AUTHOR=Patra Amlan K. , Yu Zhongtang 

TITLE=Essential oils affect populations of some rumen bacteria in vitro as revealed by microarray (RumenBactArray) analysis

JOURNAL=Frontiers in Microbiology

VOLUME=6

YEAR=2015

URL=https://www.frontiersin.org/journals/microbiology/articles/10.3389/fmicb.2015.00297

DOI=10.3389/fmicb.2015.00297

ISSN=1664-302X

ABSTRACT=<p>In a previous study origanum oil (ORO), garlic oil (GAO), and peppermint oil (PEO) were shown to effectively lower methane production, decrease abundance of methanogens, and change abundances of several bacterial populations important to feed digestion <italic>in vitro</italic>. In this study, the impact of these essential oils (EOs, at 0.50 g/L) on the rumen bacterial community composition and population was further examined using the recently developed RumenBactArray. Species richness (expressed as number of operational taxonomic units, OTUs) in the phylum <italic>Firmicutes</italic>, especially those in the class <italic>Clostridia</italic>, was decreased by ORO and GAO, but increased by PEO, while that in the phylum <italic>Bacteroidetes</italic> was increased by ORO and PEO. Species richness in the genus <italic>Butyrivibrio</italic> was lowered by all the EOs. Increases of <italic>Bacteroidetes</italic> OTUs mainly resulted from increases of <italic>Prevotella</italic> OTUs. Overall, 67 individual OTUs showed significant differences (<italic>P</italic> ≤ 0.05) in relative abundance across the EO treatments. The predominant OTUs affected by EOs were diverse, including those related to <italic>Syntrophococcus sucromutans</italic>, <italic>Succiniclasticum ruminis</italic>, and <italic>Lachnobacterium bovis</italic>, and those classified to <italic>Prevotella</italic>, <italic>Clostridium</italic>, <italic>Roseburia</italic>, <italic>Pseudobutyrivibrio</italic>, <italic>Lachnospiraceae</italic>, <italic>Ruminococcaceae</italic>, <italic>Prevotellaceae, Bacteroidales</italic>, and <italic>Clostridiales</italic>. In total, 60 OTUs were found significantly (<italic>P</italic> ≤ 0.05) correlated with feed degradability, ammonia concentration, and molar percentage of volatile fatty acids. Taken together, this study demonstrated extensive impact of EOs on rumen bacterial communities in an EO type-dependent manner, especially those in the predominant families <italic>Prevotellaceae</italic>, <italic>Lachnospiraceae</italic>, and <italic>Ruminococcaceae</italic>. The information from this study may aid in understanding the effect of EOs on feed digestion and fermentation by rumen bacteria.</p>