Preliminary evaluation of arginine deiminase activity of indigenous bacterial strains for suitable chemotherapeutic applications

•Our screening method of bacterial strains for ADI activity is rapid and economic.•Crude ADI from selected strains showed excellent serum and proteolytic half-life.•Crude ADI from selected strains exhibited remarkable anticancer activity.•The isolated strains could be very important for therapeutically active ADI.

Cancer is one of the most detrimental disease affects significant segment of human population. Arginine deiminase (ADI) is an anticancer enzyme used in chemotherapy of certain kinds of arginine auxotrophic cancers. However, high antigenicity, shorter serum half-life and low proteolytic tolerance are the major therapeutic limitations which dramatically hampers clinical efficacy of ADI. In the present study, 151 bacterial strains were screened and among them 40 bacterial strains were recorded as ADI positive strains by screening on M-9 medium containing phenol red. To confirm the ADI activity, positive strains were further screened on M-9 medium incorporated with bromocresol purple and bromothymol blue as pH indicators. By quantification of ADI activity, among 40 ADI positive strains, eight strains were considered as potential ADI producers. They exhibited ADI activity in the range of 2.91 IU ml−1 to 5.56 IU ml−1. The crude ADI obtained from these strains were evaluated for in vitro serum half-life, proteolytic tolerance and anticancer activity. Among 8 strains, crude ADI prepared from PS2 and FB1 showed significant in vitro serum half-life, strong proteolytic tolerance and potent anticancer activity. On the basis of morphological, cultural, biochemical characteristics and 16 S rRNA gene sequencing these bacterial strains were identified as Pseudomonas aeruginosa PS2 and Sphingobacterium sp. FB1. From this study, we conclude that ADI from identified bacterial strains could serve as potent anticancer agent. However, more in depth studies are required for strengthening the current findings, which are underway.

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