bluuebunny/crossref_metadata_2025_split huggingface dataset:
Purification and characterization of the main laccase produced by the white‐rot fungus Pleurotus pulmonarius on wheat bran solid state medium
Authors: Marques de Souza Cristina Giatti , Peralta Rosane Marina 
Published: July 2003

AbstractThe wood‐degrading fungus Pleurotus pulmonarius produces at least two laccase isoforms, Lcc1 and Lcc2, when grown on wheat bran solid state medium. The main laccase, Lcc2, was purified to apparent electrophoretic homogeneity by using acetone precipitation, anion‐exchange chromatography and gel filtration. Lcc2 had been purified 5.9‐fold with a yield of 49%. A specific activity of 19,750 U/mg protein was found using syringaldazine as a substrate under standard assay conditions. The enzyme is a homodimeric glycoprotein containing 44% glycosilation and an apparent molecular mass of 46 kDa. Type I and type III Cu2+ centers were identified by spectrophotometry. The laccase showed optimal activity at pH 6.2–6.5, 4.0–5.5, and 6.0–8.0 with syringaldazine, ABTS and guaiacol as substrates, respectively. For all substrates, the highest oxidation rates were obtained at 50 °C. The enzyme was stable over a large range of pH (4.5–8.0) and at temperatures up to 50 °C. Under standard assay conditions, the apparent KM values were 12, 210 and 550 μM for syringaldazine, ABTS and guaiacol, respectively. Purified Lcc2 was strongly inhibited by sodium azide, 2‐mercaptoethanol and Hg2+, and slightly inhibited by Mn+2 and the chelant agents, EDTA and EGTA. The enzyme was activated by Cu2+ and it retained a high percentage of its activity in the presence of organic solvents, such as acetonitrile and acetone.
Does the detoxification of penicillin side‐chain precursors depend on microsomal monooxygenase and glutathione S‐transferase in Penicillium chrysogenum?
Authors: Emri Tamás , Oláh Brigitta , Sámi László , Pócsi István 
Published: July 2003

AbstractThe glutathione (GSH) S‐conjugation of 1,2‐epoxy‐3‐(4′‐nitrophenoxy)propane was catalysed predominantly by microsomal glutathione S‐transferase (mGST) in Penicillium chrysogenum. The specific mGST activity unlike the cytosolic GST (cGST) activity increased substantially when the penicillin side‐chain precursor phenoxyacetic acid (POA) was included in the culture medium. Therefore, a microsomal monooxygenase (causing possible release of epoxide intermediates) and mGST‐dependent detoxification pathway may exist for the side‐chain precursors as an alternative to microsomal activation to acyl‐CoA and subsequent transfer to β‐lactam molecules. The P. chrysogenum pahA and Aspergillus nidulans phacA gene products, which are cytochrome P450 monooxygenases and are able to hydroxylate phenylacetic acid (PA) at position 2 on the aromatic ring, are unlikely to release toxic epoxide intermediates but epoxidation of PA and POA due to the action of other microsomal monooxygenases cannot be excluded. The GSH‐dependent detoxification of POA was provoked by a well‐controlled transient lowering of pH (down to 5.0) at the beginning of the production phase in a fed‐batch fermentation system. Both the specific GST and γGT activities were increased but the intracellular GSH concentrations remained unaltered unless the pH of the feed was transiently lowered below 5.0. At pH 4.6, the GSH pool was depleted rapidly but no antibiotic production was observed. Although sucrose was taken up effectively by the cells, cell death and autolysis were progressing. Therefore, the industrial exploitation of the GSH‐dependent detoxification of penicillin side‐chain precursors to reduce intracellular GSH‐levels in order to avoid the GSH inhibition of the β‐lactam biosynthetic enzymes seems to be rather unlikely. P. chrysogenum mGST and cGST were separated using GSH‐Sepharose 6B affinity chromatography. The purified cGST possessed a homodimer (α2) tertiary structure with Mr, α = 29500.
Evaluation of combined 16S rDNA and strb1 gene targeted PCR to identify and detect streptomycin‐producing Streptomyces
Authors: Gharaibeh Raad , Saadoun Ismail , Mahasneh Amjad 
Published: July 2003

AbstractIn this study, two designed primers were evaluated to identify soil Streptomyces and to detect streptomycin production by strb1 targeted PCR. Potential Streptomyces‐specific signatures were identified in their 16S rDNA sequences in regions located around nucleotide positions 576 and 995. Primer pair RI7/RI8 derived from these regions was investigated for its specificity in detecting and identifying Streptomyces isolates by PCR assays using DNA from pure cultures. The constructed primer pair showed high specificity in detecting and identifying Streptomyces type strains as well as soil isolates. Streptomycin‐producers were detected by PCR assays through the selective amplification of streptomycin biosynthetic gene (strb1). Results suggest that PCR assay facilitates the differential identification of Streptomyces‐specific antibiotic producers and a resident population of Streptomyces in Jordan with the capacity of streptomycin‐production is present.
Identification of the gene encoding the sole physiological fumarate reductase in Shewanella oneidensis MR‐1
Authors: Maier Tamara M. , Myers Judith M. , Myers Charles R. 
Published: July 2003

AbstractShewanella oneidensis MR‐1 is a Gram‐negative, nonfermentative rod with a complex electron transport system which facilitates its ability to use a variety of terminal electron acceptors, including fumarate, for anaerobic respiration. CMTn‐3, a mutant isolated by transposon (TnphoA) mutagenesis, can no longer use fumarate as an electron acceptor; it lacks fumarate reductase activity as well as a 65‐kDa soluble tetraheme flavocytochrome c. The sequence of the TnphoA‐flanking genomic DNA of CMTn‐3 did not align to those for fumarate reductase or related electron transport genes from other bacteria. Sequence analysis of the MR‐1 genomic database demonstrated that an open reading frame encoding a 65‐kDa tetraheme cytochrome c with sequence similarity to the fumarate reductase from S. frigidimarina NCIMB400 was found 8 kb away from the TnphoA‐flanking genomic DNA of CMTn‐3. PCR analysis demonstrated that a large deletion (≥9.2 kb and ≤11 kb) of genomic DNA occurred in CMTn‐3 as a result of TnphoA insertion. This deletion included at least half of the fumarate reductase gene as well as ∼8 kb of upstream DNA. Complementation of CMTn‐3 with the fumarate reductase gene plus 0.5‐kb of upstream DNA restored growth on fumarate. These studies explicitly define the sole physiological fumarate reductase gene from the several possibilities suggested by the genomic sequence of MR‐1. Surprisingly, the fumarate reductase gene plus 0.77‐kb upstream DNA from S. frigidimarina NCIMB400 did not complement CMTn‐3.
Multiplex PCR for the direct detection of Salmonella enterica from chicken, lamb and beef food products
Authors: Malkawi Hanan Issa , Gharaibeh Raad 
Published: July 2003

AbstractThree sets of known Salmonella enterica‐specific primers were used collectively, for the first time, to evaluate the use of multiplex polymerase chain reaction (m‐PCR) as a diagnostic tool to detect Salmonella enterica in naturally contaminated meat and poultry products. For this purpose a total of 300 samples representing the most frequently used fresh and frozen meat (beef and lamb) and poultry (chicken) products (whole, cut, ground, and processed) were collected from eight locations within Irbid city (Jordan). After an enrichment step, DNA was extracted directly from each food sample and amplified using six Salmonella enterica specific primers. Samples were also analyzed using conventional microbiological methods for the confirmation of Salmonella enterica presence. Out of 300 samples, 93 samples were positive by m‐PCR. On the other hand, 67 samples were positive by conventional microbiological methods and only 26 samples were positive by m‐PCR alone.The primer pairs, used here, proved to be highly specific for Salmonella enterica. Using m‐PCR, Salmonella enterica detection could be achieved easily and the results had been confirmed effortlessly within a short period of time (24–36 hours) compared to 3–8 days for the conventional microbiological methods. Our findings emphasize the value of using a combination of specific primer pairs instead of a single primer pair in the detection process to minimize any chance for any inherent experimental or natural error.
Studies on the genomic heterogeneity of Micrococcus luteus strains by macro‐restriction analysis using pulsed‐field gel electrophoresis
Authors: Murayama O. , Matsuda M. , Moore J. E. 
Published: July 2003

AbstractMacro‐restriction analysis by means of double digestion using DraI and VspI demonstrated that they cleaved the genomic DNAs from Micrococcus luteus JCM1464T, JCM3347, and JCM3348 into four to five fragments in a distinguishable manner by pulsed‐field gel electrophoresis (PFGE). Separate digestion with DraI and VspI cleaved the genomic DNA from M. luteus ATCC9341 into a relatively limited number of restriction fragments (six pieces). SspI and XbaI cleaved the genomic DNA from each of the four strains into restriction fragments in a distinctly different and distinguishable manner.Thus, PFGE profiles after digestion with these four restriction enzymes that recognize six specific base sequences demonstrated the heterogeneity at the whole genomic DNA level among the four strains of M. luteus.The size of the genomic DNA of M. luteus ATCC9341 was estimated to be approximately 2.3 Mb by the summing the lengths of the restriction fragments generated by each three restriction enzymes (DraI, SspI, and VspI) and averaging the results.
In vitro growth response of bread‐spoilage Bacillus strains to selected natural antimicrobials
Authors: Pattison T.L. , Lindsay D. , von Holy A. 
Published: July 2003

AbstractThis study assessed the in vitro responses of Bacillus (B.) strains isolated from ropey bread to natural antimicrobials under optimum growth conditions. The responses of six Bacillus strains [B. subtilis (2), B. licheniformis (2) and B. pumilus (2)] to acetic acid (AA), lactic acid (LA), calcium lactate (CL) and a lactate‐containing cocktail (LCC), singly and in combinations were determined and compared to calcium propionate (CP). Isolates were each inoculated into flasks containing Nutrient Broth (NB) and the respective antimicrobial treatments and pHs were left unadjusted. A duplicate set of flasks, also containing NB and the respective antimicrobials, but adjusted to pH's corresponding to those of baked brown bread containing the same antimicrobials was also inoculated. Growth curves were obtained spectrophotometrically and used to estimate lag times. The organic acids used in this study [0.1% (v/v) AA and 0.25% (v/v) LA] singly and in combination with each other and with CL, CP or LCC, completely inhibited the growth of all six Bacillus strains, but only at non‐adjusted pHs. The efficacies of LA, AA and CL notably decreased when the pH of the test media containing the respective preservatives was adjusted to the corresponding in situ (bread) values. However, the natural antimicrobials were still as effective as CP in retarding growth of the six Bacillus strains at the in situ (bread) pH values.
A sulfate‐reducing bacterium that can detoxify U(VI) and obtain energy via nitrate reduction
Authors: Pietzsch Katja , Babel Wolfgang 
Published: July 2003

AbstractBacterial strain UFZ B 490, which was isolated from a uranium dump and is closely related to Desulfovibrio vulgaris oxamicusT (DSM 1925T), is able to detoxify U(VI) in aqueous media. In experiments reported here, U(VI) was used as an electron acceptor and lactate as electron donor. The reduction of soluble U(VI) to solid U(IV) (uraninite) did not provide energy for growth of strain UFZ B 490. However, the isolate is able to grow when supplied with nitrate as sole electron acceptor and nitrogen source, using lactate as a source of carbon and energy. In comparative studies, the strains Desulfovibrio vulgaris oxamicusT (DSM 1925T) and Desulfovibrio vulgaris vulgarisT (DSM 644T), as well as the isolate, all utilized 0.6 mol lactate per mol U(VI) reduced. Strains UFZ B 490 and Desulfovibrio vulgaris oxamicusT (DSM 1925T) were found to consume 2.4 mol lactate per mol nitrate reduced, but Desulfovibrio vulgaris vulgarisT (DSM 644T) did not display dissimilatory nitrate reduction. In further experiments it was found that strain UFZ B 490 preferred sulfate as electron acceptor in the presence of both sulfate and nitrate, irrespective of whether it had been precultivated on sulfate or nitrate.
Effect of natural and controlled fermentation on flatus‐producing compounds of beans (Phaseolus vulgaris)
Authors: Granito Marisela , Champ Martine , Guerra Marisa , Frias Juana 
Published: July 2003

AbstractFermentation of grain legumes is an efficient method to reduce the concentration of α‐galactosidic compounds that are known to be flatulence producers. Soluble dietary fibre has also been implicated in flatulence production; however, little information exists about the effectiveness of fermentation in diminishing the effects of these compounds. The objective of this work was to study the effect of natural fermentation (NF) and controlled fermentation (CF) on the content of α‐galactosides and dietary fibre in dry beans (Phaseolus vulgaris) for 24, 48, 72 and 96 h. After 48 h, the pH during NF dropped from 6.15 to 4.00 and the nominal acidity increased six times; for CF, however, although the decrease in pH was similar to that for NF, the nominal acidity increased only three times after 48 h. Insoluble fibre content did not change the pH significantly after 96 h for NF and CF. Soluble fibre suffered an apparent removal after 48 h of NF and underwent a sharp reduction of 66% after 96 h of CF. The concentration of stachyose (the main α‐galactoside in raw beans) diminished notably after 48 h and 96 h NF (72% and 95% respectively), whereas with CF only 11% was removed after 96 h. NF of P vulgaris seems to be more effective than CF in reducing the flatulence‐producer factors (α‐galactosides and soluble dietary fibre). Copyright © 2003 Society of Chemical Industry
A new method for accelerated shelf‐life prediction for frozen foods
Authors: Reid DS , Kotte K , Kilmartin P , Young M 
Published: July 2003

AbstractShelf‐life estimation for frozen foods can be a long process because of the long duration of shelf‐life at the lower temperatures of storage. A variety of rapid procedures have been proposed to suggest whether products will have acceptable shelf‐lives at low storage temperatures. These all have limitations. In this paper a new procedure is proposed which involves direct determination of shelf‐lives at the more elevated frozen storage temperatures, where change is more rapid. This is coupled with utilisation of information on the mobility temperature to establish a low‐temperature storage datum. A plot of expected shelf‐life as a function of temperature is produced using these two data sources. The effectiveness of the procedure is validated using existing literature data and newly generated data. The procedure allows for the effective estimation of the low‐temperature storage life of a product utilising data collected on the product in question. It requires around 60 days, while effectively estimating the storage temperatures required to achieve target shelf‐lives of 1 year, 18 months, 2 years or even longer. Copyright © 2003 Society of Chemical Industry
Comparative study of six pear cultivars in terms of their phenolic and vitamin C contents and antioxidant capacity
Authors: Galvis Sánchez Andrea C , Gil‐Izquierdo Angel , Gil María I 
Published: July 2003

AbstractThe main phenolic compounds in six pear cultivars were identified and quantified using high‐performance liquid chromatography/diode array detection (HPLC/DAD) and HPLC/electrospray ionisation mass spectrometry (HPLC/ESIMS). Major quantitative differences were found in the phenolic profiles. The peel contained higher concentrations of chlorogenic acid, flavonols and arbutin than the flesh, where only chlorogenic acid was detected. Total phenolics ranged from 1235 to 2005 mg kg−1 in the peel and from 28 to 81 mg k g−1 in the flesh. Ascorbic acid and dehydroascorbic acid were detected in the peel, whereas only dehydroascorbic acid was present in the flesh. The ranges of vitamin C content were from 116 to 228 mg kg−1 in the peel and from 28 to 53 mg kg−1 in the flesh. The antioxidant capacity was correlated with the content of chlorogenic acid (r = 0.46), while ascorbic acid made only a small contribution to the total antioxidant capacity of the fruit. Copyright © 2003 Society of Chemical Industry
Quantification of monomeric and polymeric wheat proteins and the relationship of protein fractions to wheat quality
Authors: Suchy Jerry , Lukow Odean M , Fu Bin X 
Published: July 2003

AbstractWheat protein composition is important for understanding the biochemical basis of wheat quality. The objective of this study was to design a simple protein fractionation protocol with low cross‐contamination and to show that these protein fractions were associated with wheat quality. The protocol consists of three sequential extractions from 100 mg of flour with 7.5% propan‐1‐ol and 0.3 M sodium iodide (monomeric‐rich protein), 50% propan‐1‐ol (soluble glutenin‐rich protein) and 40% propan‐1‐ol and 0.2% dithiothreitol (insoluble glutenin‐rich protein). Nitrogen content of protein solubility groups was determined from dry residues using an automated combustion nitrogen analyser. About 90% of the total protein in the flour was solubilised. Cross‐contamination of protein fractions was evaluated by SDS‐PAGE, SE‐HPLC and RP‐HPLC. Variation in nitrogen content of the protein solubility fractions was lowest for monomeric‐rich protein (<2%) and insoluble glutenin‐rich protein (<4%). Three wheats with similar high‐molecular‐weight (HMW) glutenin subunit composition, Alpha 16, Glenlea and Roblin, varied significantly (P ≤ 0.05) in the proportion of monomeric‐rich and insoluble glutenin‐rich protein in the flour. Dough rheological properties were directly related to the proportion of insoluble glutenin‐rich protein and inversely related to the proportion of monomeric‐rich protein. The protocol was validated using an expanded set of 11 wheats which also showed that inter‐cultivar differences in the proportion of monomeric‐rich, insoluble glutenin‐rich protein and glutenin‐to‐gliadin ratio in the flour governed dough rheological properties such as mixograph, farinograph and microextension tests. The protocol has merit for quality screening in wheat‐breeding programmes when the sample size is too small or when time constraints limit the ability to perform traditional rheological tests. For the Department of Agriculture and Agri‐Food, Government of Canada, Copyright © Minister of Public Works and Government Services Canada 2003. Published for SCI by John Wiley & Sons, Ltd.
Effect of drought on polyamine metabolism, yield, protein content and in vitro protein digestibility in tepary (Phaseolus acutifolius) and common (Phaseolus vulgaris) bean seeds
Authors: González de Mejía Elvira , Martínez‐Resendiz Violeta , Castaño‐Tostado Eduardo , Loarca‐Piña Guadalupe 
Published: July 2003

AbstractThe objective of the present study was to investigate the effect of drought on the metabolism of proline, ornithine and polyamines, and the enzymes involved in their synthesis and degradation, in tepary and common bean seeds. Furthermore, the effect on seed yield, protein content and in vitro protein digestibility was also studied. Genotypes of tepary bean (Phaseolus acutifolius) used were: PI‐301‐801 from Nicaragua; G‐400‐35 from Oaxaca, Mexico; L‐242‐24 and L‐242‐36 from Sonora, Mexico; L‐172 from Arizona, USA; and the common bean (Phaseolus vulgaris) variety Flor de Mayo Bajío (FMB) from Mexico. The cultivars were grown in a greenhouse under controlled temperature, light and humidity. Water content in plants (WCP) decreased when irrigation was stopped (1 and 2 weeks after blooming). Common bean had the lowest WCP value (73.75%), while the best genotypes were PI‐301‐801 (91.62%), G‐400‐35 (88.70%) and L‐242‐24 (85.73%). Tepary bean plants had superior water absorption capacity, which helped to increase yield. De novo synthesis of drought proteins may explain the increased protein content present under drought conditions. The results suggest that water stress induced ornithine amino transferase activity and ornithine concentration. Proline also increased under drought conditions (p < 0.05). Genotypes L‐242‐24 and G‐400‐35, which had the highest yield, also had a major concentration of polyamines under water stress. The results also suggest that arginase activity participated in amino acid synthesis such as ornithine and, consequently, in the protein concentration under water stress. Genotypes G‐400‐35 and L‐242‐24 are good alternatives for cultivation in arid zones. Copyright © 2003 Society of Chemical Industry
Bioactivity of falcarinol and the influenceof processing and storage on its content in carrots (Daucus carota L)
Authors: Hansen Susanne L , Purup Stig , Christensen Lars P 
Published: July 2003

AbstractThe concentration‐dependent activity of the polyacetylene falcarinol ((9Z)‐heptadeca‐1,9‐dien‐4,6‐diyn‐3‐ol), isolated from carrots, was investigated in a bioassay with primary mammary epithelial cells in collagen gels and compared with that of β‐carotene, the orange pigment in carrots. Falcarinol showed biphasic activity, having stimulatory effects between 0.01 and 0.05 µg ml−1 and inhibitory effects between 1 and 10 µg ml−1, whereas β‐carotene showed no effect in the concentration range 0.001–100 µg ml−1. The results are discussed in relation to the health‐promoting effects of carrots and related vegetables. Falcarinol was quantified in the carrot cultivars Bolero, Rodelika and Fancy by analytical reverse phase HPLC, subjected to various processing and storage conditions in order to study how long‐term storage, blanching, freezing and boiling influence the content of falcarinol. Long‐term storage of raw carrot cubes (1 cm3) reduced the falcarinol content by almost 35%. A similar reduction was found in steam‐blanched carrot cubes (1 cm3). Long‐term storage at −24 °C of steam blanched carrot cubes did not reduce the falcarinol content further. A reduction of almost 70% in the falcarinol content was found in carrot pieces boiled in water for 12 min compared with raw carrots. Copyright © 2003 Society of Chemical Industry
Gelatinolytic activities in muscle of Atlantic cod (Gadus morhua), spotted wolffish (Anarhichas minor) and Atlantic salmon (Salmo salar)
Authors: Lødemel Jørgen B , Olsen Ragnar L 
Published: July 2003

AbstractThe gelatinolytic activity in muscle from Atlantic cod (Gadus morhua), spotted wolffish (Anarhichas minor) and Atlantic salmon (Salmo salar) was studied using gelatin SDS‐PAGE, gelatin affinity chromatography and enzyme inhibitors. These fish species are known to differ markedly in fillet softening and gapingpost mortem. Atlantic cod, which is a promising species for cold water marine aquaculture, often shows such negative properties, particularly after being well fed. Gelatinolytic activity bands were present in all three species. Using gelatin chromatography and enzyme inhibitors, both serine proteinases and metalloproteinases were detected in wolffish and cod muscle, while only the latter were found in salmon muscle. Activation of the metalloproteinases byp‐aminophenylmercuric acetate (APMA) resulted in a shift in activity from higher to lower molecular weight, as is known for mammalian matrix metalloproteinases. In all three species the molecular weight of the metalloproteinases was lowered from approximately 80 to about 70 kDa by activating with APMA. Copyright © 2003 Society of Chemical Industry