Abstract

Research objective is the assessment of toxicity level of ruminal fluid of cattle with use of indicator luminescent strains of bacteria developed on the basis of E. coli. According to the research results systemic toxic action of ruminal fluid with use of sensory bacterial strains with constitutive luminescence (E. coli K12 TG1 with clone luxCDABE genes Photobacterium leiognathi 54D10) were assessed. During the contact of native ruminal fluid with sensory luminescent bacteria E. coli dose-dependent inhibition of luminescence in the first seconds of contact was registered. However, by the second minute of contact quenching was up to 5.20±0.59% in baseline environment and decreased after two-time dilution procedure up to 102.56±4.83% with dilution 1:1024). After 30 min of incubation of mixture level of luminescence in the sample with native ruminal fluid reached the control level and over time it increased to 190.59±22.15% after 60 min of contact. Strain E. coli katG::lux, where the cloned promoter is responsible for the synthesis of catalase providing the neutralization of hydrogen peroxide demonstrated luminescence induction of 3.0 relative units at the 60th minute of contact. Study of genotoxic effects based on activation of repair proteins RecA/LexA using strain E. coli recA::lux, allowed to register luminescence inducing effects of the bacterial cells in contact with native rumen fluid.