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At least 1,099 records · Page 61Linked to original sources
PubMed1999

Effect of the addition of fumarate on methane production by ruminal microorganisms in vitro.

The effect of fumarate used as a feed additive on the reduction of methanogenesis in the rumen was evaluated by in vitro experiments. The addition of fumarate to the culture of mixed ruminal microorganisms that were fermenting hay powder and concentrate reduced methane production. Most fumarate was metabolized to propionate, and a slight increase was noted in other volatile fatty acids. Fumarate was utilized by mixed bacteria but not by mixed protozoa. Fibrobacter succinogenes, Selenomonas ruminantium ssp. ruminantium, Selenomonas ruminantium ssp. lactilytica, Veillonella parvula, and Wollinella succinogenes oxidized H2 by using fumarate as a final electron acceptor, suggesting that these bacteria compete with methanogens for H2, which is the main substrate for methanogenesis in the rumen. However, the affinity of these bacteria to H2 was lower than their affinity to methanogens. These fumarate-utilizing bacteria metabolized malate to products that were similar to those from fumarate, suggesting the possession of fumarate dehydratase. Fibrobacter succinogenes, V. parvula, and W. succinogenes utilized formate, another substrate for methanogenesis, as an electron donor for fumarate reduction. The affinity of these bacteria to formate was higher than the affinity methanogenes have for formate. When methanogens were cocultured with an equal cellular amount of each of the fumarate-utilizing bacteria, methane production was markedly decreased, not only from formate, but also from H2. These results suggest that the addition of fumarate to ruminant feed reduces methanogenesis and enhances propionate production in the rumen.

Adenosine Triphosphate↗
PubMed1987

Antitumor effect of kazusamycin B on experimental tumors.

Kazusamycin B, a novel antibiotic (MW 542) isolated from fermentation broth of Streptomyces sp. No. 81-484 showed a broad antitumor spectrum both in vitro and in vivo. IC50 against the growth of tumor cells was around 1 ng/ml at 72 hours-exposure in vitro. Intraperitoneal injection of the antibiotic was effective in inhibiting the growth of murine tumors, S180, P388, EL-4, and B16. It was also active against doxorubicin-resistant P388, hepatic metastases of L5178Y-ML, pulmonary metastases of 3LL, and human mammary cancer MX-1 xenografted to nude mice. However, the activity of kazusamycin B toward L1210 or human lung cancer LX-1 was weaker. According to the results of comparative studies on the effect of kazusamycins B and A, an analog of B, there seemed to be no significant difference in their effectiveness. The effective dose range and toxicity were markedly dependent on tumor lines tested and the regimen used. Maximum tolerated dose in mice with subcutaneous tumors was much higher than that in mice bearing ascitic leukemia as P388. Although intermittent administration could greatly reduce the cumulative toxicity of the drug, therapeutic effect was similar with both successive and intermittent administration schedules.

Animals↗
PubMed2001

TMC-69, a new antitumor antibiotic with Cdc25A inhibitory activity, produced by Chrysosporium sp. TC1068. Taxonomy, fermentation and biological activities.

A new antibiotic designated TMC-69 has been isolated from the fermentation broth of a fungal strain Chrysosporium sp. TC 1068. TMC-69 exhibited moderate in vitro cytotoxic activity. TMC-69-6H, a derivative of TMC-69 prepared by hydrogenation, possessed more potent in vitro cytotoxicity than TMC-69, and exhibited in vivo antitumor activity against murine P388 leukemia and B16 melanoma. TMC-69-6H was found to specifically inhibit Cdc25A and B phosphatases.

Animals↗
PubMed2001

SW-163A and B, novel immunosuppressants produced by Streptomyces sp.

SW-163A and B, novel immunosuppressants, were isolated from the culture broth of Streptomyces sp. SNA15896. The molecular formulas of SW-163A and B were determined as C34H42N2O12 and C33H40N2O12 based on the HRFAB-MS analysis, respectively. Both compounds were elucidated to be a large ring ester structure through spectroscopic analyses including various NMR measurements. SW-163A and B showed immunosuppressive and antimicrobial activities in vitro.

Amino Acids↗
PubMed2005

[The effect of short-chain fatty acids on expression of endothelial adhesion molecules stimulated by oxidatively modified LDL].

INTRODUCTION: Adhesion and migration of mononuclear leukocytes into the vascular wall is a crucial step in atherogenesis. Expression of cell adhesion molecules by endothelial cells plays a leading role in this process. Natural short-chain fatty acids produced by bacterial fermentation of dietary fiber have been attributed with antiatherogenic properties. MATERIAL AND METHODS: This in vitro study has been conceived in an attempt to shed light on the mechanisms responsible for the modulatory effect of short-chain fatty acids in atherogenesis. The following conclusions have been drawn. Butyrate and propionate are selective inhibitors of ox-LDL-stimulated VCAM-1 and ICAM-1 expression with a mechanism of action involving reduced protein and specific mRNA production through inhibition of NF-kappaB activation. Suppressed expression of VCAM-1 and ICAM-1 was associated with reduced adherence of monocytes and lymphocytes to ox-LDL stimulated endothelial cells. RESULTS: Butyrate and propionate may have anti-inflammatory and antiatherogenic properties partly attributable to an inhibitory effect on NF-kappaB activation.

Atherosclerosis↗
PubMed1988

The caries inhibitory effects of GOS-sugar in vitro and in rat experiments.

The caries inhibitory activity of GOS-sugar (panose- and maltose-rich sugar mixture) was examined and compared with that of sucrose, maltose, or glucose in in vitro and in vivo experiments. Streptococcus mutans MT8148R (serotype c) and Streptococcus sobrinus 6715 (g) did ferment GOS-sugar and produce acid in a similar way as with maltose and glucose. However, GOS-sugar could not be a substrate for the glucosyltransferases (GTases) of these mutans streptococci to synthesize the water-insoluble glucan. Also, it significantly inhibited not only the synthesis of water-insoluble glucan from sucrose by the crude GTases but also the sucrose-dependent adherence of these cells to a glass surface. In particular, adherence of growing cells of 6715 was markedly inhibited by the presence of GOS-sugar. GOS-sugar was found to induce significant but minimal dental caries in SPF rats infected with either MT8148R or 6715. Furthermore, the replacement of half of the dietary sucrose content with GOS-sugar resulted in a significant reduction of caries development in rats infected with strain 6715.

Animals↗
PubMed1991

[The course of rumen fermentation during alkalosis in cows].

The aim of the study was the investigation of rumen fermentation during alkalosis in cows. The study comprised some parameters of rumen fermentation, such as: pH, ammonia and volatile fatty acids (VFA) levels, also relationship between VFA, numbers of population of protozoa and bacteria, total production of gases in vitro particularly CO2 and CH4, amounts of lactic and total protein in rumen fluid and non-glucogenic/glucogenic ratio (NGGR) in the VFA mixture. On the basis of obtained results the amounts of fermented hexose, cell yield, ATP produced and hydrogen utilization were calculated. During alkalosis there was observed significant fall of VFA production, especially acetic and butyric acids, also lower production of gases, particularly CH4--probably as a result of selective reduction of methanogenic strain bacteria. The levelling of value of rumen pattern of fermentation occurred after the beginning of lactation probably as a result of metabolism products excretion together with milk.

Acetates↗
PubMed1984

An immobilized microbial heparinase for blood deheparinization.

A new medical application of an immobilized microbial enzyme is described. Extracorporeal devices require systemic heparin administration to prevent thrombus formation; however, the use of heparin often leads to serious hemorrhagic complications. Heparinase isolated from Flavobacterium has been immobilized and used in a fluidized bed reactor to eliminate heparin from blood passing through an extracorporeal circuit both in vitro and in vivo. This paper discusses the stepwise development of this heparinase reactor including: (1) improvements in the fermentation resulting in an inexpensive large-scale source of heparinase without the addition of the previously required inducer, heparin; (2) the use of batch processes to adapt previous purification schemes to large-scale heparinase production and the subsequent purification of heparinase to a single SDS-PAGE banding protein; (3) the immobilization of heparinase with a 91% activity recovery and good stability, (4) the design and successful testing of a fluidized bed reactor containing immobilized heparinase in the removal of clinically used quantities of heparin from both human blood in vitro and canine blood in vivo; and (5) the initiation of animal studies focusing on the toxicology of heparinase-derived heparin degradation products and the short and long term effects of exposure to these products and to heparinase.

Enzymes, Immobilized↗
PubMed2001

Administration of charcoal, Yucca schidigera, and zinc acetate to reduce malodorous flatulence in dogs.

OBJECTIVE: To determine whether feeding activated charcoal, Yucca schidigera, and zinc acetate would ameliorate the frequency and odor characteristics of flatulence in dogs. DESIGN: In vitro screening of active agents followed by a randomized controlled trial. ANIMALS: 8 adult dogs. PROCEDURE: A fecal fermentation system was used to assess the effects of activated charcoal, Yucca schidigera, and zinc acetate alone and in combination on total gas production and production of hydrogen sulfide, the primary determinant of flatus malodor in dogs. All 3 agents were subsequently incorporated into edible treats that were fed 30 minutes after the dogs ate their daily rations, and the number, frequency, and odor characteristics of flatulence were measured for 5 hours, using a device that sampled rectal gases and monitored hydrogen sulfide concentrations. RESULT: Total gas production and number and frequency of flatulence episodes were unaffected by any of the agents. Production of hydrogen sulfide in vitro was significantly reduced by charcoal, Yucca schidigera, and zinc acetate by 71, 38, and 58%, respectively, and was reduced by 86% by the combination of the 3 agents. Consumption of the 3 agents was associated with a significant decrease (86%) in the percentage of flatulence episodes with bad or unbearable odor and a proportional increase in the percentage of episodes of no or only slightly noticeable odor. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that activated charcoal, Yucca schidigera, and zinc acetate reduce malodor of flatus in dogs by altering the production or availability of hydrogen sulfide in the large intestine.

Animals↗
PubMed1994

Genetic evidence for independence between fermentative metabolism (ethanol accumulation) and yeast-cell development in the dimorphic fungus Mucor rouxii.

Three allyl-alcohol-resistant mutants were isolated in the dimorphic fungus Mucor rouxii and characterized with regard to their alcohol dehydrogenase (ADH) activity in vitro and in vivo as well as their ability to execute the morphological alternatives of dimorphism under different environmental stimuli, either in the absence or in the presence of oxygen. These studies indicated that fermentation and yeast-cell development are independent events and that ADH activity is essential for growth of the fungus in the absence of oxygen. Heterokaryon construction and analysis indicated that in the three mutant strains the corresponding genetic alterations are recessive nuclear mutations which behave as allelic in complementation tests.

Alcohol Dehydrogenase↗
PubMed1988

Influence of addition of yeast culture supplement to diets of lactating cows on ruminal fermentation and microbial populations.

Six ruminally fistulated Holstein cows were utilized in a randomized block design to examine effects of yeast culture supplement on ruminal metabolism and apparent digestibility. Cows were fed a diet of 40% corn silage and 60% concentrate (DM basis). Treatments were control (supplement without yeast cells) and yeast culture supplement. Treatment periods were 6 wk. Ruminal pH, ammonia, molar proportions of acetate and isovalerate, and acetate: propionate ratio were lower and molar proportions of propionate and valerate higher in cows receiving yeast. The concentration of anaerobic bacteria tended to be higher and cellulolytic bacteria concentrations were greater in cows fed yeast than in cows receiving control diet. Supplemental yeast did not affect molar proportions of isobutyrate or butyrate, total VFA, or viable yeast concentrations in ruminal fluid. Ruminal liquid dilution rate and total tract apparent digestibilities were not different between treatments. Rate of disappearance of cellulose in vitro was lower in cows receiving yeast. Less variation in ammonia concentrations and microbial numbers suggest that ruminal fermentation was more stable in cows receiving yeast culture supplement.

Animals↗
PubMed1994

Butyrate is a potent inhibitor of urokinase secretion by normal colonic epithelium in vitro.

BACKGROUND/AIMS: Because the neutral protease urokinase is important in control of cell adhesion and migration, the effects of the physiologically relevant fermentation product butyrate on urokinase secretion by colonic epithelium were examined. METHODS: Secreted and cell-associated levels of urokinase and plasminogen activator inhibitor 1 were measured in colonic crypt cells within 24 hours of isolation from macroscopically normal mucosa of normal or cancer-bearing colons. RESULTS: Butyrate caused a concentration-dependent inhibition of both secreted (56% +/- 4% inhibition after 24-hour exposure to 1 mmol/L butyrate; n = 20; mean +/- SEM; P < 0.001) and cell-associated urokinase content (35% +/- 6%; P = 0.003). Acetate and propionate had minimal effects. Butyrate also stimulated plasminogen activator inhibitor 1 secretion by 25% +/- 7% (P = 0.013). Net urokinase activities were suppressed in supernates and cell homogenates by butyrate. Levels of transcripts for urokinase and the inhibitor changed with butyrate exposure in parallel to the levels of secretion of the respective proteins. Cells from the cancer group showed significantly reduced inhibitor secretion and abnormal responses to butyrate (greater inhibition of urokinase secretion and no stimulation of inhibitor secretion), probably reflecting the diffuse disturbance of colonic epithelial biology associated with colorectal cancer. CONCLUSIONS: Butyrate has dual effects in markedly reducing colonic epithelial urokinase activity, and these may have important implications to understanding colonic epithelial physiology and the pathogenesis and treatment of colonic diseases.

Acetates↗
PubMed1994

Artificial fiber complexes composed of cellulose and guar gum or psyllium may be better sources of soluble fiber for rats than comparable fiber mixtures.

Three fiber complexes composed of cellulose and the same weight of guar gum, cornstarch or psyllium were constructed as three-dimensional networks of cellulose fiber filled with the soluble components. Physiological properties of these fiber complexes were examined in comparison with a mixture of powdered cellulose and the corresponding polysaccharides at a ratio of 1:1 in rats. Another group of rats was fed a fiber-free diet. Body weight gain in the guar gum-cellulose mixture group, but not in guar gum-cellulose complex group, was lower than that of the fiber-free group. The cecal walls in the groups fed the guar gum-cellulose and psyllium-cellulose mixture diets were heavier than those in the corresponding fiber complex-fed groups. Weights of the small intestinal wall and ileal mucosa were also greater in the guar gum-cellulose mixture-fed group than in the guar gum-cellulose complex-fed and the fiber-free diet-fed groups. Fermentable energy in dietary fiber estimated from fecal energy excretion, short-chain fatty acid contents and in vitro short-chain fatty acid production rates in the cecum of the complex-fed groups were similar to those in the fiber mixture-fed groups. However, butyric acid content and production rate in the group fed the guar gum-cellulose complex were markedly higher than in the other groups. The lowering effects of guar gum-cellulose and psyllium-cellulose mixtures on plasma cholesterol concentration tended to be greater than those of guar gum-cellulose and psyllium-cellulose complexes. These findings demonstrate that the artificial fiber complexes supply soluble fibers without increasing mechanical stress to the intestines and decreasing cecal fermentation.

Animals↗
PubMed1999

Influence of peptides and amino acids on fermentation rate and de novo synthesis of amino acids by mixed micro-organisms from the sheep rumen.

The influence of different N sources on fermentation rate and de novo amino acid synthesis by rumen micro-organisms was investigated in vitro using rumen fluid taken from four sheep receiving a mixed diet comprising (g/kg DM): grass hay 500, barley 299.5, molasses 100, fish meal 91, minerals and vitamins 9.5. Pancreatic casein hydrolysate (P; comprising mainly peptides with some free amino acids; 10 g/l), free amino acids (AA; casein acid hydrolysate + added cysteine and tryptophan; 10 g/l), or a mixture of L-proline, glycine, L-valine and L-threonine (M; 0.83 g/l each) were added to diluted (1:3, v/v), strained rumen fluid along with 15NH4Cl (A; 1.33 g/l) and 6.7 g/l of a mixture of starch, cellobiose and xylose (1:1:1, by weight). P and AA, but not M, stimulated net gas production after 4 and 8 h incubation (P < 0.05) in comparison with A alone. P increased microbial-protein synthesis (P < 0.05) compared with the other treatments. All of the microbial-N formed after 10 h was synthesized de novo from 15NH3 in treatment A, and the addition of pre-formed amino acids decreased the proportion to 0.37, 0.55, and 0.86 for P, AA, and M respectively. De novo synthesis of amino acids (0.29, 0.42 and 0.69 respectively) was lower than cell-N. Enrichment of alanine, glutamate and aspartate was slightly higher than that of other amino acids, while enrichment in proline was much lower, such that 0.83-0.95 of all proline incorporated into particulate matter was derived from pre-formed proline. Glycine, methionine, lysine, valine and threonine tended to be less enriched than other amino acids. The form in which the amino acids were supplied, as P or AA, had little influence on the pattern of de novo synthesis. When the concentration of peptides was decreased, the proportion of microbial-N formed from NH3 increased, so that at an initial concentration of 1 g peptides/l, similar to the highest reported ruminal peptide concentrations, 0.68 of cell-N was formed from NH3. Decreasing the NH3 concentration at 1.0 g peptides/l caused proportionate decreases in the fraction of cell-N derived from NH3, from 0.81 at 0.53 g NH3-N/l to 0.40 at 0.19 g NH3-N/l. It was concluded that different individual amino acids are synthesized de novo to different extents by mixed rumen micro-organisms when pre-formed amino acids are present, and that the source of N used for synthesis of cell-N and amino acids depends on the respective concentrations of the different N sources available; however, supplementing only with amino acids whose synthesis is lowest when pre-formed amino acids are present does not stimulate fermentation or microbial growth.

Amino Acids↗
PubMed1985

Mutations that alter the allosteric nature of cAMP receptor protein of Escherichia coli.

Mutations which permit cAMP binding protein (CRP) to act in the absence of cAMP have been isolated by in vitro mutagenesis of a plasmid containing the cloned crp gene. Adenylate cyclase deficient cells harbouring the mutant (crp*) plasmids exhibited a variety of fermentation profiles on MacConkey indicator plates containing various sugars. beta-galactosidase synthesis in cells carrying the crp* plasmids was activated most by the addition of cGMP as well as cAMP. The sites of mutations which are responsible for the cAMP independent phenotype were determined by in vitro recombination and DNA sequencing. The amino acid substitutions in the mutant proteins were found in two specific regions of the crp gene encoding residues 53-62 and 141-148 of CRP polypeptide. The first region may participate in cAMP binding, while the second appears to be the inter-domain region of the N-terminal cAMP-binding and C-terminal DNA-binding domains.

Alleles↗
PubMed2003

Variability in polyene content and cellular toxicity among deoxycholate amphotericin B formulations.

STUDY OBJECTIVE: To evaluate the toxicity of amphotericin B deoxycholate formulations. DESIGN: In vitro experiment. SETTING: University research center. MATERIAL: Human mononuclear THP-1 cells. INTERVENTION: The human mononuclear cells were exposed in vitro for 2 hours to the following deoxycholate formulations of amphotericin B, in 2.5- and 5-micro/ml concentrations: Apothecon, Pharmacia, Sigma, Gensia, Pharma-Tek, and VHA. MEASUREMENTS AND MAIN RESULTS: Toxicity of the amphotericin B formulations were assessed by measuring interleukin (IL)-1beta expression in an in vitro model. Amphotericin B content was measured by enzyme-linked immunosorbent assay (ELISA), and amphotericin A and B contents were assessed by spectrophotometry. Endotoxin contamination was evaluated in all reagents. Expression of IL-1beta from Sigma, Pharmacia, and Pharma-Tek formulations was increased approximately 250%, 50%, and 25%, respectively, compared with amphotericin A. Amphotericin B content of Sigma, Pharmacia, Pharma-Tek, and Gensia formulations, as measured by ELISA, was increased approximately 450%, 200%, 200%, and 100%, respectively, compared with Apothecon. This variation could not be explained by differences in amphotericin A or B content as measured by spectrophotometry. CONCLUSION: Amphotericin B is obtained from a fermentation plant and manufactured as a pharmaceutical at different facilities. Both previous clinical observations and the current in vitro evaluation revealed significant differences among the formulations. Likely, other polyenes or pyrogenic toxins in differing amounts are in these formulations, thus explaining the variability in toxicity observed among the formulations.

Amphotericin B↗
PubMed1982

Synthesis and characterization of a novel inhibitor of an aminoglycoside-inactivating enzyme.

A novel low-molecular weight inhibitor of an aminoglycoside-inactivating enzyme, initially isolated from fermentation broths of Streptomyces neyagawaensis, was determined to be 7-hydroxytropolone. Its structure was confirmed by synthesis. In vitro synergy was demonstrated between 7-hydroxytropolone and certain aminoglycosides against bacteria which were resistant to those aminoglycosides by virtue of a 2"-O-adenylyltransferase. The synthesis and characterization of some analogs of 7-hydroxytropolone is also described.

Anti-Bacterial Agents↗