Development of biomass of industrial bacterial strains for the production of therapeutic and prophylactic drugs

This article presents the results of experimental studies aimed at producing highly immunogenic antigenic components of an associated vaccine for the specific prevention of gastrointestinal diseases in calves. Using a wide range of elective nutrient media, we produced bacterial biomass of Cl. perfringens serotypes A, C, and D; E. coli, synthesizing adhesion antigens K99 and A20; Streptococcus; Salm. enteritidis and Salm. dublin for the production of an associated vaccine against anaerobic enterotoxemia, escherichiosis, salmonellosis and streptococcosis in calves. The parameters for inactivating bacterial cells and the exotoxins they produce, used to construct the vaccine, were scientifically substantiated and optimized. Devitalization of production strain cultures was carried out using a formaldehyde solution under controlled thermostatic conditions at an optimum temperature of 37 to 38°C. Studies were conducted using nutrient media for growing microorganisms and in vivo on laboratory animals (white mice). It was experimentally proven that complete devitalization of Cl. perfringens, Salm. enteritidis and Salm. dublin bacteria and their toxins are inactivated after 240 hours under the combined action of heat and an inactivating agent, after 120 hours for E. coli and after 72 hours for Streptococcus. The purity of the resulting bacterial suspensions was monitored by light microscopy of Gram-stained smears, and the completeness of nactivation was verified by culture by plating samples on selective and differential diagnostic media: GRM agar, GRM broth, blood GRM-agar, Kitt- Tarozzi medium and Saburo agar. No microbial proliferation was observed on the nutrient media after incubation in a thrmostat for 10 days. This indicates their absolute sterility and suitability for the subsequent construction of an associated bioproduct.