Articles of Significant Interest Selected from This Issue by the Editors
Microbial Life Thrives on Floating Pumice
In 2011, an explosive megaeruption of the Puyehue-Cardon Caulle volcanic complex in Chile discharged >100 million metric tons of ash and pumice into the Patagonian landscape. Much of this pumice fell into and then floated on surrounding lakes. Elser et al. (p. 1542–1549) used 16S rRNA sequencing to characterize the microbial communities that colonized floating pumice in two regional lakes, identifying taxa that thrived on these harsh and dynamic substrata. They also showed that by midsummer the pumice-loving microbes contributed significantly to whole-lake demand for nutrients (nitrogen and phosphorus).
Molecular Processes of Viral Inactivation for Hepatitis C Virus Uncovered
Viral inactivation methods are essential parts of infection control in medical settings, but the mechanisms of viral inactivation remain relatively poorly understood. Pfaender and colleagues (p. 1616–1621) showed that different inactivation methods, like chemical disinfectants or heat and UV treatment, resulted in a loss of hepatitis C virus infectivity by targeting different parts of the virus particle. Understanding virus inactivation on a basic mechanistic level will aid in predicting the susceptibility of nonculturable virus strains and should improve methods for combating viral transmission and inactivation in the future.
New Insights into the Genome Plasticity of Ruminant-Pathogenic Mycoplasmas
Integrative conjugative elements (ICEs), a group of mobile genetic elements widely spread across bacteria, are key players in genome plasticity and horizontal gene transfer. Yet evidence of ICEs in Mycoplasma is scarce, raising the question of their biological significance in these minimal bacteria. Tardy et al. (p. 1634–1643) revealed the occurrence and maintenance of functional ICEs in a large number of field isolates from different ruminant-pathogenic species. Since they encode the conjugative machinery and are associated with chromosomal transfer, mycoplasma ICEs may contribute to gene exchange and to the emergence of new genotypes in pathogenic species of veterinary importance.
Bacillus cereus Group: an Excellent Reservoir of Novel Lanthipeptides
Lantibiotics can inhibit many Gram-positive clinical pathogens, including some multidrug-resistant ones, and mining novel lantibiotics may provide a new strategy for treatment of diseases caused by these organisms. So far, research on lantibiotics has focused primarily on lactic acid bacteria and other Firmicutes species. Here Xin et al. (p. 1765–1774) reveal that Bacillus cereus group bacteria are actually an excellent reservoir of novel lanthipeptides. This work not only improves the understanding of the classification, distribution, and diversity of the lanthipeptide gene cluster in the B. cereus group but also provides a new means to quickly discover many more novel lantibiotics.
Population Biology of Enterococcus from Intestinal Colonization in Hospitalized and Nonhospitalized Individuals of Different Age Groups
A novel analysis of enterococcal populations by Tedim et al. (p. 1820–1831) demonstrated similar rates of fecal colonization by enterococcal species in fecal samples of hospitalized and nonhospitalized individuals of different ages, with some lineages being predominant at certain ages and/or in the hospital environment. Some populations were common in certain groups of individuals but reduced in others, suggesting that extinction of genotypes with different ecological roles is prevented by the frequency-dependent evolution of specific populations. The Bayesian analysis of population structure (BAPS) performed broadened previously obtained results on Enterococcus faecium's population structure. For Enterococcus faecalis, associations of BAPS groups with age or hospitalization were not established.
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