PSXI-18 Clove oil and cashew nut shell liquid have antibacterial activity against some ruminal Prevotella

Abstract

This work was carried out to evaluate in vitro antimicrobial activity of cashew nut shell liquid (CNSL) and clove essential oil (Eugenia caryophyllata) on Prevotella albensis (DSM 11370), Prevotella bryantii (DSM 11371) and Prevotella ruminicola (ATCC^® 19189™). The experiments were designed using each bacterium exposed to two different doses (1:500 and 1:5000 g/L on Tween) of either clove oil or CNSL and with six replicates. Bacteria were cultivated on Hobson’s M2 medium in Hungate tubes. Cultures without addition of any oils were considered as control. Antimicrobial activity was evaluated using Spectrophotometer Evolution 201 UV-visible (Thermo Scientific) at 600 nm. Readings were performed at 0, 8, 12 and 24 hours after inoculation. Data were analysed using linear mixed models and NLME Procedure in R software. Both clove oil and CNSL had an inhibitory effect against the tested bacteria. However, each bacterium responded differently to the treatment. Clove oil decreased (P < 0.05) the microbial growth of P. ruminicola (-32% and -31%) when doses 1:500 and 1:5000 were used. However, there was no effect of clove oil P. bryantii and P. albensis. The use of CNSL reduced growth of P. albensis (-38 and -41%), P. bryantii (-44% and 52%) and P. ruminicola (-41 and -52%), when doses 1:500 and 1:5000, respectively. These results demonstrate the effect of clove oils and CNSL to inhibit growth of gram negative ruminal bacteria. These results provide a prospect of the use of both products to modulate the rumen. For example, the Prevotellaceae family is responsible to degrade protein, amino acid deamination and formation of volatile fatty acids in the rumen. Thus, CNSL and clove oils have potential to modulate the ruminal fermentation by having antibacterial activity against gram negative bacteria.