Characterization of footrot bacteria Dichelobacter nodosus using PCR amplification and DNA sequence analysis

Abstract

Dichelobacter nodosus is an essential causative agent of footrot in ruminants, particularly in sheep, goats and cattle. In this study, more than 100 footrot samples were collected from 4 different farming regions in New Zealand (NZ). Selective media were chosen and isolation and routine growth conditions were optimized for NZ D. nodosus serotypes. Approximately 1000 primary plates were anaerobically subcultured several times and examined with Gram staining in order to detect single colonies of D. nodosus. Both the variable region and a part of the conserved region of fimbrial subunit gene (fimA) were amplified from bacterial DNA using polymerase chain reaction (PCR). On the basis of PCR and DNA sequencing, 6 new D. nodosus isolates were identified and characterized from NZ. These sequences of D. nodosus fimA gene from NZ were genetically different from previously reported strains in the GenBank (NCBI) and commercial vaccine strains.