Isolation of naringinase producing soil bacteria from Psidium guajava L. and Terminalia chebula Retz and its enzymatic activity

In commercial citrus juice, bitterness causes serious challenges in fruit juice manufacturing industries. The prime cause of bitterness is due to the presence of naringin compound. It is noted that microbial enzyme retains some specific catalytic reactions of physicochemical and biological properties possessing high degree of industrial and medical applications. The microbial enzyme naringinase can be immobilized for industrial use to reduce the cost of debittering of juice. Since environment friendly industrial biocatalysts are economically more viable, so the focus on the present study is debittering of juice at low cost without using chemicals which alter the nutrient composition. In the present study, four strains of naringin degrading bacteria were isolated from the soil of Psidium guajava L. and Terminalia chebula Retz in Dibrugarh University Botanical Garden and were investigated for naringinase activity of soil microbes and their growth conditions at different parameters. The turbidity of cell culture and concentration of proteins in the culture media have been utilized for the optimization of various growth conditions, like temperature and pH for microbial growth. The optimal growth of the four isolates was observed in a media of pH 6 and selected for further study. All the four isolates showed good extracellular naringinase activity. Among the four isolates, oval and rod shaped gram positive bacteria showed the highest specific activity (405.31 U/mg) and lowest activity was shown by rod shaped gram negative bacteria (231.77 U/mg). Furthermore, rod shaped isolate exhibited maximum growth and highest protein content among the four isolates. These results suggested that in addition to the naringinase enzyme, some other proteins were also produced by the isolates. These proteins might have some significance in supporting the growth of the microorganisms.