Construction of the recombinant Escherichia coli strain producing a homologous thermolabile toxin subunit

Colibacteriosis is an acute zoonotic disease manifested by septicaemia, toxemia, enteritis, body dehydration, and central nervous system damage. Depending on the presence of virulence factors and the nature of interaction with the intestinal mucosa, enterotoxigenic, enteroinvasive, enteropathogenic, and enterohemorrhagic E. coli are isolated. Enterotoxigenic strains of E. coli occupy one of the leading places in the etiological structure of calf colibacteriosis in many livestock farms of the Republic of Belarus. The main reason why this disease develops is the presence of thermolabile and thermostable toxins in the causative strain. The thermolabile toxin subunit B is a potent antigen that allows pet immunity to be acquired against E. coli-induced cattle diarrhea. Many foreign vaccines used against intestinal infections of cattle contain either a native or recombinant variant of the subunit B. As a result of the work, we have created a new strain of E. coli 42eLTB – the producer of the recombinant subunit B of the thermolabile toxin E. coli. The producing capacity of the obtained strain is 480 mg with 1 culture liquid liter, which exceeds the already known strains 1.37 times. 186 Doklady of the National Academy of Sciences of Belarus, 2021, vol. 65, no. 2, рр. 185–190