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July 7, 2019

Complete genome sequence of Actinobacillus equuli subspecies equuli ATCC 19392(T).

Actinobacillus equuli subsp. equuli is a member of the family Pasteurellaceae that is a common resident of the oral cavity and alimentary tract of healthy horses. At the same time, it can also cause a fatal septicemia in foals, commonly known as sleepy foal disease or joint ill disease. In addition, A. equuli subsp. equuli has recently been reported to act as a primary pathogen in breeding sows and piglets. To better understand how A. equuli subsp. equuli can cause disease, the genome of the type strain of A. equuli subsp. equuli, ATCC 19392(T), was sequenced using the PacBio RS II sequencing system. Its genome is comprised of 2,431,533 bp and is predicted to encode 2,264 proteins and 82 RNAs.


July 7, 2019

Comparative analyses of clinical and environmental populations of Cryptococcus neoformans in Botswana.

Cryptococcus neoformans var. grubii (Cng) is the most common cause of fungal meningitis, and its prevalence is highest in sub-Saharan Africa. Patients become infected by inhaling airborne spores or desiccated yeast cells from the environment, where the fungus thrives in avian droppings, trees and soil. To investigate the prevalence and population structure of Cng in southern Africa, we analysed isolates from 77 environmental samples and 64 patients. We detected significant genetic diversity among isolates and strong evidence of geographic structure at the local level. High proportions of isolates with the rare MATa allele were observed in both clinical and environmental isolates; however, the mating-type alleles were unevenly distributed among different subpopulations. Nearly equal proportions of the MATa and MATa mating types were observed among all clinical isolates and in one environmental subpopulation from the eastern part of Botswana. As previously reported, there was evidence of both clonality and recombination in different geographic areas. These results provide a foundation for subsequent genomewide association studies to identify genes and genotypes linked to pathogenicity in humans. © 2015 The Authors. Molecular Ecology published by John Wiley & Sons Ltd.


July 7, 2019

Complete genome sequence of Burkholderia cepacia strain LO6.

Burkholderia cepacia strain LO6 is a betaproteobacterium that was isolated from a cystic fibrosis patient. Here we report the 6.4 Mb draft genome sequence assembled into 2 contigs. This genome sequence will aid the transcriptomic profiling of this bacterium and help us to better understand the mechanisms specific to pulmonary infections. Copyright © 2015 Belcaid et al.


July 7, 2019

Sequence type 1 group B Streptococcus, an emerging cause of invasive disease in adults, evolves by small genetic changes.

The molecular mechanisms underlying pathogen emergence in humans is a critical but poorly understood area of microbiologic investigation. Serotype V group B Streptococcus (GBS) was first isolated from humans in 1975, and rates of invasive serotype V GBS disease significantly increased starting in the early 1990s. We found that 210 of 229 serotype V GBS strains (92%) isolated from the bloodstream of nonpregnant adults in the United States and Canada between 1992 and 2013 were multilocus sequence type (ST) 1. Elucidation of the complete genome of a 1992 ST-1 strain revealed that this strain had the highest homology with a GBS strain causing cow mastitis and that the 1992 ST-1 strain differed from serotype V strains isolated in the late 1970s by acquisition of cell surface proteins and antimicrobial resistance determinants. Whole-genome comparison of 202 invasive ST-1 strains detected significant recombination in only eight strains. The remaining 194 strains differed by an average of 97 SNPs. Phylogenetic analysis revealed a temporally dependent mode of genetic diversification consistent with the emergence in the 1990s of ST-1 GBS as major agents of human disease. Thirty-one loci were identified as being under positive selective pressure, and mutations at loci encoding polysaccharide capsule production proteins, regulators of pilus expression, and two-component gene regulatory systems were shown to affect the bacterial phenotype. These data reveal that phenotypic diversity among ST-1 GBS is mainly driven by small genetic changes rather than extensive recombination, thereby extending knowledge into how pathogens adapt to humans.


July 7, 2019

Covalent modification of bacteriophage T4 DNA inhibits CRISPR-Cas9.

The genomic DNAs of tailed bacteriophages are commonly modified by the attachment of chemical groups. Some forms of DNA modification are known to protect phage DNA from cleavage by restriction enzymes, but others are of unknown function. Recently, the CRISPR-Cas nuclease complexes were shown to mediate bacterial adaptive immunity by RNA-guided target recognition, raising the question of whether phage DNA modifications may also block attack by CRISPR-Cas9. We investigated phage T4 as a model system, where cytosine is replaced with glucosyl-hydroxymethylcytosine (glc-HMC). We first quantified the extent and distribution of covalent modifications in T4 DNA by single-molecule DNA sequencing and enzymatic probing. We then designed CRISPR spacer sequences targeting T4 and found that wild-type T4 containing glc-HMC was insensitive to attack by CRISPR-Cas9 but mutants with unmodified cytosine were sensitive. Phage with HMC showed only intermediate sensitivity. While this work was in progress, another group reported examples of heavily engineered CRISRP-Cas9 complexes that could, in fact, overcome the effects of T4 DNA modification, indicating that modifications can inhibit but do not always fully block attack.Bacteria were recently found to have a form of adaptive immunity, the CRISPR-Cas systems, which use nucleic acid pairing to recognize and cleave genomic DNA of invaders such as bacteriophage. Historic work with tailed phages has shown that phage DNA is often modified by covalent attachment of large chemical groups. Here we demonstrate that DNA modification in phage T4 inhibits attack by the CRISPR-Cas9 system. This finding provides insight into mechanisms of host-virus competition and also a new set of tools that may be useful in modulating the activity of CRISPR-Cas9 in genome engineering applications. Copyright © 2015 Bryson et al.


July 7, 2019

BreakSeek: a breakpoint-based algorithm for full spectral range INDEL detection.

Although recent developed algorithms have integrated multiple signals to improve sensitivity for insertion and deletion (INDEL) detection, they are far from being perfect and still have great limitations in detecting a full size range of INDELs. Here we present BreakSeek, a novel breakpoint-based algorithm, which can unbiasedly and efficiently detect both homozygous and heterozygous INDELs, ranging from several base pairs to over thousands of base pairs, with accurate breakpoint and heterozygosity rate estimations. Comprehensive evaluations on both simulated and real datasets revealed that BreakSeek outperformed other existing methods on both sensitivity and specificity in detecting both small and large INDELs, and uncovered a significant amount of novel INDELs that were missed before. In addition, by incorporating sophisticated statistic models, we for the first time investigated and demonstrated the importance of handling false and conflicting signals for multi-signal integrated methods.© The Author(s) 2015. Published by Oxford University Press on behalf of Nucleic Acids Research.


July 7, 2019

Complete genome sequencing of a multidrug-resistant and human-invasive Salmonella enterica serovar Typhimurium strain of the emerging sequence type 213 genotype.

Salmonella enterica subsp. enterica serovar Typhimurium strain YU39 was isolated in 2005 in the state of Yucatán, Mexico, from a human systemic infection. The YU39 strain is representative of the multidrug-resistant emergent sequence type 213 (ST213) genotype. The YU39 complete genome is composed of a chromosome and seven plasmids. Copyright © 2015 Calva et al.


July 7, 2019

Complete genome sequence of Salmonella enterica subsp. enterica serovar Agona 460004 2-1, associated with a multistate outbreak in the United States.

Within the last several years, Salmonella enterica subsp. enterica serovar Agona has been among the 20 most frequently isolated serovars in clinical cases of salmonellosis. In this report, the complete genome sequence of S. Agona strain 460004 2-1 isolated from unsweetened puffed-rice cereal during a multistate outbreak in 2008 was sequenced using single-molecule real-time DNA sequencing. Copyright © 2015 Hoffmann et al.


July 7, 2019

Complete genome sequence of Pragia fontium 24613, an environmental bacterium from the family Enterobacteriaceae.

The complete genome sequence of Pragia fontium 24613 was determined using PacBio RSII, Roche 454, and SOLiD sequencing. A total of 3,579 genes were predicted, including 3,338 protein-coding sequences and 146 pseudogenes. This is the first whole-genome sequence of a strain belonging to the environmental genera of the family Enterobacteriaceae. Copyright © 2015 Snopková et al.


July 7, 2019

Surveillance of Klebsiella pneumoniae and antibiotic resistance a retrospective and comparative study through a period in Nepal

Among the Enterobacteriacea Klebsiella pneumoniae is for the most part obtained from clinical samples and most probable cause of a typical form of primary pneumonia. It can also responsible for a variety of extrapulmonary infections, counting enteritis and meningitis in infants, urinary tract infections in children and adults and septicaemia in all age groups. Like wise these pathogens are significant cause of hospital acquired infections right through the world. The remarkable increase in the prevalence of antibiotic resistance in bacteria noticed in recent years represents a considerable challenge to public health microbiology worldwide. Klebsiellae have a tendency to possess antibiotic resistant plasmids; as a result, infections with multiple antibiotic-resistant strains can be likely. Only some degree of studies had been accounted in this regard from Nepal. The study was performed from January 1999 to March 2001. To come upon the existing dated antibiotic resistance pattern of Klebsiella pneumoniae. The study was carried out at TUTH laboratory with the objectives to ascertain the prevalence of Klebsiella pneumoniae in conjunction with to calculate the significance antibiotic resistance correlation between various antibiotics. By which the later 15 years analysis of antibiotic resistance was evaluated with comparison to this study.In this scrutiny the result was established that the numbers of total isolates including both klebsiella pneumoniae and other Kebsiella species were 62 from urine samples, 78 from pus samples and 96 from sputum samples and 34 from other miscellaneous samples. In this study positive culture for Klebsiella pneumoniae was 32.83% for sputum samples, 23.62.% for urine samples and 24.57% for pus samples. Majority of the strains isolated were sensitive to ß- lactamases, Floroquinolones, Aminoglycosides, Tetracycline and Cotrimoxazole, combined antibiotics. The current review study from 1999 to 2014 discloses the frequency of infections due to klebsiella pneumoniae strains in the hospitalized patients and their tendency towards antibiotic resistance was on the increase. Large quantity of antibiotics exploited for human therapy has resulted in the selection of pathogenic bacteria resistant to multiple antimicrobial drugs. This has become a vital clinical and infection control challenge, particularly in resource-limited settings with far above the ground a raising rate of antimicrobial resistance.


July 7, 2019

Discovery of microbial natural products by activation of silent biosynthetic gene clusters.

Microorganisms produce a wealth of structurally diverse specialized metabolites with a remarkable range of biological activities and a wide variety of applications in medicine and agriculture, such as the treatment of infectious diseases and cancer, and the prevention of crop damage. Genomics has revealed that many microorganisms have far greater potential to produce specialized metabolites than was thought from classic bioactivity screens; however, realizing this potential has been hampered by the fact that many specialized metabolite biosynthetic gene clusters (BGCs) are not expressed in laboratory cultures. In this Review, we discuss the strategies that have been developed in bacteria and fungi to identify and induce the expression of such silent BGCs, and we briefly summarize methods for the isolation and structural characterization of their metabolic products.


July 7, 2019

Complete genome sequence of Bordetella pertussis D420.

Bordetella pertussis is the causative agent of whooping cough, a highly contagious, acute respiratory illness that has seen resurgence despite the use of vaccines. We present the complete genome sequence of a clinical strain of B. pertussis, D420, which is representative of a currently circulating clade of this pathogen. Copyright © 2015 Boinett et al.


July 7, 2019

Identification and heterologous expression of the chaxamycin biosynthetic gene cluster from Streptomyces leeuwenhoekii.

Streptomyces leeuwenhoekii, isolated from the hyperarid Atacama Desert, produces the new ansamycin-like compounds chaxamycins A to D, which possess potent antibacterial activity and moderate antiproliferative activity. We report the development of genetic tools to manipulate S. leeuwenhoekii and the identification and partial characterization of the 80.2-kb chaxamycin biosynthesis gene cluster, which was achieved by both mutational analysis in the natural producer and heterologous expression in Streptomyces coelicolor A3(2) strain M1152. Restoration of chaxamycin production in a nonproducing ?cxmK mutant (cxmK encodes 3-amino-5-hydroxybenzoic acid [AHBA] synthase) was achieved by supplementing the growth medium with AHBA, suggesting that mutasynthesis may be a viable approach for the generation of novel chaxamycin derivatives. Copyright © 2015, American Society for Microbiology. All Rights Reserved.


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