J. FERMENT. BIOENG.,

Abstracts of the Articles Printed in Seibutsu-kogaku Kaishi

Vol . 71, N o . 4 (1993)

Genetic Properties of Low-Temperature-Growing Yeasts. DAmo KAWAMURA 1. and Ardo TOI~-E 2 (Hiroshima Prefectural Food Technological Research Center, Hijiyama-honmachi, Minami-ku, Hiroshima 7321; Laboratory o f Genetics, Department o f Botany, Faculty o f Science, University o f Tokyo, Hongo, Bunkyo-ku, Tokyo 1132) Seibutsu-kogaku "/1: 225-232. 1993.

Yeast mutants capable of growing at a low temperature (5°C) were isolated. Two dominant loci were assigned for the mutations, and tentatively designated as LTGI and LTG2 (low-temperature- growth). In general, haploid strains having two LTG genes (LTGI-I LTG2-1) and diploid strains having two (LTGI-1/LTGI-1, LTGI- 1/+ LTG2-1/+, or LTG2-I/LTG2-1) or three (LTGI-1/LTGI-1 LTG2-1/+ or LTGI-I /+ LTG2-1/LTG2-1) genes grew faster at a low temperature. In particular, among the strains tested, the LTGI- 1/L TGI-I diploid strains grew fastest at a low temperature. Low-tem- perature-growing mutant strains (L TG2-6~9) were also isolated from haploids of sake yeast strains (Nihon J6z6 Kyokai no. 9). Fermenta- tion at low temperatures (10°C or 15°C) in sake mash was improved in the mutant strains.

* Corresponding author.

Photo-Dependent Astaxanthin Biosynthesis in a Green Alga, Haematoeoccus pluvtalis. MAKIO KOBAYASm, l* TosmHmE KAKIZOSO, 2 and SHmo NAGAI 2 (Research Laboratory, Higashimaru-Shoyu Co., Ltd., Tominaga, Tatsuno-cho, Tatsuno, Hyogo 679-4P; Department of Fermenta- tion Technology, Faculty o f Engineering, Hiroshima University, Kagamiyama, Higashi-Hiroshima, Hiroshima 7242) Seibutsu-kogaku 71: 233-237. 1993.

In a green alga Haematococcus pluvialis, acetate-induced asta- xanthin biosynthesis was activated by oxidative stress such as Fe 2+ and H202 addition. In the light condition, astaxanthin formation was more enhanced at higher light intensity, whereas no activation was found in the dark. Moreover, induction of both the encystment ac- companying protein degradation and astaxanthin biosynthesis needed more than 18 h of illumination time after acetate addition. Such photo-dependent induction and activation of carotenogenesis have been observed in H. pluvialis growing on acetate medium, suggesting that the alga has a novel photo-dependent regulation system for asta- xanthin biosynthesis.

* Corresponding author.

Coflocculation between Ca2+-Dependent Floc-Forming Bacteria Belonging to the Family Enterobacteriaceae Isolated from Sewage Activated Sludge. KAzoo KAKn,* Yore KATO, Hmortrrd KATO, TOUKO B ~ , D~SUKE KOaAYAsm, ~ SOTOKAWA, and Mrrstlo KIm~AUA (Depart- ment o f Applied Chemistry, Faculty of Engineering, Utsunomiya University, 2753, Ishii-cho, Utsunomiya 321) Seibutsu-kogaku 71: 239-244. 1993.

Using Ca2+-dependent floc-forming bacteria belonging to the genera Kluyvera, Enterobacter, and Citrobacter and their non-floccu- lent mutants, bacterial flocculation was investigated in individual and mixed systems. In the absence of Ca 2+, all of three flocculent strains flocculated in a different manner in a weakly acidic pH range, but

their non-flocculent mutants would not flocculate at all at any pH value. Cells of the flocculent strains were strongly adsorbed by a hydrophobic carrier, Octyl-Sepharose CL-4B, but those of the mutants were scarcely adsorbed. Furthermore, treatment of cells of the flocculent strains with trypsin altered the hydrophobic cell surface to a hydrophilic one. In the presence of Ca 2+, three flocculent strains showed good flocculation at pH 7. Coflocculation was also observed between any two flocculent strains. However, trypsin-treated cells of the flocculent strains and cells of the non-flocculent mutants did not coflocculate at all with cells of the flocculent strains.

* Corresponding author.

Production of Fish Sauce from Fish Meal Treated with Kofl-Mold. Kncosm HAY~WA, ** YOSmE UENO, 1 SADAIIIRO N , ~ I s m , ~ YASUSm HONDA, 2 Hrrosm KoMtmo, 2 StrsAo IOKtlSmUA, 3 and SAKIKO SI~OU 3 (Kyoto Prefectural Comprehensive Guidance Center for Small and Medium Enterprises, Chudoji Minami-machi 17, Shimogyo-ku, Kyoto 6001; Kyoto Soy-Sauce Cooperative Associa- tion, Shimogawara, Toyota, Tanba-cho, Funai-gun, Kyoto 629-042; Hishiroku Co., Ltd., Yamatoofi-higashiiru, Matsubaradori, Higashi- yama-ku, Kyoto 6053) Seibutsu-kogaku 71: 245-251. 1993.

A new process was developed to digest fish meal with kofi-mold to produce fish sauce without an unpleasant fish odor. A similar method of mold cultivation of soy sauce resulted in abundant growth of koji-infecting bacteria. Good fish meal kojis were obtained with low water content, about 28% of the koji medium at seeding, using a katsuobushi-koji starter, Eurotium repens HG-306, and a soy-koji starter, Aspergillus oryzae HO-117. The fish meal koji was mixed thoroughly with sodium chloride solution, made into moromi mash and fermented at 25°C for a period of 180 d. The fish sauce obtained in the new process had a pleasant smell. A sake-kofi starter, Aspergil- lus oryzae H-3, was also effective as a koji starter in this process.

* Corresponding author.

Control of Bioproeesses Using Knowledge-Based Approaches t --Monograph-- KONST~Tm B. KONSTANTINOV (Department of Chemical Engineer- ing, University of Delaware, Newark, DE 19716, USA) Seibutsu- kogaku 71: 253-265. 1993.

The development of intelligent control in biotechnical processes, which only a decade ago was considered an exiting, but obscure vision, has today become an area of intensive and realistic research. Stimulated by rapid progress in the field of real-time expert systems, knowledge-based methodology has now reached a more mature phase. A growing interest among the biotechnology community, and fruitful research being undertaken both in universities and in indus- try, suggest that large-scale application of knowledge-based systems for the control of bioprocesses is inevitable. The present paper dis- cusses the recent trends in this new area, and introduces a generic structure of an intelligent bioprocess control system with enhanced functionality. The underlying concepts are illustrated by examples from recombinant phenylalanine production.

t Paper presented at the Annual Meeting of the Society for Fermentation and Bioengineering, Japan, Osaka, November, 1992.

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