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Eleven distinct fragments of Clostridium sp. stain Fl (which was isolated and identified in this laboratory) DNAhave been cloned in E. coli and shown to express enzymatic activities related to cellulose hydrolysis. Six of the ll E. coli clones showed endoglucanase activity, 2 showed cellobiohydrolase activity as well as endoglycanase activity, one showed /?-glucosidase activity and the 2 others showedexoglucanase activity as well as xylanase activity. On comparingthe restriction mapsof the plasmids constructed in this study with those of C. thermocellum genes, it was concluded that 7 of the 1 1 clones carried hitherto unidentified cellulase genes, i.e., 4 endoglucanase genes, l/?-glucosidase gene and 2 xylanase/exoglucanase genes, and that the 4 other clones carried the same genes as those found in C. thermocellum.

An inducible acetylesterase was purified from the culture medium of Aspergillus awamori strain IFO4033 growing on wheat-bran culture by ion-exchange, gel-filtration and hydrophobic-interaction chromatographies. The purified enzyme had an Mr of 31000 and contained Asn-linked oligosaccharides. The enzyme liberated acetic acid from wheat bran, hydrolysed only alpha-naphthyl acetate and propionate when aromatic esters were used for the substrate, and was tentatively classified as a carboxylic esterase (EC 3.1.1.1). The gene encoding acetylesterase was cloned and sequenced. The deduced amino acid sequence showed that acetylesterase was produced as a 304-amino-acid-residue precursor, which was converted post-translationally into a 275-amino-acid-residue mature protein. Part of the sequence of acetylesterase was similar to the region near the active-site serine of lipases of Geotrichum candidum and Candida cylindracea. A unique site of putative Asn-linked oligosaccharides was presented.

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