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Kléber de Sousa Oliveira, Paulo Roberto Martins Queiroz, Isabel Cristina Marques Fensterseifer, Ludovico Migliolo, Aline Lima Oliveira, Octávio Luiz Franco
Gram-positive pathogens such as methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant Enterococcus faecium (VRE) have been frequently associated with bacterial resistance mechanisms. These mechanisms, in turn, restrict a range of therapeutic opportunities for the treatment of infections caused by these micro-organisms. Faced with this problem, the present study aims to isolate and characterize molecules with antimicrobial activity derived from the fungus Penicillium citrinum isolated from Cerrado soil...
October 18, 2017: Microbiology
Kumari Sweta, Preeti Dabas, Kamal Jain, Nimisha Sharma
Transcriptional elongation is a critical step for regulating expression of protein-coding genes. Multiple transcription elongation factors have been identified in vitro, but the physiological roles of many of them are still not clearly understood. The ELL (Eleven nineteen Lysine rich Leukemia) family of transcription elongation factors are conserved from fission yeast to humans. Schizosaccharomyces pombe contains a single ELL homolog (SpELL) that is not essential for its survival. Therefore to gain insights into the in vivo cellular functions of SpELL, we identified phenotypes associated with deletion of ell1 in S...
October 18, 2017: Microbiology
Emma Camacho, Christine Chrissian, Radames J B Cordero, Livia Liporagi-Lopes, Ruth E Stark, Arturo Casadevall
Cryptococcus neoformans is an environmental fungus that belongs to the phylum Basidiomycetes and is a major pathogen in immunocompromised patients. The ability of C. neoformans to produce melanin pigments represents its second most important virulence factor, after the presence of a polysaccharide capsule. Both the capsule and melanin are closely associated with the fungal cell wall, a complex structure that is essential for maintaining cell morphology and viability under conditions of stress. The amino sugar N-acetylglucosamine (GlcNAc) is a key constituent of the cell-wall chitin and is used for both N-linked glycosylation and GPI anchor synthesis...
October 18, 2017: Microbiology
Xiqian Wang, Anna N Kondakova, Yutong Zhu, Yuriy A Knirel, Aidong Han
Genus Comamonas is a group of bacteria that are able to degrade a variety of environmental waste. Comamonas aquatica CJG (C. aquatica) in this genus is able to absorb low-density lipoprotein but not high-density lipoprotein of human serum. Using (1)H and (13)C NMR spectroscopy, we found that the O-polysaccharide (O-antigen) of this bacterium is comprised of a disaccharide repeat (O-unit) of d-glucose and 2-O-acetyl-l-rhamnose, which is shared by Serratia marcescens O6. The O-antigen gene cluster of C. aquatica, which is located between coaX and tnp4 genes, contains rhamnose synthesis genes, glycosyl and acetyl transferase genes, and ATP-binding cassette transporter genes, and therefore is consistent with the O-antigen structure determined here...
October 16, 2017: Microbiology
Rolando Daniel Moreira-Soto, Ethel Sanchez, Cameron R Currie, Adrian A Pinto-Tomás
Leaf-cutter ants (Atta and Acromyrmex) use fresh leaves to cultivate a mutualistic fungus (Leucoagaricus gongylophorus) for food in underground gardens. A new ant queen propagates the cultivar by taking a small fragment of fungus from her parent colony on her nuptial flight and uses it to begin her own colony. Recent research has shown that the ants' fungus gardens are colonized by symbiotic bacteria that perform important functions related to nitrogen fixation and have been implicated in contributing to plant biomass degradation...
October 16, 2017: Microbiology
Amber L Murch, Paul J Skipp, Peter L Roach, Petra C F Oyston
During conditions of nutrient limitation bacteria undergo a series of global gene expression changes to survive conditions of amino acid and fatty acid starvation. Rapid reallocation of cellular resources is brought about by gene expression changes coordinated by the signalling nucleotides' guanosine tetraphosphate or pentaphosphate, collectively termed (p)ppGpp and is known as the stringent response. The stringent response has been implicated in bacterial virulence, with elevated (p)ppGpp levels being associated with increased virulence gene expression...
October 16, 2017: Microbiology
Maria T Brock, Galya C Fedderly, Grace I Borlee, Michael M Russell, Liliana K Filipowska, Doreene R Hyatt, Ryan A Ferris, Bradley R Borlee
Overuse of antibiotics is contributing to an emerging antimicrobial resistance crisis. To better understand how bacteria adapt tolerance and resist antibiotic treatment, Pseudomonas aeruginosa isolates obtained from infection sites sampled from companion animals were collected and evaluated for phenotypic differences. Selected pairs of clonal isolates were obtained from individual infection samples and were assessed for antibiotic susceptibility, cyclic di-GMP levels, biofilm production, motility and genetic-relatedness...
October 16, 2017: Microbiology
Shigeki Ehira, Yuka Shimmori, Satoru Watanabe, Hiroaki Kato, Hirofumi Yoshikawa, Masayuki Ohmori
Cyanobacteria acclimatize to nitrogen deprivation by changing cellular metabolism. The nitrogen-regulated response regulator A (NrrA) is involved in regulation of carbon metabolism in response to nitrogen deprivation. However, it has not been elucidated whether these regulatory functions of NrrA are particular to a few model strains or are general among diverse cyanobacteria. In this study, we showed that regulation and functions of NrrA were highly conserved among β-cyanobacteria, which included physiologically and ecologically diverse strains...
October 12, 2017: Microbiology
Viviana Teresa Orlandi, Fabrizio Bolognese, Eleonora Martegani, Vincenzo Cantaluppi, Claudio Medana, Paola Barbieri
Clinicians often have to deal with infections that are difficult to control because they are caused by superbugs resistant to many antibiotics. Alternatives to antibiotic treatment include antimicrobial photodynamic therapy (aPDT). The photodynamic process causes bacterial death, inducing oxidative stress through the photoactivation of photosensitizer molecules in the presence of oxygen. No PDT-resistant bacteria have been selected to date, thus the response to photo-oxidative stress in non-phototrophic bacteria needs further investigation...
October 12, 2017: Microbiology
Megan Y Nas, Nicholas P Cianciotto
Stenotrophomonas maltophilia, a Gram-negative, multi-drug-resistant bacterium, is increasingly recognized as a key opportunistic pathogen. Thus, we embarked upon an investigation of S. maltophilia iron acquisition. To begin, we determined that the genome of strain K279a is predicted to encode a complete siderophore system, including a biosynthesis pathway, an outer-membrane receptor for ferrisiderophore, and other import and export machinery. Compatible with these data, K279a and other clinical isolates of S...
October 6, 2017: Microbiology
David Kostner, Michael Rachinger, Wolfgang Liebl, Armin Ehrenreich
Bacillus licheniformis strains are used for the large-scale production of industrial exoenzymes from proteinaceous substrates, but details of the amino acid metabolism involved are largely unknown. In this study, two chromosomal genes putatively involved in amino acid metabolism of B. licheniformis were deleted to clarify their role. For this, a convenient counterselection system for markerless in-frame deletions was developed for B. licheniformis. A deletion plasmid containing up- and downstream DNA segments of the chromosomal deletion target was conjugated to B...
October 6, 2017: Microbiology
Theresa Kouril, Johann J Eicher, Bettina Siebers, Jacky L Snoep
In (hyper)thermophilic organisms metabolic processes have to be adapted to function optimally at high temperature. We compared the gluconeogenic conversion of 3-phosphoglycerate via 1,3-bisphosphoglycerate to glyceraldehyde-3-phosphate at 30 °C and at 70 °C. At 30 °C it was possible to produce 1,3-bisphosphoglycerate from 3-phosphoglycerate with phosphoglycerate kinase, but at 70 °C, 1,3-bisphosphoglycerate was dephosphorylated rapidly to 3-phosphoglycerate, effectively turning the phosphoglycerate kinase into a futile cycle...
October 6, 2017: Microbiology
Hasan Nazik, Lydia-Marie Joubert, Patrick R Secor, Johanna M Sweere, Paul L Bollyky, Gabriele Sass, Lynette Cegelski, David A Stevens
Pseudomonas aeruginosa (Pa) and Candida albicans (Ca) are major bacterial and fungal pathogens in immunocompromised hosts, and notably in the airways of cystic fibrosis patients. The bacteriophages of Pa physically alter biofilms, and were recently shown to inhibit the biofilms of Aspergillus fumigatus. To understand the range of this viral-fungal interaction, we studied Pa phages Pf4 and Pf1, and their interactions with Ca biofilm formation and preformed Ca biofilm. Both forms of Ca biofilm development, as well as planktonic Ca growth, were inhibited by either phage...
October 6, 2017: Microbiology
Namrata Rana, Helen E Jesse, Mariana Tinajero-Trejo, Jonathan A Butler, John D Tarlit, Milena L von Und Zur Muhlen, Christoph Nagel, Ulrich Schatzschneider, Robert K Poole
Carbon monoxide-releasing molecules (CORMs) are a promising class of new antimicrobials, with multiple modes of action that are distinct from those of standard antibiotics. The relentless increase in antimicrobial resistance, exacerbated by a lack of new antibiotics, necessitates a better understanding of how such novel agents act and might be used synergistically with established antibiotics. This work aimed to understand the mechanism(s) underlying synergy between a manganese-based photoactivated carbon monoxide-releasing molecule (PhotoCORM), [Mn(CO)3(tpa-κ(3)N)]Br [tpa=tris(2-pyridylmethyl)amine], and various classes of antibiotics in their activities towards Escherichia coli EC958, a multi-drug-resistant uropathogen...
September 28, 2017: Microbiology
Tracy Youngster, Julie A Wushensky, Ludmilla Aristilde
We investigated the co-catabolism of carbohydrate mixtures in Bacillus megaterium QM B1551 using a (13)C-assisted metabolomics profiling approach. Specifically, we monitored the ability of B. megaterium to achieve the simultaneous catabolism of glucose and a common disaccharide - cellobiose, maltose, or sucrose. Growth experiments indicated that each disaccharide alone can serve as a sole carbon source for B. megaterium, in accordance with the genetic analysis of this bacterium, which predicted diverse metabolic capabilities...
September 28, 2017: Microbiology
Charlton Lam, Melissa Jamerson, Guy Cabral, Ana Maris Carlesso, Francine Marciano-Cabral
Naegleria fowleri is a free-living amoeba found in freshwater lakes and ponds and is the causative agent of primary amoebic meningoencephalitis (PAM), a rapidly fatal disease of the central nervous system (CNS). PAM occurs when amoebae attach to the nasal epithelium and invade the CNS, a process that involves binding to, and degradation of, extracellular matrix (ECM) components. This degradation is mediated by matrix metalloproteinases (MMPs), enzymes that have been described in other pathogenic protozoa, and that have been linked to their increased motility and invasive capability...
September 28, 2017: Microbiology
Jonathan G Hughes, Xiangsheng Zhang, Juanito V Parales, Jayna L Ditty, Rebecca E Parales
Soil bacteria such as pseudomonads are widely studied due to their diverse metabolic capabilities, particularly the ability to degrade both naturally occurring and xenobiotic aromatic compounds. Chemotaxis, the directed movement of cells in response to chemical gradients, is common in motile soil bacteria and the wide range of chemicals detected often mirrors the metabolic diversity observed. Pseudomonas putida F1 is a soil isolate capable of chemotaxis toward, and degradation of, numerous aromatic compounds...
September 28, 2017: Microbiology
Emma Peel, Yuanyuan Cheng, Julianne T Djordjevic, Michael Kuhn, Tania Sorrell, Katherine Belov
With the growing demand for new antibiotics to combat increasing multi-drug resistance, a family of antimicrobial peptides known as cathelicidins has emerged as potential candidates. Expansions in cathelicidin-encoding genes in marsupials and monotremes are of specific interest as the peptides they encode have evolved to protect immunologically naive young in the harsh conditions of the pouch and burrow. Our previous work demonstrated that some marsupial and monotreme cathelicidins have broad-spectrum antibacterial activity and kill resistant bacteria, but the activity of many cathelicidins is unknown...
September 27, 2017: Microbiology
Andrea L Herrera, Kuta Suso, Stephanie Allison, Abby Simon, Evelyn Schlenker, Victor C Huber, Michael S Chaussee
The mortality associated with influenza A virus (IAV) is often due to the development of secondary bacterial infections known as superinfections. The group A streptococcus (GAS) is a relatively uncommon cause of IAV superinfections, but the mortality of these infections is high. We used a murine model to determine whether the surface-localized GAS M protein contributes to the outcome of IAV-GAS superinfections. A comparison between wild-type GAS and an M protein mutant strain (emm3) showed that the M3 protein was essential to virulence...
September 25, 2017: Microbiology
Luis Linares-Otoya, Virginia Linares-Otoya, Lizbeth Armas-Mantilla, Cyntia Blanco-Olano, Max Crüsemann, Mayar L Ganoza-Yupanqui, Julio Campos-Florian, Gabriele M König, Till F Schäberle
The antibiotically bioactive thiopeptide compound kocurin was identified in extracts from a newly isolated Kocuria rosea strain. The axenic strain was retrieved from a soil sample of the intertidal area at the Paracas National Park, Peru. The genetic basis of this promising natural product with activity against methicillin-resistant Staphylococcus aureus (MRSA) strains was revealed by comparative genome analysis of this new isolate and other reported thiopeptide producer strains. The functionality of the predicted gene locus was experimentally proven by heterologous expression in Streptomyces coelicolor M1146...
September 25, 2017: Microbiology
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