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Mutagenic effect of acridine orange on the expression of penicillin G acylase and β ‐lactamase in Escherichia coli
Author(s) -
Arshad R.,
Farooq S.,
Iqbal N.,
Ali S.S.
Publication year - 2006
Publication title -
letters in applied microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.698
H-Index - 110
eISSN - 1472-765X
pISSN - 0266-8254
DOI - 10.1111/j.1472-765x.2005.01819.x
Subject(s) - escherichia coli , acridine orange , mutant , penicillin amidase , penicillin , microbiology and biotechnology , enzyme , bacteria , enterobacteriaceae , biology , orange (colour) , beta lactamase , chemistry , biochemistry , food science , antibiotics , gene , apoptosis , genetics
Aims: The present work aimed to improve the production of penicillin G acylase (PGA) and reduce the β ‐lactamase activity through acridine orange (AO) induced mutation in Escherichia coli . Methods and Results: Three wild E. coli strains BDCS‐N‐FMu10, BDCS‐N‐S21 and BDCS‐N‐W50, producing both the enzymes PGA and β ‐lactamase were treated by AO. Minimum inhibitory concentration of AO was 10 μ g ml −1 and it was noted that bacterial growth was gradually suppressed by increasing the concentration of AO from 10 to 100 μ g ml −1 . The highest concentration that gave permissible growth rate was 50 μ g ml −1 . The isolated survivals were screened on the bases of PGA and β ‐lactamase activities. Among the retained mutants, the occurrence of β ‐lactamase deficient ones (91%) was significantly higher than penicillin acylase deficient ones (27%). Conclusions: In seven of the mutants, PGA activity was enhanced with considerable decrease in β ‐lactamase activity. One of the mutant strains (BDCS‐N‐M36) exhibited very negligible expression of β ‐lactamase activity and twofold increase in PGA activity [12·7 mg 6‐amino‐penicillanic acid (6‐APA) h −1 mg −1 wet cells] compared with that in the wild‐type strain (6·3 mg 6‐APA h −1 mg −1 wet cells). Significance and Impact of the Study: The treatment of E. coli cells with AO resulted in mutants with enhanced production of PGA and inactivation of β ‐lactamase. These mutants could be used for industrial production of PGA.