Essential gene 3 Gale 3 Mucoid mutant 3 Salmonella enterica 3 Salmonella enterica subsp. enterica serovar Typhimurium 3 Typhimurium 3 article 3 bacterial gene 3 bacterial genome 3 bacterium colony 3 colanic acid 3 controlled study 3 gene cassette 3 gene expression 3 gene function 3 gene inactivation 3 gene insertion 3 gene mutation 3 gene product 3 genetic analysis 3 genetic complementation 3 genetic variability 3 igaA 3 kanamycin 3 lethality 3 molecular cloning 3 mucM 3 nonhuman 3 null allele 3 open reading frame 3