Search results for "Bacillus Subtilis"

Genetic and Biochemical Analysis of PadR-padC Promoter Interactions during the Phenolic Acid Stress Response in Bacillus subtilis 168

2011

ABSTRACT Bacillus subtilis 168 is resistant to phenolic acids by expression of an inducible enzyme, the phenolic acid decarboxylase (PadC), that decarboxylates these acids into less toxic vinyl derivatives. In the phenolic acid stress response (PASR), the repressor of padC , PadR, is inactivated by these acids. Inactivation of PadR is followed by a strong expression of padC . To elucidate the functional interaction between PadR and the padC promoter, we performed (i) footprinting assays to identify the region protected by PadR, (ii) electrophoretic mobility shift assays (EMSAs) with a modified padC promoter protected region to determine the interacting sequences, and (iii) random mutagenesi…

Gram-positive bacteria on grass pollen exhibit adjuvant activity inducing inflammatory T cell responses.

2011

BACKGROUND: Recently, it has been established that pollen grains contain Th2-enhancing activities besides allergens. OBJECTIVE: The aim of this study was to analyse whether pollen carry additional adjuvant factors like microbes and what immunological effects they may exert. METHODS: Timothy pollen grains were collected and disseminated on agar plates, and the growing microorganisms were cultivated and defined. Furthermore, the immunologic effects of microbial products on DC and T cell responses were analysed. RESULTS: A complex mixture of bacteria and moulds was detected on grass pollen. Besides Gram-negative bacteria that are known to favour Th1-directed immune responses, moulds were ident…

5-Methoxyuridine, a new modified constituent in tRNAs of Bacillaceae.

1976

Temporal patterns in immune responses to a range of microbial insults (Tenebrio molitor).

2008

8 pages; International audience; Much work has elucidated the pathways and mechanisms involved in the production of insect immune effector systems. However, the temporal nature of these responses with respect to different immune insults is less well understood. This study investigated the magnitude and temporal variation in phenoloxidase and antimicrobial activity in the mealworm beetle Tenebrio molitor in response to a number of different synthetic and real immune elicitors. We found that antimicrobial activity in haemolymph increased rapidly during the first 48h after a challenge and was maintained at high levels for at least 14 days. There was no difference in the magnitude of responses …

2019

The Gram-positive soil bacterium Bacillus subtilis relies on the glutamine synthetase and the glutamate synthase for glutamate biosynthesis from ammonium and 2-oxoglutarate. During growth with the carbon source glucose, the LysR-type transcriptional regulator GltC activates the expression of the gltAB glutamate synthase genes. With excess of intracellular glutamate, the gltAB genes are not transcribed because the glutamate-degrading glutamate dehydrogenases (GDHs) inhibit GltC. Previous in vitro studies revealed that 2-oxoglutarate and glutamate stimulate the activator and repressor function, respectively, of GltC. Here, we have isolated GltC variants with enhanced activator or repressor fu…

Understanding the Effects of High Pressure on Bacterial Spores Using Synchrotron Infrared Spectroscopy

2020

International audience; Bacterial spores are extremely resistant life-forms that play an important role in food spoilage and foodborne disease. The return of spores to a vegetative cell state is a three-step process, these being activation, germination, and emergence. High-pressure (HP) processing is known to induce germination in part of the spore population and even to inactivate a high number of Bacillus spores when combined with other mild treatments such as the addition of nisin. The aim of the present work was to investigate the mechanisms involved in the sensitization of spores to nisin following HP treatment at ambient temperature or with moderate heating leading to a heterogeneous …

Activity against Microorganisms Affecting Cellulosic Objects of the Volatile Constituents of Leonotis nepetaefolia from Nicaragua

2014

The chemical composition of the essential oil from aerial parts of L. nepetaefolia (L.) R. Br. collected in Nicaragua was evaluated by GC and GC-MS. The main components were ( Z)-phytol (22.8%), caryophyllene oxide (18.9%) and hexahydrofarnesylacetone (9.0%). The antibacterial activity against several Gram + and Gram - bacteria, including Bacillus cereus and B. subtilis, both infesting historical cellulosic material, was also determined. B. cereus, B. subtilis and Staphylococcus epidermis were the most affected by the action of the oil.

Degradation of vanillic acid and production of guaiacol by microorganisms isolated from cork samples

2003

The presence of guaiacol in cork stoppers is responsible for some cases of cork taint causing unpleasant alterations to wine. We have performed a characterization of the cork-associated microbiota by isolating 55 different microorganisms: eight yeast, 14 filamentous fungi or molds, 13 actinomycetes and 20 non-filamentous bacteria. A screening for degradation of vanillic acid and guaiacol production showed that none of the filamentous fungi could achieve any of these processes. By contrast, five of the eight yeast strains isolated were able to degrade vanillic acid, although it was not converted to guaiacol. Guaiacol production was only detected in four bacterial strains: one isolate of Baci…

Theoretical insights in enzyme catalysis

2004

In this tutorial review we show how the methods and techniques of computational chemistry have been applied to the understanding of the physical basis of the rate enhancement of chemical reactions by enzymes. This is to answer the question: Why is the activation free energy in enzyme catalysed reactions smaller than the activation free energy observed in solution? Two important points of view are presented: Transition State (TS) theories and Michaelis Complex (MC) theories. After reviewing some of the most popular computational methods employed, we analyse two particular enzymatic reactions: the conversion of chorismate to prephenate catalysed by Bacillus subtilis chorismate mutase, and a m…

QM/MM calculations of kinetic isotope effects in the chorismate mutase active site.

2003

Kinetic isotope effects have been computed for the Claisen rearrangement of chorismate to prephenate in aqueous solution and in the active site of chorismate mutase from B. subtilus. These included primary 13C and 18O and secondary 3H effects for substitutions at the bond-making and bond-breaking positions. The initial structures of the putative stationary points on the potential energy surface, required for the calculations of isotope effects using the CAMVIB/CAMISO programs, have been selected from hybrid QM/MM molecular dynamical simulations using the DYNAMO program. Refinement of the reactant complex and transition-state structures has been carried out by means of AM1/CHARMM24/TIP3P cal…