SciCombinator

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Concept: Proteobacteria

830

The recent discovery of a plasmid-borne colistin resistance gene, mcr-1, heralds the emergence of truly pan-drug resistant bacteria (1).….

Concepts: DNA, Gene, Bacteria, Genome, Antibiotic resistance, Escherichia coli, Plasmid, Proteobacteria

180

In 2015, scientists reported the emergence of the plasmid-encoded mcr-1 gene conferring bacterial resistance to the antibiotic colistin (1), signaling potential emergence of a pandrug-resistant bacterium. In May 2016, mcr-1-positive Escherichia coli was first isolated from a specimen from a U.S. patient (2) when a Pennsylvania woman was evaluated for a urinary tract infection. The urine culture and subsequent testing identified the gene in an extended-spectrum beta-lactamase (ESBL)-producing E. coli with reduced susceptibility to colistin. The patient had no international travel for approximately 1 year, no livestock exposure, and a limited role in meal preparation with store-bought groceries; however, she had multiple and repeated admissions to four medical facilities during 2016.

Concepts: Kidney, Bacteria, Evolution, Urinary tract infection, Urine, Antibiotic resistance, Escherichia coli, Proteobacteria

166

Campylobacter jejuni is an important cause of human foodborne gastroenteritis; strategies to prevent infection are hampered by a poor understanding of the complex interactions between host and pathogen. Previous work showed that C. jejuni could bind human histo-blood group antigens (BgAgs) in vitro and that BgAgs could inhibit the binding of C. jejuni to human intestinal mucosa ex vivo. Here, the major flagella subunit protein (FlaA) and the major outer membrane protein (MOMP) were identified as BgAg-binding adhesins in C. jejuni NCTC11168. Significantly, the MOMP was shown to be O-glycosylated at Thr(268); previously only flagellin proteins were known to be O-glycosylated in C. jejuni. Substitution of MOMP Thr(268) led to significantly reduced binding to BgAgs. The O-glycan moiety was characterized as Gal(β1-3)-GalNAc(β1-4)-GalNAc(β1-4)-GalNAcα1-Thr(268); modelling suggested that O-glycosylation has a notable effect on the conformation of MOMP and this modulates BgAg-binding capacity. Glycosylation of MOMP at Thr(268) promoted cell-to-cell binding, biofilm formation and adhesion to Caco-2 cells, and was required for the optimal colonization of chickens by C. jejuni, confirming the significance of this O-glycosylation in pathogenesis.

Concepts: Immune system, Protein, Bacteria, Glucose, Proteobacteria, Gastroenteritis, Campylobacter, Campylobacter jejuni

166

Macroalgae harbor microbial communities whose bacterial biodiversity remains largely uncharacterized. The goals of this study were 1) to examine the composition of the bacterial community associated with Porphyra umbilicalis Kützing from Schoodic Point, ME, 2) determine whether there are seasonal trends in species diversity but a core group of bacteria that are always present, and 3) to determine how the microbial community associated with a laboratory strain (P.um.1) established in the presence of antibiotics has changed. P. umbilicalis blades (n = 5, fall 2010; n = 5, winter 2011; n = 2, clonal P.um.1) were analyzed by pyrosequencing over two variable regions of the 16 S rDNA (V5-V6 and V8; 147,880 total reads). The bacterial taxa present were classified at an 80% confidence threshold into eight phyla (Bacteroidetes, Proteobacteria, Planctomycetes, Chloroflexi, Actinobacteria, Deinococcus-Thermus, Firmicutes, and the candidate division TM7). The Bacteroidetes comprised the majority of bacterial sequences on both field and lab blades, but the Proteobacteria (Alphaproteobacteria, Gammaproteobacteria) were also abundant. Sphingobacteria (Bacteroidetes) and Flavobacteria (Bacteroidetes) had inverse abundances on natural versus P.um.1 blades. Bacterial communities were richer and more diverse on blades sampled in fall compared to winter. Significant differences were observed between microbial communities among all three groups of blades examined. Only two OTUs were found on all 12 blades, and only one of these, belonging to the Saprospiraceae (Bacteroidetes), was abundant. Lewinella (as 66 OTUs) was found on all field blades and was the most abundant genus. Bacteria from the Bacteroidetes, Proteobacteria and Planctomycetes that are known to digest the galactan sulfates of red algal cell walls were well-represented. Some of these taxa likely provide essential morphogenetic and beneficial nutritive factors to P. umbilicalis and may have had unexpected effects upon evolution of macroalgal form as well as function.

Concepts: Archaea, Bacteria, Gut flora, Microbiology, Cell wall, Proteobacteria, Bacteroidetes, Porphyra

166

We report the preparation and characterization of spherical core-shell structured Fe3O4-Au magnetic nanoparticles, modified with two component self-assembled monolayers (SAMs) consisting of 3-mercaptophenylboronic acid (3-MBA) and 1-decanethiol (1-DT). The rapid and room temperature synthesis of magnetic nanoparticles was achieved using the hydroxylamine reduction of HAuCl4 on the surface of ethylenediaminetetraacetic acid (EDTA)-immobilized iron (magnetite Fe3O4) nanoparticles in the presence of an aqueous solution of hexadecyltrimetylammonium bromide (CTAB) as a dispersant. The reduction of gold on the surface of Fe3O4 nanoparticles exhibits a uniform, highly stable, and narrow particle size distribution of Fe3O4-Au nanoparticles with an average diameter of 9 ± 2 nm. The saturation magnetization value for the resulting nanoparticles was found to be 15 emu/g at 298 K. Subsequent surface modification with SAMs against glucoside moieties on the surface of bacteria provided effective magnetic separation. Comparison of the bacteria capturing efficiency, by means of different molecular recognition agents 3-MBA, 1-DT and the mixed monolayer of 3-MBA and 1-DT was presented. The best capturing efficiency of E. coli was achieved with the mixed monolayer of 3-MBA and 1-DT-modified nanoparticles. Molecular specificity and selectivity were also demonstrated by comparing the surface-enhanced Raman scattering (SERS) spectrum of E. coli-nanoparticle conjugates with bacterial growth media.

Concepts: Bacteria, Gut flora, Nanoparticle, Escherichia coli, Chemistry, Magnetism, Proteobacteria, Magnetite

145

Lactococcus lactis is a Gram-positive (endotoxin-free) food-grade bacteria exploited as alternative to Escherichia coli for recombinant protein production. We have explored here for the first time the ability of this platform as producer of complex, self-assembling protein materials.

Concepts: DNA, Bacteria, Gut flora, Recombinant DNA, Escherichia coli, Biotechnology, Proteobacteria, Genetic recombination

144

We aimed to investigate the prevalence of extended-spectrum β-lactamases (ESBL)-producing Escherichia coli (E. coli) in Beijing Tongren hospital and find the relationship between colonization and infection. The clinical data of 650 inpatients included between March 2012 and July 2012 were retrospectively reviewed. The prevalence of ESBL-producing E. coli among inpatients was 25.7% (167/650), with the highest of 50.0% in rheumatology ward and lowest of 10.0% in intensive care unit. Hospital stay more than 2 years, usage of antibiotics less than 3 months, and use of glucocorticoids or immunosuppressive were found to be significantly associated with ESBL carriage (P < 0.05). Totally, 76 sequence types (ST) were revealed by MLST. ST38 (n = 12, 7.2%) was the most common type, followed by ST10 (n = 10, 6.0%), ST131 and ST167 (n = 9, 5.4%). Among the faecal carriers, only one patient suffered infection, which was resulted by a ST38 strain. In conclusion, in Beijing Tongren hospital, the prevalence of ESBL-producing E. coli was not high. The risk factors for ESBL carriage were hospitalization and usage of antibiotics, glucocorticoids and immunosuppressive. ST38, ST10, ST131 and ST167 were the prominent genotypes, but almost 50.0% ST were dispersedly distributed.

Concepts: Bacteria, Hospital, Antibiotic resistance, Escherichia coli, Enterobacteriaceae, Escherichia, Proteobacteria, Beta-lactamase

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The stomach bacterium Helicobacter pylori is one of the most prevalent human pathogens. It has dispersed globally with its human host, resulting in a distinct phylogeographic pattern that can be used to reconstruct both recent and ancient human migrations. The extant European population of H. pylori is known to be a hybrid between Asian and African bacteria, but there exist different hypotheses about when and where the hybridization took place, reflecting the complex demographic history of Europeans. Here, we present a 5300-year-old H. pylori genome from a European Copper Age glacier mummy. The “Iceman” H. pylori is a nearly pure representative of the bacterial population of Asian origin that existed in Europe before hybridization, suggesting that the African population arrived in Europe within the past few thousand years.

Concepts: Bacteria, Africa, Pathogen, Stomach, Europe, Helicobacter pylori, Proteobacteria, Helicobacter

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For 2013-2014, we prospectively identified US adults with flank pain, temperature >38.0°C, and a diagnosis of acute pyelonephritis, confirmed by culture. Cultures from 453 (86.9%) of 521 patients grew Escherichia coli. Among E. coli isolates from 272 patients with uncomplicated pyelonephritis and 181 with complicated pyelonephritis, prevalence of fluoroquinolone resistance across study sites was 6.3% (range by site 0.0%-23.1%) and 19.9% (0.0%-50.0%), respectively; prevalence of extended-spectrum β-lactamase (ESBL) production was 2.6% (0.0%-8.3%) and 12.2% (0.0%-17.2%), respectively. Ten (34.5%) of 29 patients with ESBL infection reported no exposure to antimicrobial drugs, healthcare, or travel. Of the 29 patients with ESBL infection and 53 with fluoroquinolone-resistant infection, 22 (75.9%) and 24 (45.3%), respectively, were initially treated with in vitro inactive antimicrobial drugs. Prevalence of fluoroquinolone resistance exceeds treatment guideline thresholds for alternative antimicrobial drug strategies, and community-acquired ESBL-producing E. coli infection has emerged in some US communities.

Concepts: Urinary tract infection, Antibiotic resistance, Escherichia coli, Enterobacteriaceae, Escherichia, Proteobacteria, Beta-lactamase, Pyelonephritis

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The volumetric heating values of today’s biofuels are too low to power energy-intensive aircraft, rockets, and missiles. Recently, pinene dimers were shown to have a volumetric heating value similar to that of the tactical fuel JP-10. To provide a sustainable source of pinene, we engineered Escherichia coli for pinene production. We combinatorially expressed three pinene synthases (PS) and three geranyl diphosphate synthases (GPPS), with the best combination achieving ∼28 mg/L of pinene. We speculated that pinene toxicity was limiting production; however, toxicity should not be limiting at current titers. Because GPPS is inhibited by geranyl diphosphate (GPP) and to increase flux through the pathway, we combinatorially constructed GPPS-PS protein fusions. The Abies grandis GPPS-PS fusion produced 32 mg/L of pinene, a 6-fold improvement over the highest titer previously reported in engineered E. coli. Finally, we investigated the pinene isomer ratio of our pinene-producing microbe and discovered that the isomer profile is determined not only by the identity of the PS used but also by the identity of the GPPS with which the PS is paired. We demonstrated that the GPP concentration available to PS for cyclization alters the pinene isomer ratio.

Concepts: Protein, Bacteria, Antibiotic resistance, Escherichia coli, Biotechnology, Enterobacteriaceae, Escherichia, Proteobacteria