Enzymes of Carbohydrate Metabolism of Mycelial Fungi from Marine Environments. beta-1,3-Glucanase of the Marine Fungus Chaetomium indicum

Yu. V. Burtseva, V. V. Sova, M. V. Pivkin, and T. N. Zvyagintseva^*

Pacific Institute of Bioorganic Chemistry, Far Eastern Branch of the Russian Academy of Sciences, pr. 100-letiya Vladivostoka 159, Vladivostok, 690022 Russia; fax: (4232) 31-4050; E-mail: piboc@stl.ru (subject: for Zvyagintseva)

^* To whom correspondence should be addressed.

Received November 29, 1999; Revision received January 17, 2000

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Thirty samples of fungi belonging to 17 species living in marine environments were studied for their ability to produce extracellular enzymes. In the culture fluids, a variety of glycosidases (beta-glucosidases, N-acetyl-beta-glucosaminidase, beta-galactosidases, and alpha-mannosidases) and glucanases (amylases and beta-1,3-glucanases) were found. Several cultures were found that could be used as efficient producers of either individual enzymes or a whole complement of enzymes degrading carbohydrate-containing compounds. Optimal growth conditions for the fungus Chaetomium indicum and beta-1,3-glucanase biosynthesis were developed. beta-1,3-Glucanase was isolated by a combination of ion-exchange chromatography, ultrafiltration, and gel chromatography. The molecular mass of the enzyme determined by gel-filtration was 54 kD. The enzyme was stable at temperatures below 50°C, had a temperature optimum for activity at 60°C, and retained activity between pH 4.5 and 7.5. The pH dependence of the beta-1,3-glucanase activity showed two maxima, at pH 4.4 and 5.6; this suggested the existence of two forms of the enzyme. Analysis of the products of enzymatic hydrolysis of laminaran, transglycosylating ability, and the effect of a specific natural inhibitor indicates that both forms are exo-beta-1,3-glucanases.

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KEY WORDS: marine mycelial fungi, Chaetomium indicum, beta-1,3-glucanase, amylase, N-acetyl-beta-glucosaminidase, beta-glucosidase, beta-galactosidase, alpha-mannosidase, CM-cellulase

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