The Improved Assay Method of Blasticidin S

Abstract

The bioassay of blasticidin S had been reported by Takeuchi et al.²⁾ using Bacillus subtilis PCI 219 as the test organism. The procedure reported covered the concentration range of about 50—1,000 u/ml by a cup-plate method. Afterwards, Iizuka⁸⁾ and Koyama⁸⁾ revealed that Bacillus cereus is more excellent in the formation of the clear-cut zone with blasticidin S than Bacillus subtilis PCI 219. Thus, at present time, Bacillus cereus is used widely for the purpose of the bioassay of blasticidin S. However, to keep accuracy of the determination, the relative insensitivity of Bacillus cereus to blasticidin S is quite unsatisfactory for the assay procedure in which the further precision of the assay is required. Aiming the selection of the more sensitive test organism than Bacillus cereus for the assay procedure of blasticidin S, the authors have found Bacillus circulans IAM-1112 as the most favorable test organism for the assay procedure of blasticidin S. It is the purpose of this paper to describe the merits of Bacillus circulans in the cup-plate assay procedure for blasticidin S.