Using the previously cloned Aspergillus niger N756 pectin lyase D gene as a probe, the corresponding pelD gene has been isolated from a genomic library of the laboratory strain A. niger N400. This gene encodes PLD, previously described as PLI, which is one of the two major pectin lyases isolated from the commercial pectinase preparation Ultrazym. Heterologous hybridization of the A. niger N400 genomic library with the pelD gene led to the isolation of another five genes: pelA, B, C, E, and F. These genes differ in their hybridization patterns with probes containing either the entire pelD gene, or 5' or 3' parts thereof. By partial sequencing, and expression in an A. niger transformant containing multiple copies of the pelA gene, we show that this gene, which hybridizes strongest with the pelD gene, encodes the other major pectin lyase from Ultrazym, PLII.