[Braun Sergei]


Born 1941, Riga (Latvia); Ph.D. 1982, Hebrew Univ.; Lect. 1984; Sen. Lect. 1988; Assoc. Prof. 1997

E-mail: sergei@vms.huji.ac.il

Website: http://www.ls.huji.ac.il/~sergei

Tel: 972-2-658-5412; Fax: 972-2-651-9597

Research Interests:

Enzymology and industrial enzymology: development, preparation and stabilization of industrial enzymes; immobilization of enzymes in sol-gel glasses; biosensors; surface properties of native and modified proteins.

Industrial microbiology: development of new industrial microorganisms and processes; genetic engineering of industrial microorganisms; regulation of mycelial morphology in submerged fermentation; production of fungal spores and secondary metabolites; new microbial insecticides.

Adhesion properties of microorganisms.

Research Projects:

Sol-gel immobilized enzymes: a new approach to the design of biocatalysts. Industrial funding.

Devlopment of new industrial microorganisms. Industrial funding.

Abstracts of Current Research:


Sol-gel immobilized proteins:

New enzyme catalysts and biosensors: The main obstacle to the wide use of biological catalysts is their notorious instability. It was found in this laboratory that silicate-protein gels obtained through the sol-gel process confer an unusual stability to labile enzymes. The formation of specifically oriented H-bonds between the protein and the matrix seems to account for this phenomenon.

Biological research and industry:

This applied research laboratory is an active participant in the development of industrial biotechnology. At least 12 firms on three continents have financed its industrial research. The main activity was invested in the isolation of microorganisms with an industrial potential and their improvement through genetic engineering. Among other activities, the successful control of mycelial aggregation in fungi and Actinomyces, crucial to the success of many industrial fermentations. The aggregate size was found to be an important parameter in the optimization of secondary metabolite production by filamentous microorganisms, in improving methods for obtaining fungal spores and enzymes in submerged fermentation vessels.


Biotechnology; immobilized enzymes; sol-gel matrices; microbiology, biosensors; biocatalysis

Recent Publications (since 1995):

Heichal-Segal, O., Rappoport, S. and Braun, S. (1995) Immobilization in alginate-silicate sol-gel matrix protects ?-glucosidase against thermal and chemical denaturation. Bio/Technology, 13, 798-800.

Bressler, E. and Braun, S. (1996) Use of sol-gel entrapment techniques for the resolution of itaconic acid biosynthetic pathway in Aspergillus terreus. J. Sol-Gel Sci.Technol.,7,129-134.

Birk, R., Ikan, A., Bravdo, B., Braun, S and Shoseyov, O. (1996) Synthesis of isopropyl-1-thio-?-D-glucopyranoside (IPTGlc), an inducer of Aspergillus niger B1 beta-glucosidase production. Appl. Biochem. Biotechnol. 66, 25-30.

Uspensky, I., Klein, D. and Braun, S. (1998) Persistence of Bacillus sphaericus in cadavers of mosquito larvae. Isr. J. Entomol. 32, 49-56.

Bressler, E. and Braun, S. (1999) Separation mechanisms of citric and itaconic acids by water-immiscible amines. J. Chem. Technol. Biotechnol. 74, 891-896.

Bressler, E. and Braun, S. (2000) Conversion of citric to itaconic in a novel liquid membrane bioreactor. J. Chem. Technol. Biotechnol. 75, 1-7.


Doped sol-gel glasses for obtaining chemical interactions. U.S. Patent 5,650,311, July 22, 1995.

Doped Sol-Glass for obtaining chemical interactions. European Patent No. 0 439 318 B1 May 20 1998.

Process for preparation of long-chain alkyl glycosides. Israeli Application No. 111208, US Application No. PGT/G895/02373 Oct. 2, 1995.

Doped sol-gel glasses for obtaining chemical interactions. U.S. Patent 5,824,526, October 20, 1998.

A bacterial strain, processed plant extracts and probiotic compositions for human and veterinary uses. Israeli Application No. 130303, June 3, 1999.

Process for extracting carotenoids from carotenoid sources such as biomass and for preparing feed materials. US Application. January 2000.

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