Fatty acid oxidation products (‘green odour’) released from perennial ryegrass following biotic and abiotic stress, potentially have antimicrobial properties against the rumen microbiota resulting in decreased biohydrogenation

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Type Article
Original languageEnglish
Pages (from-to)1081-1090
JournalJournal of Applied Microbiology
Issue number5
Early online date21 Aug 2013
Publication statusPublished - Nov 2013
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In this experiment, we investigated the effect of ‘green odour’ products typical of those released from fresh forage postabiotic and biotic stresses on the rumen microbiota and lipid metabolism.

Methods and Results
Hydroperoxyoctadecatrienoic acid (HP), a combination of salicylic and jasmonic acid (T), and a combination of both (HPT) were incubated in vitro in the presence of freeze-dried ground silage and rumen fluid, under rumen-like conditions. 16S rRNA (16S cDNA) HaeIII-based terminal restriction fragment length polymorphism-based (T-RFLP) dendrograms, canonical analysis of principal coordinates graphs, peak number and Shanon-Weiner diversity indices show that HP, T and HPT likely had antimicrobial effects on the microbiota compared to control incubations. Following 6 h of in vitro incubation, 15·3% of 18:3n-3 and 4·4% of 18:2n-6 was biohydrogenated in control incubations, compared with 1·3, 9·4 and 8·3% of 18:3n-3 for HP, T and HPT treatments, respectively, with negligible 18:2n-6 biohydrogenation seen. T-RFLP peaks lost due to application of HP, T and HPT likely belonged to as yet uncultured bacteria within numerous genera.

Hydroperoxyoctadecatrienoic acid, T and HPT released due to plant stress potentially have an antimicrobial effect on the rumen microbiota, which may explain the decreased biohydrogenation in vitro.

Significance and Impact of the Study
These data suggest that these volatile chemicals may be responsible for the higher summer n-3 content of bovine milk.


  • bacteria, biohydrogenation, fatty acid, green odour, hydroperoxides, jasmonic acid, rumen, salicylic acid