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April 21, 2020  |  

Molecular Characterization of a Multidrug-Resistant Klebsiella pneumoniae Strain R46 Isolated from a Rabbit

To investigate the mechanisms of multiple resistance and the horizontal transfer of resistance genes in animal pathogens, we characterized the molecular structures of the resistance gene-related sequences in a multidrug-resistant Klebsiella pneumoniae strain R46 isolated from a rabbit. Molecular cloning was performed to clone the resistance genes, and minimum inhibitory concentrations (MICs) were measured to determine the resistance characteristics of the cloned genes and related strains. A conjugation experiment was conducted to assess the transferability of the resistance plasmids. Sequencing and comparative genomic methods were used to analyze the structures of the resistance gene-related sequences. The K. pneumoniae R46 genome consisted of a chromosome and three resistance plasmids named pR46-27, pR46-42, and pR46-270, respectively. The whole genome encoded 34 antibiotic resistance genes including a newly identified chromosome-encoded florfenicol resistance gene named mdfA2. pR46-270, besides encoding 26 antibiotic resistance genes, carried four clusters of heavy metal resistance genes and several virulence-related genes or gene clusters. The plasmid-encoded resistance genes were mostly associated with mobile genetic elements. The plasmid with the most similarity to the floR gene-harboring plasmid pR46-27 was pCTXM-2271, a plasmid from Escherichia coli. The results of this work demonstrated that the plasmids with multidrug resistance genes were present in animal-derived bacteria and more florfenicol resistance genes such as mdfA2 could be present in bacterial populations. The resistance genes encoded on the plasmids may spread between the bacteria of different species or genera and cause the resistance dissemination.


April 21, 2020  |  

Large-scale ruminant genome sequencing provides insights into their evolution and distinct traits.

The ruminants are one of the most successful mammalian lineages, exhibiting morphological and habitat diversity and containing several key livestock species. To better understand their evolution, we generated and analyzed de novo assembled genomes of 44 ruminant species, representing all six Ruminantia families. We used these genomes to create a time-calibrated phylogeny to resolve topological controversies, overcoming the challenges of incomplete lineage sorting. Population dynamic analyses show that population declines commenced between 100,000 and 50,000 years ago, which is concomitant with expansion in human populations. We also reveal genes and regulatory elements that possibly contribute to the evolution of the digestive system, cranial appendages, immune system, metabolism, body size, cursorial locomotion, and dentition of the ruminants. Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.


April 21, 2020  |  

A microbial factory for defensive kahalalides in a tripartite marine symbiosis.

Chemical defense against predators is widespread in natural ecosystems. Occasionally, taxonomically distant organisms share the same defense chemical. Here, we describe an unusual tripartite marine symbiosis, in which an intracellular bacterial symbiont (“Candidatus Endobryopsis kahalalidefaciens”) uses a diverse array of biosynthetic enzymes to convert simple substrates into a library of complex molecules (the kahalalides) for chemical defense of the host, the alga Bryopsis sp., against predation. The kahalalides are subsequently hijacked by a third partner, the herbivorous mollusk Elysia rufescens, and employed similarly for defense. “Ca E. kahalalidefaciens” has lost many essential traits for free living and acts as a factory for kahalalide production. This interaction between a bacterium, an alga, and an animal highlights the importance of chemical defense in the evolution of complex symbioses.Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.


April 21, 2020  |  

The replication-competent HIV-1 latent reservoir is primarily established near the time of therapy initiation.

Although antiretroviral therapy (ART) is highly effective at suppressing HIV-1 replication, the virus persists as a latent reservoir in resting CD4+ T cells during therapy. This reservoir forms even when ART is initiated early after infection, but the dynamics of its formation are largely unknown. The viral reservoirs of individuals who initiate ART during chronic infection are generally larger and genetically more diverse than those of individuals who initiate therapy during acute infection, consistent with the hypothesis that the reservoir is formed continuously throughout untreated infection. To determine when viruses enter the latent reservoir, we compared sequences of replication-competent viruses from resting peripheral CD4+ T cells from nine HIV-positive women on therapy to viral sequences circulating in blood collected longitudinally before therapy. We found that, on average, 71% of the unique viruses induced from the post-therapy latent reservoir were most genetically similar to viruses replicating just before ART initiation. This proportion is far greater than would be expected if the reservoir formed continuously and was always long lived. We conclude that ART alters the host environment in a way that allows the formation or stabilization of most of the long-lived latent HIV-1 reservoir, which points to new strategies targeted at limiting the formation of the reservoir around the time of therapy initiation.Copyright © 2019 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.


April 21, 2020  |  

Complete Genome Sequence of a Parabacteroides distasonis Strain (CavFT hAR46) Isolated from a Gut Wall-Cavitating Microlesion in a Patient with Severe Crohn’s Disease.

Crohn’s disease (CD) is a chronic inflammatory bowel disease (IBD) of the digestive tract in humans. There is evidence that Parabacteroides distasonis could contribute to IBD. Here, we present the complete genome sequence of a strain designated CavFT-hAR46, which was isolated from a gut intramural cavernous fistulous tract (CavFT) microlesion in a CD patient.Copyright © 2019 Yang et al.


April 21, 2020  |  

Complete Genome Sequence of Leisingera aquamixtae R2C4, Isolated from a Self-Regenerating Biocathode Consortium.

Here, we present the complete genome sequence of Leisingera aquamixtae R2C4, isolated from the electroautotrophic microbial consortium biocathode MCL (Marinobacter-Chromatiaceae-Labrenzia). As an isolate of a current-producing system, the genome sequence of L. aquamixtae will yield insights regarding electrode-associated microorganisms and communities. A dark pigment is also observed during cultivation.Copyright © 2019 Bird et al.


April 21, 2020  |  

Draft Genome Sequence of Dicyma pulvinata Strain 414-3, a Mycoparasite of Cladosporium fulvum, Causal Agent of Tomato Leaf Mold.

Dicyma pulvinata strain 414-3, isolated from the surface of a tomato leaf, is a mycoparasitic fungus of Cladosporium fulvum, which causes leaf mold of tomato. We report here the draft genome sequence of strain 414-3, which will contribute to elucidating the molecular mechanisms involved in the mycoparasitism.Copyright © 2019 Sushida et al.


April 21, 2020  |  

Complete Genome Sequence of Subcluster 5.2 Synechococcus sp. Strain CB0101, Isolated from the Chesapeake Bay.

Synechococcus sp. strain CB0101 is a model strain for cyanobacteria living in the estuarine environment. It is also a representative member of marine Synechococcus subcluster 5.2. The draft genome sequence of CB0101 was reported in 2014 with 454 sequencing. Here, we report the complete genome sequence of CB0101, obtained with PacBio sequencing. CB0101 contains a specialized array of genes which are involved in sensing, responding to, and persisting in the presence of environmental stress.Copyright © 2019 Fucich et al.


April 21, 2020  |  

Complete Genome Sequence of Streptomyces sp. Strain SGAir0924, an Actinobacterium Isolated from Outdoor Air in Singapore.

Streptomyces sp. strain SGAir0924 was isolated from outdoor air collected in Singapore. Its genome was assembled using long reads generated by single-molecule real-time sequencing. The final assembly had one chromosome of 7.65?Mb and three plasmids with an average length of 142 kb. The genome contained 6,825 protein-coding genes, 68 tRNAs, and 18 rRNAs.Copyright © 2019 Gupta et al.


April 21, 2020  |  

Draft Genome Sequence of Streptomyces sp. Strain RKND-216, an Antibiotic Producer Isolated from Marine Sediment in Prince Edward Island, Canada.

Streptomyces sp. strain RKND-216 was isolated from marine sediment collected in Prince Edward Island, Canada, and produces a putatively novel bioactive natural product with antitubercular activity. The genome assembly consists of two contigs covering 5.61?Mb. Genome annotation identified 4,618 predicted protein-coding sequences and 19 predicted natural product biosynthetic gene clusters.Copyright © 2019 Liang et al.


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