Effect of stoned olive pomace on rumen microbial communities and polyunsaturated fatty acids biohydrogenation: an in vitro study.

Background The stoned olive pomace (SOP), which represents approximately 50% of the conversion process of olive in oil, is largely not-utilized and creates costs for its disposal and problems related to environmental impact. In-vitro trial experiments were employed to study the effect of feeds integrated with this bio-waste rich in polyphenols on rumen biohydrogenation, using sheep rumen liquor as inoculum. Results Fatty acid (FA) analysis and polymerase chain reaction denaturing gradient gel electrophoresis (DGGE) approach aimed to microbial community characterization showed that including SOP in feeds at the level of 50 g/kg and 90 g/kg induced changes in FA profile and in microbial populations. The contemporary decrease of Butyrivibrio proteoclasticus and the accumulation of vaccenic acid was observed. A depression of Neisseria weaveri, Ruminobacter amylophilus and other unclassified bacteria related to members of the Lachnospiraceae and Pasteurellaceae families was detected, suggesting that these microbial groups may be involved in rumen biohydrogenation. Conclusions Supplementation of feeds with SOP changes rumen bacterial community, including bacteria responsible for vaccenic acid hydrogenation to stearic acid, thus modifying FA profile of rumen liquor. Hence, an use of SOP aimed to produce meat or dairy products enriched in functional lipids could be hypothesized.