For direct and efficient ethanol production from cellulosic materials, we constructed a novel cellulosedegrading yeast strain by genetically codisplaying two cellulolytic enzymes on the cell surface of Saccharomyces cerevisiae. By using a cell surface engineering system based on ␣-agglutinin, endoglucanase II (EGII) from the filamentous fungus Trichoderma reesei QM9414 was displayed on the cell surface as a fusion protein containing an RGSHis6 (Arg-Gly-Ser-His 6 ) peptide tag in the N-terminal region. EGII activity was detected in the cell pellet fraction but not in the culture supernatant. Localization of the RGSHis6-EGII-␣-agglutinin fusion protein on the cell surface was confirmed by immunofluorescence microscopy. The yeast strain displaying EGII showed significantly elevated hydrolytic activity toward barley ␤-glucan, a linear polysaccharide composed of an average of 1,200 glucose residues. In a further step, EGII and ␤-glucosidase 1 from Aspergillus aculeatus No.

The alpha-amylase from Bacillus sp. no. 195 (BAA) consists of two domains: one is the catalytic domain similar to alpha-amylases from animals and Streptomyces in the N-terminal region; the other is the functionally unknown domain composed of an approx. 90-residue direct repeat in the C-terminal region. The gene coding for BAA was expressed in Streptomyces lividans TK24. Three active forms of the gene products were found. The pH and thermal profiles of BAAs, and their catalytic activities for p-nitrophenyl maltopentaoside and soluble starch, showed almost the same behaviours. The largest, 69 kDa, form (BAA-alpha) was of the same molecular mass as that of the mature protein estimated from the nucleotide sequence, and had raw-starch-binding and -degrading abilities. The second largest, 60 kDa, form (BAA-beta), whose molecular mass was the same as that of the natural enzyme from Bacillus sp. no. 195, was generated by proteolytic processing between the two repeat sequences in the C-terminal region, and had lower activities for raw starch binding and degrading than those of BAA-alpha. The smallest, 50 kDa, form (BAA-gamma) contained only the N-terminal catalytic domain as a result of removal of the C-terminal repeat sequence, which led to loss of binding and degradation of insoluble starches. Thus the starch adsorption capacity and raw-starch-degrading activity of BAAs depends on the existence of the repeat sequence in the C-terminal region. BAA-alpha was specifically adsorbed on starch or dextran (alpha-1,4 or alpha-1,6 glucan), and specifically desorbed with maltose or beta-cyclodextrin. These observations indicated that the repeat sequence of the enzyme was functional in the starch-binding domain (SBD). We propose the designation of the homologues to the SBD of glucoamylase from Aspergillus niger as family I SBDs, the homologues to that of glucoamylase from Rhizopus oryzae as family II, and the homologues of this repeat sequence of BAA as family III.

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Penicillium simplicissimum AK-40, which was isolated from a soil sample, produced novel insecticidal compounds when cultured with okara (the insoluble residue of whole soybean). The metabolites, named okaramine A (1) and B(2), were crystalline products with molecular formulas C32H32N4O3 and C33H34N4O5, respectively. The structure of 1 was deduced from the structure of acetylokaramine Athat was established by single crystal X-ray diffraction. The structure of 2 was determined from the data of UV, IR, NMR(*H and 13C) and mass spectrometry. 1 and 2 showed insecticidal activity against the 3rd instar larvae of silkworm at doses of 3/ig/g of diet and 0.1 /ig/g of diet, respectively.

We tried genetically to immobilize cellulase protein on the cell surface of the yeast Saccharomyces cerevisiae in its active form. A cDNA encoding FI-carboxymethylcellulase (CMCase) of the fungus Aspergillus aculeatus, with its secretion signal peptide, was fused with the gene encoding the C-terminal half (320 amino acid residues from the C terminus) of yeast alpha-agglutinin a protein involved in mating and covalently anchored to the cell wall. The plasmid constructed containing this fusion gene was introduced into S. cerevisiae and expressed under the control of the glyceraldehyde-3-phosphate dehydrogenase promoter from S. cerevisiae. The CMCase activity was detected in the cell pellet fraction. The CMCase protein was solubilized from the cell wall fraction by glucanase treatment but not by sodium dodecyl sulphate treatment, indicating the covalent binding of the fusion protein to the cell wall. The appearance of the fused protein on the cell surface was further confirmed by immunofluorescence microscopy and immunoelectron microscopy. These results proved that the CMCase was anchored on the cell wall in its active form.