Characterization of ruminal bacteria in grazing Nellore steers

Abstract

Background: Rumen microorganisms have developed a series of complex interactions, representing one of the best examples of symbiosis between microorganisms in nature. Conventional taxonomic methods based on culture techniques are being replaced by molecular techniques that are faster and more accurate. Objective: To characterize rumen bacterial diversity of Nellore steers grazing on tropical pastures by sequencing the 16S rRNA gene using Illumina sequenctng. Methods: Three rumen-cannulated Nellore steers were used. The liquid and solid fractions of the rumen contents were processed to extract metagenomic DNA, and the VI and V2 hypervariable regions of the 16S rRNA gene were sequenced using Illumina sequencing. Results: A total of 11,407,000 reads of adequate quality were generated, and 812 operational taxonomic units (OTUs) were found at the species level. Twenty-seven phyla were identified, and the predominant phyla were Firmicutes (23%), Bacteroidetes (14%), Proteobacteria (10%), Spirochaetes (9%), Fibrobacteres (7%), Tenericutes (5%), and Actinobacteria (2%), which represented 70% of the total phyla identified in the rumen content. Conclusion: Rumen environment in grazing Nellore steers showed high bacterial diversity, with Firmicutes, Bacteroidetes, Proteobacteria, Spirochaetes, and Fibrobacteres as the predominant phyla.

Characterization of rumen microbiome and immune genes expression of crossbred beef steers with divergent residual feed intake phenotypes

“…This might imply that the low-RFI steers could partition their methane production via alternative pathways especially when a lower proportion of H 2 and CO 2 is being produced during the fermentation process by the rest of microbiota. For instance, carbohydrates are fermented to propionic acid with no net loss of CO 2 and thus lower substrate for Methanobrevibacter to produce methane [ 32 , 33 ].Previous studies have shown that Methanobrevibacter are predominant methanogens in the rumen and their abundance has also been correlated with higher levels of methane emissions [ 34 , 35 ] and poorer feed efficiency [ 36 , 37 ]. Cattle with negative RFI phenotype have been reported to have reduced daily methane production [ 7 ].…”

A Review of the Rumen Microbiota and the Different Molecular Techniques Used to Identify Microorganisms Found in the Rumen Fluid of Ruminants

“…The microbiota is composed of a set of thousands of species of microorganisms, consisting of bacteria, archaea, fungi, and protozoa [39,58]. At significant values, the bacteria represent the largest and most important ruminal microbial community, consisting of approximately 1.010 bacteria, 10 7 protozoa, 10 6 fungi per mL of rumen content [44], and 10 7 -10 8 cells per gram of ruminal content of methanogenic archaea [37,59].…”

“…Gender-level taxonomic affiliations for readings generated from the 16S rRNA fragment sequences of bovine ruminal content using the Illumina platform. Adapted from Jesus et al[39].…”