The chromosome walking strategy has been used in this experiment and a 10 kb DNA fragment was cloned from the cosmid library of Streptomyces ansochromogenes using a partial DNA fragment involved in the nikkomycin biosynthesis as a probe. The nucleotide sequence showed that the DNA fragment contains two complete open reading frames (ORFs), they are designated as sanK and sanL respectively. The sanL is located on the upstream of sanK, it has 1281 nucleotides with ATG at 345 position as start codon and TGA at 623 position as stop codon. The deduced product is L-lysine 2-aminotransferase using Blastx program. The experiment of gene disruption indicated that this gene is closely related to nikkomycin biosynthesis of Streptomyces ansochromogenes.