Cloning, sequence and expression of the gene coding for rhamnogalacturonase (RHG) of Aspergillus aculeatus; a novel pectinolytic enzyme

Rhamnogalacturonase was purified from culture filtrate of Aspergillus aculeatus after growth on sugar-beet pulp. A gene coding for rhamnogalacturonase (rhgA) was isolated from a λ cDNA expression library as well as from a recombinant phage λ genomic library. The cloned rhgA gene is interrupted by three introns and encodes a protein of 440 amino acids. Limited homology with A. niger polygalacturonase amino acid sequences is found. A. aculeatus and A. awamori strains overexpressing rhamnogalacturonase were obtained by transformation. The recombinant rhamnogalacturonase can degrade modified hairy regions and has a positive effect in the apple hot-mash liquefaction process.