Biology subjects

Kautz, S.

Publications and source records attributed to Kautz, S..

2 recordsLinked to original sources

bioRxiv2025

Verification of emerging genomic mutations in Mycobacterium tuberculosis allows transmission chains to be distinguished in an epidemiological typing cluster extending over thirty years.

Whole genome sequencing (WGS) is able to identify epidemiological links between Mycobacterium tuberculosis isolates. Recent clustering can be ruled out using a pre-defined single nucleotide polymorphism (SNP) threshold. If WGS clusters grow significantly over time limited genetic variability hampers epidemiological investigations. Newly emerging (informative) SNPs in isolates of an extended cluster growing for more than 30 years to >150 cases in the Netherlands were analysed. WGS data was analyzed from 61 sequencing files from 54 patients. Genomic positions that varied within the cluster isolates were carefully screened for minority populations in other isolates from the cluster. A transmission scheme was generated on the basis of WGS data alone then compared to the epidemiological information available. Fifty-two informative SNPs were identified, eight of which were also detected as mixed variants. One emerging SNP in dnaA (1199G>A R400H) has been observed in other transmitted strains and may be under selection. There was high concordance between the transmission chains suggested on basis of the newly emerging SNPs and scenarios identified using classical epidemiological cluster investigations. Analysis of filtered SNPs accumulating in the genome of M. tuberculosis in large clusters contains information on transmission dynamics and can be used to support epidemiological investigations.

microbiology↗

bioRxiv2017

Mutualistic acacia-ants show that specialized bacteria are not required for the evolution of herbivory

Acacia-ant mutualists in the genus Pseudomyrmex nest obligately in acacia plants and, through stable isotope analysis, we show that they are among the strictest of herbivores, feeding exclusively from their hosts. The diets of herbivorous insects such as these are often enriched by obligate bacterial endosymbionts through nitrogen recycling and even gaseous di-nitrogen fixation. We, therefore, examine the bacterial communities associated with mutualistic acacia-ants, comparing them with related non-mutualists in order to determine whether they host bacterial partners likely to contribute to the enrichment of their diets. However, despite their low trophic position, we find no evidence for bacteria-assisted nutrition in either adults or larvae. These acacia-ants do not host any species- or clade-specific bacteria, though several lineages of acetic acid bacteria present across social insects do differ in abundance between mutualists and non-mutualists, likely in response to the sugar-rich diets of their hosts. In addition, two novel lineages of Actinomycetales inhabit both mutualistic and non-mutualistic Pseudomyrmex and differ in abundance between the juveniles of these groups, potentially serving as defensive symbionts. Metagenomic sequencing of these taxa reveal substantial capacity for the production of defensive chemicals. Overall, we find little evidence for nutrition-associated bacteria in these strictly herbivorous ants, showing that bacteria are not as essential to animal nutrition as is often hypothesized.

ecology↗