Kazuhiko Okamura

Application of cyclodextrin to microbial transformation of vitamin D3 to 25-hydroxyvitamin D3 and 1α,25-dihydroxyvitamin D3

Abstract Amycolata autotrophica converts vitamin D3(VD3) to 1α,25-dihydroxyvitamin D3(1α,25(OH)2VD3) via 25-hydroxyvitamin D3(25(OH)VD3) by hydroxylation of VD3 at C-25 and C-1. In this microbial hydroxylation, it was found that cyclodextrin (CD) had the ability to enhance the hydroxylation of VD3. Addition of partially-methylated-β-cyclodextrin (PMCD) increased the productivity of 25(OH)VD3 about seven-fold compared to that without CD. Combined use of PMCD and γ-CD increased the production of 1α,25(OH)2VD3 in a tank fermentor about sixteen-fold compared to that without CD.

Preferential and high-yield production of a cephamycin C by dissolved oxygen controlled fermentation

Abstract Streptomyces sp. P6621-RS1726, a high cephamycin C producing mutant, usually produces cephamycin C together with its precursor, penicillin N, in flask fermentation. The fermentation conditions for selective and high yield production of cephamycin C were investigated using 20-l jar fermentors. As a result, cephamycin C was preferentially produced without penicillin N when the DO level was maintained at least higher than at 10% during the production phase. However, when the agitation speed was too high at the initial stage of the fermentation, the cell growth was inhibited, resulting in suppression of both cephamycin C and penicillin N production, even if the DO was maintained at a high level. Based on these experiments, a computer control system for preferential and high-yield production of cephamycin C was constructed. By using this computer control system, scale-up from a 20-l jar fermentor to a 1,500-l pilot fermentor was carried out with control of the DO level at 20% of saturation during the cephamycin C production phase. As a result, the profile of cephamycin C production in the former was favorably reproduced in the latter.

A novel pyrazine compound produced from chitin by the activity of the enzyme from Vibrio alginolyticus TK-24

Abstract An enzyme from Vibrio alginolyticus TK-24 which converted chitin to a novel pyrazine compound, VAPY was purified to electrophoretic homogeneity and is suggested to be a novel enzyme as determined from examination of its ten N-terminal amino acid residue sequence and its characteristic activity. The structure of VAPY was elucidated by mass spectroscopy, 1 H nuclear-magnetic-resonance ( 1 H NMR) and 13 C nuclear-magnetic-resonance ( 13 C NMR) spectroscopy, and from the spectroscopic data it was determined to be a novel pyrazine compound.

Preferential production of a carbapenem antibiotic, PS-5 by dissolved oxygen controlled fermentation

Abstract As Streptomyces fulvoviridis A933-17M9 usually produces several carbapenem analogs including PS-5, the submerged fermentation conditions were optimized for preferential production of PS-5. The scale of PS-5 fermentation was expanded stepwise from a 2.5- l mini-jar fermentor to a 1500- l pilot-scale fermentor. For production of PS-5 as a major product among related carbapenem analogs, the concentration of dissolved oxygen during fermentation was controlled at levels where microbial conversion of PS-5 to epithienamycins A and C and further to MM17880 was largely prevented without deleterious influences on the carbapenem-biosynthesizing activity of mycelia.