Enhancement of clavulanic acid production by mutant Streptomyces clavuligerus

Abstract

Background: Clavulanic acid (CA) is a potent β-lactamase inhibitor used to combat resistance to penicillin and cephalosporin antibiotics. There are several pathogenic microorganisms that are capable of secreting β-Lactamases. These enzymes catalyze the hydrolysis of the β-lactam ring of penicillins and cephalosporins, and their hydrolysis products have no antibiotic activity. Since the first clinical applications, the efficiency of the β-lactam antibiotics has been declining, due to the astonishing increasing number of bacteria capable of displaying β-lactam resistance. Thus, the genetic production improvement using physical and chemical mutagenic agents is an important strategy in programs of industrial production of bioactive metabolites, such as CA. Objective: The objective of the study was to enhance CA production using chemical and UV mutagenesis on Streptomyces clavuligerus. Methods: Streptomyces clavuligerus ATCC 27064 was used as the standard strain in all the experiments. The mutant strain was first obtained by chemical mutagenesis using the agent MMS and next the same strain undergoing one more mutation was obtained by UV light. Cellular biomass was analyzed based on the dry weight method and the concentration of CA was determined by HPLC analysis. Results: CA production increased by 28% with mutant strain when compared to the wild-type strain. The mutant strain obtained 812mg L-1 concentration in 72h of fermentation, while the wild-type strain obtained only 639.7.1mg L-1 at the same time, and the productivity at this moment was 11.28 and 8.88mg L-1 h-1 respectively. The mutant strain had a significant increase in biomass growth between 36 and 60h. Conclusion: The study showed that random mutations can lead to the improvement in CA production in S. clavuligerus. This finding reinforces the importance of using this method for productivity improvement.