Hachiro Ozaki

Mycophenolic acid production by drug-resistant and methionine or glutamic-acid requiring mutants of Penicillium brevicompactum.

Penicillium brevicompactum ATCC 16024 produced 1.7 g/1 of mycophenolic acid (MPA) in the culture medium. Various drug-resistant mutants, showing resistance to such as polyene antibiotics, chemotherapeutic agents, redox indicator and surfactants, were derived from the fungus. Most of the mutants produced 2.0 ~2.5 g/1 of MPA. A clofibrate and dodecyltrimethylammonium chloride double resistant mutant, No. 4–23–11, produced 4.7 g/1 of MPA. A monofluoroacetic acid resistant strain, No. 5–1, derived from No. 4–23–11 produced 5.3 g/1 of MPA.A methionine auxotroph, M-l, derived from ATCC 16024, produced 4.0 g/1 of MPA. A glutamate auxotroph, G-42, derived from strain No. 4–23–11 produced 5.8 g/1 of MPA. G-42 grew on l-aspartate instead of l-glutamate, and showed one-third the pyruvate carboxylase activity of the parent. Another glutamate auxotroph, G-78, did not produce MPA but accumulated 1.5 g/1 of acetate in the culture medium, and showed one-fifth the citrate synthase activity of the parent strain.

Effects of l-serine dehydratase activity on l-serine production by Corynebacterium glycinophilum and an examination of the properties of the enzyme

Abstract The results with Corynebacterium glycinophilum AJ-3170 and various mutants from AJ-3170 indicated that l -serine production was almost inversely proportional to l -serine degrading activity. The crude extract of the parental strain, AJ-3170, showed l -serine and l -threonine degrading activities. The 2 activities were completely separated from each other by gel-filtration, indicating that each activity comes from a different enzyme. The l -serine degrading enzyme, l -serine dehydratase (SD), was purified 30-fold from AJ-3170. Molecular weight of SD was 130,000. The enzyme was specific for l -serine, activated slightly by FeCl 2 and inhibited by MnCl 2 . The double reciprocal plots of SD rate against substrate concentration gave an upwards-curved line. The value of [S] 0.5 was 35 mM.

O-Acetylhomoserine sulfhydrylase from Brevibacterium flavum

Publisher Summary In Brevibacterium flavum, L-methionine is synthesized from L-homoserine via O-acetylhomoserine and L-homocysteine. The formation of L-homocysteine from O-acetyl-L-homoserine is catalyzed by O-acetylhomoserine sulfhydrylase, in contrast to enteric bacteria and Neurospora, in which L-homocysteine is synthesized through cystathionine formation. . The assay procedure, which uses the nitroprusside reaction to determine homocysteine in the presence of sulfide, is a slight modification of that for O-acetylserine sulfhydrylase described by Kredich and Becker. O-Acetyl-e-homoserine and sulfide are incubated with bacterial extract. The homocysteine formed is converted to a stable S-nitrosothiol derivative by adding nitrous acid, which also stops the reaction. Excess nitrous acid is removed by the addition of ammonium sulfamate, and then mercuric chloride, sulfanilamide, and N-l-naphthylethylenediamine are added. The S-nitrosothiol derivative of homocysteine decomposes in the presence of mercuric ion to give nitrous acid which diazotizes the sulfanilamide. The diazotized sufanilamide couples with naphthylethylenediamine to give the chromophore, an azo dye.

Effects various adsorbents on mycelium formation and mycophenolic acid production by Penicillium brevicompactum.

A drug-resistant mutant, No. 4–23–11, which had been derived from Penicillium brevicompactum ATCC 16024, was cultured in a liquid medium for the production of mycophenolic acid (MPA) in the presence and absence of various adsorbents, that is, celites, zeolites, aluminas, talc, silica, charcoals, carbon blacks, natural graphite and carbonaceous mesophase spheres. In the absence of an adsorbent, MPA production (0.2 ~4.8 g/1) and the size of mycelium pellets (5~0.5mm) markedly depended on the concentration of spores inoculated (104~ 107/ml), whereas in the presence of one of these adsorbents, small pellets (smaller than 1 mm in diameter) were formed and the high production of MPA (4.5 — 5.4 g/1) was observed, independently of the spore concentration between approximately 104~ 107/ml. Microscopic observation of the pellets revealed that numerous particles of the adsorbents adhered to the surface of the hyphae. These results suggest that the adsorbents might interfere with the adhesion of hyphae to each other ...