Utility of redesigned cpn60 UT primers and novel fungal specific cpn60 primers for microbial profiling
The cpn60 gene is a DNA barcode for bacteria. Recently, the PCR primers that have been used extensively to amplify the cpn60 Universal Target (UT) region of bacteria were redesigned to improve their utility for fungal taxa. Additional novel primers were designed to amplify other regions of the cpn60 gene, specifically from fungal genomes. Design of the redesigned and novel primers was based on 61 nucleotide full-length cpn60 reference sequences available in 2012, including Ascomycota (51), Basidiomycota (5), Chytridiomycota (2), Glomeromycota (1), and Oomycota (2). The research described here investigated the utility of these primers for detecting and identifying fungal taxa and for profiling mixed communities of bacteria and fungi. The redesigned primers were used to discover cpn60 UT sequences for Ascomycota (1), Basidiomycota (2), and Chytridiomycota (1). The novel primers were used to discover new cpn60 sequence data for Ascomycota (3), Basidiomycota (1), and Zygomycota (1). To be adopted for use in studies of microbial communities that are predominantly bacterial, the redesigned cpn60 UT primers must perform at least as well as the original primers for bacterial profiling. Bacterial profiles, created using the original and redesigned primers and two DNA template samples created by pooling DNA extracts from vaginal swabs from individual women, were compared. These included comparisons of diversity indices, rarefaction curve analysis and Operational Taxonomic Unit abundances. Diversity indices and rarefaction curve analysis for bacterial profiles with original and redesigned primers were similar. OTU abundance estimates with the original and redesigned primers were compared at higher and lower taxonomic levels. The overall patterns produced were similar. For one template only, the phylum Bacteroidetes had a greater apparent abundance with the original primers than with the redesigned primers. The greater apparent abundance of Bacteroidetes taxa was balanced by a lesser apparent abundance of taxa that were not assigned to a phylum. These differences may reflect differences in the performance of the two primer sets. At lower taxonomic level, most OTU were represented with apparently equal abundances with redesigned and original primers in same template. Very few OTU were represented with different proportional abundances with redesigned and original primers. Different OTU having same reference cpn60 UT sequence as best hit were sometimes represented by different proportional abundance with same primer in same template that made the analysis difficult. On the whole, the redesigned cpn60 UT primers behaved at least as good as the original cpn60 UT primers. The overall results showed that the redesigned and novel primers used in this study had substantial utility for the identification of fungal samples and mixed microbial communities.
DegreeMaster of Science (M.Sc.)
DepartmentMicrobiology and Immunology
ProgramMicrobiology and Immunology
CommitteeGoldie, Hughes; Chelico, Linda
Copyright DateDecember 2015
cpn60, Microbial communities, vaginal microbiome, pyrosequencing