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PubMed2000

Growth of Helicobacter pylori in various liquid and plating media.

The objectives of this research were to compare commonly used liquid and plating media to elucidate whether one medium provided superior growth of Helicobacter pylori in vitro. The liquid media compared were Mueller-Hinton broth, brain heart infusion broth and H. pylori special peptone broth, formulated in this laboratory. No significant differences in growth rates were noted and shaking during the incubation of broths was not essential for good growth. The plating media compared included Columbia agar, Mueller-Hinton agar, modified Glupczynski's Brussels campylobacter charcoal agar, Johnson-Murano agar and H. pylori special peptone agar (HPSPA). None of the non-specific plating media that have been used historically to culture H. pylori exhibited any particular advantage. However, HPSPA provided an obvious advantage in colony size. Helicobacter pylori special peptone agar enhances the cultivation of H. pylori and could improve the recovery of the bacterium from clinical samples in vitro.

Agar↗
PubMed1991

Role of transferrin, transferrin receptors, and iron in macrophage listericidal activity.

It is not yet known what properties distinguish macrophages which can kill facultative intracellular bacteria, such as Listeria monocytogenes, from those which cannot. Listeria is an organism which requires iron for growth, yet macrophage listericidal mechanisms are also likely to be iron dependent. We show here that resident peritoneal macrophages and thioglycollate-elicited macrophages cannot kill listeria, but proteose peptone-elicited and FCS-elicited macrophages can. All these cell populations phagocytose listeria. Transferrin receptor expression is low on resident cells, intermediate on peptone- and FCS-elicited cells, and high on thioglycollate-elicited cells. Transferrin transports iron into cells via the transferrin receptor: thus, iron content of resident cells is low, of peptone- and FCS-elicited cells is intermediate, and of thioglycollate-elicited cells is high. Moreover, antibody to transferrin, which prevents it binding its receptor, inhibits listericidal macrophages from killing this bacterium. Finally, nonlistericidal cells with high transferrin receptor expression and high intracellular iron become listericidal if they are incubated with apotransferrin, an iron-free ligand which prevents iron uptake by cells. These data suggest that macrophages must have enough available intracellular iron to support listericidal mechanisms, but too much iron favors growth of the bacterium, which no longer can be killed by the macrophage.

Animals↗
PubMed1986

Concentrations of secretin and CCK in plasma and pancreatico-biliary secretion in response to intraduodenal acid and fat.

To study the effect of emulsified oleic acid on pancreatic secretion and concentrations of secretin and cholecystokinin (CCK) in plasma, eight normal subjects received three sets of duodenal perfusates containing peptone pH 6.0 or pH 2.7, with and without 20 mM oleic acid. Pancreatic secretion was measured by an indicator dilution technique. At pH 6.0, peptone and oleic acid was about as effective as peptone pH 2.7 in stimulating secretin release. However, oleic acid in addition produced a three-fold increase in plasma CCK and was five times as effective as pH 2.7 in stimulating duodenal flow. Also, at pH 2.7, oleic acid augmented pancreatic secretion and concentrations of CCK and secretin in plasma. Duodenal output of amylase and bile salts was independent of the pH of infusate. Low pH alone was a very weak stimulant of CCK release and did not stimulate output of amylase and bile. Emulsified oleic acid is a potent releaser of secretin and CCK and augments the acid-induced pancreatic secretion.

Adult↗
PubMed1995

The role of peptide metabolism in the growth of Listeria monocytogenes ATCC 23074 at high osmolarity.

The growth of Listeria monocytogenes ATCC 23074 in defined medium is sensitive to high osmolarity when compared with its growth in complex media, such as brain heart infusion (BHI). The two major contributors to this difference in growth rate are the availability in BHI of the osmoprotectant glycine betaine and peptides. Peptone plays two major roles: firstly as a nutritional supplement for protein synthesis, and secondly as a source of amino acids and peptides that serve as a mechanism of maintaining turgor. In the presence of peptone the total amino acid pool at high osmolarity is substantial and even in the presence of glycine betaine the amino acid pool makes a major contribution to turgor maintenance. At high osmolarity there is a general increase in amino acid pools, with particularly substantial pools of glutamate, aspartate, proline, hydroxyproline and glycine. Peptides are also accumulated by cells from the peptone supplied in the medium. Glycine-containing peptides are accumulated in the cytoplasm under all conditions. Specific glycine- and proline-containing peptides stimulate growth at high osmolarity. The peptide prolyl-hydroxyproline accumulates in cells to high levels in response to growth at high osmolarity, and the pools of the derived amino acids also show a dependence on the external osmotic pressure. However, proline only confers significant osmoprotection when supplied as peptides. The significance of these data in the context of the occurrence of L. monocytogenes in foods with high peptide content is discussed.

Amino Acids↗
PubMed1982

Variable sugar fermentation by clostridia.

Forty-two sugar fermentation characteristics recorded as "d" in the 8th edition of Bergey's Manual of Determinative Bacteriology were reinvestigated by using eight different peptone media and 205 strains of nine species of pathogenic clostridia. In the absence of sugar, the final pH of 7-day cultures in the basal medium varied widely depending on the peptone employed, the species tested, and even the strain of the species. In the presence of sugar, the final pH of 7-day cultures was markedly influenced by these factors. Since the sugars with reactions recorded as "d" were weakly fermented and, consequently, the fermentation reactions were easily affected by cultural variations resulting in strain instability, we employed the pH difference method (delta pH method) in which the pH difference of 0.5 between cultures with and without sugar was used as the critical level. Thirty-six (86%) of the 42 sugar reactions recorded as "d" were sorted into "+" or "-" by the delta pH method. Six sugars, however, still remained as "d" because of their extremely weak fermentation characters. The use of the delta pH method in any peptone medium not only minimizes incorrect evaluation but also can provide some distinct criteria for identification of clostridia.

Carbohydrate Metabolism↗
PubMed1990

Prolonged inhibition of acid secretion causes hypergastrinaemia without altering pH inhibition of gastrin release in humans.

Hypergastrinaemia induced by potent inhibitors of acid secretion is thought to occur as a result of the elimination of the inhibitory effects of intragastric acid on gastrin release. The present study was designed to determine if the mechanisms responsible for feedback inhibition of gastrin release and acid secretion by intragastric acid are preserved during four weeks of varying degrees of drug-induced acid inhibition. Forty-eight healthy male volunteers were randomly assigned to one of four treatments for four weeks: 10 mg omeprazole o.m., 20 mg omeprazole o.m., 40 mg omeprazole o.m. or 150 mg ranitidine b.d. Gastrin release and acid secretion in response to peptone meals maintained at pH 2.5 and pH 5.5 by intragastric titration, and 24-hour gastrin profiles in response to standard meals were determined before treatment, at the fourth week of treatment and two weeks after discontinuing treatment. As expected, omeprazole produced dose-related effects on acid secretion and gastrin concentrations that were largely reversed after treatment was discontinued. Gastrin release in response to pH 5.5 peptone meals remained significantly greater than gastrin release in response to pH 2.5 meals during treatment with all doses of omeprazole. The ratio of pH 5.5/pH 2.5 peptone meal-stimulated gastrin release was approximately 1.5, and remained constant for all treatment groups throughout the study period. These data indicate that four weeks of drug induced hypochlorhydria causes an apparent increase in overall G-cell function, but it does not interfere with normal feedback inhibition of gastrin release and acid secretion mediated by intragastric acidity.

Adolescent↗
PubMed1983

Dynamics of salmonella isolation with modified Rappaport's medium (R10).

Enhanced growth of salmonellas in Rappaport's medium as modified by Vassiliadis et al. (1976) after pre-enrichment in buffered peptone water during the first 6 h was obtained by replacement of tryptone by soya peptone. The competing bacteria, i.e. those which grow on brilliant green agar and which may interfere with the isolation of salmonellas when Rappaport's medium (R10) incubated at 43 degrees C is used for enrichment were inhibited or reduced in numbers when the normal amount of 5 g soya peptone/litre was used. When the amount was increased to 10 g/l, growth occurred, mainly of Enterobacter and Klebsiella species. The isolation of salmonellas was found to be largely dependent on the number and the ratio of their competitors. Every measure taken to reduce the number of competitive bacteria increases the possibility of isolating salmonellas. This explains the effect of improved selectivity of Rappaport's medium when small inocula are used. Rapid onset of growth of salmonellas by employing soya peptone introduces the possibility of using shorter incubation times 48 h.

Bacteria↗
PubMedDate not supplied

Enzyme release by Trichophyton rubrum depends on nutritional conditions.

Enzymes liberated by growing dermatophytes are of pathogenetic importance in tinea. To investigate the influence of nutrients on this enzyme release, Trichophyton rubrum was grown in media containing peptone, keratin and lipids, to which glucose was added in separate assays. The culture supernatants were compared for extracellular enzyme activities by use of the api-zym test. Our results clearly show that the extracellular enzyme activity is dependent on the nutrients supplied. Seven different enzymes were released when keratin was supplied, as compared with only five and two respectively when lipids or peptone were available. Among these enzymes alkaline phosphatase and N-acetyl-beta-glucosaminidase were detected in all cultures lacking glucose. Enzyme release was inhibited completely when glucose was added to the media, except for N-acetyl-beta-glucosaminidase in peptone cultures. This dependency of enzyme release on fungal nutrition can be expected to occur in vivo too. In addition, it has to be considered for in vitro cultural conditions. Alkaline phosphatase and acetylglucosaminidase may be more important in tinea than has been assumed so far.

Culture Media↗
PubMed1974

Gastric and pancreatic responses to meals varying in pH.

1. Gastric acid response to a test meal of 10% peptone was measured in chronic gastric and pancreatic fistula cats using the Fordtran and Walsh method, monitoring the rate at which a solution of 0.5 M sodium bicarbonate had to be added to maintain constant pH of gastric content at pre-selected values ranging from 5.0 to 1.0. Simultaneously, pancreatic secretion was determined by the standard collection technique. In this way the pH profile for the inhibition of gastric secretion and stimulation of pancreatic secretion has been established in cats.2. A peptone meal adjusted to pH 5.0 produced gastric acid output similar to the maximal response to histamine or pentagastrin. It provoked a negligible stimulation of pancreatic flow rate and bicarbonate output but a large protein output.3. Graded decrease of the peptone meal pH to below 4.0 resulted in inhibition of gastric acid production and in a concomitant stimulation of pancreatic secretory volume and bicarbonate output. A meal adjusted to pH 1.0 stimulated gastric secretion only about 30% of the response recorded at pH 5.0. Pancreatic secretion with a meal adjusted to pH 3.0 reached the highest level of about 70% of the maximal response to exogenous secretin.4. Since the observed changes in the secretory activity of the stomach and the pancreas induced by test meals adjusted to pH 3.0 can be fully reproduced by exogenous secretin, it is suggested that in the cat this hormone may be responsible for the gastric inhibitory and pancreatic stimulatory mechanisms activated during normal digestion of food.

Animals↗
PubMed1976

Preparation and evaluation of two microbiological media from shrimp heads and hulls.

Two peptones were extracted from raw shrimp waste after autolytic digestion. Digests were derived from shrimp heads and shrimp hulls, both of which are by-products of the shrimp processing industry. Digests were evaluated for suitability in supporting growth of microorganisms by measuring the total cell mass produced by five genera of bacteria and five genera of fungi in broths formulated from the peptones. Comparison was made to five commercially available medium preparations and a catfish peptone. A 0.5% solution of the lyophilized shrimp head digest, heated at 121 C for 15 min, resulted in a cloudy suspension. However, the digest supported excellent growth of fungi and good growth of bacteria. A heated 0.5% solution of the hull digest was clear and supported good growth of both bacteria and fungi.

Autolysis↗
PubMed1969

Effect of cultural environment on the blood group activity of microorganisms.

Blood group activity was proven to be a property of the bacterium per se which possesses it, although such activity was influenced by the cultural environment of the organism. High concentrations of peptones having blood group activity were able to transfer this activity to inactive organisms; however, the conferred activity was proportional to the concentration. As a result of the low concentrations, the blood group activity of peptones was eliminated upon incorporation in culture media, and the activity of the peptones had no effect on the blood group activity levels of microorganisms when grown in these media. Conversely, the vitamin content of culture media did affect blood group active organisms. Multiple vitamins in media decreased the activity levels by blocking the reactive sites of the active organisms on which activity detection depended. Blood group activity levels were highest in media of minimal or no vitamin content. Therefore, it can be concluded that a choice of cultural medium becomes an important factor in the quantitation of bacterial blood group activity.

Blood Group Antigens↗
PubMed1970

Optimum skin blending method for quantifying poultry carcass bacteria.

Optimum blending fluids and blending times for use in quantifying bacteria on poultry carcass skin by the skin "blending" method were determined. Butterfield's buffered-phosphate diluent, physiological saline solution (0.85% NaCl), peptone water (0.1% peptone), and deionized water, each at four different skin blending times of 1, 2, 3, and 4 min, were compared. The comparison was based on relative numbers of bacteria per cm(2) of skin, enumerated by each combination on turkey carcasses. Peptone water and physiological saline solution each yielded significantly (P < 0.01) higher bacteria counts from turkey carcass skin samples than did Butterfield's buffered-phosphate diluent or deionized water. There were no significant differences among the four skin blending times and no significant interaction effect between the two factors tested.

Analysis of Variance↗
PubMed1972

Chromogenicity of Streptomyces.

A simplified technique to detect polyphenol oxidase and melanin formation by Streptomyces culture filtrates was developed. The procedure involves the direct assay of pigment formation by the culture filtrate with 3-(3,4-dihydroxyphenyl)-L-alanine (L-dopa) as a substrate. Among cultures of the International Streptomyces Project, 34 failed to produce a diffusible dark brown pigment on peptone-yeast extract-iron-agar and synthetic tyrosine-agar and gave a negative reaction to the melanin formation test. Sixteen cultures produced a diffusible dark brown pigment on both peptone-yeast extract-iron-agar and synthetic tyrosine-agar and gave positive reactions to the test with either L-tyrosine or L-dopa as substrate. Twenty-one cultures produced a diffusible dark brown pigment on peptone-yeast extract-iron-agar, but failed to do so on synthetic tyrosine-agar. Most of these cultures gave a positive reaction to the test when L-dopa was used as the substrate. The correlation between chromogenicity on complex organic media and melanin formation was more clearly established with L-dopa as substrate than with synthetic tyrosine-agar in the present test. The melanin formation test by the present technique, instead of chromogenicity on complex organic media, is recommended as a key feature for the classification of Streptomyces.

Agar↗
PubMed1978

Impaired chemotactic responsiveness of macrophages from gnotobiotic rats.

Peptone-induced macrophages obtained from gnotobiotic (GB) rats responded poorly to chemotactic stimuli that have a powerful, attractive influence upon the cells of conventional donors. Monocyte recruitment from the circulation into peptone-induced exudates also was impaired in GB subjects. Although relatively more resident cells are present in exudates borne by GB donors, their number cannot in itself account for the sluggish response of peptone-induced cells from GB rats. Neutrophil accumulation in the inflamed peritoneal cavities and their responsiveness in vitro were similar in GB and conventional rats. The levels of serum-derived chemotactic factors were similar in such animals. Furthermore, germ-free rats exhibited no obvious defects in their capacity to generate lymphocyte-dependent monocyte chemotactic activity in situ upon specific stimulation with Listeria monocytogenes. It is suggested that the diminished chemotactic responsiveness of exudate macrophages is related in some way to the level of cell activation. This state of affairs might account for the impairment of delayed-type hypersensitivity in GB animals and their inability to resist intracellular bacterial infections.

Ascitic Fluid↗
PubMed1974

Serum gastrin and gastric acid responses to meals at various pH levels in man.

Serum gastrin and gastric acid responses to a test meal of 10% peptone were measured in six duodenal ulcer patients using intragastric titration at pH levels ranging from 5.5 to 1.0. In this way the pH profile for inhibition of serum gastrin release and gastric acid secretion was established. A peptone meal adjusted to pH 5.5 produced gastric acid similar to the maximal response to histamine. A graded decrease of pH of the peptone meal to 1.0 resulted in the progressive inhibition of the gastric acid secretion and the concomitant suppression of the serum gastrin level. Exogenous secretin given in graded doses ranging from 0.25 to 2.0 U/kg-hr caused a dose-related inhibition of gastric acid secretion and the suppression of serum gastrin level. The results of the study indicate that gastric acid secretion and the rise in serum gastrin levels in response to an experimental meal are less when the gastric contents become more acid. The mechanism may involve release of secretin from the small intestine by acid.

Adult↗
PubMed1994

Evaluation and use of a low nutrient medium and reduced incubation temperature to study bacterial contamination in the water supply of dental units.

A low nutrient medium, dilute peptone, and reduced incubation temperatures (25 or 30 degrees C) were used to recover bacteria from dental unit water supply. Significantly greater numbers of bacterial colony-forming units were recovered on the dilute peptone medium than on the enriched media, blood agar or trypticase soy agar. Lower incubation temperatures yielded greater numbers of colony-forming units on all media. The bacterial population in dental unit water supply following stagnation in the supply lines and flushing of the lines was studied using dilute peptone incubated at 25 degrees C. No significant differences in the numbers of colony-forming units were found in stagnant water versus fresh water. Flushing the water lines for 10 min did not significantly reduce the numbers of colony-forming units.

Agar↗
PubMed1981

Somatostatin and gastrin release into the gastric lumen in rats.

Somatostatin and gastrin release into the gastric lumen was investigated in anaesthetized, vagally intact rats. The stomach was perfused at a flow rate of 0.5 mL.min-1. During perfusion with 0.1 M HCl or buffers of varying pH the somatostatin ans gastrin concentrations in the perfusate were less than 10 pg.mL -1 and approximately 30 pg.mL-1, respectively. Peptone caused a gastrin concentrations in the perfusate were less than 10 pg.mL-1 and approximately 30 pg.mL-1, respectively. Peptone caused a slight pH-independent increase in somatostatin release; gastrin release was unchanged despite an increase in serum gastrin from a basal of 15 +/- 4 to 155 +/- 34 pg.mL-1 during peptone stimulation. intravenous infusion of carbachol (1 microgram.kg-1.min-1) strongly stimulated luminal somatostatin and gastrin release (from 5 +/- 1 to 192 +/- 52 pg.mL-1 and from 27 +/- 5 to 198 +/- 41 pg.mL-1, respectively) during perfusion with 0.1 M HCl. Phosphate buffer perfusion at pH 7.5 abolished the cholinergic-mediated somatostatin release but the gastrin response was unaffected. It is suggested that changes of luminal hormone concentrations in the rat stomach do not reflect the secretory activity of the endocrine cells in the gastric mucosa.

Animals↗
PubMed1997

Role of vagus nerves and gastrin in the gastric phase of acid secretion in male anesthetized rats.

We used the pylorus ligation model to determine the role of vagus nerves and gastrin in acid secretion induced by mechanical and chemical stimulation of the gastric lumen in anesthetized male rats. Gastric distension induced by intragastric instillation of saline resulted in a 17-fold increase in acid secretion over the basal level without an alteration in serum gastrin levels. Distension-stimulated acid secretion was inhibited by bilateral subdiaphragmatic vagotomy but not by CI-988, a gastrin receptor antagonist. Intragastric peptone produced a 71-fold increase in acid secretion over the basal level that was accompanied by a significant increase in serum gastrin levels. Whereas vagotomy almost abolished peptone-stimulated acid secretion, CI-988 inhibited peptone-stimulated acid secretion by only 50%. We conclude that the vagus nerves mediate acid secretion by mechanical and chemical stimulation and that gastrin mediates acid secretion partly by chemical stimulation but not by mechanical stimulation in anesthetized male rats.

Animals↗