Mutagenic effect of acridine orange on the expression of penicillin G acylase and beta-lactamase in Escherichia coli.
OBJECTIVE
The present work aimed to improve the production of penicillin G acylase (PGA) and reduce the beta-lactamase activity through acridine orange (AO) induced mutation in Escherichia coli.


RESULTS
Three wild E. coli strains BDCS-N-FMu10, BDCS-N-S21 and BDCS-N-W50, producing both the enzymes PGA and beta-lactamase were treated by AO. Minimum inhibitory concentration of AO was 10 microg ml(-1) and it was noted that bacterial growth was gradually suppressed by increasing the concentration of AO from 10 to 100 microg ml(-1). The highest concentration that gave permissible growth rate was 50 microg ml(-1). The isolated survivals were screened on the bases of PGA and beta-lactamase activities. Among the retained mutants, the occurrence of beta-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 beta-lactamase activity. One of the mutant strains (BDCS-N-M36) exhibited very negligible expression of beta-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).


CONCLUSIONS
The treatment of E. coli cells with AO resulted in mutants with enhanced production of PGA and inactivation of beta-lactamase. These mutants could be used for industrial production of PGA.
Arshad
R
R
Nuclear Institute for Agriculture and Biology (NIAB), Faisalabad, Pakistan. arshadrubina@hotmail.com
Farooq
S
S
Iqbal
N
N
Ali
S S
SS
D000165:Acridine Orange / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D004926:Escherichia coli / Q000187:drug effects* / Q000201:enzymology*; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects*; D016296:Mutagenesis; D010399:Penicillin Amidase / Q000235:genetics / Q000378:metabolism*; D001618:beta-Lactamases / Q000187:drug effects / Q000378:metabolism*
D010399:Penicillin Amidase; D001618:beta-Lactamases; D000165:Acridine Orange