Recoding anaerobic regulator fnr of Salmonella Typhimurium attenuates it's pathogenicity

•Here we recoded fnr, an anaerobic regulator, by substituting all of it's codons with synonymous rare codons of Salmonella Typhimurium.•First time we found that recoding fnr significantly compromised its growth, decreased motility, biofilm forming ability and survival within macrophages.•The recoded fnr strain also showed reduced colonisation ability and faecal shedding in mice thus making the recoded fnr mutant a potential vaccine candidate.