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This Week in PLOS: Jul 11, 2016

In PLOS Genetics, researchers from the US, Canada, and Argentina compare genetic features found in wild and domesticated strains of a yeast species associated with lager-style beer. Lagers tend to be brewed at lower temperatures than ales, as members of the team reported last summer, using hybrid yeast strains that originated more than once through crosses between Saccharomyces eubayanus and the more common ale yeast S. cerevisiae. Results from the group's new genome sequencing analysis of nearly three dozen wild or lager-related strains revealed relationships between S. eubayanus populations in the Americas, Australasia, Asia, and Europe, pointing to enhanced genetic diversity in two South American populations, without identifying any single wild population that had closer genetic ties to all hybrid lager strains.

For a paper published in PLOS Neglected Tropical Diseases, Kenyan researchers report on results from a phylogenetic study of Rickettsia africae, the tick-borne pathogen behind African tick bite fevers. Using amplicon sequencing, the team assessed five rickettsia genes in samples from 57 ticks collected in different parts of Kenya, all believed to harbor R. africae. The genetic data indicated that three of the samples contained R. aeschlimanii, while a fourth harbored a new rickettsiae species, which the group dubbed Candidatus Rickettsia moyalensis. For the pathogens that were genetically verified as R. africae, meanwhile, the investigators detected considerable genetic diversity within the two main clades they identified.

A team from Sichuan University and Fudan University describe the analytical approach it used to find infections involving multiple strains of the malaria-causing parasite Mycobacterium tuberculosis. As they explain in PLOS One, the researchers came up with a new phylogenetic method for uncovering these mixed infections from whole-genome sequencing data. When they applied this approach to sequence data for nearly 800 M. tuberculosis strains described in public databases, for example, they identified tens of thousands of single nucleotide variants and found 47 mixed infections.