Inhibition of Bacterial Quorum Sensing by the Ruminal Fluid of Cattle

Abstract

Rumen fluid contains factors that inactivate autoinducers, monitor microflora development and prevent the mobilization of virulence properties, and thus, the formation of resistant bacteria. The aim of this study was to assess the ability of rumen fluid to suppress the intercellular communication of bacteria by inactivating the N-acyl-homoserine lactones. We used strains of luminescent Escherichia coli JLD271 which were transformed with plasmids containing quorum sensing genes and luminescence genes. Bacteria were cultivated in LB agar medium containing 10 ug/ml doxycycline then in LB medium until the early exponential growth phase. The autoinducers used were N-butyryl-L-homoserine lactone (C4-HSL), N-(3-oxo)-hexanoyl-L-homoserine lactone (oxo-С6-HSL) and N-dodecanoyl-L-homoserine lactone (C12-HSL). The ruminal fluid of young calves was collected via a fistula. Equal volumes of ruminal fluid and autoinducers were incubated then added to the cultures of luminescent bacterial strains. Dilution of the ruminal fluid up to 12.5% did not affect the luminescence of the bacterial biosensors. Incubation of ruminal fluid with N-acyl-homoserine lactones decreased their activity, marked by unexpressed specificity. The most effective inhibition of the N-(3-oxo)-hexanoyl-L-homoserine lactone was observed at 10 -7 M, and above this concentration the efficiency of quorum sensing inhibition decreased. Ruminal fluid was able to inactivate Nacyl-homoserine lactones, and the efficiency of inhibition was not related to the length of the alkyl tail in the signal molecule. This suggests the ability of the ruminant digestive system to control bacteria by the inactivation of N-acyl-homoserine lactones, which regulate the quorum sensing system.

Mixtures of Biologically Active Substances of Oak Bark Extracts Change Immunological and Productive Indicators of Broilers

“…It is known that tannings may participate in modulation of the composition and activity of intestinal microflora and its interaction with the entering compounds. It is reported that gram-positive bacteria are more sensitive to plant-based extracts rich in tannin-like substances [28,29]. It is also confirmed by properties of compounds earlier found in Quercus cortex extract [12,13].…”

The effect of selenium supplements on selenium metabolism, performance and intestinal microbiome in farm animals (review)

“…тором, лимитирующим эффективность животноводства, является дефицит микронутриентов, в том числе эссенциальных элементов, с последующим развитием ассоциированных патологий [5]. При этом коррекция уровня обмена отдельных металлов характеризуется снижением риска развития данных заболеваний и может в ряде случаев обладать стимулирующим влиянием на продуктивные качества сельскохозяйственных животных [6].…”