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At least 793 records · Page 44Linked to original sources
PubMed1999

Dissimilatory reduction of Fe(III) by thermophilic bacteria and archaea in deep subsurface petroleum reservoirs of western siberia

Twenty-five samples of stratal fluids obtained from a high-temperature (60-84 degrees C) deep subsurface (1700-2500 m) petroleum reservoir of Western Siberia were investigated for the presence of dissimilatory Fe(III)-reducing microorganisms. Of the samples, 44% and 76% were positive for Fe(III) reduction with peptone and H2 respectively as electron donors. In most of these samples, the numbers of culturable thermophilic H2-utilizing iron reducers were in the order of 10-100 cells/ml. Nine strains of thermophilic anaerobic bacteria and archaea isolated from petroleum reservoirs were tested for their ability to reduce Fe(III). Eight strains belonging to the genera Thermoanaerobacter, Thermotoga, and Thermococcus were found capable of dissimilatory Fe(III) reduction, with peptone or H2 as electron donor and amorphous Fe(III) oxide as electron acceptor. These results demonstrated that Fe(III) reduction may be a common feature shared by a wide range of anaerobic thermophiles and hyperthermophiles in deep subsurface petroleum reservoirs.http://link.springer-ny. com/link/service/journals/00284/bibs/39n2p99.html

Journal Article↗
PubMed2004

Optimization of Serratia marcescens lipase production for enantioselective hydrolysis of 3-phenylglycidic acid ester.

Lipase production and cell growth of Serratia marcescens ECU1010 were optimized in shake flasks, with lipase production being enhanced 9.5-fold (4,780 U/l) compared with the initial activity (500 U/l). Optimal carbon and nitrogen sources were Tween-80 and peptone, and the optimal ratio of Tween-80 to peptone was 1:3. The optimized cultivation conditions were 25 degrees C and pH 6.5. Lipase activity, particularly specific activity, could be improved by decreasing the cultivation temperature from 35 to 25 degrees C. Enzyme stability was significantly improved by simple immobilization with synthetic adsorption resin no. 8244. After five reaction cycles, enzyme activity decreased only very slightly, while enantioselectivity of the preparation remained constant, and the ees (enantiomeric excess of the remaining substrate) achieved in all cases was higher than 97%. The resin-8244-lipase preparation can be used for efficient enantioselective hydrolysis of trans-3-(4'-methoxyphenyl)glycidic acid methyl ester [(+/-)-MPGM], a key intermediate in the synthesis of Diltiazem.

Enzyme Stability↗
PubMed2006

Substrate and metabolite diffusion within model medium for soft cheese in relation to growth of Penicillium camembertii.

Penicillium camembertii was cultivated on a jellified peptone-lactate based medium to simulate the composition of Camembert cheese. Diffusional limitations due to substrate consumption were not involved in the linear growth recorded during culture, while nitrogen (peptone) limitation accounted for growth cessation. Examination of gradients confirmed that medium neutralization was the consequence of lactate consumption and ammonium production. The diffusion of the lactate assimilated from the core to the rind and that of the ammonium produced from the rind to the core was described by means of a diffusion/reaction model involving a partial linking of consumption or production to growth. The model matched experimental data throughout growth.

Cheese↗
PubMed2005

Macrophage-stimulating activity of exo-biopolymer from cultured rice bran with Monascus pilosus.

To find a new use of rice bran, five fungi were examined for the production of exo-biopolymer with macrophage-stimulating activity from rice bran. Among the exo-biopolymers produced from the cultures, Monascus pilosus had the most potent macrophage stimulating activity in a liquid culture rather than in a solid culture. In order to improve the yield of exo-biopolymer with macrophage-stimulating activity, a suitable medium for exo-biopolymer was tested in submerged culture of M. pilosus. The highest amount of exo-biopolymer (13.9 mg/mL) was obtained in a medium containing rice bran as an only carbon source followed by media with additional maltose and sucrose (13.8 and 13.7 mg/mL, respectively). The addition of peptone resulted in the production of high amount of exo-biopolymer (15.1 mg/mL), meanwhile the addition of ammonium chloride resulted in 264.0 microg/mL of glucosamine content. Among eight different kinds of inorganic salts tested, potassium phosphate (0.1%) was the most effective inorganic salt for the mycelial growth and exo-biopolymer production. Therefore the optimal medium composition was as follows (g/L): 20 g of rice bran, 5 g of peptone, and 1 g of KH2PO4. The optimal culture pH and time for mycelial growth and exo-biopolymer production was pH 5.0 and 25 degrees C, respectively. The maximum exo-biopolymer (20.1 mg/mL) was observed at the fourth day of cultivation. Exo-biopolymer, a crude polysaccharide fraction, mainly contained neutral sugar (81.8%) with considerable amounts of uronic acid (18.2%). Component sugar analysis showed that the active fraction consisted mainly of arabinose, galactose, glucose, which was digested from starch of rice bran during cultivation, and uronic acid (molar ratio; 0.8:1.0:0.7:0.8).

Animals↗
PubMed2005

Production of poplar xyloglucan endotransglycosylase using the methylotrophic yeast Pichia pastoris.

The gene XET16A encoding the enzyme xyloglucan endotransglycosylase (XET) from hybrid aspen (Populus tremula x tremuloides Mich) was transformed into Pichia pastoris GS115 and the enzyme was secreted to the medium. The influence of process conditions on the XET production, activity, and proteolytic degradation were examined. Inactivation of XET occurred in the foam, but could be decreased significantly by using an efficient antifoam. Rich medium (yeast extract plus peptone) was needed for product accumulation, but not for growth. The proteolytic degradation of the enzyme in the medium was substantially decreased by also adding yeast extract and peptone to the glycerol medium before induction with methanol. Decreasing the fermentation pH from 5.0 to 4.0 further reduced the proteolysis. The specific activity was further improved by production at 15 degrees C instead of 22 degrees C. In this way a XET production of 54 mg/L active enzyme could be achieved in the process with a specific activity of 18 Unit/mg protein after a downstream process including centrifugation, micro- and ultrafiltration, and ion exchange chromatography.

Cell Culture Techniques↗
PubMed1991

Activation of macrophages for ADCC in vitro: effects of IL-4, TNF, interferons-alpha/beta, interferon-gamma, and GM-CSF.

Macrophages in varying states of activation differ in their ability to perform antibody-dependent cellular cytotoxicity (ADCC) and antibody-independent macrophage-mediated tumor cytotoxicity (MTC). To define further the activation requirements for macrophages to perform various cytolytic functions, we stimulated peptone-elicited peritoneal macrophages, which are only poorly cytolytic, with one of a panel of cytokines and then quantified three distinct cytolytic capacities. The peptone-elicited macrophages, after stimulation with IFN-alpha/beta, IL-4, or TNF, had increased ability to perform both the rapid and slow variants of ADCC but not to perform MTC. Stimulation with high doses of IFN-gamma, however, increased the macrophages' ability to perform all three cytolytic functions. GM-CSF had no effects on any cytolytic capacity. The effects of IL-4, TNF, IFN-gamma, and IFN-alpha/beta on the macrophages' capacity for both forms of ADCC were dose-dependent. IFN-gamma and IFN-alpha/beta increased the macrophages' capacity for both variants of ADCC within 4 hr of treatment, whereas IL-4 and TNF did so only after prolonged treatment. These results suggest that three forms of macrophage cytolytic capacity can be enhanced by cytokine treatment but that the requirements for enhancing each of the three forms of macrophage cytolytic capacity differ.

Animals↗
PubMed1983

Viability of micrococci and lactobacilli upon freezing and freeze-drying in the presence of different cryoprotectants.

Studies were conducted on the viability of Micrococcus varians strain M95 and Lactobacillus plantarum strain L4 upon freezing and freeze-drying using five cryoprotectants (sucrose, lactose, sodium glutamate, peptone, dry nonfat milk) singly or in combinations with gelatin, glutamic acid, and sodium acetate. The number of survivals was determined immediately after treatment and after storage at room temperature or refrigeration temperatures, under vacuum or in air. Dry nonfat milk and peptone introduced at the levels of 8 and 5%, respectively, to broth culture, were found to be the best cryoprotectants providing a 100% viability determined immediately after the treatment of the strains under investigation. Immediately after freezing and freeze-drying, the numbers of viable micrococci remain high, the percentage viability in the presence of almost all the protectants used being 100%. During storage, those numbers decrease rapidly, reaching zero in 3 months upon storage at room temperature in air. The storage ability of lactobacilli is considerably better and, regardless of the fact that the percentage viability decreases, sufficient numbers of viable cells remain after 6 months of storage at both test temperatures. The best results are obtained on storing the microorganisms under vacuum in ampoules under reduced temperatures (+5 degrees C).

Cryoprotective Agents↗
PubMed1986

Inhibition of gastric acid secretion by brain peptides in the dog. Role of the autonomic nervous system and gastrin.

We have studied the effects of 30 peptides administered intracerebroventricularly on basal and pentagastrin-stimulated (8 micrograms/kg s.c.) gastric acid secretion in conscious dogs. None of the peptides significantly increased basal gastric acid secretion. Twelve peptides (2 nmol/kg) significantly (p less than 0.01) decreased the pentagastrin-stimulated 2-h acid output (percentage inhibition in parentheses): human calcitonin (CT) (36%), neurotensin (NT) (52%), rat corticotropin-releasing factor (CRF) (59%), human calcitonin gene-related peptide (CGRP) (59%), ovine CRF (66%), beta-endorphin (beta-End) (80%), urotensin-I (81%), rat CT (81%), porcine gastrin-releasing peptide (GRP) (83%), sauvagine (Svg) (85%), rat CGRP (87%), and bombesin (Bom) (95%). Blockade of the autonomic nervous system with chlorisondamine abolished the gastric inhibitory action induced by CRF, beta-End, CT, and NT, but not by CGRP and Bom (1 nmol/kg each). Corticotropin-releasing factor, beta-End, CT, NT, CGRP, and Bom significantly inhibited gastric acid secretion stimulated by an intragastric 8% peptone meal for 2 h. None of these six peptides significantly altered plasma gastrin concentrations in response to the peptone meal as compared with control experiments. A rise of plasma concentrations of gastrin, CT, CRF, and CGRP could not be detected by radioimmunoassay in animals after intracerebroventricular administration of these four peptides. The results of this study indicate that CT, CGRP, NT, beta-End, and peptides of the CRF and Bom families act within the brain to inhibit pentagastrin- and meal-stimulated gastric acid secretion in conscious dogs. None of the 30 peptides administered intracerebroventricularly increased basal gastric acid secretion in the dog. Inhibition of gastric acid secretion induced by CRF, beta-End, CT, and NT, but not by CGRP and Bom is mediated by the autonomic nervous system. Gastrin does not appear to play a role in gastric acid inhibition induced by the six brain peptides studied.

Animals↗
PubMed1991

A Nycodenz gradient method for the purification of neutrophils from the peripheral blood of rats.

A Nycodenz gradient technique is described which permits the separation of functionally active polymorphonuclear neutrophils (PMN) from the peripheral blood of rats. PMN are obtained at greater than 90% purity and fractionate at a peak density of 1.0919 g/ml. The method is suitable for isolating PMN when the circulating PMN count is low (less than 20%) as in normal rats and when the count is high (greater than 30%), as a result of inducing inflammation in the subcutaneous air pouch of rats by the intra-pouch injection of peptone. The chemotactic responsiveness of rat PMN was found to be markedly less than that of human PMN when the formyl peptides were used as chemoattractants but not when zymosan-activated serum was the chemoattractant. Blood PMN from normal rats and from peptone-treated rats showed no significant difference in their response to ZAS indicating that priming of their activity by the induction of long term (8 day) inflammation was not a feature of these experiments. However, air pouch-derived PMN displayed a highly significant reduction in activity compared with their isologous blood-PMN. The Nycodenz method offers an alternative to the Percoll separation method for rat blood and will be useful when comparative studies of elicited and non-elicited PMN are required since the latter are obtained in sufficiently high yield and purity for microassays on their function to be performed.

Animals↗
PubMed1996

Inhibitory effects of gastrin releasing peptide on gastric emptying in rats.

Gastrin-releasing peptide (GRP) has a wide range of biological actions, including stimulation of the frequency of antral contractions and delaying gastric emptying. The present study was designed to evaluate the role of GRP in the control of gastric emptying of liquid test meals in the rat. The emptying of methyl cellulose given by gavage to fasted rats, or of saline given via the fistula to conscious gastric fistula rats was not influenced by the GRP antagonists, NC-8-89 (Leu13-psi-(CH2NH)-Leu14-bombesin) and 2258U89 ((de-NH2)Phe19, D-Ala24, D-Pro26 psi (CH2NH)Phe27(-GRP (19-27)), at 2 mg/kg, s.c. However, both antagonists (0.02, 0.2 and 2 mg/kg) reversed the inhibitory effect of HCI on gastric emptying in gastric fistula rats (P < 0.05-0.001). When peptone was administered after a preload, but not otherwise, the inhibition of emptying was also partly reversed by both antagonists at all doses used (P < 0.05-0.001). Interestingly, the delay in the emptying of hyperosmolal saline compared to saline, was enhanced at a dose of 0.2 mg/kg of both antagonists (P < 0.05 and P < 0.01). Food intake did not change significantly with the two lower doses of antagonists, but was decreased by the highest dose of NC 8-89. We conclude that GRP specifically inhibits gastric emptying of acid and peptone solutions in the conscious rat.

Animals↗
PubMed1996

Ferrioxamine E-supplemented pre-enrichment and enrichment media improve various isolation methods for Salmonella.

Supplementation of pre-enrichment broth and enrichment broth media with ferrioxamine E (1 microgram/ml) significantly improved the recovery of Salmonella from artificially or naturally contaminated foods. Based on the selectivity of ferrioxamine E, Salmonella enteritidis and S. typhimurium could be isolated also from various mixed cultures (one Salmonella cell in 10(3)-10(4)-fold concentration of cells of competitors) by shaking for 6 h in supplemented buffered peptone water followed by cultivation on XLD- or XLT-4 agars. Isolation of Salmonella from these pre-enrichment cultures by use of Dynabeads-Anti-Salmonella was highly effective. 27 S. typhimurium strains were isolated from 762 naturally infected chicken giblets by use of unsupplemented Tetrathionate broth. However, 33 S. typhimurium isolates were obtained with ferrioxamine E-supplemented Tetrathionate broth from the same samples. Three Salmonella isolates out of 50 evenly divided meat meal samples were obtained by use of ferrioxamine E-supplemented buffered peptone water followed by direct streaking onto XLD- and Rambach agars, no Salmonella isolates could be detected by the conventional method.

Animals↗
PubMed1981

Purification of a high-affinity discoidin I-binding proteoglycan from axenic Dictyostelium discoideum growth medium.

The axenic Dictyostelium discoideum growth medium HL-5, prepared using Difco proteose peptone No. 2, contains an extremely potent inhibitor of the binding of 125I-labeled discoidin I to glutaraldehyde-fixed, cohesive D. discoideum cells. Axenic strain A3 D. discoideum cells bind or internalize the inhibitor during growth in HL-5 medium and subsequently shed or excrete it while differentiating in suspension. The inhibitor has been purified from Difco proteose peptone No. 2 by sequential gel filtration on Sepharose 4B and affinity adsorption using discoidin I-Sepharose. The inhibitor is heterogeneous in molecular weight (4 . 10(5)--2 . 10(6)), but is relatively homogeneous in density on CsCl density gradients. The size and activity of the inhibitor are resistant to periodate, reduction and maleylation, proteases, nucleases and heating in the absence or presence of sodium dodecyl sulfate. Mild alkali causes a partial reduction in activity and converts the higher molecular weight fraction of the inhibitor to a lower molecular weight. The purified inhibitor contains neutral hexose, hexosamine and amino acid in an approximate molar ratio of 4 : 3 : 2. These and other properties suggest that the inhibitor is an unusual proteoglycan. Certain well-characterized glycosaminoglycans are relatively potent inhibitors of discoidin I binding. The proteoglycan reported here is the most potent discoidin I-binding inhibitor ever identified.

Amino Acids↗
PubMed1987

Effect of antimicrobials on blood cultures in endocarditis.

To study the effect of antimicrobials on bacterial growth in blood cultures, we used both simulated blood cultures and cultures obtained from rabbits with experimental endocarditis. Four strains of bacteria were incubated individually with six antimicrobials in nine blood culture media. Positivity rates varied with the ratio of the antimicrobial concentration to the MIC of the organism: 161 of 162 cultures (99%) were positive when the ratio was less than 1/10; 52 of 108 (48%) were positive when the ratio was between 1/10 and one; and none of 54 were positive when the ratio was greater than one. Endocarditis was produced in 28 rabbits with either E. coli, P. aeruginosa, S. aureus, or viridans streptococcus. Following a single dose of an antimicrobial, blood was taken for culture in eight media. Only for viridans streptococcus did recovery rates vary significantly in different media. Recovery rates for this organism in two supplemented peptone broths (78% and 89%) and in hypertonic supplemented peptone (78%) were each higher than in thioglycolate (22%), Columbia (22%), Bactec aerobic and anaerobic (11%), and trypticase soy broths (11%) (p less than 0.05 for each pair). Growth of bacteria in blood cultures containing antimicrobials depended on the ratio of the antimicrobial concentration to the MIC and, for viridans streptococcus, the blood culture medium.

Animals↗
PubMed1994

Growth and division of Escherichia coli under microgravity conditions.

The growth rate in glucose minimal medium and time of entry into the stationary phase in pepton cultures were determined during the STS 42 mission of the space shuttle Discovery. Cells were cultured in plastic bags and growth was stopped at six different time points by lowering the temperature to 5 degrees C, and at a single time point, by formaldehyde fixation. Based on cell number determination, the doubling time calculated for the flight samples of glucose cells was shorter (46 min) than for the ground samples (59 min). However, a larger cell size expected for more rapidly growing cells was not observed by volume measurements with the electronic particle counter, nor by electron microscopic measurement of cell dimensions. Only for cells fixed in flight was a larger cell length and percentage of constricted cells found. An optical density increase in the peptone cultures showed an earlier entry into the stationary phase in flight samples, but this could not be confirmed by viability counts. The single sample with cells fixed in flight showed properties indicative of growth stimulation. However, taking all observations together, we conclude that microgravity has no effect on the growth rate of exponentially growing Escherichia coli cells.

Cell Division↗
PubMed2006

Human dental plaque microcosm biofilms: effect of nutrient variation on calcium phosphate deposition and growth.

UNLABELLED: Plaque mineralisation is a multi-factorial process involving plaque pH, nucleation, inhibitors and promotors. It is poorly understood because of its complexity. OBJECTIVE: To establish the effects of amino acids and peptones in the simulated oral fluid BMM, a saliva analogue DMM and modifications of these on mineral deposition into dental plaque biofilm microcosms. METHODS: Microcosms were cultured for up to 35 days in an Artificial Mouth pulsed with sucrose, followed by 10 days periodic treatment with a pH 5.0 calcium-phosphate-monofluorophosphate-urea solution (CPMU). RESULTS: Initial biofilm doubling times were 3-7h, which then slowed and varied under the different nutrient conditions although their pH behaviour was similar. In BMM, mineral deposition was 20% that of DMM, but removal of BMM peptones increased deposition 12-fold. Substitution of the amino acids in DMM by casein did not affect deposition levels, but their removal leaving mucin the sole macronutrient, increased mineral deposition three-fold, reaching 40 mmol Ca/g protein. CONCLUSIONS: These substantial increases in mineral deposition when the macronutrient concentration is reduced indicates probable changes in the nucleating, inhibitory and Ca-binding properties of the simulated oral fluids themselves and/or changes in the plaque microbiota and their crystal nucleators and inhibitors.

Biofilms↗
PubMed2005

Joint effect of nitrogen sources and B vitamin supplementation of date juice on lactic acid production by Lactobacillus casei subsp. rhamnosus.

The use of date juice as a substrate for lactic acid production was investigated. Various nitrogen sources were compared with yeast extract for efficient lactic acid production by Lactobacillus casei subsp. rhamnosus. Among different nitrogen sources added to date juice (yeast extract, ammonium sulfate, tryptic soy, urea, peptone, and casein hydrolysate), yeast extract was the most efficient. The effect of yeast extract could have been due to its B vitamin content. The addition of five B vitamins at less than 25 mg/l to date juice with any nitrogen source enhanced lactic acid production to some extent, except for date juice with yeast extract or urea or peptone. The most significant increase was obtained with ammonium sulfate. Half of the yeast extract content (10 g/l) in a supplemented date juice could be replaced by a mixture of B vitamins at less than 25 mg/l, and ammonium sulfate at 2.6 g/l with no significant decrease in lactic acid production.

Ammonium Sulfate↗
PubMed2006

Sequential batch culture studies for the decolorisation of reactive dye by Coriolus versicolor.

The white rot fungus Coriolus versicolor could decolorise reactive dye Remazol Brilliant Violet to almost 90%. The fungal mycelia removed color as well as COD up to 95% and 75%, respectively, in a batch reactor. Decolorising activity was observed during the repeated reuse of the fungus. It was possible to substantially increase the dye decolorising activity of the fungus by carefully selecting the operational conditions such as media composition, age of fungus and nitrogen source. The fungal pellets could be used for eight cycles during the long term operation, where medium and dye was replenished at the end of each cycle and the fungus was recycled. Presence of a nitrogen source and nutrient content of media played an important role in sustaining the decolorisation activity of the fungus. The form of nitrogen source (e.g. peptone vs. urea) was also important to maintain the decolorising activity with peptone showing better decolorisation.

Basidiomycota↗
PubMed2005

Optimization of the medium composition for production of mycelial biomass and exo-polymer by Grifola frondosa GF9801 using response surface methodology.

In this work, a three-level Box-Behnken factorial design was employed combining with response surface methodology (RSM) to optimize the medium composition for the production of the mycelial biomass and exo-polymer in submerged cultures by Grifola frondosa GF9801. A mathematical model was then developed to show the effect of each medium composition and their interactions on the production of mycelial biomass and exo-polymer. The model estimated that, a maximal yield of mycelial biomass (17.61 g/l) could be obtained when the concentrations of glucose, KH2PO4, peptone were set at 45.2 g/l, 2.97 g/l, 6.58 g/l, respectively; while a maximal exo-polymer yield (1.326 g/l) could be achieved when setting concentrations of glucose, KH2PO4, peptone at 58.6 g/l, 4.06 g/l and 3.79 g/l, respectively. These predicted values were also verified by validation experiments. Compared with the values obtained by other runs in the experimental design, the optimized medium resulted in a significant increase in the yields of mycelial biomass and exo-polymer. Maximum mycelial biomass yield of 22.50 g/l was achieved in a 15-l fermenter using the optimized medium.

Biomass↗