μmole, respectively. The enzyme activity and the total solid protease sample of crude enzyme of PMOJ-01 (Micrococcus) and PMOJ-05 (Bacillus) were 0.299 U/ml and 0.289 U/ml and 1.37 U/mg and 1.199 U/mg respectively. The partially purified enzyme of PMOJ-01 and PMOJ-05 had total solid protease of 2.05 U/mg and 11.55 U/mg and Enzyme activity of 0.242 U/ml and 0.231 U/ml respectively. The result of scum removal, hair removal, egg stain removal and blood stain removal revealed that the purified protease enzyme of PMOJ-01 and PMOJ-05 can be used in detergent and leather industries. Thus, the use of protease in leather processing could potentially minimize the use of hazardous chemicals such as sodium, lime and solvents and greatly minimize environmental pollution.