Production and Characterization of Halo Tolerant Alkaline Protease of Enterobacter aerogenes Strain ZB and Its Application

Abstract

Aims: The present investigation was carried out to isolate a halo tolerant Enterobacter aerogenes strain ZB for the production of alkaline protease to degrade protein wastes from the tannery wastewater. Study Design: Halo tolerant protease producing bacteria was isolated from the salt pan. It was used for the production of halo tolerant protease in submerged fermentation. The crude protease thus obtained was characterized and its protein removal efficacy was tested in tannery wastewater. Place and Duration of Study: Smykon Biotech Private LtD, Nagercoil, Kanyakumari District, Tamilnadu, India between January 2017 and March 2017.  Methodology: The halo tolerant bacterial isolates were screened for the production of alkaline protease using skimmed milk agar plates. Then a potent bacterial isolate was selected for the production of halo tolerant protease in submerged fermentation. Crude protease was used treat tannery wastewater and the protein removal efficacy of the enzyme was evaluated.      Results: A halo tolerant strain able to grow at wide sodium chloride concentration was isolated from a salt pan and identified as E. aerogenes strain ZB. The isolate was the potential to produce protease which showed catalytic activity under high saline conditions. The E. aerogenes strain ZB protease activity was found to be maximum at pH 8.0 and enzyme activity was reduced at pH 10.0. The protease from E. aerogenes strain ZB was highly stable upto pH 8.0 and declined at higher pH. Enzyme activity was found to be maximum at 50°C and was stable upto 40°C. Enzyme was highly active in the presence of ions like Ca2+, Na+ and Mg2+ ions (0.005 M) and the enzyme activity was 101.3%, 109% and 102% respectively. This halo tolerant enzyme showed the protein degrading capacity in tannery wastewater at 1% and 5% enzyme concentrations. Conclusion: This halo tolerant enzyme effectively removed proteinaceous waste from the tannery wastewater. A maximum protein removal was achieved at 5% enzyme concentration. The proteases produced by E. aerogenes strain ZB could have potential application in tannery wastewater treatment.