Aspergillus fumigatus is a ubiquitous, critical priority human fungal pathogen. Despite its clinical importance, there is limited knowledge regarding the variations of the genome within mitochondria, the powerhouse organelle within eukaryotic cells. In this study, we leveraged publicly available raw, whole genome sequence data from 1939 isolates to investigate the variations in the mitochondrial genomes of A. fumigatus. These isolates were isolated from 22 countries on six continents, as well as from outer space and from within the International Space Station. In total, our analysis revealed 39 mitochondrial single nucleotide polymorphisms (mtSNPs) within this global sample and together, these 39 mtSNPs grouped the 1939 isolates into 79 mitochondrial multilocus genotypes (MLGs). Among the 79 MLGs, 39 were each distributed in at least two countries and 30 were each shared by at least two continents. The two most frequent MLGs were also broadly distributed: MLG11 represented 420 isolates from 11 countries and four continents and while MLG79 represented 418 isolates from 18 countries and five continents, consistent with long-distance dispersals of mitogenomes. Our population genetic analyses of the mtSNPs revealed limited differentiation among continental populations but highly variable genetic differences among national populations, largely due to localized clonal expansions of different MLGs. Phylogenetic analysis and Discriminant Analysis of Principal Components of mtSNPs suggested the presence of at least three mitogenome clusters. Linkage disequilibrium, Index of Association, and phylogenetic incompatibility analyses collectively suggested evidence for mitogenome recombination in natural populations of A. fumigatus. In addition, sequence read depth analyses revealed an average ratio of ~20 mitogenomes per nuclear genome in this global population but the ratios varied among strains within and between certain geographic populations. Together, our results suggest evidence for organelle dynamics, genetic differentiation, recombination, and both widespread and localized clonal expansion of the mitogenomes in the global A. fumigatus population.

Streptococcus pneumoniae is the major cause of invasive pneumococcal disease (IPD). Since 1998, multilocus sequence typing (MLST) has been used for identifying the genotypes of strains of S. pneumoniae and helped reveal a diversity of local and regional epidemiological patterns for IPD, resulting in an archived MLST dataset of over 74,000 isolates. However, the global patterns of MLST sequence type (ST) and allele type (AT) distributions remain largely unexplored. In this study, we investigated the spatial and temporal patterns of AT and ST distributions of S. pneumoniae. We extracted S. pneumoniae MLST data from PubMLST.org and conducted various population genetic and phylogenetic analyses. Our analyses demonstrated both shared and unique distributions of STs and ATs among continental and national/regional populations. Among the 17915 STs in the dataset, 36 STs representing 15263 isolates were broadly shared among all six continents, consistent with recent gene flow and clonal dispersal of this pathogen. The analysis of molecular variance revealed that >96% genetic variations were found within individual continental and national/regional populations. However, though low (<4%), statistically significant genetic differentiation among continental and national populations were observed. Comparisons between non-clone-corrected and clone-corrected datasets showed that localized clonal expansion contributed significantly to the observed genetic differentiations among continents and countries/regions. Temporal analyses of the isolates showed that implementation of pneumococcal conjugate vaccine impacted the distributions of STs. Linkage disequilibrium analyses identified evidence for non-random recombination in all continental populations of this species. We discussed the implications of our analyses to the global epidemiology and future vaccine developments for S. pneumoniae.

The fungal family Microthyriaceae is represented by relatively few mycelial cultures and DNA sequences. As a result, the taxonomy and classification of this group of organisms remain poorly understood. Here, based on DNA sequences at four gene fragments (nuLSU rDNA, nuSSU rDNA, TEF1 and RPB2) in our analyses of aquatic hyphomycetes from southern China, we identify and report four new genera (Antidactylaria, Isthmomyces, Keqinzhangia, Pseudocoronospora) and thirteen new species (Antidactylaria minifimbriata, Pseudocoronospora hainanensis, Isthmomyces oxysporus, I. dissimilis, I. macrosporus, I. relanceatus, Keqinzhangia aquatica, Triscelophorus anakonajensis, T. anisopterioides, T. guizhouensis, T. mugecuoensis, T. multibrachiatus, T. neoseptatus; new combinations Isthmomyces asymmetrica, I. basitruncata, I. geniculata, I. lanceata, I. minima, I. rotundata) belonging to Microthyriaceae. Our results provided the first molecular evidence of asexual morph of this family and strengthened the phylogenetic placement of the family in class Dothideomycetes. The addition of these new taxa made Microthyriaceae the largest family comprising freshwater asexual genera in Pleosporomycetidae. In addition, we confirmed the monophyly of the genus Triscelophorus, the paraphyly of the genus Isthmolongispora, and revised 6 new combinations in Isthmolongispora. ITS barcoding of 13 species were also provided to help identify aquatic hyphomycetes in the future. Our results suggest that the asexual genera and sexual genera identified so far within this family have completely different ecological niches.