Publications by authors named "Kun D Huang"

6 Publications

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Hallstatt miners consumed blue cheese and beer during the Iron Age and retained a non-Westernized gut microbiome until the Baroque period.

Curr Biol 2021 Oct 8. Epub 2021 Oct 8.

Prehistoric Department, Museum of Natural History Vienna, Burgring 7, 1010 Vienna, Austria. Electronic address:

We subjected human paleofeces dating from the Bronze Age to the Baroque period (18 century AD) to in-depth microscopic, metagenomic, and proteomic analyses. The paleofeces were preserved in the underground salt mines of the UNESCO World Heritage site of Hallstatt in Austria. This allowed us to reconstruct the diet of the former population and gain insights into their ancient gut microbiome composition. Our dietary survey identified bran and glumes of different cereals as some of the most prevalent plant fragments. This highly fibrous, carbohydrate-rich diet was supplemented with proteins from broad beans and occasionally with fruits, nuts, or animal food products. Due to these traditional dietary habits, all ancient miners up to the Baroque period have gut microbiome structures akin to modern non-Westernized individuals whose diets are also mainly composed of unprocessed foods and fresh fruits and vegetables. This may indicate a shift in the gut community composition of modern Westernized populations due to quite recent dietary and lifestyle changes. When we extended our microbial survey to fungi present in the paleofeces, in one of the Iron Age samples, we observed a high abundance of Penicillium roqueforti and Saccharomyces cerevisiae DNA. Genome-wide analysis indicates that both fungi were involved in food fermentation and provides the first molecular evidence for blue cheese and beer consumption in Iron Age Europe.
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http://dx.doi.org/10.1016/j.cub.2021.09.031DOI Listing
October 2021

Metagenomic analysis of ancient dental calculus reveals unexplored diversity of oral archaeal Methanobrevibacter.

Microbiome 2021 09 30;9(1):197. Epub 2021 Sep 30.

Institute for Mummy Studies, Eurac Research, 39100, Bolzano, Italy.

Background: Dental calculus (mineralised dental plaque) preserves many types of microfossils and biomolecules, including microbial and host DNA, and ancient calculus are thus an important source of information regarding our ancestral human oral microbiome. In this study, we taxonomically characterised the dental calculus microbiome from 20 ancient human skeletal remains originating from Trentino-South Tyrol, Italy, dating from the Neolithic (6000-3500 BCE) to the Early Middle Ages (400-1000 CE).

Results: We found a high abundance of the archaeal genus Methanobrevibacter in the calculus. However, only a fraction of the sequences showed high similarity to Methanobrevibacter oralis, the only described Methanobrevibacter species in the human oral microbiome so far. To further investigate the diversity of this genus, we used de novo metagenome assembly to reconstruct 11 Methanobrevibacter genomes from the ancient calculus samples. Besides the presence of M. oralis in one of the samples, our phylogenetic analysis revealed two hitherto uncharacterised and unnamed oral Methanobrevibacter species that are prevalent in ancient calculus samples sampled from a broad range of geographical locations and time periods.

Conclusions: We have shown the potential of using de novo metagenomic assembly on ancient samples to explore microbial diversity and evolution. Our study suggests that there has been a possible shift in the human oral microbiome member Methanobrevibacter over the last millennia. Video abstract.
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http://dx.doi.org/10.1186/s40168-021-01132-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8485483PMC
September 2021

Reconstruction of ancient microbial genomes from the human gut.

Nature 2021 06 12;594(7862):234-239. Epub 2021 May 12.

Section on Pathophysiology and Molecular Pharmacology, Joslin Diabetes Center, Boston, MA, USA.

Loss of gut microbial diversity in industrial populations is associated with chronic diseases, underscoring the importance of studying our ancestral gut microbiome. However, relatively little is known about the composition of pre-industrial gut microbiomes. Here we performed a large-scale de novo assembly of microbial genomes from palaeofaeces. From eight authenticated human palaeofaeces samples (1,000-2,000 years old) with well-preserved DNA from southwestern USA and Mexico, we reconstructed 498 medium- and high-quality microbial genomes. Among the 181 genomes with the strongest evidence of being ancient and of human gut origin, 39% represent previously undescribed species-level genome bins. Tip dating suggests an approximate diversification timeline for the key human symbiont Methanobrevibacter smithii. In comparison to 789 present-day human gut microbiome samples from eight countries, the palaeofaeces samples are more similar to non-industrialized than industrialized human gut microbiomes. Functional profiling of the palaeofaeces samples reveals a markedly lower abundance of antibiotic-resistance and mucin-degrading genes, as well as enrichment of mobile genetic elements relative to industrial gut microbiomes. This study facilitates the discovery and characterization of previously undescribed gut microorganisms from ancient microbiomes and the investigation of the evolutionary history of the human gut microbiota through genome reconstruction from palaeofaeces.
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http://dx.doi.org/10.1038/s41586-021-03532-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8189908PMC
June 2021

Analysis of 1321 Eubacterium rectale genomes from metagenomes uncovers complex phylogeographic population structure and subspecies functional adaptations.

Genome Biol 2020 06 8;21(1):138. Epub 2020 Jun 8.

Department CIBIO, University of Trento, Trento, Italy.

Background: Eubacterium rectale is one of the most prevalent human gut bacteria, but its diversity and population genetics are not well understood because large-scale whole-genome investigations of this microbe have not been carried out.

Results: Here, we leverage metagenomic assembly followed by a reference-based binning strategy to screen over 6500 gut metagenomes spanning geography and lifestyle and reconstruct over 1300 E. rectale high-quality genomes from metagenomes. We extend previous results of biogeographic stratification, identifying a new subspecies predominantly found in African individuals and showing that closely related non-human primates do not harbor E. rectale. Comparison of pairwise genetic and geographic distances between subspecies suggests that isolation by distance and co-dispersal with human populations might have contributed to shaping the contemporary population structure of E. rectale. We confirm that a relatively recently diverged E. rectale subspecies specific to Europe consistently lacks motility operons and that it is immotile in vitro, probably due to ancestral genetic loss. The same subspecies exhibits expansion of its carbohydrate metabolism gene repertoire including the acquisition of a genomic island strongly enriched in glycosyltransferase genes involved in exopolysaccharide synthesis.

Conclusions: Our study provides new insights into the population structure and ecology of E. rectale and shows that shotgun metagenomes can enable population genomics studies of microbiota members at a resolution and scale previously attainable only by extensive isolate sequencing.
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http://dx.doi.org/10.1186/s13059-020-02042-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7278147PMC
June 2020

The Prevotella copri Complex Comprises Four Distinct Clades Underrepresented in Westernized Populations.

Cell Host Microbe 2019 11 10;26(5):666-679.e7. Epub 2019 Oct 10.

CIBIO Department, University of Trento, 38123 Trento, Italy. Electronic address:

Prevotella copri is a common human gut microbe that has been both positively and negatively associated with host health. In a cross-continent meta-analysis exploiting >6,500 metagenomes, we obtained >1,000 genomes and explored the genetic and population structure of P. copri. P. copri encompasses four distinct clades (>10% inter-clade genetic divergence) that we propose constitute the P. copri complex, and all clades were confirmed by isolate sequencing. These clades are nearly ubiquitous and co-present in non-Westernized populations. Genomic analysis showed substantial functional diversity in the complex with notable differences in carbohydrate metabolism, suggesting that multi-generational dietary modifications may be driving reduced prevalence in Westernized populations. Analysis of ancient metagenomes highlighted patterns of P. copri presence consistent with modern non-Westernized populations and a clade delineation time pre-dating human migratory waves out of Africa. These findings reveal that P. copri exhibits a high diversity that is underrepresented in Western-lifestyle populations.
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http://dx.doi.org/10.1016/j.chom.2019.08.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6854460PMC
November 2019

Rates of Mutation and Recombination in Siphoviridae Phage Genome Evolution over Three Decades.

Mol Biol Evol 2018 05;35(5):1147-1159

Genomic Microbiology Group, Institute of General Microbiology, Kiel University, Kiel, Germany.

The evolution of asexual organisms is driven not only by the inheritance of genetic modification but also by the acquisition of foreign DNA. The contribution of vertical and horizontal processes to genome evolution depends on their rates per year and is quantified by the ratio of recombination to mutation. These rates have been estimated for bacteria; however, no estimates have been reported for phages. Here, we delineate the contribution of mutation and recombination to dsDNA phage genome evolution. We analyzed 34 isolates of the 936 group of Siphoviridae phages using a Lactococcus lactis strain from a single dairy over 29 years. We estimate a constant substitution rate of 1.9 × 10-4 substitutions per site per year due to mutation that is within the range of estimates for eukaryotic RNA and DNA viruses. The reconstruction of recombination events reveals a constant rate of five recombination events per year and 4.5 × 10-3 nucleotide alterations due to recombination per site per year. Thus, the recombination rate exceeds the substitution rate, resulting in a relative effect of recombination to mutation (r/m) of ∼24 that is homogenous over time. Especially in the early transcriptional region, we detect frequent gene loss and regain due to recombination with phages of the 936 group, demonstrating the role of the 936 group pangenome as a reservoir of genetic variation. The observed substitution rate homogeneity conforms to the neutral theory of evolution; hence, the neutral theory can be applied to phage genome evolution and also to genetic variation brought about by recombination.
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http://dx.doi.org/10.1093/molbev/msy027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5913663PMC
May 2018
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