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Biomedical subjects

E H Marth

Publications and source records attributed to E H Marth.

At least 55 records · Page 3Linked to original sources
PubMed1978

Aflatoxin is degraded by mycelia from toxigenic and nontoxigenic strains of aspergilli grown on different substrates.

The ability of 9-day-old mycelia of Aspergillus parasiticus NRRL 2999 to degrade aflatoxin varied depending on the substrate used to grow the mold. Substrates which allowed substantial mycelial growth yielded mycelia which actively degraded aflatoxin. Substrates which allowed minimal growth of mycelia yielded mycelia with little ability to degrade aflatoxin. Biodegradation of aflatoxin was also strain-dependent. A. parasiticus NRRL 2999 and NRRL 3000 actively degraded aflatoxin, A. flavus NRRL 3353 was less active, and A. flavus NRRL 482 and A. parasiticus NRRL 3315 degraded minimal amounts of aflatoxins. Those aspergilli producing greatest amounts of aflatoxin also degraded aflatoxins most rapidly, whereas those strains which produced minimal amounts of aflatoxin generally degraded aflatoxins less effectively. Substrates which allowed maximum aflatoxin production also yielded mycelia which actively degraded aflatoxins, whereas media which allowed limited production of aflatoxin generally yielded mycelia with minimal ability to degrade the toxin. Although exceptions exist, generally as aflatoxin production increased so did the ability of mycelia to degrade the toxin.

Aflatoxins↗
PubMed1978

Aflatoxin at several initial concentrations is degraded by different amounts of mycelium of Aspergillus parasiticus.

Increasing amounts of a blendure of 9-day-old mycelia of Aspergillus parasiticus NRRL 2999 added to aflatoxin-salts reaction mixtures resulted in increased rates at which aflatoxin B1 and G1 were degraded. Similarly, increasing the amount(s) of aflatoxin B1 and/or G1 in the aflatoxin-salts reaction mixture resulted in increased rates of degradation of aflatoxins B1 and G1 by mycelia. This mycelial blendure degraded aflatoxin G1 approximately 1.6 times more rapidly than aflatoxin B1 when comparable amounts of the aflatoxins were initially present. When the same mycelial blendure was used to compared combined effects of size of inoculum and initial aflatoxin concentration on aflatoxin degradation, it appeared that increasing the amount of either inoculum or aflatoxin resulted in a comparable increase in degradation of aflatoxin B1 and G1. Hence, doubling the amount of inoculum or of aflatoxin resulted in approximately doubled rates at which aflatoxins B1 and G1 were degraded.

Aflatoxins↗
PubMed1978

Degradation of aflatoxin by lactoperoxidase.

Three concentrations of lactoperoxidase, 5, 50, and 500 units/ml of reaction mixture, degraded aflatoxin in the presence of 225 micrometer NaCl and 50 micrometer H2O2 at 28 degrees C. Increasing the amount of lactoperoxidase from 50 to 500 units/ml of reaction mixture resulted in increasing the rate of degradation of aflatoxin B1 from 3.6 to 5.1%/24 h. When comparable amounts of lactoperoxidase were present, aflatoxin G1 was degraded approximately 1.5 times faster than was aflatoxin B1. At a given concentration of lactoperoxidase, aflatoxin degradation was independent of initial aflatoxin concentration. Derivatives that cochromatographed with aflatoxin B2a and derivatives that were water soluble were the major degradation products of aflatoxin B1. Similar derivatives, but in greater proportions, were noted as degradation products that resulted from activity of a blendure of mycelia of Aspergillus parasiticus.

Aflatoxins↗
PubMed1978

Incorporation of labeled small molecules into rubratoxin.

A sterile glucose-mineral salts broth was inoculated with conidia of Penicillium rubrum P-13 and P-3290. Radiolabeled compounds were added to some cultures, these being incubated quiescently at 28 degrees C for 14 days. Other stationary cultures were grown for 21 days, received labeled compounds, and were then grown for 5 more days. The remaining cultures were inoculated with 72-h-old mycelial pellets, received labeled materials and were incubated with shaking for 60 h. Rubratoxin was resolved by thin-layer chromatography. Labeled [1(14)C]acetate, [1,5(14)C]citrate, [2(14)C]malonate, [1(14)C]glucose, [U14C]glucose or [1(14)C]hexanoate were incorporated into rubratoxins A and B by P. rubrum 3290 and into rubratoxin B by P. rubrum 13. Incorporation of [1(14)C]acetate and [2(14)C]malonate increased when exogenous unlabeled acetate, malonate, pyruvate, or phosphoenol-pyruvate was added. Acetate incorporation was influenced by cultural conditions, attaining maximum amounts in quiescent cultures which received labeled acetate after 21 days of incubation. Acetate incorporation in shake cultures was enhanced by reduced nicotinamide adenine dinucleotide phosphate (NADPH) and by unlabeled exogenous citrate.

Acetates↗
PubMed1977

Aflatoxin production by Aspergillus parasiticus in a competitive environment.

Aspergillus parasiticus NRRL 2999 was grown in the presence of Rhizopus nigricans, Saccharomyces cerevisiae, Acetobacter aceti, or Brevibacterium linens and aflatoxin concentration was determined after 3,5,7, and 10 days of incubation at 28C. R. nigricans and S. cerevisiae inhibited growth and aflatoxin production by A. parasiticus. B. linens caused slight inhibition and A. aceti stimulated growth and aflatoxin production by A. parasiticus.

Acetobacter↗
PubMed1977

Synthesis of macromolecules and rubratoxin by Penicillium rubrum.

The relationship between primary metabolism and biosynthesis of rubratoxin was studied with replacement cultures of Penicillium rubrum 3290. Synthesis of protein and RNA was measured by determining incorporation of [U14C]L-leucine and [2(14)C]-uridine into the respective components of the fungal biomass. Rubratoxin formation was measured by determining incorporation of [1(14)C]acetate into the toxin. Both protein and RNA were synthesized rapidly with synthesis increasing during 108 h of incubation and then decreasing rapidly. Rubratoxin formation increased up to 72 h, declined through 96 h, became maximal at 108 h, and then decreased rapidly. Cycloheximide, at 100 microgram/ml, moderately blocked accumulation of dry weight and protein synthesis by the mold; at 150 microgram/ml, cycloheximide completely blocked in vivo synthesis of protein. When cycloheximide was added to cultures after synthesis of toxin had begun, protein synthesis, but not toxin formation, was blocked. Inhibition of protein synthesis by cycloheximide was reversed by washing the drug out of mold cultures. Rubratoxin was formed throughout the incubation; a transitional phase, characteristic of secondary biosynthesis, was not observed.

Cycloheximide↗
PubMed1977

Production of aflatoxin by Aspergillus parasiticus NRRL-2999 during growth in the presence of curing salts.

Aspergillus parasiticus NRRL-2999 was inoculated into meat mixtures with curing salts and into yeast extractsucrose (YES) and sucrose-ammonium salts (SAS) broth with and without curing salts to determine if the presence of curing salts significantly affected growth and aflatoxin production by the mold. The effect of individual curing salts or curing salt mixtures on growth and toxin elaboration by the aspergillus was substrate dependent. When YES broth contained 100 ppm of NaNO2, 2% NaCl, or 1 or 2% NaCl plus 200 ppm of NaNO2 or 200 ppm of NaNO3, growth and/or aflatoxin production was depressed. Biosynthesis of aflatoxin B1 was enhanced by presence of 1 and 4% NaCl in YES broth. The SAS broth containing only NaCl or NaCl combined with nitrite or nitrate yielded less aflatoxin than did control broth or no aflatoxin at all. When compared to the control, an increase in growth and amount of aflatoxin occurred in SAS broth which contained 200 ppm of NaNO3. Sausages containing 100 and 200 ppm NaNO2 and no NaCl supported more mold growth and aflatoxin production than did control sausage with 3% NaCl and 100 ppm of NaNO2. Addition of 2 and 3% NaCl and no nitrite to sausage resulted in less aflatoxin than in control sausage.

Aflatoxins↗
PubMed1977

Production of aflatoxin B1 and G1 by Aspergillus parasiticus on silica gels.

Silica gels were prepared by acidifying alkaline silicate solutions with phosphoric or tartaric acid. Various combinations of glucose, sucrose, yeast extract, and salts were included in the gels an nutrients. Maximum production of aflatoxins B1 and G1 occurred when silica gel (0.4 to 0.5 cm deep in a petri dish) containing 20% sucrose and 2% yeast extract, and gelled with tartaric acid, was inoculated with approximately 120 to 12000 spores of Aspergillus parasiticus per plate; and plates were incubated at 28 degrees C for 10 days.

Aflatoxins↗
PubMed1977

Methods to purify and determine rubratoxins.

Rubratoxin were recovered from cultures of Penicillium rubrum after the mold grew in natural substrates, a semi-synthetic medium, and a glucosemineral salts broth. Substrates that contained rubratoxins were extracted with: diethyl ether, ethyl acetate-benzene, ethanol (100%), ethanol-acetone, acetonitrile, or diethyl ether with refluxing at 45 degrees C. Extracts were screened for rubratoxins by thin-layer chromatography. Some extracts were partially purified with a column of silicic acid using acetone as the eluant. Other extracts were purified (primarily removal of pigments) using columns of silica gel plus Celite and gradient solvent elution. Most rubratoxin B (1.9 mg/g or 0.77 mg/ml) was recovered when corn, rice, or glucose-salts broth were extracted successively with diethyl ether, ethyl acetate-benzene, and diethyl ether or when samples were adjusted to pH 1.5 before refluxing with diethyl ether at 45 degrees C for 1--4h. Most rubratoxin A (0.1--0.15 mg/ml or 1.0 mg/g) was obtained from samples of corn extracted twice each with ethyl alcohol, acetone, and ethyl acetate; from glucose-mineral salts broth extracted with diethyl ether; or from yeast extract sucrose broth extracted with diethyl ether and refluxed for 4 h at 45 degrees C. Large amounts of fairly pure rubratoxin A (up to 400 mg) and rubratoxin B (greater than lg) were obtained with a combination of preparative thin-layer and column chromatography.

Chromatography, Thin Layer↗
PubMed1977

Bioproduction of rubratoxin in a glucose-mineral salts broth with nutritional supplements and metabolic inhibitors.

A sterile glucose-salts broth fortified with various metabolic inhibitors and nutritional supplements was inoculated with conidia of Penicillium rubrum P3290, and incubated quiescently at 28 degrees C for 14 days. Potassium sulfite and sodium metabisulfite at all test concentrations caused moderate reduction in rubratoxin formation; at high concentrations (greater than or equal to 2.7 X 10(-2)M) accumulation of fungal tissue was also retarded. Production of rubratoxin and cell mass was inhibited by p-aminobenzoic acid; syntheses of toxin were completely blocked by 7.5 X 10(-2)M of the vitamin. Effects of sodium fluoride on P. rubrum cultures grown on inorganic nitrogen sources varied from inhibition of mold growth and (or) rubratoxin A production to reduction in formation of rubratoxin B. With organic nitrogen sources, fluoride caused a 30 and 60% reduction in synthesis of rubratoxins A and B, respectively. Sodium acetate at all test concentrations enhanced formation of rubratoxin; mold growth was enhanced when acetate concentration was larger than or equal to 6.0 X 10(-2)M. A moderate reduction in mold growth was caused by lower acetate concentrations (1.2 X 10(-2)M or 2.4 X 10(-2)M). Sodium arsenite and iodoacetate at test concentrations blocked mold growth and toxin formation; sodium azide and 2,4-dinitrophenol caused a marked reduction in mold growth but inhibited toxin formation completely. However, sodium azide permitted slight growth and toxin formation when mold cultures were incubated for 28 days.

4-Aminobenzoic Acid↗
PubMed1976

Growth and synthesis of rubratoxin by Penicillium rubrum in a chemically defined medium fortified with organic acids and intermediates of the tricarboxylic acid cycle.

A sterile glucose-mineral salts broth was fortified with equimolar concentrations (10--3 M) of various organic acids and intermediates in the tricarboxylic acid cycle. Appropriate media were neutralized with 2 N NaOH, inoculated with spore suspensions or mycelial pellets of Penicillium rubrum and incubated quiescently for 14 days or with shaking for 5 days. Rubratoxins were recovered from culture filtrates by ether extraction and resolved by thin-layer chromatography. Toxin formation in quiescent cultures was enhanced by malonate but was not markedly affected by ethyl malonate, shikimate, and acetate or by isocitrate or oxaloacetate added in the presence of malonate. Citrate, cis-aconitate, alpha-ketoglutarate, succinate, fumarate, and malonate when present in the medium alone or in conjunction with malonate caused a 15 to 50% reduction in rubratoxin formation. Acetyl-CoA (10--5 M/flask) caused an 80% increase in toxin yield. Rubratoxin formation in shake cultures was not affected by succinate and malonate. All other combinations of intermediates and malonate caused a 10 to 50% reduction in toxin formation. At 10--3 M, citrate enhanced rubratoxin B formation and stimulated rubratoxin A production by as much as 100%. Above 10--3 M, citrate inhibited toxin production. Incorporation of [2-14C]acetate into rubratoxin was enhanced by malonate, fumarate, and malonate. A combination of pyruvate and malonate produced a 40% increase in [2-14C]acetate incorporation into rubratoxin. The highest reduction of labeled acetate incorporation (36%) was caused by succinate or alpha-ketoglutarate combined with malonate.

Acetates↗
PubMed1976

Inhibition of growth and aflatoxin production of Aspergillus parasiticus by citrus oils.

Aspergillus parasiticus was inoculated into grapefruit juice and a glucose-yeast extract medium; both contained 500-7000 ppm of citrus oils that were incorporated into the media by sonication. Orange and lemon oil were more inhibitory to mold growth and aflatoxin production than was dlimonene, the main constituent of the two peel oils. After 7 days at 28 degrees C, 2000 ppm of lemon and 3000 ppm of orange oil in grapefruit juice afforded maximum suppression of mold growth and toxin formation. When the glucose-yeast extract medium was used, 3000 ppm of either oil were needed to achieve the same result. After 4 days at 28 degrees C, orange oil at 3500 ppm in either medium markedly inhibited mold growth (as evidenced by dry weight of mold mycelium) and aflatoxin production (only 14 and 1% of the amount normally produced in the juice and artificial medium, respectively). Higher concentrations of orange oil further reduced mold growth and aflatoxin production and also delayed the onset of sporulation, if it occurred. Although aflatoxin was detected in all samples, only 0.2 to 0.5% of the amount found in controls (without the citrus oil) was present when the medium contained 7000 ppm orange oil. The mold consistently grew, albeit very poorly, on the glass at the liquid-atmosphere interface even when the substrate contained a large amount of citrus oil.

Aflatoxins↗
PubMed1976

Radioactivity in urine and feces of mink (Mustela vison) treated with [14C] aflatoxin B1.

Excretion of radioactivity by mink (Mustela vison) during 7 days after intraperitoneal injection of two different amounts of aflatoxin B1 was studied. Male mink that received a single dose of 25 mug aflatoxin B1/kg body weight excreted an average of 89.5% of administered radioactivity (56.8% via feces, 32.7% via urine); whereas female mink excreted an average of 85% (63.6% via feces, 21.4% via urine) of administered radioactivity during the 7-day period. Male and female mink given 150 mug aflatoxin B1/kg body weight excreted an average of 76.9-80.1% of administered radioactivity during the 7 days that followed treatment with toxin. These mink excreted somewhat more of the administered radioactivity in their urine than did the mink that received the lower dose of aflatoxin (37.2 vs. 32.7% for males and 32.7 vs. 21.4% for females). Regardless of sex and dosage of toxin, most of the radioactivity ultimately excreted either through feces or urine appeared in the first 24 h after toxin was administered to mink.

Aflatoxins↗
PubMed1976

Distribution of aflatoxin B1 in tissues of mink (Mustela vison).

Seven female mink (Mustela vison) were injected intraperitoneally with a single dose of 100 mug aflatoxin B1 (14 C-label and unabeled). They were sacrificed 1, 2, 4, and 24 h after dosing. Liver, instestines, stomach, lung, kidney, brain, pancrease, spleen, urinary bladder, uterus, and bile were removed and examined for the retained radioactivity. 1 h after dosing, intestines and their contents retained the largest amount of 14C-radioacivity (18.9% of the amount that was administered) which was followed by liver (13.2%) and the bile (10.8%). At this time all other tissues retained less than 1% of the administered radioactivity. Generally, the amount of radioactivity retained in all tissues declined with time. Only 1.2 and 0.6% of the administered radioactivity was found in testines and bile, respectively, 24 h after dosing; however, the liver still contained 6.6% of the initial radioactivity. Examination of subcellular fractions of liver revealed that at all time intervals most of the radioactivity was associated with the micrososmal supernatant fluid.

Aflatoxins↗
PubMed1976

Silica gel medium to detect molds that produce aflatoxin.

A chemically defined nutrient solution containing tartaric acid was made solid by mixing it with an alkaline silicate solution. Production of aflatoxin by asperfilli growing on the silica gel medium coincided with the presence of a blue fluorescent area surrounding colonies, as observed under long-wave ultraviolet light. Presence of aflatoxin in the medium was confirmed by drying the gels, extracting them with chloroform-methanol, and examining extracts for fluorescent materials by viewing them on thin-layer chromatograms under ultraviolet light.

Aflatoxins↗
PubMed1976

Experimental acute aflatoxicosis in mink (Mustela vison).

Susceptibility of mink to intoxication by aflatoxins was studied by giving mink single doses (300, 600, and 900 mug of aflatoxins B1 and G1 (40:60)/kg of body weight) and observing them for 8 weeks. One, 2, and 4 of 5 mink in each group died within 4 days after ingesting the small, medium, and large doses, respectively. Enlarged liver with pale yellow to yellowish pink spots was the most consistent lesion observed in mink that died of acute aflatoxicosis. Some lobules of liver also appeared hemorrhagic and fragile, whereas others showed fatty metamorphosis. Histopathologic examination of the liver showed different degrees of fat infiltration, bile duct proliferation, and necrosis of liver cells. Hematologically, mink that survived were not appreciably different from control mink in terms of hemoglobin content, packed cell volume, and white blood cell count. Liver specimen from aflatoxin-treated mink contained more fat, was larger, and contained less protein, RNA and DNA than did liver from control mink. Aflatoxin residue (only B1 ) was recovered from liver of 6 mink and were between 0.1 and 7.6 mug of the original dose.

Animals↗
PubMed1976

Mortality and some biochemical changes in mink (Mustela vison) given sublethal doses of aflatoxin each day.

Two feeding trials were done to study the susceptibility of mink (Mustela vison) to multiple sublethal doses of aflatoxins. In the 1st trial, twenty 3-month-old male mink were divided equally among groups. Each mink in groups 1, 2, 3, and 4 was given a meatball daily that contained 15, 30, 45, or 0 mug of aflatoxins (B1:G1, 40:60), respectively. All mink in group 3 died between the 25th and the 30th days of the feeding trial. Each mink had ingested 1,035 to 1,480 mug of aflatoxins. Four of the mink in group 2 died almost as soon as did mink in group 3. Four mink in group 1 died between 40 and 59 days after the start of the feeding trial. Generally, a marked increase in plasma cholesterol and alkaline phosphatase activity appeared before mink died. The liver from animals that died of aflatoxicosis showed prominent pathologic changes which included hemorrhages and appearance of pink yellow spots. Histopathologic examination of liver from dead mink revealed fatty infiltration, bile duct proliferation, bile stasis, pseudotubular formation, congestion, and fibrosis. The feeding trial was repeated with 20 mink (8 males and 12 females) that were 1.5 to 2 years old. In this instance, 0, 20, 40, and 60 mug of aflatoxins were administered each day. All treated animals, except 1, were dead within 37 days after the experiment started. The survivor was given the lowest dosage of toxins and died after 52 days by which time 960 mug of aflatoxins were consumed. Plasma cholesterol content and alkaline phosphatase activity generally were similar to those observed in younger mink of the 1st feeding trial.

Aflatoxins↗