Abstract

OPTIMUM CONDITIONS FOR CYTOSINE DEAMINASE PRODUCTION BY LOCAL ISOLATE OF ESCHERICHIA COLI E9.

*Ali Saadi Al-Baer and Asmaa A. Hussein

Abstract

This study was aimed to isolate a higher cytosine deaminase producer Escherichia coli and studying the optimum condition for its production, a total of twenty-five urine samples were collected for the isolation of E. coli bacterium from Al-Imamein AlKadhumain medical city hospital in Baghdad. From these samples, a total of 10 bacterial isolates were obtained when subjected to morphological and microscopical tests. Cytosine deaminase enzyme activity was determined using cytosine as substrate, results indicated that 10 isolates of them are cytosine deaminase producer with different specific activity ranged between (0.122-0.35) U/mg and the isolate Escherichia coli E9 was the most efficient in the production of cytosine deaminase with specific activity of 0.35 U/mg protein. Therefore, it was chosen to determine the optimum conditions for cytosine deaminase production. Maximum cytosine deaminase production was achieved after supplementation of the minimal salt medium (pH 8.5) with 0.1% citric acid, 0.1% peptone and incubated at 37oC for 24h. Under these conditions, the specific activity of cytosine deaminase produced in culture supernatant was sharply increased to 0.7 U/mg protein.

Keywords: This study was aimed Al-Imamein AlKadhumain to 0.7 U/mg protein.