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July 7, 2019

Genome sequence of the nicotine-degrading Agrobacterium tumefaciens S33.

Agrobacterium tumefaciens S33 is capable of growing with nicotine as the sole source of carbon and nitrogen, and has the potential to dispose of tobacco wastes and transform nicotine into functionalized pyridines intermediates, which are important precursors for some valuable drugs and insecticides. Here we report the complete genome sequence of strain S33 and predict the gene cluster involved in nicotine catabolism according to the annotation. Copyright © 2016 Elsevier B.V. All rights reserved.

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July 7, 2019

Gene duplication confers enhanced expression of 27-kDa ?-zein for endosperm modification in quality protein maize.

The maizeopaque2(o2) mutant has a high nutritional value but it develops a chalky endosperm that limits its practical use. Genetic selection foro2modifiers can convert the normally chalky endosperm of the mutant into a hard, vitreous phenotype, yielding what is known as quality protein maize (QPM). Previous studies have shown that enhanced expression of 27-kDa ?-zein in QPM is essential for endosperm modification. Taking advantage of genome-wide association study analysis of a natural population, linkage mapping analysis of a recombinant inbred line population, and map-based cloning, we identified a quantitative trait locus (q?27) affecting expression of 27-kDa ?-zein.q?27was mapped to the same region as the majoro2 modifier(o2 modifier1) on chromosome 7 near the 27-kDa ?-zein locus.q?27resulted from a 15.26-kb duplication at the 27-kDa ?-zein locus, which increases the level of gene expression. This duplication occurred before maize domestication; however, the gene structure ofq?27appears to be unstable and the DNA rearrangement frequently occurs at this locus. Because enhanced expression of 27-kDa ?-zein is critical for endosperm modification in QPM,q?27is expected to be under artificial selection. This discovery provides a useful molecular marker that can be used to accelerate QPM breeding.

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July 7, 2019

Genome sequencing and analysis of the first complete genome of Lactobacillus kunkeei strain MP2, an Apis mellifera gut isolate

Background. The honey bee (Apis mellifera) is the most important pollinator in agriculture worldwide. However, the number of honey bees has fallen significantly since 2006, becoming a huge ecological problem nowadays. The principal cause is CCD, or Colony Collapse Disorder, characterized by the seemingly spontaneous abandonment of hives by their workers. One of the characteristics of CCD in honey bees is the alteration of the bacterial communities in their gastrointestinal tract, mainly due to the decrease of Firmicutes populations, such as the Lactobacilli. At this time, the causes of these alterations remain unknown. We recently isolated a strain of Lactobacillus kunkeei (L. kunkeei strain MP2) from the gut of Chilean honey bees. L. kunkeei, is one of the most commonly isolated bacterium from the honey bee gut and is highly versatile in different ecological niches. In this study, we aimed to elucidate in detail, the L. kunkeei genetic background and perform a comparative genome analysis with other Lactobacillus species. Methods. L. kunkeei MP2 was originally isolated from the guts of Chilean A. mellifera individuals. Genome sequencing was done using Pacific Biosciences single-molecule real-time sequencing technology. De novo assembly was performed using Celera assembler. The genome was annotated using Prokka, and functional information was added using the EggNOG 3.1 database. In addition, genomic islands were predicted using IslandViewer, and pro-phage sequences using PHAST. Comparisons between L. kunkeei MP2 with other L. kunkeei, and Lactobacillus strains were done using Roary. Results. The complete genome of L. kunkeei MP2 comprises one circular chromosome of 1,614,522 nt. with a GC content of 36,9%. Pangenome analysis with 16 L. kunkeei strains, identified 113 unique genes, most of them related to phage insertions. A large and unique region of L. kunkeei MP2 genome contains several genes that encode for phage structural protein and replication components. Comparative analysis of MP2 with other Lactobacillus species, identified several unique genes of L. kunkeei MP2 related with metabolism, biofilm generation, survival under stress conditions, and mobile genetic elements (MGEs). Discussion. The presence of multiple mobile genetic elements, including phage sequences, suggest a high degree of genetic variability in L. kunkeei. Its versatility and ability to survive in different ecological niches (bee guts, flowers, fruits among others) could be given by its genetic capacity to change and adapt to different environments. L. kunkeei could be a new source of Lactobacillus with beneficial properties. Indeed, L. kunkeei MP2 could play an important role in honey bee nutrition through the synthesis of components as isoprenoids.

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July 7, 2019

Single-molecule sequencing assists genome assembly improvement and structural variation inference.

Dear editor, The single-molecule real-time (SMRT) sequencing platform presented by Pacific Biosciences (PacBio) is regarded as a third-generation sequencing technology (Eid et al., 2009, Roberts et al., 2013). PacBio delivers long reads from several to tens of kilobases (kbs), which are ideal for filling unsequenced gaps due to unusual sequence contexts, such as high-GC content or repeat-rich regions (Bashir et al., 2012, Berlin et al., 2015, Chaisson et al., 2015). PacBio long reads are also favorable for detecting large DNA fragments harboring structural variations (SVs), such as inversions, translocations, duplications, and large insertions/deletions (indels) (Ritz et al., 2010, English et al., 2014). However, one drawback of PacBio is the high error rate of base calling for single pass coverage of the genome (Au et al., 2012, Koren et al., 2012). This drawback can be mitigated by increasing sequencing coverage to achieve high consensus accuracy, but the requirements may be prohibitive for the de novo assembly of large- or medium-size genomes using only PacBio when considering both budgetary and computational costs. Alternatively, PacBio may be used for assembly improvement of near-finished reference genomes, especially for filling gaps in which unsequenced bases are represented by the letter N (English et al., 2012). Here, we combined PacBio (~15x) with Illumina reads (~40x) to improve the genome assemblies of African wild (Oryza barthii) and cultivated rice (O. glaberrima), and to infer large SVs between O. barthii and O. glaberrima.

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July 7, 2019

Complete genome sequence of Salmonella enterica serovar Typhimurium strain SO3 (sequence type 302) isolated from a baby with meningitis in Mexico.

The complete genome of Salmonella entericaserovar Typhimurium strain SO3 (sequence type 302), isolated from a fatal meningitis infection in Mexico, was determined using PacBio technology. The chromosome hosts six complete prophages and is predicted to harbor 51 genomic islands, including 13 pathogenicity islands (SPIs). It carries the Salmonella virulence plasmid (pSTV). Copyright © 2016 Vinuesa et al.

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July 7, 2019

Genome sequence of Aeromicrobium erythreum NRRL B-3381, an erythromycin-producing bacterium of the Nocardioidaceae.

Aeromicrobium erythreumNRRL B-3381 has a 3,629,239-bp circular genome that has 72% G+C content. There are at least 3,121 coding sequences (CDSs), two rRNA gene operons, and 47 tRNAs. The genome and erythromycin (ery) biosynthetic gene sequences provide resources for metabolic and combinatorial engineering of polyketides. Copyright © 2016 Harrell and Miller.

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July 7, 2019

Complete genome sequence of a low-temperature active and alkaline-stable endoglucanase-producing Paenibacillus sp. strain IHB B 3084 from the Indian Trans-Himalayas.

A genome of 5.88Mb with 46.83% G+C content is reported for an endoglucanase-producing bacterium Paenibacillus sp. strain IHB B 3084 isolated from the cold environments of the Indian Trans-Himalayas. The psychrotrophic bacterium produces low-temperature active and alkaline-stable endoglucanases of industrial importance. The genomic data has provided insight into genomic basis of cellulase production and survival of the bacterium in the cold environments. Copyright © 2016. Published by Elsevier B.V.

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July 7, 2019

De novo assembly of complete genome sequence of Planococcus kocurii ATCC 43650(T), a potential plant growth promoting bacterium.

Planococcus kocurii ATCC 43650(T) is a halotolerant and psychrotolerant bacterium isolated from the skin of a North sea cod. Here, we present the first complete genome and annotation of P. kocurii ATCC 43650(T), identifying its potential as a plant growth promoting bacterium and its capability in the biosynthesis of butanol. Copyright © 2016 Elsevier B.V. All rights reserved.

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July 7, 2019

Mechanisms involved in acquisition of blaNDM genes by IncA/C2 and IncFIIY plasmids.

blaNDM genes confer carbapenem resistance and have been identified on transferable plasmids belonging to different incompatibility (Inc) groups. Here we present the complete sequences of four plasmids carrying a blaNDM gene, pKP1-NDM-1, pEC2-NDM-3, pECL3-NDM-1 and pEC4-NDM-6, from four clinical samples originating from four different patients. Different plasmids carry segments that align to different parts of the blaNDM region found on Acinetobacter plasmids. pKP1-NDM-1 and pEC2-NDM-3, from Klebsiella pneumoniae and Escherichia coli, respectively, were identified as type 1 IncA/C2 plasmids with almost identical backbones. Different regions carrying blaNDM are inserted in different locations in the antibiotic resistance island known as ARI-A and ISCR1 may have been involved in acquisition of blaNDM-3 by pEC2-NDM-3. pECL3-NDM-1 and pEC4-NDM-6, from Enterobacter cloacae and E. coli, respectively, have similar IncFIIY backbones but different regions carrying blaNDM are found in different locations. Tn3-derived Inverted-repeat Transposable Elements (TIME) appear to have been involved in acquisition of blaNDM-6 by pEC4-NDM-6 and the rmtC 16S rRNA methylase gene by IncFIIY plasmids. Characterisation of these plasmids further demonstrates that even very closely related plasmids may have acquired blaNDM genes by different mechanisms. These findings also illustrate the complex relationships between antimicrobial resistance genes, transposable elements and plasmids and provide insights into the possible routes for transmission of blaNDM genes amongst species of the Enterobacteriaceae family. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

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July 7, 2019

Evolution of coreceptor utilization to escape CCR5 antagonist therapy.

The HIV-1 envelope interacts with coreceptors CCR5 and CXCR4 in a dynamic, multi-step process, its molecular details not clearly delineated. Use of CCR5 antagonists results in tropism shift and therapeutic failure. Here we describe a novel approach using full-length patient-derived gp160 quasispecies libraries cloned into HIV-1 molecular clones, their separation based on phenotypic tropism in vitro, and deep sequencing of the resultant variants for structure-function analyses. Analysis of functionally validated envelope sequences from patients who failed CCR5 antagonist therapy revealed determinants strongly associated with coreceptor specificity, especially at the gp120-gp41 and gp41-gp41 interaction surfaces that invite future research on the roles of subunit interaction and envelope trimer stability in coreceptor usage. This study identifies important structure-function relationships in HIV-1 envelope, and demonstrates proof of concept for a new integrated analysis method that facilitates laboratory discovery of resistant mutants to aid in development of other therapeutic agents. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

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July 7, 2019

Prediction of putative resistance islands in a carbapenem-resistant Acinetobacter baumannii global clone 2 clinical isolate.

We investigated the whole genome sequence (WGS) of a carbapenem-resistant Acinetobacter baumannii isolate belonging to the global clone 2 (GC2) and predicted resistance islands using a software tool.A. baumannii strain YU-R612 was isolated from the sputum of a 61-yr-old man with sepsis. The WGS of the YU-R612 strain was obtained by using the PacBio RS II Sequencing System (Pacific Biosciences Inc., USA). Antimicrobial resistance genes and resistance islands were analyzed by using ResFinder and Genomic Island Prediction software (GIPSy), respectively.The YU-R612 genome consisted of a circular chromosome (ca. 4,075 kb) and two plasmids (ca. 74 kb and 5 kb). Its sequence type (ST) under the Oxford scheme was ST191, consistent with assignment to GC2. ResFinder analysis showed that YU-R612 possessed the following resistance genes: four ß-lactamase genes bla(ADC-30), bla(OXA-66), bla(OXA-23), and bla(TEM-1); armA, aadA1, and aacA4 as aminoglycoside resistance-encoding genes; aac(6′)Ib-cr for fluoroquinolone resistance; msr(E) for macrolide, lincosamide, and streptogramin B resistance; catB8 for phenicol resistance; and sul1 for sulfonamide resistance. By GIPSy analysis, six putative resistant islands (PRIs) were determined on the YU-R612 chromosome. Among them, PRI1 possessed two copies of Tn2009 carrying bla(OXA-23), and PRI5 carried two copies of a class I integron carrying sul1 and armA genes.By prediction of resistance islands in the carbapenem-resistant A. baumannii YU-R612 GC2 strain isolated in Korea, PRIs were detected on the chromosome that possessed Tn2009 and class I integrons. The prediction of resistance islands using software tools was useful for analysis of the WGS.

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July 7, 2019

Complete genome sequence of the larvicidal bacterium Lysinibacillus sphaericus strain OT4b.25.

Lysinibacillus sphaericus OT4b.25 is a native Colombian strain isolated from coleopteran larvae in an oak forest near Bogotá D.C.; this strain has shown high levels of pathogenic activity against Culex quinquefasciatus larvae in laboratory assays compared to that of other members of the same species. Using Pacific Biosciences sequencing technology, we propose a chromosomal contig of 4,665,775 bp that, according to comparative analysis, is highly similar to that of reference strain L. sphaericus C3-41. Copyright © 2016 Rey et al.

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July 7, 2019

Complete genome sequence of Lactobacillus plantarum ZJ95, a potential probiotic strain producing bacteriocins and B-group vitamin riboflavin.

Lactobacillus plantarum ZJ95 is a potential probiotic isolated from newborn infant fecal and it is identified to produce riboflavin with great antimicrobial activity. The complete genome sequence of this strain was reported in the present study. The genome contains a 3,261,418-bp chromosome and two plasmids. Genes, related to the biosynthesis of bacteriocins and riboflavin, were identified. This work will facilitate to reveal the biosynthetic mechanism of bacteriocins and B-group vitamins in lactic acid bacteria and provide evidence for its potential application in food industry. Copyright © 2016. Published by Elsevier B.V.

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July 7, 2019

Complete nucleotide sequence of pH11, an IncHI2 plasmid conferring multi-antibiotic resistance and multi-heavy metal resistance genes in a clinical Klebsiella pneumoniae isolate.

The complete 284,628bp sequence of pH11, an IncHI2 plasmid, was determined through single-molecule, real-time (SMRT) sequencing. Harbored by a clinical Klebsiella pneumoniae strain H11, and isolated in Beijing, this plasmid contains multiple antibiotic resistance genes, including catA2, aac(6′)-Ib, strB, strA, dfrA19, blaTEM-1, blaSHV-12, sul1, qacE delta 1, ereA, arr2, and aac3. The aac(6′)-Ib is carried by a class I integron. Plasmid pH11 also carries several genes associated with resistance to heavy metals, such as tellurium, mercury, cobalt, zinc, nickel, copper, lead and cadmium. This plasmid exhibits numerous characteristics, including HipBA and RelBE toxin-antitoxin systems, two major transfer (Tra) regions closely related to those of Salmonella enterica serovar plasmid pRH-R27, a type II restriction modification system (EcoRII R-M system), several methyltransferases and methylases and genes encoding Hha and StpA. These characteristics suggest that pH11 may adapt to various hosts and environments. Multiple insertion sequence elements, transposases, recombinases, resolvases and integrases are scattered throughout pH11. The presence of these genes may indicate that horizontal gene transfer occurs frequently in pH11 and thus may facilitate the dissemination of antimicrobial resistance determinants. Our data suggest that pH11 is a chimera gradually assembled through the integration of different horizontally acquired DNA segments via transposition or homologous recombination. Copyright © 2016 Elsevier Inc. All rights reserved.

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