• Journal of Microbiology and Biotechnology
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• v.15 no.5
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• pp.971-976
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• 2005

In a 30-1 bioreactor culture, whole differentiation occurred from 48 h, and then proceeded rapidly. As swollen hyphal fragments and arthrospores increased, cephalosporin C (CPC) production increased exponentially to $1.85\;g/1^{-1}$ at 72 h. To explain the morphological changes of Cephalosporium acremonium M25 more quantitatively, specific differentiation rates and fractal analysis were employed. Specific differentiation rates of morphological factors varied greatly during the period of culture time from 48 h to 72 h, when CPC production increased significantly. Changes of fractal dimensions showed a pattern similar to that of the specific rate of arthrospores. Furthermore, it was inversely related to the specific rate of tips. Overall, it was suggested that the fractal dimension had potential for a new morphological parameter of fungal morphology, showing complex differentiation patterns.

• Korean Journal of Microbiology
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• v.25 no.3
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• pp.205-211
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• 1987

Cephalosporium acremonium MAR-80, a strain of methionine analogue-resistant mutant, showed good activity of sulfate utilization as only sulfur source. The effect of methionine on the sulfate uptake system was investigated by using $Na_{2}^{35}SO_{4}$ as a tracer in the resting cell system. From this result, it was revealed that sulfate permease of this strain was less repressed and/or less inhibited by methionine than parent type. This deregulation was due to low actibity of methionine uptake, which was operated by somewhat simple diffusion. From these studies, it could by anticipated that the improved productivity of cephalosporin C and lower dependence of cephalosporin C production on methionine were related to increased uptake rate of sulfate.

• Microbiology and Biotechnology Letters
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• v.17 no.6
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• pp.611-618
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• 1989

Effects of methionine on cephalosporin C(CPC) production in a fluidized-bed bioreactor were investigated using bioparticles of Cephalosporium acremonium. Since methionine was found to be an important metabolic regulator on the synthesis of cephalosporin C, the effects of its concentration in the cuture broth and feeding mode to the bioreactor were studied. It was observed that the presence of initial methionine was essential for higher cephalosporin C production and there existed an optimal content of methionine. Carbon consumption rate also increased significantly under the presence of methionine. Production of cephalosporin C was most active when methionine was exhausted in the broth; however its additional feeding did not enhance the antibiotic production in the fluidized-bed bioreactor as much as expected. It was therfore considered important to feed an optimal content of methionine at the early operating stage for a higher cephalosporin C production in a fluidized-bed bioreactor. An interesting thing to note was that titre of the antibiotic with reused bioparticles was about 2 times higher in the methionine containing medium than that without methionine. Therefore repeated use of bioparticles, with an optimal content of methionine, was believed to be very useful to enhance to process productivity.

• Microbiology and Biotechnology Letters
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• v.15 no.5
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• pp.361-367
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• 1987

A DL-seleno-methionine resistant mutant, Cephalosporium acremonium MS-92 showed increased activities of sulfate and L-methionine uptake than the parent strain, and accumulated excess methionine and S-adenosylmethionine (SAM) intracellularly. And the sulfate uptake system was severely inhibited by L-cysteine. In crude enzyme extracts, the mutant MS-92 showed lower L-serine sulfhydrylase (identical with cystathionine $\beta$-synthase) activity than the parent. Also, cysteine desulfhydrylase activity, an index of intracellular L-cysteine concentration, of the mutant MS-92 was decreased by about 50% as com-pared with that of the parent. Thus, it was supposed that the mutant MS-92 should have n lower level of L-cysteine than the parent. In C. acremonium like A. nidulans, the enzymes related to the biosynthesis of methionine might be regulated by L-cysteine, but not by methionine or SAM.