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Itaru Suzuki, Takehiko Shimizu, Hidenobu Senpuku
Actinomyces oris expresses type 1 and 2 fimbriae on the cell surface. Type 2 fimbriae mediate co-aggregation and biofilm formation and are composed of the shaft fimbrillin FimA and the tip fimbrillin FimB. Short-chain fatty acids (SCFAs) are metabolic products of oral bacteria, but the effects of exogenous SCFAs on FimA-dependent biofilm formation are poorly understood. We performed two types of biofilm formation assays using A. oris MG1 or MG1.Δ fimA to observe the effects of SCFAs on FimA-dependent biofilm formation in 96-well and six-well microtiter plates and a flow cell system...
November 13, 2018: Microorganisms
Sarah De Backer, Julia Sabirova, Ines De Pauw, Henri De Greve, Jean-Pierre Hernalsteens, Herman Goossens, Surbhi Malhotra-Kumar
In methicillin-sensitive Staphylococcus aureus (MSSA), the tricarboxylic acid (TCA) cycle is known to negatively regulate production of the major biofilm-matrix exopolysaccharide, PIA/PNAG. However, methicillin-resistant S. aureus (MRSA) produce a primarily proteinaceous biofilm matrix, and contribution of the TCA-cycle therein remains unclear. Utilizing USA300-JE2 Tn-mutants (NARSA) in genes encoding TCA- and urea cycle enzymes for transduction into a prolific biofilm-forming USA300 strain (UAS391-Erys ), we studied the contribution of the TCA- and urea cycle and of proteins, eDNA and PIA/PNAG, to the matrix...
October 29, 2018: Microorganisms
Mariano Larzábal, Wanderson Marques Da Silva, Nahuel A Riviere, Ángel A Cataldi
Enterohemorrhagic Escherichia coli (EHEC) and enteropathogenic Escherichia coli (EPEC) are attaching and effacing (A/E) pathogens, which translocate effector proteins to intestinal enterocytes through a type III secretion system (T3SS). T3SS and most of its effector proteins are encoded in a pathogenicity island called LEE. Recently, new effectors have been located outside the LEE. This study aimed to characterize EspY3, a novel non-LEE encoded T3SS effector of EHEC. EspY3 shares homology with SopD and PipB2 effector proteins of Salmonella's T3SS-1 and T3SS-2, respectively...
October 27, 2018: Microorganisms
Flavia Sacerdoti, María Luján Scalise, Juliana Burdet, María Marta Amaral, Ana María Franchi, Cristina Ibarra
Gastrointestinal infection with Shiga toxin-producing Escherichia coli (STEC) causes diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS), characterized by hemolytic anemia, thrombocytopenia and acute renal failure. The main virulence factor of STEC is Shiga toxin (Stx), which is responsible for HUS development. STEC can produce Stx type 1 and/or 2 (Stx1, Stx2) and their variants, Stx2 being more frequently associated with severe cases of HUS. This pathology occurs in 5⁻15% of cases with STEC infection when Stx gain access to the bloodstream and causes damage in the target organs such as the kidney and brain...
October 23, 2018: Microorganisms
Hiroyuki Hori, Takuya Kawamura, Takako Awai, Anna Ochi, Ryota Yamagami, Chie Tomikawa, Akira Hirata
To date, numerous modified nucleosides in tRNA as well as tRNA modification enzymes have been identified not only in thermophiles but also in mesophiles. Because most modified nucleosides in tRNA from thermophiles are common to those in tRNA from mesophiles, they are considered to work essentially in steps of protein synthesis at high temperatures. At high temperatures, the structure of unmodified tRNA will be disrupted. Therefore, thermophiles must possess strategies to stabilize tRNA structures. To this end, several thermophile-specific modified nucleosides in tRNA have been identified...
October 20, 2018: Microorganisms
Juan Miguel Gonzalez
Developments in protein expression, analysis and computational capabilities are decisively contributing to a better understanding of the structure of proteins and their relationship to function. Proteins are known to be adapted to the growth rate of microorganisms and some microorganisms (named (hyper)thermophiles) thrive optimally at high temperatures, even above 100 °C. Nevertheless, some biomolecules show great instability at high temperatures and some of them are universal and required substrates and cofactors in multiple enzymatic reactions for all (both mesophiles and thermophiles) living cells...
October 20, 2018: Microorganisms
María-Efigenia Álvarez-Cao, Roberto González, María A Pernas, María Luisa Rúa
Thermophilic proteins have evolved different strategies to maintain structure and function at high temperatures; they have large, hydrophobic cores, and feature increased electrostatic interactions, with disulfide bonds, salt-bridging, and surface charges. Oligomerization is also recognized as a mechanism for protein stabilization to confer a thermophilic adaptation. Mesophilic proteins are less thermostable than their thermophilic homologs, but oligomerization plays an important role in biological processes on a wide variety of mesophilic enzymes, including thermostabilization...
October 19, 2018: Microorganisms
Mark E M Obrenovich
'Leaky gut' syndrome, long-associated with celiac disease, has attracted much attention in recent years and for decades, was widely known in complementary/alternative medicine circles. It is often described as an increase in the permeability of the intestinal mucosa, which could allow bacteria, toxic digestive metabolites, bacterial toxins, and small molecules to 'leak' into the bloodstream. Nervous system involvement with celiac disease is know to occur even at subclinical levels. Gluten and gluten sensitivity are considered to trigger this syndrome in individuals genetically predisposed to celiac disease...
October 18, 2018: Microorganisms
Marcos Heredero, Sandra Garrigues, Mónica Gandía, Jose F Marcos, Paloma Manzanares
Antimicrobial peptides (AMPs) have been proposed as candidates to develop new antimicrobial compounds for medicine, agriculture, and food preservation. PAF26 is a synthetic antifungal hexapeptide obtained from combinatorial approaches with potent fungicidal activity against filamentous fungi. Other interesting AMPs are the antifungal proteins (AFPs) of fungal origin, which are basic cysteine-rich and small proteins that can be biotechnologically produced in high amounts. A promising AFP is the AfpB identified in the phytopathogen Penicillium digitatum ...
October 15, 2018: Microorganisms
Luka Šafarič, Sepehr Shakeri Yekta, Tong Liu, Bo H Svensson, Anna Schnürer, David Bastviken, Annika Björn
Knowledge of microbial community dynamics in relation to process perturbations is fundamental to understand and deal with the instability of anaerobic digestion (AD) processes. This study aims to investigate the microbial community structure and function of a thermophilic AD process, fed with a chemically defined substrate, and its association with process performance stability. Next generation amplicon sequencing of 16S ribosomal RNA (rRNA) genes revealed that variations in relative abundances of the predominant bacterial species, Defluviitoga tunisiensis and Anaerobaculum hydrogeniformans, were not linked to the process performance stability, while dynamics of bacterial genera of low abundance, Coprothermobacter and Defluviitoga (other than D...
October 11, 2018: Microorganisms
Toktam Taghavi, Chyer Kim, Alireza Rahemi
Small fruits are a multi-billion dollar industry in the US, and are economically important in many other countries. However, they are perishable and susceptible to physiological disorders and biological damage. Food safety and fruit quality are the major concerns of the food chain from farm to consumer, especially with increasing regulations in recent years. At present, the industry depends on pesticides and fungicides to control food spoilage organisms. However, due to consumer concerns and increasing demand for safer produce, efforts are being made to identify eco-friendly compounds that can extend the shelf life of small fruits...
October 5, 2018: Microorganisms
Susanne Günther, Daniela Becker, Thomas Hübschmann, Susann Reinert, Sabine Kleinsteuber, Susann Müller, Christian Wilhelm
Generating chemical energy carriers and bulk chemicals from solar energy by microbial metabolic capacities is a promising technology. In this long-term study of over 500 days, methane was produced by a microbial community that was fed by the mono-substrate glycolate, which was derived from engineered algae. The microbial community structure was measured on the single cell level using flow cytometry. Abiotic and operational reactor parameters were analyzed in parallel. The R-based tool flowCyBar facilitated visualization of community dynamics and indicated sub-communities involved in glycolate fermentation and methanogenesis...
October 4, 2018: Microorganisms
Abimbola Allison, Shahid Chowdhury, Aliyar Fouladkhah
As many as 99% of illnesses caused by Listeria monocytogenes are foodborne in nature, leading to 94% hospitalizations, and are responsible for the collective annual deaths of 266 American adults. The current study is a summary of microbiological hurdle validation studies to investigate synergism of mild heat (up to 55 °C) and elevated hydrostatic pressure (up to 380 MPa) for decontamination of Listeria monocytogenes and natural background microflora in raw milk and phosphate-buffered saline. At 380 MPa, for treatments of 0 to 12 min, d -values of 3...
October 3, 2018: Microorganisms
Yuri Yamamoto, Yumiko Nakanishi, Shinnosuke Murakami, Wanping Aw, Tomoya Tsukimi, Ryoko Nozu, Masami Ueno, Kyoji Hioki, Kenji Nakahigashi, Akiyoshi Hirayama, Masahiro Sugimoto, Tomoyoshi Soga, Mamoru Ito, Masaru Tomita, Shinji Fukuda
Commensal microbiota colonize the surface of our bodies. The inside of the gastrointestinal tract is one such surface that provides a habitat for them. The gastrointestinal tract is a long organ system comprising of various parts, and each part possesses various functions. It has been reported that the composition of intestinal luminal metabolites between the small and large intestine are different; however, comprehensive metabolomic and commensal microbiota profiles specific to each part of the gastrointestinal lumen remain obscure...
September 29, 2018: Microorganisms
Alfredo G Torres, Maria M Amaral, Leticia Bentancor, Lucia Galli, Jorge Goldstein, Alejandra Krüger, Maricarmen Rojas-Lopez
Pathogenic Escherichia coli are known to be a common cause of diarrheal disease and a frequently occurring bacterial infection in children and adults in Latin America. Despite the effort to combat diarrheal infections, the south of the American continent remains a hot spot for infections and sequelae associated with the acquisition of one category of pathogenic E. coli , the Shiga toxin-producing E. coli (STEC). This review will focus on an overview of the prevalence of different STEC serotypes in human, animals and food products, focusing on recent reports from Latin America outlining the recent research progress achieved in this region to combat disease and endemicity in affected countries and to improve understanding on emerging serotypes and their virulence factors...
September 28, 2018: Microorganisms
Rocío Colello, Alejandra Krüger, José Di Conza, John W A Rossen, Alexander W Friedrich, Gabriel Gutkind, Analía I Etcheverría, Nora L Padola
The aim of this study was to investigate the presence of class 1 integrons in a collection of Shiga toxin-producing Escherichia coli (STEC) from different origins and to characterize pheno- and genotypically the antimicrobial resistance associated to them. A collection of 649 isolates were screened for the class 1 integrase gene ( intI1 ) by Polymerase chain reaction The variable region of class 1 integrons was amplified and sequenced. Positive strains were evaluated for the presence of antimicrobial resistance genes with microarray and for antimicrobial susceptibility by the disk diffusion method...
September 28, 2018: Microorganisms
Daria A Kashtanova, Olga N Tkacheva, Ekaterina N Doudinskaya, Irina D Strazhesko, Yulia V Kotovskaya, Anna S Popenko, Alexander V Tyakht, Dmitry G Alexeev
The aim of this paper was to study gut microbiota composition in patients with different metabolic statuses. METHODS: 92 participants aged 25⁻76 years (26 of whom were men), with confirmed absence of cardiovascular and other chronic diseases (but with the possible presence of cardiovascular risk factors) were included. Carotid ultrasound examinations, 16 S rRNA sequencing of stool samples and diet assessments were performed. Statistical analysis was performed using R programming language, 3...
September 25, 2018: Microorganisms
Anthony J Finch, Jin Ryoun Kim
Literature from the past two decades has outlined the existence of a trade-off between protein stability and function. This trade-off creates a unique challenge for protein engineers who seek to introduce new functionality to proteins. These engineers must carefully balance the mutation-mediated creation and/or optimization of function with the destabilizing effect of those mutations. Subsequent research has shown that protein stability is positively correlated with "evolvability" or the ability to support mutations which bestow new functionality on the protein...
September 25, 2018: Microorganisms
Prashant Singh, Sylvain Santoni, Patrice This, Jean-Pierre Péros
Plant surface or phyllosphere is the habitat of hyperdiverse microbial communities and it is always exposed to the fluctuating environmental factors, which is thought to be one of the potential drivers of microbial community structuring. Impact of grapevine genotypes in variable environmental factors (i.e., at different geographic locations) on the phyllosphere has never been studied and is the main objective of this report. Using high throughput short amplicon sequencing of 16S rRNA genes and internal transcribed spacer (ITS), we analyzed the impacts of genotypes of Vitis Vinifera (coming from three genetic pool), on the microbial (bacterial and fungal) assemblage in the phyllosphere...
September 21, 2018: Microorganisms
James F White, Kathryn L Kingsley, Satish K Verma, Kurt P Kowalski
In this paper, we describe a mechanism for the transfer of nutrients from symbiotic microbes (bacteria and fungi) to host plant roots that we term the 'rhizophagy cycle.' In the rhizophagy cycle, microbes alternate between a root intracellular endophytic phase and a free-living soil phase. Microbes acquire soil nutrients in the free-living soil phase; nutrients are extracted through exposure to host-produced reactive oxygen in the intracellular endophytic phase. We conducted experiments on several seed-vectored microbes in several host species...
September 17, 2018: Microorganisms
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