Nitto Chemical Industry Co., Ltd.

Nitto Kagaku Kogyo Kabushiki Kaisha

Toshiaki Doi

Atsushi Fujiwara

Koji Tamura

Takakazu Endo

Masashi Nishida

Kanehiko Enomoto

Yoshiaki Satoh

Yasumasa Yamaguchi

Yasutaka Nakashima

Kouzo Murao

Yuji Hirata

Hiroyasu Bamba

Kouzou Murao

Ashina Yoshiro

Cells having enzyme activity, and the enzyme activity thereof, are preserved for a prolonged period of time, as a suspension of microbial cells or as a suspension of immobilized cells in particles, in an aqueous medium that is a neutral or weakly basic aqueous solution of inorganic salts, having a molarity ranging from 100 mM to the saturation concentration of the inorganic salts. Preferably, the microbial cells are cells containing the enzyme, nitrile hydratase or nitrilase, such as Gordona terrae or Rhodococcus rhodochrous, and the inorganic salts are phosphates, borates, sulfates, sulfites or hydrochlorides. The present invention provides an industrially useful method for preserving a large quantity of cells or immobilized cells in particles having nitrile hydratase or nitrilase enzyme activity for a prolonged period of time (e.g., 300 days) without cell lysis or enzyme deterioration even at room temperature. The present invention also renders possible a sharp reduction in labor and cooling cost, which are necessary in the conventional preservation process.

Method for preserving nitrile hydratase or nitrilase activity of

Biocatalysts such as cells and enzymes are immobilized in a polymer gel by forming a mixture containing a biocatalyst, an N,N-dialkylacrylamide monomer, a cationic acrylamide monomer and a water-soluble cross-linking monomer, and copolymerizing the monomers to produce a polymer gel entrapping the biocatalyst. Preferably, the N, N-dialkylacrylamide is N,N-dimethylacrylamide or N,N-diethylacrylamide in an amount of about 70 to about 99.8% by weight, the cationic acrylamide monomer is N,N-dimethylaminopropylacrylamide, N,N-dimethylaminopropylmethacrylamide, N,N-diethylaminopropylmethacrylamide, N,N-diethylaminopropylacrylamide and quaternary compounds thereof in a amount of about 0.1 to about 10% by weight and the cross-linking monomer is N,N'-methylenebisacrylamide, N,N'-methylenebismethacrylamide, N,N'-(1,2-dihydroxyethlene)bisacrylamide, 1,3-diacrylamide methyl-2-imidazolidone or diacrylamide methylene urea in an amount of about 0.1 to about 20% by weight. The polymer gel containing a biocatalyst has excellent storage stability and does not putrefy even after one month of storage at ordinary temperature.

Biocatalysts immobilized in a storage stable copolymer gel

In a process for hydrating a nitrile compound by the action of a microorganism having nitrilase activity to convert the nitrile compound into the corresponding amide compound, the performances such as yield and reaction velocity are markedly enhanced by irradiation of the microorganism with light. The process of the present invention is characterized in that (a) the microorganism having nitrilase activity is a positive gram-staining microorganism, (b) the microbial cells are allowed to accept light energy of at least about 1.times.10.sup.-2 .mu.E/g microbial cells second before termination of the hydration reaction, and (c) the hydration reaction is carried out in a vessel composed at least partly of a non-light transmitting material.

Process for producing amides by use of microoganisms

A method for purifying a reaction solution obtained by using a microbial cell, an immobilized microbial cell, or an immobilized enzyme as a catalyst in a water medium is disclosed. The method comprises repeatedly filtering the reaction solution to remove fine solid matter using a polyethylene porous hollow fiber membrane having a bubble point of from 1 to 20 kg/cm.sup.2, and repeatedly washing the hollow fiber membrane before it has been clogged to such an extent that a differential pressure thereof exceeds 3 kg/cm.sup.2. By this method, a filter membrane can be repeatedly regenerated at high efficiency and can stably be used for a long period of time.

Method for purifying reaction solution obtained by using microbial cell,

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Kanagawa, Japan

Toshiaki Doi