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Sanjida Halim Topa, Sujatha Subramoni, Enzo A Palombo, Peter Kingshott, Scott A Rice, Linda L Blackall
Bacterial biofilms can cause serious health care complications associated with increased morbidity and mortality. There is an urge to discover and develop new biofilm inhibitors from natural products or by modifying natural compounds or understanding the modes of action of existing compounds. Cinnamaldehyde (CAD), one of the major components of cinnamon oil, has been demonstrated to act as an antimicrobial agent against a number of Gram-negative and Gram-positive pathogens, including Pseudomonas aeruginosa, Helicobacter pylori and Listeria monocytogenes...
July 12, 2018: Microbiology
Suhail Yousuf, Rajendra Kumar Angara, Ajit Roy, Shailesh Kumar Gupta, Rohan Misra, Akash Ranjan
Lipid metabolism is critical to Mycobacterium tuberculosis survival and infection. Unlike Escherichia coli, which has a single FadR, the M. tuberculosis genome encodes five proteins of the FadR sub-family. While the role of E. coli FadR as a regulator of fatty acid metabolism is well known, the definitive functions of M. tuberculosis FadR proteins are still under investigation. An interesting question about the M. tuberculosis FadRs remains open: which one of these proteins is the functional homologue of E...
July 11, 2018: Microbiology
Grith Miriam Maigaard Hermansen, Morten Lindqvist Hansen, Seyed Mohammad Hossein Khademi, Lars Jelsbak
Regulating intracellular levels of biological metal ions is essential for all bacterial species, as they are needed for virulence and a range of metabolic processes. Zinc is the second most abundant metal ion in Pseudomonas aeruginosa, but little is known about its regulation. Recent studies have identified a novel operon, zrmABCD (also called cntOLMI), encoding a metallophore system (pseudopaline) involved in zinc acquisition. Expression of this operon has been implicated in human infections and is regulated by the transcriptional regulator Zur (Zn2+ uptake regulator)...
July 3, 2018: Microbiology
Karukriti Kaushik Ghosh, Aman Prakash, Prateek Shrivastav, Vinayagamurthy Balamurugan, Manish Kumar
The outer membrane proteins of the pathogen are targeted to understand host-pathogen interactions and are central to the development of diagnostics. We report that Leptospira interrogans serovar Copenhageni strain Fiocruz L1-130 contains a gene LIC13341 that encodes a conserved outer membrane/periplasmic lipoprotein. The gene LIC13341 was cloned into expression vector pET28a and the recombinant LIC13341 (r-LIC13341) protein was purified from Escherichia coli BL21 (DE3) using affinity chromatography. The secondary structure of the purified r-LIC13341 protein featured a typical β-strand when observed by circular dichroism spectroscopy...
July 3, 2018: Microbiology
Amy Switzer, Dimitrios Evangelopoulos, Rita Figueira, Luiz Pedro S de Carvalho, Daniel R Brown, Sivaramesh Wigneshweraraj
The initial adaptive transcriptional response to nitrogen (N) starvation in Escherichia coli involves large-scale alterations to the transcriptome mediated by the transcriptional activator, NtrC. One of these NtrC-activated genes is yeaG, which encodes a conserved bacterial kinase. Although it is known that YeaG is required for optimal survival under sustained N starvation, the molecular basis by which YeaG benefits N starved E. coli remains elusive. By combining transcriptomics with targeted metabolomics analyses, we demonstrate that the methionine biosynthesis pathway becomes transcriptionally dysregulated in ΔyeaG bacteria experiencing sustained N starvation...
June 29, 2018: Microbiology
Kazuyuki Tanno, Kensaku Maejima, Akio Miyazaki, Hiroaki Koinuma, Nozomu Iwabuchi, Yugo Kitazawa, Takamichi Nijo, Masayoshi Hashimoto, Yasuyuki Yamaji, Shigetou Namba
Phytoplasmas are plant-pathogenic bacteria that infect many important crops and cause serious economic losses worldwide. However, owing to an inability to culture phytoplasmas, screening of antimicrobials on media is difficult. The only antimicrobials being used to control phytoplasmas are tetracycline-class antibiotics. In this study, we developed an accurate and efficient screening method to evaluate the effects of antimicrobials using an in vitro plant-phytoplasma co-culture system. We tested 40 antimicrobials, in addition to tetracycline, and four of these (doxycycline, chloramphenicol, thiamphenicol and rifampicin) decreased the accumulation of 'Candidatus (Ca...
June 28, 2018: Microbiology
Julian R Marchesi
No abstract text is available yet for this article.
June 26, 2018: Microbiology
Ricardo Perez-Dulzaides, Emma Camacho, Radames J B Cordero, Arturo Casadevall
Melanization is an intrinsic characteristic of many fungal species, but details of this process are poorly understood because melanins are notoriously difficult pigments to study. While studying the binding of cell-wall dyes, Eosin Y or Uvitex, to melanized and non-melanized Cryptococcus neoformans cells we noted that melanization leads to reduced fluorescence intensity, suggesting that melanin interfered with dye binding to the cell wall. The growth of C. neoformans in melanizing conditions with either of the cell-wall dyes resulted in an increase in supernatant-associated melanin, consistent with blockage of melanin attachment to the cell wall...
June 25, 2018: Microbiology
Gwen Knight, Helen Lambert, Edward Feil, Mark Holmes, Jodi Lindsay
No abstract text is available yet for this article.
June 20, 2018: Microbiology
Kazuki Nosho, Koji Yasuhara, Yuto Ikehata, Tomohiro Mii, Taichiro Ishige, Shunsuke Yajima, Makoto Hidaka, Tetsuhiro Ogawa, Haruhiko Masaki
Most bacterial cells in nature exhibit extremely low colony-forming activity, despite showing various signs of viability, impeding the isolation and utilization of many bacterial resources. However, the general causes responsible for this state of low colony formation are largely unknown. Because liquid cultivation typically yields more bacterial cell cultures than traditional solid cultivation, we hypothesized that colony formation requires one or more specific gene functions that are dispensable or less important for growth in liquid media...
June 15, 2018: Microbiology
Zachary Saylor, Robert Maier
Nickel metabolism and trafficking in Helicobacter pylori is complex, perhaps more so than in any other pathogen. Along with nickel enzymes and their associated nickel-binding maturation machinery, H. pylori contains nickel storage proteins, Hpn and Hpnl. Through a combined crosslinking and enrichment approach, we show that Hpn/Hpnl interact with a wide array of partners; over 100 proteins were captured, including known nickel-enzyme maturation proteins, and other proteins outside known H. pylori nickel-associated proteins...
June 15, 2018: Microbiology
Fernando Uriel Rojas-Rojas, Anuar Salazar-Gómez, María Elena Vargas-Díaz, María Soledad Vásquez-Murrieta, Ann M Hirsch, René De Mot, Maarten G K Ghequire, J Antonio Ibarra, Paulina Estrada-de Los Santos
The Burkholderia cepacia complex (Bcc) comprises a group of 24 species, many of which are opportunistic pathogens of immunocompromised patients and also are widely distributed in agricultural soils. Several Bcc strains synthesize strain-specific antagonistic compounds. In this study, the broad killing activity of B. cenocepacia TAtl-371, a Bcc strain isolated from the tomato rhizosphere, was characterized. This strain exhibits a remarkable antagonism against bacteria, yeast and fungi including other Bcc strains, multidrug-resistant human pathogens and plant pathogens...
June 15, 2018: Microbiology
Shivjee Sah, Riyaz Ahmad Shah, Ashwin Govindan, Rajagopal Varada, Kervin Rex, Umesh Varshney
Dihydrofolate reductase (DHFR) and 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) transformylase/IMP cyclohydrolase (PurH) play key roles in maintaining folate pools in cells, and are targets of antimicrobial and anticancer drugs. While the activities of bacterial DHFR and PurH on their classical substrates (DHF and 10-CHO-THF, respectively) are known, their activities and kinetic properties of utilisation of 10-CHO-DHF are unknown. We have determined the kinetic properties (kcat/Km) of conversion of 10-CHO-DHF to 10-CHO-THF by DHFR, and to DHF by PurH...
May 25, 2018: Microbiology
Takeshi Yamada, Mari Miyashita, Jun Kasahara, Tatsuhito Tanaka, Masayuki Hashimoto, Hiroki Yamamoto
Wall teichoic acids (WTAs) are anionic polymers that are covalently linked to peptidoglycan and play important roles in cell shape determination, cell division, autolysis, pathogenesis and antibiotic resistance in Gram-positive bacteria. In Bacillus subtilis, WTA is synthesized in the cytoplasm and translocated by an ABC transporter, TagGH. In this study, we found that the transmembrane segment of TagH is required for WTA transport under high temperatures. Cells expressing TagH302-FL (a construct fused to the 6×FLAG tag after the transmembrane segment, which lacks the C-terminal extracellular domain) grew normally at high temperatures, similar to those expressing the full-length TagH-FL fusion...
July 2018: Microbiology
Danielle V Miller, Benjamin J Rauch, Kim Harich, Huimin Xu, John J Perona, Robert H White
The methionine salvage pathway (MSP) is critical for regeneration of S-adenosyl-l-methionine (SAM), a widely used cofactor involved in many essential metabolic reactions. The MSP has been completely elucidated in aerobic organisms, and found to rely on molecular oxygen. Since anaerobic organisms do not use O2, an alternative pathway(s) must be operating. We sought to evaluate whether the functions of two annotated MSP enzymes from Methanocaldococcus jannaschii, a methylthioinosine phosphorylase (MTIP) and a methylthioribose 1-phosphate isomerase (MTRI), are consistent with functioning in a modified anaerobic MSP (AnMSP)...
July 2018: Microbiology
Nastassia V Patin, Dimitrios J Floros, Chambers C Hughes, Pieter C Dorrestein, Paul R Jensen
Bacterial genome sequences consistently contain many more biosynthetic gene clusters encoding specialized metabolites than predicted by the compounds discovered from the respective strains. One hypothesis invoked to explain the cryptic nature of these gene clusters is that standard laboratory conditions do not provide the environmental cues needed to trigger gene expression. A potential source of such cues is other members of the bacterial community, which are logical targets for competitive interactions. In this study, we examined the effects of such interactions on specialized metabolism in the marine actinomycete Salinispora tropica...
July 2018: Microbiology
Changhan Lee, Hyunhee Kim, James C A Bardwell
It has long been thought that chaperones are primarily attracted to their clients through the hydrophobic effect. However, in in vitro studies on the interaction between the chaperone Spy and its substrate Im7, we recently showed that long-range electrostatic interactions also play a key role. Spy functions in the periplasm of Gram-negative bacteria, which is surrounded by a permeable outer membrane. The ionic conditions in the periplasm therefore closely mimic those in the media, which allowed us to vary the ionic strength of the in vivo folding environment...
July 2018: Microbiology
Erianna M Basgall, Samantha C Goetting, Megan E Goeckel, Rachael M Giersch, Emily Roggenkamp, Madison N Schrock, Megan Halloran, Gregory C Finnigan
No abstract text is available yet for this article.
July 2018: Microbiology
Raedeen Russell, Hongxia Wang, Jorge A Benitez, Anisia J Silva
Hypervirulent atypical El Tor biotype Vibrio cholerae O1 isolates harbour mutations in the DNA-binding domain of the nucleoid-associated protein H-NS and the receiver domain of the response regulator VieA. Here, we provide two examples in which inactivation of H-NS in El Tor biotype vibrios unmasks hidden regulatory connections. First, deletion of the helix-turn-helix domain of VieA in an hns mutant background diminished biofilm formation and exopolysaccharide gene expression, a function that phenotypically opposes its phosphodiesterase activity...
July 2018: Microbiology
Lauren B Jones, Pallab Ghosh, Jung-Hyun Lee, Chia-Ni Chou, Daniel A Kunz
A genetic linkage between a conserved gene cluster (Nit1C) and the ability of bacteria to utilize cyanide as the sole nitrogen source was demonstrated for nine different bacterial species. These included three strains whose cyanide nutritional ability has formerly been documented (Pseudomonas fluorescens Pf11764, Pseudomonas putida BCN3 and Klebsiella pneumoniae BCN33), and six not previously known to have this ability [Burkholderia (Paraburkholderia) xenovorans LB400, Paraburkholderia phymatum STM815, Paraburkholderia phytofirmans PsJN, Cupriavidus (Ralstonia) eutropha H16, Gluconoacetobacter diazotrophicus PA1 5 and Methylobacterium extorquens AM1]...
July 2018: Microbiology
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