Microbial Meteorology and Dispersal
Although atmospheric processes are known to affect the dispersion of aerosolized microbes, certain microbes may influence atmospheric processes in ways that expedite their return to the surface. Joyce et al. (e01567-19) characterized microbial assemblages deposited over a 2-year period in Louisiana precipitation and found that the most efficient ice-nucleating particles (INPs) originated from bacteria and air masses that had interacted with terrestrial surfaces. Precipitation from nimbostratus clouds during winter contained the highest abundances of INPs, implying that certain microbial aerosols have the capacity to influence the formation of precipitation under those meteorological conditions.
Response of Membrane Fluidity to Ethanol Toxicity
Yeast (Saccharomyces cerevisiae) strains with superior ethanol tolerance are desirable to winemakers and bioethanol industries. The cellular membrane plays a vital role in yeast ethanol tolerance; however, how the membrane is regulated to fight the toxic effect of ethanol remains to be elucidated. Yang et al. (e01620-19) suggest that membrane fluidity is variably regulated by OLE1 to offset the disruptive effect of ethanol. OLE1 expression and unsaturated fatty acid synthesis could slow the rate of decline in membrane fluidity, thus minimizing the fluidizing impact of ethanol toxicity. Current work will help in the development of more-ethanol-tolerant yeast strains for the wine and fuel ethanol industries.
Endogenous CRISPR-Cas System Harnessed for Gene Replacement in Heliobacterium modesticaldum
The Heliobacteriaceae are the only family of phototrophic bacteria in the phylum Firmicutes. Baker et al. (e01644-19) have demonstrated clean genome editing in Heliobacterium modesticaldum, a new model organism for this family. While reliance on homologous recombination alone was found to be prohibitively inefficient, utilizing the organism’s native CRISPR-Cas system to attack the targeted locus enabled a chromosome editing efficiency of over 80%. In this work, the gene encoding the photochemical reaction center core polypeptide was replaced with an antibiotic resistance gene, creating a nonphototrophic mutant strain. This technique may be applicable to other types of genetic manipulation in this organism.
Rapid and Improved Salmonella Serotype Determination Using Whole-Genome Sequencing Data
Serotyping is the basis of public health surveillance for Salmonella. It remains a first-line subtyping method even as such surveillance continues to be transformed by whole-genome sequencing. Zhang and colleagues (e01746-19) developed SeqSero2, an algorithmic transformation and functional update of the original SeqSero tool. It allows improved performance and incorporates new functions to further strengthen the application of molecular serotype prediction in routine and large-scale surveillance of Salmonella by whole-genome sequencing.
Multidrug-Resistant Escherichia coli Can Dominate in the Guts and Urine of Healthy Women
Multidrug-resistant bacteria, including the pandemic ciprofloxacin-resistant Escherichia coli strain ST131-H30, are increasingly found to colonize healthy people. A novel method developed by Shevchenko et al. (e01866-19) allowed assessment of clonal diversity of cocolonizing E. coli strains in fecal or urine samples and showed that up to six different strains can be carried in the gut of a healthy woman. However, ST131-H30 was often found to outcompete all other gut E. coli strains even in the absence of antibiotic use. Moreover, full dominance by this E. coli strain was found to be especially common in the urinary bladders of symptomless carriers.
- Copyright © 2019 American Society for Microbiology.
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- Article
- Microbial Meteorology and Dispersal
- Response of Membrane Fluidity to Ethanol Toxicity
- Endogenous CRISPR-Cas System Harnessed for Gene Replacement in Heliobacterium modesticaldum
- Rapid and Improved Salmonella Serotype Determination Using Whole-Genome Sequencing Data
- Multidrug-Resistant Escherichia coli Can Dominate in the Guts and Urine of Healthy Women
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