Biology subjects

Dougherty, M. K.

Publications and source records attributed to Dougherty, M. K..

3 recordsLinked to original sources

bioRxiv2024

Metagenomic, metabolomic, and lipidomic shifts associated with fecal microbiota transplantation for recurrent Clostridioides difficile infection

Recurrent C. difficile infection (rCDI) is an urgent public health threat for which the last resort and lifesaving treatment is a fecal microbiota transplant (FMT). However, the exact mechanisms which mediate a successful FMT are not well understood. Here we use longitudinal stool samples collected from patients undergoing FMT to evaluate changes in the microbiome, metabolome, and lipidome after successful FMTs. We show changes in the abundance of many lipids, specifically acylcarnitines and bile acids, in response to FMT. These changes correlate with Enterobacteriaceae, which encode carnitine metabolism genes, and Lachnospiraceae, which encode bile salt hydrolases and baiA genes. LC-IMS-MS revealed a shift from microbial conjugation of primary bile acids pre-FMT to secondary bile acids post-FMT. Here we define the structural and functional changes in successful FMTs. This information will help guide targeted Live Biotherapeutic Product development for the treatment of rCDI and other intestinal diseases.

microbiology↗

bioRxiv2022

Distinct bile salt hydrolase substrate preferences dictate C. difficile pathogenesis

Summary paragraphBile acids (BAs) mediate the crosstalk between human and microbial cells and influence intestinal diseases including Clostridioides difficile infection (CDI). While bile salt hydrolases (BSHs) shape the BA pool by deconjugating conjugated BAs, the basis for their substrate preferences and impact on C. difficile remain elusive. Here, we survey the diversity of Lactobacillus BSHs and unravel the structural basis of their substrate preference. We show that leveraging BSH activity and specificity is an effective strategy to prevent C. difficile growth in clinically relevant CDI models. A range of non-canonical conjugated BAs is also identified, comprising unique BSH substrates that also inhibit C. difficile spore germination. These findings establish BSHs as intestinal enzymes essential to BA homeostasis and colonization resistance against C. difficile. One sentence summaryBile salt hydrolase activity inhibits C. difficile by shaping the conventional and non-canonical conjugated bile acid pools

microbiology↗

bioRxiv2018

High-throughput amplicon sequencing of the full-length 16S rRNA gene with single-nucleotide resolution

Targeted PCR amplification and high-throughput sequencing (amplicon sequencing) of 16S rRNA gene fragments is widely used to profile microbial communities. New long-read sequencing technologies can sequence the entire 16S rRNA gene, but higher error rates have limited their attractiveness when accuracy is important. Here we present a high-throughput amplicon sequencing methodology based on PacBio circular consensus sequencing and the DADA2 sample inference method that measures the full-length 16S rRNA gene with single-nucleotide resolution and a near-zero error rate.\n\nIn two artificial communities of known composition, our method recovered the full complement of full-length 16S sequence variants from expected community members without residual errors. The measured abundances of intra-genomic sequence variants were in the integral ratios expected from the genuine allelic variants within a genome. The full-length 16S gene sequences recovered by our approach allowed E. coli strains to be correctly classified to the O157:H7 and K12 sub-species clades. In human fecal samples, our method showed strong technical replication and was able to recover the full complement of 16S rRNA alleles in several E. coli strains.\n\nThere are likely many applications beyond microbial profiling for which high-throughput amplicon sequencing of complete genes with single-nucleotide resolution will be of use.

microbiology↗