Influence of carvacrol on growth and toxin production by Bacillus cereus.

The natural antimicrobial compound carvacrol was investigated for its effect on diarrheal toxin production by Bacillus cereus. Carvacrol (0-0.06 mg/ml) reduced the viable count and the maximal specific growth rate (mumax) of B.

Preheating effects on the textural strength of canned green beans. 1. Cell wall chemistry.

Variable preheating conditions allowed the modification of the firmness of two green bean cultivars after processing. The aim of this study was to elucidate the biochemical basis of this phenomenon and to relate pectin differences to different inherent firmness of two cultivars. The preheating temperature, which resulted in the highest retention of firmness after sterilization, corresponded with the optimal temperature for pectin methylesterase activity.

Adaptation of the food-borne pathogen Bacillus cereus to carvacrol.

Carvacrol, a natural antimicrobial compound present in the essential oil fraction of oregano and thyme, is bactericidal towards Bacillus cereus. A decrease of the sensitivity of B. cereus towards carvacrol was observed after growth in the presence of non-lethal carvacrol concentrations.

Utilisation of saccharides in extruded domestic organic waste by Clostridium acetobutylicum ATCC 824 for production of acetone, butanol and ethanol.

Domestic organic waste (DOW) collected in The Netherlands was analysed and used as substrate for acetone, butanol and ethanol (ABE) production. Two different samples of DOW, referred to as fresh DOW and dried DOW, were treated by extrusion in order to expand the polymer fibres present and to obtain a homogeneous mixture. The extruded material was analysed with respect to solvent and hot water extractives, uronic acids, lignin, sugars and ash.

Denaturation of proteins from a non-food perspective.

Controlled denaturation, or the prevention of denaturation, is an important aspect in the development of food applications of proteins. For the use of proteins in non-food applications such as surfactants, adhesives, coatings or plastics, it is discussed that a certain degree of denaturation must occur in order to make proteins processable, and to reach the required product properties such as strength, water resistance or adhesion. By adjusting the processing parameters (temperature, water content, chemicals) conditions can be created to allow structural changes in the protein.

Expression and secretion of human alpha1(I) procollagen fragment by Hansenula polymorpha as compared to Pichia pastoris.

Secretion of a human collagen alpha1(I) chain fragment was achieved in Hansenula polymorpha using the native alpha1(I) procollagen secretory signal sequence. The N-terminal propeptide in the fragment was cleaved off during secretion, yielding the N-terminus of mature alpha1(I) collagen. In Pichia pastoris transformants, the expression of the fragment could be detected on RNA-level, but the product could not be determined extracellularly.

Antimicrobial activity of carvacrol toward Bacillus cereus on rice.

The antimicrobial activity of carvacrol, a compound present in the essential oil fraction of oreganum and thyme, toward the foodborne pathogen Bacillus cereus on rice was studied. Carvacrol showed a dose-related inhibition of growth of the pathogen. Concentrations of 0.

Alternative sources of natural rubber.

Rubber (cis-1,4-polyisoprene) is one of the most important polymers naturally produced by plants because it is a strategic raw material used in more than 40,000 products, including more than 400 medical devices. The sole commercial source, at present, is natural rubber harvested from the Brazilian rubber tree, Hevea brasiliensis. Primarily due to its molecular structure and high molecular weight (> 1 million daltons) this rubber has high performance properties that cannot easily be mimicked by artificially produced polymers, such as those derived from, e.

Isolation and partial characterization of thermostable isoperoxidases from potato (Solanum tuberosum L.) tuber sprouts.

Peroxidases (POD; EC 1.11.1.

Cloning and characterization of the Yarrowia lipolytica squalene synthase (SQS1) gene and functional complementation of the Saccharomyces cerevisiae erg9 mutation.

The squalene synthase (SQS) gene encodes a key regulatory enzyme, farnesyl-diphosphate farnesyltransferase (EC 2.5.1.

Controlling Maillard reactions in the heating process of blockmilk using an electronic nose.

An electronic nose has been used to classify blockmilk products subjected to various heating processes based on their volatile composition. Multivariate analyses of electronic nose and GC/MS data are highly comparable with respect to relative changes in aroma profile going from raw to final product. Predictive properties of various neural networks based on the raw sensor output were moderate to good.

Activation of a latent mushroom (Agaricus bisporus) tyrosinase isoform by sodium dodecyl sulfate (SDS). Kinetic properties of the SDS-activated isoform.

This study reports the activation of a latent mushroom tyrosinase isoform by sodium dodecyl sulfate (SDS). The activation process of latent mushroom tyrosinase by SDS is characterized by the presence of a lag period (tau) prior to the attainment of a steady-state rate (V(ss)). This could be related to a slow conformational change of the latent enzyme to render the active isoform.

Kinetic study of the activation process of a latent mushroom (Agaricus bisporus) tyrosinase by serine proteases.

Latent mushroom tyrosinase can be considered as a zymogen when activated by proteases because the activation process fulfilled all of the kinetic dependencies predicted by a theoretical zymogen activation model previously reported. The activation was studied under two assay conditions: high and low ratio of latent tyrosinase/serine protease (trypsin and subtilisin Carlsberg) concentrations, in the presence and in the absence of a serine protease inhibitor (aprotinin). The size of the latent enzyme was 67 kDa, determined by denaturing SDS-PAGE electrophoresis and Western blot assays.

Kinetics of activation of latent mushroom (Agaricus bisporus) tyrosinase by benzyl alcohol.

A latent isoform of Agaricus bisporus tyrosinase has been isolated and activated by benzyl alcohol, one of the major volatile compounds in mushrooms of this genus. The progress curve that describes the activation process reached the steady-state rate (V(ss)) after a lag period (tau). The rate of active tyrosinase formation was calculated by coupling the oxidation of o-diphenols to the activation process.

Kinetic study of the oxidation of gamma-L-glutaminyl-4-hydroxybenzene catalyzed by mushroom (Agaricus bisporus) tyrosinase.

Despite the importance of the substrate gamma-L-glutaminyl-4-hydroxybenzene (GHB) in the melanin biosynthesis pathway in mushrooms Agaricus bisporus, the kinetics of its oxidation catalyzed by tyrosinase has never been properly characterized. For this purpose GHB and its corresponding o-diphenol (GDHB) were isolated and purified from A. bisporus mushrooms.

Slow-binding inhibition of mushroom (Agaricus bisporus) tyrosinase isoforms by tropolone.

A kinetic study of the inhibition of mushroom tyrosinase by tropolone has been made. Three tyrosinase isoforms were used: two commercial tyrosinases from Fluka and Sigma (isoelectric points of 4. 3 and 4.

Combined action of nisin and carvacrol on Bacillus cereus and Listeria monocytogenes.

Nisin, a small antimicrobial protein, was tested for its bactericidal action against Listeria monocytogenes and Bacillus cereus and a typical biphasic reduction of the viable count was observed. The reduction was most fast during the first 10 min of exposure, while the viable count remained stable in the last part of the exposure period. Bacillus cereus was more sensitive towards nisin than L.

Biochemical and physiological aspects of brown blotch disease of Agaricus bisporus.

Pseudomonas tolaasii is a bacterium endemic to the compost beds where common mushroom (Agaricus bisporus) is cultivated. Under some environmental conditions still not well-determined, but influenced by temperature and relative humidity, the bacterium can become pathogenic and provoke the brown blotch disease. This review describes the interaction between P.

High-yield secretion of recombinant gelatins by Pichia pastoris.

Recombinant non-hydroxylated gelatins based on mouse type I and rat type III collagen sequences were secreted from the methylotrophic yeast Pichia pastoris, using the Saccharomyces cerevisiae alpha-mating factor prepro signal. Proteolytic degradation could be minimized to a large extent by performing fermentations at pH 3.0 and by adding casamino acids to the medium, even though gelatin is extremely susceptible to proteolysis due to its open, unfolded structure.

Development of environmentally friendly coatings and paints using medium-chain-length poly(3-hydroxyalkanoates) as the polymer binder.

Unsaturated medium-chain-length poly(3-hydroxyalkanoates) (mcl-PHAs) produced by Pseudomonas putida from linseed oil fatty acids (LOFA) and tall oil fatty acids (TOFA), were used as the polymer binder in the formulation of high solid alkyd-like paints. The relatively high concentration of unsaturated alkyl side chains incorporated into the PHA resins resulted in oxidative drying PHA paints having excellent coating properties. The homogeneously pigmented PHA coatings yielded high-gloss, smooth and strong films upon curing and showed an excellent flexibility, a good adhesion to different substrates, cohesive film properties and resistance to chipping.

Medium optimization for spore production of coniothyrium minitans using statistically-based experimental designs.

Statistically-based experimental designs were used to optimize a chemically defined solid medium for the spore production of Coniothyrium minitans. In the first optimization step the influence of starch, urea, phosphate, magnesium, calcium, thiamin and trace elements on spore production was evaluated using a fractional factorial design. Starch and trace elements influenced spore production positively while urea affected spore production negatively.

Antibiosis plays a role in the context of direct interaction during antagonism of Paenibacillus polymyxa towards Fusarium oxysporum.

Interaction of Fusarium oxysporum and Paenibacillus polymyxa starts with polar attachment of bacteria to the fungal hyphae followed by the formation of a large cluster of non-motile cells embedded in an extracellular matrix in which the bacteria develop endospores. Enumeration of fungal viable counts showed that less than one of 36,000 colony-forming units survived in paired cultures for 71 h. Effective antagonism was not observed below pH5 and was specific for the bacterial species.

Bactericidal activity of carvacrol towards the food-borne pathogen Bacillus cereus.

Carvacrol, a natural plant constituent occurring in oregano and thyme, was investigated for its bactericidal effect towards the food-borne pathogen Bacillus cereus. Carvacrol showed a dose-related growth inhibition of B. cereus.

Engineering of factors determining alpha-amylase and cyclodextrin glycosyltransferase specificity in the cyclodextrin glycosyltransferase from Thermoanaerobacterium thermosulfurigenes EM1.

The starch-degrading enzymes alpha-amylase and cyclodextrin glycosyltransferase (CGTase) are functionally and structurally closely related, with CGTases containing two additional domains (called D and E) compared to the three domains of alpha-amylases (A, B and C). Amino acid residue 196 (Thermoanaerobacterium thermosulfurigenes EM1 CGTase numbering) occupies a dominant position in the active-site cleft. All alpha-amylases studied have a small residue at this position (Gly, Leu, Ser, Thr or Val), in contrast to CGTases which have a more bulky aromatic residue (Tyr or Phe) at this position, which is highly conserved.

Interactions of nisin and pediocin PA-1 with closely related lactic acid bacteria that manifest over 100-fold differences in bacteriocin sensitivity.

The natural variation in the susceptibilities of gram-positive bacteria towards the bacteriocins nisin and pediocin PA-1 is considerable. This study addresses the factors associated with this variability for closely related lactic acid bacteria. We compared two sets of nonbacteriocinogenic strains for which the MICs of nisin and pediocin PA-1 differed 100- to 1,000-fold: Lactobacillus sake DSM20017 and L.