Isolation of a spontaneous pyrF mutant in C. hydrothermalis . (A) Chromosomal map of the uridine monophosphate (UMP) biosynthetic gene cluster in C. hydrothermalis JWCH006. The 99-bp spontaneous deletion in ΔpyrF is indicated by the line below the diagram. 462 bp lie upstream and 357 bp lie downstream of the deletion. Bent arrows depict primers used to verify the structure of the pyrF gene in the JWCH006 strain. (B) Gel depicting PCR products of the pyrF region in the wild-type strain (1.13 kb) compared to the JWCH006 strain (1.02 kb) amplified by the indicated primers (DC163 and DC164). M: 1 kb DNA ladder (NEB); 1: wild-type genomic DNA; 2: JWCH006 genomic DNA; 3: negative control.