Biology subjects

Wicki-Emmenegger, D.

Publications and source records attributed to Wicki-Emmenegger, D..

2 recordsLinked to original sources

bioRxiv2024

Reduced functional fungal communities in two species of sloths (Bradypus variegatus and Choloepus hoffmanni) suggest a link to slow digestion

Sloths, with their ruminant-like digestive systems, possess the slowest digestion among mammals due to their low metabolic rate, minimal food intake, and extremely low-energy diet. However, no comprehensive studies have characterized the sloths gut microbiota, including fungi, and their role in digestion. This study hypothesized that effective plant fiber-degrading fungi (e.g., Neocallimastigomycota) would be scarce in the sloths gut. The aim was to describe the gut microbiota of three-toed (Bradypus variegatus) and two-toed (Choloepus hoffmanni) sloths to understand their link to slow digestion. Microbial composition and functionality were analyzed using shotgun metagenomics, metatranscriptomics, fungal metabarcoding (ITS 1 and 2 nrDNA), and cellulose degradation analysis. Microbial communities were dominated by bacteria (92-97%), followed by viruses (1-7%). Fungi accounted for only 0.06-0.5% of metagenomic reads and 0.1% of transcripts. Functional analysis revealed minimal CAZy abundance (1.7-1.9% in metagenomes, 0.2% in metatranscriptomes), with no fungal CAZys or glycoside hydrolases detected. Neocallimastigomycota had negligible abundance in metagenomic data and was absent in metatranscriptomic or ITS metabarcoding data. Bradypus variegatus showed overall lower CAZy abundance and fungal presence compared to Choloepus hoffmanni. Lastly, cellulose degradation analyses revealed that only [~]5-35% of the intake was digested. This study highlights the unique microbial ecosystem in sloths guts, showing minimal presence of plant fiber-degrading anaerobic fungi and limited microbial CAZys, aligning with their slow digestion and low metabolic rate, thus enhancing our understanding of their digestive efficiency and metabolic adaptations.

microbiology↗

bioRxiv2020

The putative phosphate transporter PitB (PP1373) is involved in tellurite uptake in Pseudomonas putida KT2440

Tellurium oxyanions are chemical species with great toxicity; their presence in the environment has increased because of mining industries and photovoltaic and electronic waste. Recovery strategies based on microorganisms for this metalloid are of interest, but further studies of the transport systems and enzymes responsible for implementing tellurium transformations are required because many mechanisms remain unknown. Here, we investigated the involvement in tellurite uptake of the putative phosphate transporter PitB (PP1373) in soil bacterium Pseudomonas putida KT2440. For this purpose, through a method based on the CRISPR/Cas9 system, we generated a strain deficient in pitB gene and characterized its phenotype on exposing it to varied concentrations of tellurite. Growth curves and Transmission Electronic Microscopy experiments of wild type and {Delta}pitB showed that both strains were able to internalize tellurite into the cytoplasm and reduce the oxyanion to black nano-sized and rod-shaped tellurium particles, however, {Delta}pitB strain showed an increased resistance to the tellurite toxic effects. At a concentration of 100 uM tellurite, where the biomass formation of wild type strain decreased by half, we observed a greater ability of {Delta}pitB to reduce this oxyanion with respect to wild type strain (~38% vs ~16%), which is related by the greater biomass production of {Delta}pitB and not by a greater consumption of tellurite per cell. The phenotype of the mutant was restored on over-expressing pitB in trans. In summary, our results indicate that PitB is one of several transporters responsible for tellurite uptake in P. putida KT2440.

microbiology↗