Production and Property of Beta-Lactamases in Streptomyces : Comparison of the Strains Isolated Newly and Thirty Years Ago

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Abstract
Productivity and property of β-lactamases of Streptomyces strains isolated from soil some 30 years ago were studied in comparison with those of the newly isolated strains. At least three-quarters of the Streptomyces strains produced β-lactamase constitutively and extracellularly, mainly as penicillinases, as in the cases of those from the newly isolated strains. Strains such as S. albus, S. diastatochromogenes, S. fradiae, and S. lavendulae were the highest producing strains, and the amounts of β-lactamase activity they produced were comparable to those produced by Bacillus cereus 569/H and B. licheniformis 749/C. In isoelectric focusing, most strains contained one main β-lactamase band with a number of satellite bands, but some strains contained one band only. Although β-lactamases from most strains showed isoelectric points of pH 5 to 6, some strains produced β-lactamases with strongly basic isoelectric points of pH 8 to 9. Molecular weights were between 20,000 and 30,000. From these results, it is suggested that the proportion of the producing strains of Streptomyces and the properties of the β-lactamases have not been affected significantly by the introduction of penicillin into the natural environment, in contrast to the cases of other microorganisms.