April 21, 2020  |  

Efficacy of Newly Isolated and Highly Potent Bacteriophages in a Mouse Model of XDRAB Bacteremia.

Bacteremia can be caused by Acinetobacter baumannii with clinical manifestations ranging from transient bacteremia to septic shock. Extensively drug-resistant A. baumannii (XDRAB) strains producing the New Delhi metallo-ß-lactamase, which confers resistance to all ß-lactams including carbapenems, have emerged and infected patients suffer increased mortality, morbidity and length of hospitalization. The lack of new antimicrobials led to a renewed interest into phage therapy, the so-called forgotten cure. Accordingly, we tested new lytic bacteriophages in a Galleria mellonella and a mouse model of XDRAB-induced bacteremia.Galleria mellonella were challenged with 5.105 CFU of the XDRAB strain FER. Phages vB_AbaM_3054 and vB_AbaM_3090 were administrated alone or in combination 30?min. after bacterial challenge. Saline and imipenem were injected as controls. Mice were challenged i.p. with 6.107 CFU of A. baumannii FER. vB_AbaM_3054 and vB_AbaM_3090 were administrated i.p. alone or in combination 2?h after bacterial challenge. Saline and imipenem were injected as controls. Larvae and mice survival were followed for 7 days and compared with Log-Rank (Mantel-Cox) and Gehan-Breslow-Wilcoxon tests.Phage-based treatments showed high efficacy in larvae (ca. 100% survival at 80?h) and mice (ca. 100% survival at day 7) compared to the untreated control (0% survival at 48?h and 24?h in larvae and mice, respectively).The present data reporting efficacy of phage therapy in a mouse model of bacteremia support the development of phage-based drugs to manage infection due to multi-drug resistant A. baumannii and particularly XDRAB.Copyright © 2019. Published by Elsevier Ltd.


April 21, 2020  |  

Medusavirus, a Novel Large DNA Virus Discovered from Hot Spring Water.

Recent discoveries of new large DNA viruses reveal high diversity in their morphologies, genetic repertoires, and replication strategies. Here, we report the novel features of medusavirus, a large DNA virus newly isolated from hot spring water in Japan. Medusavirus, with a diameter of 260?nm, shows a T=277 icosahedral capsid with unique spherical-headed spikes on its surface. It has a 381-kb genome encoding 461 putative proteins, 86 of which have their closest homologs in Acanthamoeba, whereas 279 (61%) are orphan genes. The virus lacks the genes encoding DNA topoisomerase II and RNA polymerase, showing that DNA replication takes place in the host nucleus, whereas the progeny virions are assembled in the cytoplasm. Furthermore, the medusavirus genome harbored genes for all five types of histones (H1, H2A, H2B, H3, and H4) and one DNA polymerase, which are phylogenetically placed at the root of the eukaryotic clades. In contrast, the host amoeba encoded many medusavirus homologs, including the major capsid protein. These facts strongly suggested that amoebae are indeed the most promising natural hosts of medusavirus, and that lateral gene transfers have taken place repeatedly and bidirectionally between the virus and its host since the early stage of their coevolution. Medusavirus reflects the traces of direct evolutionary interactions between the virus and eukaryotic hosts, which may be caused by sharing the DNA replication compartment and by evolutionarily long lasting virus-host relationships. Based on its unique morphological characteristics and phylogenomic relationships with other known large DNA viruses, we propose that medusavirus represents a new family, MedusaviridaeIMPORTANCE We have isolated a new nucleocytoplasmic large DNA virus (NCLDV) from hot spring water in Japan, named medusavirus. This new NCLDV is phylogenetically placed at the root of the eukaryotic clades based on the phylogenies of several key genes, including that encoding DNA polymerase, and its genome surprisingly encodes the full set of histone homologs. Furthermore, its laboratory host, Acanthamoeba castellanii, encodes many medusavirus homologs in its genome, including the major capsid protein, suggesting that the amoeba is the genuine natural host from ancient times of this newly described virus and that lateral gene transfers have repeatedly occurred between the virus and amoeba. These results suggest that medusavirus is a unique NCLDV preserving ancient footprints of evolutionary interactions with its hosts, thus providing clues to elucidate the evolution of NCLDVs, eukaryotes, and virus-host interaction. Based on the dissimilarities with other known NCLDVs, we propose that medusavirus represents a new viral family, Medusaviridae.Copyright © 2019 Yoshikawa et al.


April 21, 2020  |  

Still Something to Discover: Novel Insights into Escherichia coli Phage Diversity and Taxonomy.

The aim of this study was to gain further insight into the diversity of Escherichia coli phagesfollowed by enhanced work on taxonomic issues in that field. Therefore, we present the genomiccharacterization and taxonomic classification of 50 bacteriophages against E. coli isolated fromvarious sources, such as manure or sewage. All phages were examined for their host range on a setof different E. coli strains, originating, e.g., from human diagnostic laboratories or poultry farms.Transmission electron microscopy revealed a diversity of morphotypes (70% Myo-, 22% Sipho-, and8% Podoviruses), and genome sequencing resulted in genomes sizes from ~44 to ~370 kb.Annotation and comparison with databases showed similarities in particular to T4- and T5-likephages, but also to less-known groups. Though various phages against E. coli are already describedin literature and databases, we still isolated phages that showed no or only few similarities to otherphages, namely phages Goslar, PTXU04, and KWBSE43-6. Genome-based phylogeny andclassification of the newly isolated phages using VICTOR resulted in the proposal of new generaand led to an enhanced taxonomic classification of E. coli phages.


April 21, 2020  |  

Characterization of the genome of a Nocardia strain isolated from soils in the Qinghai-Tibetan Plateau that specifically degrades crude oil and of this biodegradation.

A strain of Nocardia isolated from crude oil-contaminated soils in the Qinghai-Tibetan Plateau degrades nearly all components of crude oil. This strain was identified as Nocardia soli Y48, and its growth conditions were determined. Complete genome sequencing showed that N. soli Y48 has a 7.3?Mb genome and many genes responsible for hydrocarbon degradation, biosurfactant synthesis, emulsification and other hydrocarbon degradation-related metabolisms. Analysis of the clusters of orthologous groups (COGs) and genomic islands (GIs) revealed that Y48 has undergone significant gene transfer events to adapt to changing environmental conditions (crude oil contamination). The structural features of the genome might provide a competitive edge for the survival of N. soli Y48 in oil-polluted environments and reflect the adaptation of coexisting bacteria to distinct nutritional niches.Copyright © 2018. Published by Elsevier Inc.


April 21, 2020  |  

Genomic Characterization of a Newly Isolated Rhizobacteria Sphingomonas panacis Reveals Plant Growth Promoting Effect to Rice

This article reports the full genome sequence of Sphingomonas panacis DCY99T (=KCTC 42347T =JCM30806T), which is a Gram-negative rod-shaped, non-spore forming, motile bacterium isolated from rusty ginseng root in South Korea. A draft genome of S. panacis DCY99T and a single circular plasmid were generated using the PacBio platform. Antagonistic activity experiment showed S. panacis DCY99T has the plant growth promoting effect. Thus, the genome sequence of S. panacis DCY99T may contribute to biotechnological application of the genus Sphingomonas in agriculture.


April 21, 2020  |  

A Newly Isolated Bacillus subtilis Strain Named WS-1 Inhibited Diarrhea and Death Caused by Pathogenic Escherichia coli in Newborn Piglets.

Bacillus subtilis is recognized as a safe and reliable human and animal probiotic and is associated with bioactivities such as production of vitamin and immune stimulation. Additionally, it has great potential to be used as an alternative to antimicrobial drugs, which is significant in the context of antibiotic abuse in food animal production. In this study, we isolated one strain of B. subtilis, named WS-1, from apparently healthy pigs growing with sick cohorts on one Escherichia coli endemic commercial pig farm in Guangdong, China. WS-1 can strongly inhibit the growth of pathogenic E. coli in vitro. The B. subtilis strain WS-1 showed typical Bacillus characteristics by endospore staining, biochemical test, enzyme activity analysis, and 16S rRNA sequence analysis. Genomic analysis showed that the B. subtilis strain WS-1 shares 100% genomic synteny with B. subtilis with a size of 4,088,167 bp. Importantly, inoculation of newborn piglets with 1.5 × 1010 CFU of B. subtilis strain WS-1 by oral feeding was able to clearly inhibit diarrhea (p < 0.05) and death (p < 0.05) caused by pathogenic E. coli in piglets. Furthermore, histopathological results showed that the WS-1 strain could protect small intestine from lesions caused by E. coli infection. Collectively, these findings suggest that the probiotic B. subtilis strain WS-1 acts as a potential biocontrol agent protecting pigs from pathogenic E. coli infection. Importance: In this work, one B. subtilis strain (WS-1) was successfully isolated from apparently healthy pigs growing with sick cohorts on one E. coli endemic commercial pig farm in Guangdong, China. The B. subtilis strain WS-1 was identified to inhibit the growth of pathogenic E. coli both in vitro and in vivo, indicating its potential application in protecting newborn piglets from diarrhea caused by E. coli infections. The isolation and characterization will help better understand this bacterium, and the strain WS-1 can be further explored as an alternative to antimicrobial drugs to protect human and animal health.


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