The invention provides a mutant hydrolase protein with enhanced kinetics and functional expression, as well as polynucleotides encoding the mutant proteins and methods of using the polynucleotides and mutant proteins.

Provided are an Aspergillus mutant strain which can dramatically enhance production of a heterologous enzyme when a saccharifying enzyme gene is transferred into the strain to perform transformation and a transformant having a saccharifying enzyme gene transferred into the Aspergillus mutant strain. The Aspergillus mutant strain has been completely or partially deficient in three genes of Aspergillus oryzae strain HO2 (accession number: NITE BP-01750): a prtR gene coding for a transcription factor; a pepA gene coding for an extracellular acid protease; and a cpI gene coding for an extracellular acid carboxypeptidase.

Described is a method for the production of 3-hydroxy-3-methylbutyric acid by enzyme-catalyzed covalent bond formation between the carbon atom of the oxo group of acetone and the methyl group of a compound which provides an activated acetyl group. Also described are recombinant organisms which produce 3-hydroxy-3-methylbutyric acid, and related compositions and methods.

A protein selected from the following (a) to (c), a gene encoding the protein, a transformant in which the gene is subjected to deletion, mutation or repression of gene expression, and a method of producing a glycolipid using the transformant are provided, wherein: (a) is a protein consisting of an amino acid sequence set forth in SEQ ID NO: 1; (b) is a protein consisting of an amino acid sequence having 50% or more identity with the amino acid sequence set forth in SEQ ID NO: 1, and having alcohol oxidase activity; and (c) is a protein consisting of an amino acid sequence in which one to several amino acids are subjected to deletion, substitution, insertion or addition in the amino acid sequence set forth in SEQ ID NO: 1, and having alcohol oxidase activity.

The invention provides an improved host strain for production of desired protein.