Phospholipid Substitution Dynamics and Novel Substitutes in a Phosphorus-Stressed Marine Diatom
Phytoplankton replace phosphorus (P)-containing membrane lipids with non-P analogues, enhancing growth in P-limited oceans. Here Hunter et al. (e02034-17) describe lipid substitution dynamics in the model marine diatom Thalassiosira pseudonana. Substitution is shown to follow a prior depletion of nonlipid cellular P and to proceed via a switch in biosynthesis accompanied by a minor degree of degradative breakdown, releasing P for other processes. The remaining P-containing lipids become more highly unsaturated in fatty acid composition, and several diglycosylceramide lipid substitutes are also reported. This work contributes to our mechanistic understanding of this powerful and widespread adaptation to P stress.
Vaginal Microbiota Lacks Lactobacillus spp. Postpartum
Bacterial communities found in the vagina have been associated with a high relative abundance of Lactobacillus spp. if in a healthy state. These associations have previously been based on small studies of populations in the United States and Europe. Doyle et al. (e02150-17) have expanded this knowledge base after analyzing the vaginal microbiota of 1,107 postpartum women in rural Malawi. They showed a population dominated by Gardnerella vaginalis soon after delivery, which persisted as the dominant organism for up to a year postpartum. This study demonstrates the difficulty in providing a single all-encompassing definition of what is a normal vaginal microbiota.
How Fimbriae and Fluid Shear Affect Escherichia coli Biofilms at Single-Cell Resolution
Bacterial biofilms, which can lead to severe contamination problems in the medical and food industries, are usually studied at a coarse macroscopic level. Thus, little is known about multicellular architecture and individual bacterium behavior within biofilms. Wang et al. (e02343-17) applied confocal laser scanning microscopy to visualize Escherichia coli microcolonies at a single-cell resolution. This work suggests that type I fimbriae are vital to the initiation of bacterial proliferation on surfaces and that the responses of biofilm architecture and cell membrane permeability of the constituent bacteria to fluid shear are regulated by the three-dimensional morphology and the population of microcolonies, respectively.
Evolution of a Dominant Clone of Escherichia coli in a Human Host over the Course of a Year
The evolution of Escherichia coli has been largely studied via experimental evolution in vitro or in vivo, using mouse gut colonization. However, much less is known about E. coli evolution in its major host, humans. Ghalayini et al. (e02377-17) followed a dominant clone through whole-genome sequencing of multiple isolates sampled over the course of a year from a healthy human gut. Their results suggest an evolution compatible with that of a small population under no selection pressure. This observation contrasts with the overwhelming signature of selection observed in experimental evolution and, therefore, brings into question the population dynamics of E. coli in the human gut.
Unique Microbiota within Animals and Humans on Pig Farms
An association between having pets and the composition of the human nasal microbiota has been previously shown. However, a study by Kraemer and colleagues (e02470-17) demonstrates the unique influence on the human nasal microbiota of keeping pigs. By performing 16S rRNA amplicon sequencing and using the DADA2 analysis pipeline, a large number of sequence variants (n = 82) were found to be pig farm rather than human specific. The findings also suggest that the pig farm environment—or, more precisely, the airborne microbiota—strongly influences the compositions of animal and human microbial communities.
- Copyright © 2018 American Society for Microbiology.
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- Phospholipid Substitution Dynamics and Novel Substitutes in a Phosphorus-Stressed Marine Diatom
- Vaginal Microbiota Lacks Lactobacillus spp. Postpartum
- How Fimbriae and Fluid Shear Affect Escherichia coli Biofilms at Single-Cell Resolution
- Evolution of a Dominant Clone of Escherichia coli in a Human Host over the Course of a Year
- Unique Microbiota within Animals and Humans on Pig Farms
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