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A beta-1,3-glucanase gene, encoding a protein of 1,793 amino acids, was cloned from a strain of Paenibacillus sp. in this study. This large protein, designated as LamA, consists of many putative functional units, which include, from N to C terminus, a leader peptide, three repeats of the S-layer homologous module, a catalytic module of glycoside hydrolase family 16, four repeats of the carbohydrate-binding module of family CBM_4_9, and an analogue of coagulation factor Fa5/8C. Several truncated proteins, composed of the catalytic module with various organizations of the appended modules, were successfully expressed and characterized in this study. Data indicated that the catalytic module specifically hydrolyze beta-1,3- and beta-1,3-1,4-glucans. Also, laminaritriose was the major product upon endolytic hydrolysis of laminarin. The CBM repeats and Fa5/8C analogue substantially enhanced the hydrolyzing activity of the catalytic module, particularly toward insoluble complex substrates, suggesting their modulating functions in the enzymatic activity of LamA. Carbohydrate-binding assay confirmed the binding capabilities of the CBM repeats and Fa5/8C analogue to beta-1,3-, beta-1,3-1,4-, and even beta-1,4-glucans. These appended modules also enhanced the inhibition effect of the catalytic module on the growth of Candida albicans and Rhizoctonia solani.

A 44-kDa 1,3-beta-glucanase was purified from the culture medium of a Paenibacillus strain with a 28-fold increase in specific activity with 31% recovery. The purified enzyme preferentially catalyzes the hydrolysis of glucans with 1,3-beta-linkage and has an endolytic mode of action. The enzyme also showed binding activity to various insoluble polysaccharides including unhydrolyzable substrates such as xylan and cellulose. The antifungal activity of this Paenibacillus enzyme and a previously purified 1,3-beta-glucanase from Streptomyces sioyaensis were examined in this study. Both enzymes had the ability to damage the cell-wall structures of the growing mycelia of phytopathogenic fungi Pythium aphanidermatum and Rhizoctonic solani AG-4. Nonetheless, the Paenibacillus enzyme had a much stronger effect on inhibiting the growth of fungi tested.

A new methanogenic isolate, designated as strain N2M9705 (=OCM 668), was isolated from an aquaculture fishpond near Wang-gong, Taiwan. This strain grew on trimethylamine and methanol, but it did not catabolize H2-CO2, acetate, or formate. The cells were stained Gram-negative, nonmotile, irregular coccus 0.6-0.8 micrometer in diameter. Gas vacuoles were observed and cell aggregated to form various sizes of granules. Cells grew optimally at 32 degrees -37 degrees C with 1% NaCl. The pH range of growth was 6.2-7.4, and higher pH inhibited the cell growth. The cells grew well in minimal medium, but growth was greatly stimulated by yeast extract and peptone. A comparison of 16S rDNA sequences of this organism phylogenetically related to Methanosarcina mazei. This is the first report of methyltrophic methanogenic isolated from an aquaculture fishpond.