10. Isolation, screening, characterization of proteolytic bacteria and production of protease with its potential applications

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Aneela Sharif , Zahida Nasreen and Sehrish Kalsoom


The purpose of this study was production of protease enzyme by isolated bacteria and evaluation of their potential for various industrial applications. Two strains AN16 and AN13 exhibiting maximum proteolytic activity were used for further studies. The activity of crude enzymes was completely inhibited by phenyl-methyl-sulphobnyl fluoride (PMSF) and ethylene diamine tetra-acetic acid (EDTA) had no such negative effect on activity. Enzymes were relatively stable in presence of surface active agents such as Triton X-100, Tween-80, Tween-20 and oxidizing agent H₂O₂. The enzymes exhibited maximum activity within pH range of 7-9. The optimum temperature was recorded to be 37⁰C.  The relative activity of isolate AN13 protease in presence of metal ions Ca2+, Fe2+, Mn2+, Mg2+, Zn2+, Co2+, Hg2+, Na+ was as follow: 107%, 99%, 156%, 100%, 105%, 97%, 90%, 104% and102%, 101%, 145%, 80%, 98%, 90%, 98%, 96% for AN16 protease, respectively.  The degradation percentage of chicken feathers by crude protease was recorded to be 55.50% for AN16 followed by AN13 (39.79%). Study of dehairing activity of protease resulted in complete removal of hairs from hide. De-staining studies showed excellent proteinaceous stain removal efficiency. Antibacterial and antifungal activity of synthesized Silver nanoparticles (AgNPs) used against E. coli (25mm), Salmonella typhus (18mm) and fungal strain Malassezia (17mm) were also recorded. Removal of gelatin from waste x-ray films by enzyme extract showed a weight loss of about 6% (AN16) and 5% (AN13). Different low cost media were also tested to support the growth of these proteolytic bacteria exhibiting positive results.

Keywords: AgNP; Dehairing; Detergents additives; Feather degradation; Protease; Silver Recovery


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