Submitted to: Applied and Environmental Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 3, 2013
Publication Date: January 15, 2014
Repository URL: http://handle.nal.usda.gov/10113/58712
Citation: Ziemer, C.J. 2014. Newly cultured bacteria with broad diversity isolated from 8 week continuous culture enrichments of cow feces on complex polysaccharides. Applied and Environmental Microbiology. 80:574-585. Interpretive Summary: Mammals like humans, cows, and pigs cannot digest most of the carbohydrates contained in plants because we lack the necessary enzymes. Bacteria that live in the large intestine have the enzymes to utilize plant carbohydrates and through that supply energy to the host. We isolated bacteria that can degrade these complex carbohydrates from cow feces by feeding them only one carbohydrate, either cellulose or a xylan/pectin 2:1 mix. Over 80% of our isolates have not been previously isolated, with many likely representing new bacterial genera. Most of the isolates were from two main groups, Bacteroides and Clostridia, but there was also a wide range of other bacterial species among our isolates. These isolates represent new opportunities to study the genomic and metabolic capacities of these members of the complex intestinal microbiota that utilize plant carbohydrates. Researchers in animal and human health will benefit by gaining important information about the interactions of host and bacteria in health and disease.
Technical Abstract: One of the fascinating functions of the mammalian intestinal microbiota is the fermentation of plant cell wall components. Eight week continuous culture enrichments of cow feces with cellulose and xylan/pectin were used to isolate bacteria from this community. A total of 459 bacterial isolates were classified phylogenetically using 16S rRNA gene sequencing. Six phyla were represented: Firmicutes (52.1%), Bacteroidetes (30.9%), Proteobacteria (11.1%), Actinobacteria (3.5%), Synergistetes (1.5%), and Fusobacteria (1.1%). The majority of bacterial isolates (86.2%) had less than 97% similarity to cultured bacteria with sequences in the RDP, representing new species and/or genera. Within the Firmicutes isolates, most were classified in the families of Lachnospiraceae, Ruminococcaceae, Erysipelotrichaceae, and Clostridiaceae I. The majority of the Bacteroidetes were most closely related to Bacteroides thetaiotaomicron, B. ovatus and B. xylanisolvens, and Porphyromonadaceae family. Many of the Firmicutes and Bacteroidetes isolates were related to species demonstrated to possess enzymes which ferment plant cell wall components, the rest likely support these bacteria. The microbial communities that arose in these enrichment cultures had broad bacterial diversity. With over 86% of the isolates not represented in culture, there are new opportunities to study genomic and metabolic capacities of these members of the complex intestinal microbiota.