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At least 1,441 records · Page 80Linked to original sources
PubMed2005

Cutinase-like enzyme from the yeast Cryptococcus sp. strain S-2 hydrolyzes polylactic acid and other biodegradable plastics.

A purified lipase from the yeast Cryptococcus sp. strain S-2 exhibited remote homology to proteins belonging to the cutinase family rather than to lipases. This enzyme could effectively degrade the high-molecular-weight compound polylactic acid, as well as other biodegradable plastics, including polybutylene succinate, poly (epsilon-caprolactone), and poly(3-hydroxybutyrate).

Amino Acid Sequence↗
PubMed2005

Identification of 9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid, 4-hydroxy-2-oxohexanoic acid, and 2-hydroxyhexa-2,4-dienoic acid and related enzymes involved in testosterone degradation in Comamonas testosteroni TA441.

Comamonas testosteroni TA441 utilizes testosterone via aromatization of the A ring followed by meta-cleavage of the ring. The product of the meta-cleavage reaction, 4,5-9,10-diseco-3-hydroxy-5,9,17-trioxoandrosta-1(10),2-dien-4-oic acid, is degraded by a hydrolase, TesD. We directly isolated and identified two products of TesD as 9,17-dioxo-1,2,3,4,10,19-hexanorandrostan-5-oic acid and (2Z,4Z)-2-hydroxyhexa-2,4-dienoic acid. The latter was a pure 4Z isomer. 2-Hydroxyhexa-2,4-dienoic acid was converted by a hydratase, TesE, and the product isolated from the reaction solution was identified as 2-hydroxy-4-hex-2-enolactone, indicating the direct product of TesE to be 4-hydroxy-2-oxohexanoic acid.

Bacterial Proteins↗
PubMed1967

Decarboxylation of alpha-keto acids by Streptococcus lactis var. maltigenes.

Decarboxylation rates for a series of C-3 to C-6 alpha-keto acids were determined in the presence of resting cells and cell-free extracts of Streptococcus lactis var. maltigenes. The C-5 and C-6 acids branched at the penultimate carbon atom were converted most rapidly to the respective aldehydes in the manner described for alpha-carboxylases. Pyruvate and alpha-ketobutyrate did not behave as alpha-carboxylase substrates, in that O(2) was absorbed when they were reacted with resting cells. The same effect with pyruvate was noted in a nonmalty S. lactis, accounting for CO(2) produced by some "homofermentative" streptococci. Mixed substrate reactions indicated that the same enzyme was responsible for decarboxylation of alpha-ketoisocaproate and alpha-ketoisovalerate, but it appeared unlikely that this enzyme was responsible for the decarboxylation of pyruvate. Ultrasonic disruption of cells of the malty culture resulted in an extract inactive for decarboxylation of pyruvate in the absence of ferricyanide. Dialyzed cell-free extracts were inactive against all keto acids and could not be reactivated.

Butyrates↗
PubMed1968

Direct quantitative gas chromatographic separation of C2-C6 fatty acids, methanol, and ethyl alcohol in aqueous microbial fermentation media.

A method is described for the direct quantitative gas chromatographic separation of C(2)-C(6) lower fatty acid homologues, methanol, and ethyl alcohol in aqueous microbial fermentation media. A hydrogen flame detector and a single-phase solid column packing, comprising beads of a polyaromatic resin (polystyrene cross-linked with divinyl benzene), were employed. Direct injections of 1 to 10 muliters of aqueous culture supernatant fluids were made. Quantitative recoveries of C(2)-C(6) acids added to culture supernatant fluids were obtained.

Acetates↗
PubMed1969

Ester production by Pseudomonas fragi. II. Factors influencing ester levels in milk cultures.

Cultures of Pseudomonas fragi were grown at 21 C in sterile homogenized milk and reconstituted skim milk media supplemented with ethyl alcohol. Quantitative determinations of ethyl butyrate and ethyl hexanoate by gas-liquid chromatography showed definite increases in the concentrations of the two esters produced in these media in comparison to media not supplemented with ethyl alcohol. Supplementation with butyric acid in addition to ethyl alcohol generally elevated the ethyl butyrate concentration and usually depressed the cell count slightly. Aeration of any of the media during growth tended to reduce the cell population slightly. A relationship between increase in cell number and increase in concentration of esters during the growth of the culture was observed. Media containing high concentrations of ethyl alcohol plus milk fat or low-molecular-weight fatty acids were conducive to the production of a fruity aroma by P. fragi.

Animals↗
PubMed1969

In vitro antiviral activity of mycophenolic acid and its reversal by guanine-type compounds.

With the agar diffusion test and BS-C-1 cells, mycophenolic acid was found to give a straight-line dose-response activity in inhibiting the cytopathic effects of vaccinia, herpes simplex, and measles viruses. Plaque tests have shown 100% reduction of virus plaques by mycophenolic acid over drug ranges of 10 to 50 mug/ml and virus input as high as 6,000 plaque-forming units (PFU) per flask. Back titration studies with measles virus inhibited by mycophenolic acid have indicated that extracellular virus titers were reduced by approximately 3 logs(10) and total virus was reduced by 1 log(10). The agar diffusion test system lends itself readily to drug reversal studies. Mycophenolic acid incorporated into agar at 10 mug/ml gave 100% protection to virus-infected cells. Filter paper discs impregnated with selected chemical agents at concentrations of 1,000 mug/ml (20 mug per filter paper disc) were placed on the agar surface. Reversal of the antiviral activity of mycophenolic acid was indicated by virus breakthrough in those cells in close proximity to the filter paper disc. Chemicals showing the best reversal of the antiviral activity of mycophenolic acid were guanine, guanosine, guanylic acid, deoxyguanylic acid, and 2,6-diaminopurine. The reversal of antiviral activity was confirmed by titrations of virus produced with various amounts of both mycophenolic acid and guanine present and by isotope tracer methods with uptakes of labeled uridine, guanine, leucine, and thymidine in treated and nontreated, infected and noninfected cells as parameters. All antiviral effects of mycophenolic acid at 10 mug/ml could be reversed to the range shown by untreated controls by the addition of 10 mug/ml of those chemicals exhibiting reversal activity.

Animals↗
PubMed1972

Potential production and detoxification of penicillic acid in mold-fermented sausage (salami).

About 10% of 346 Penicillium cultures isolated from mold-fermented sausage synthesized the toxic metabolite penicillic acid on liquid media. Five of these producing cultures inoculated onto sausage failed to produce this toxin in up to 70 days of ripening. Several amino acids normally occurring in meat (cysteine, glutathione, arginine, histidine, and lysine) were found capable of readily reacting with penicillic acid. The adducts formed by the reaction between cysteine or glutathione with penicillic acid were identified and found to be non-toxic to mice, quails, and in the rabbit skin test but exhibited toxicity to the chick embryo. Hypotheses accounting for this residual toxicity are advanced.

Alkylation↗
PubMed1972

Analysis of tobacco and smoke condensate for penicillic acid.

Gas chromatographic analyses of smoke condensate from commercial, unfiltered cigarettes spiked with penicillic acid (500 or 1,000 ppm), a reported carcinogenic substance from certain fungi, indicated approximately 3% of unchanged compound was transported in the smoke. Analysis of tobacco on which either Aspergillus ochraceus or Penicillium cyclopium was grown revealed microgram quantities of the compound. Small amounts of the material were also found in moldy tobacco from commercial storage. The results of these investigations suggest that fungi may be a source of carcinogenic compounds in tobacco and tobacco smoke.

Air Pollution↗
PubMed1972

Control of Penicillium martensii development and penicillic acid production by atmospheric gases and temperatures.

The effects of various gaseous environments and temperatures on development of Penicillium martensii NRRL 3612 and production of penicillic acid (PA) were determined. Accumulation of PA in mold-inoculated corn was measured following incubation under air; 20% CO(2), 20% O(2), 60% N(2); 40% CO(2), 20% O(2), 40% N(2); and 60% CO(2), 20% O(2), 20% N(2). Although reduced temperature initially inhibited PA production, at the end of the trial the largest quantity of PA (120 mug/g of corn) was found in air-incubated corn at the lowest test temperature (5 C). Atmospheres enriched with 60% CO(2) reduced PA accumulation below a detectable level at 5 and 10 C after a 4-week incubation period. Spore germination tests were carried out in a liquid growth medium incubated for 16 hr under several test conditions. Germ tube outgrowth at 30 C ranged from 36% in air to 2% in 60% CO(2), whereas no germination was observed in CO(2)-enriched gases at 10 C. When spore respiration rates were measured in air and O(2) in a liquid growth medium, complete removal of CO(2) from the reaction atmosphere did not reduce O(2) uptake.

Air↗
PubMed1973

Identification of the volatile compounds produced in sterile fish muscle (Sebastes melanops) by Pseudomonas fragi.

Volatile compounds produced by Pseudomonas fragi strain 18 in sterile fish muscle (Sebastes melanops) were identified by combined gas-liquid chromatography and mass spectrometry. Compounds positively identified included dimethyl sulfide, acetaldehyde, ethyl acetate, ethyl alcohol, and dimethyl disulfide. Methyl mercaptan, ethyl butyrate, ethyl hexanoate, and butanone were tentatively identified by relative retention times of the authentic compounds. The fruity odor that developed in fish muscle during incipient spoilage was attributed to a synergistic flavor interaction involving the ethyl esters of acetate, butyrate, and hexanoate.

Acetaldehyde↗
PubMed1973

Mycotoxin-producing strains of Penicillium viridicatum: classification into subgroups.

Fifty-two isolates of Penicillium viridicatum Westling were divided into three groups based on ability to produce ochratoxin and/or citrinin, color, growth rate, type of growth, odor, and isolation source. Members of group I resemble one of the representative strains of P. viridicatum described in the literature; those belonging to group II differ from group I strains in several characteristics; group III is a heterogeneous series of highly variable isolates. Although three subgroupings can be recognized, retention of all isolates in the species P. viridicatum is deemed most appropriate at this time. Spore macerates of all isolates were examined for virus-like particles but none were detected.

Caproates↗
PubMed1974

Paper chromatography as an adjunct in the identification of anaerobic bacteria.

Modified paper chromatography procedures for the analysis of fatty acids produced by anaerobic bacteria are described. Both ethylamine and hydroxylamine derivatives of fatty acids were prepared from inoculated anaerobic culture broth. The derivatives were spotted on chromatography paper and developed with appropriate solvents. Paper chromatography is a valuable alternative to gas liquid chromatography as an ancillary procedure in the identification of anaerobic bacteria in the clinical bacteriology laboratory.

Acetates↗
PubMed1974

Effect of potassium sorbate on salmonellae, Staphylococcus aureus, Clostridium perfringens, and Clostridium botulinum in cooked, uncured sausage.

Skinless precooked, uncured sausage links with and without potassium sorbate (0.1% wt/wt) were inoculated with salmonellae, Staphylococcus aureus, Clostridium perfringens, and Clostridium botulinum and held at 27 C to represent temperature abuse of the product. Total counts of uninoculated product showed that the normal spoilage flora was delayed 1 day when sorbate was present. Growth of salmonellae was markedly retarded by sorbate. Growth of S. aureus was delayed 1 day in the presence of sorbate, after which growth occurred to the same level as in product without sorbate. C. perfringens declined to below detectable levels within the first day in product with and without sorbate. Sorbate retarded the growth of C. botulinum. Botulinal toxin was detected in 4 days in product without sorbate but not until after 10 days in product with sorbate.

Anti-Bacterial Agents↗
PubMed1975

Metabolism of glutamic acid in Aspergillus ochraceus during the biosynthesis of ochratoxin A.

The uptake and utilization of glutamic acid in the biosynthesis of ochratoxin A by Aspergillus ochraceus were studied. Uniformly labeled L[14C]glutamic acid was incorporated into both the phenylalanine and isocoumarin moieties of ochratoxin A. Penicillic acid was also labeled. During the early stages of development, the amino acid was used mainly for the synthesis of ribonucleic acid and protein. A portion of glutamic acid was oxidized and was recovered as metabolic 14CO-2. The initial uptake velocity of glutamic acid decreased with age and was pH and temperature dependent. No relationship was found between the initial uptake velocities and ochratoxin A biosynthesis.

Aspergillus↗
PubMed1975

Mycotoxin-producing potential of mold flora of dried beans.

To evaluate the potential for mycotoxin production by molds in dried beans, the mold flora of 114 samples was determined both before and after surface disinfection of the beans with 5% NaOCl. Surface disinfection substantially reduced mold incidence, indicating that contamination was mainly on the surface. The flora, both before and after disinfection, was dominated by species of the Aspergillus glaucus group, the toxicogenic species A ochracues, Penicillium cyclopium, and P. viridicatum, and species of Alternaria, Cladosporium, and Fusarium. The toxicogenic species Aspergillus flavis, A. versicolor, Penicillium Citrinum, P. expansum, P. islandicum, and P. urticae were encountered less frequently. Of 209 species of Aspergillus and Penicillium screened for mycotoxin production on sterile rice substrate, 114 produced one or more of the following mycotoxins: A. flavus, aflatoxins; A. ochraceus, ochratoxins; A. nidulans, A. unguis, and A. versicolor, sterigmatocystin; P. cyclopium, penicillic acid; P. citrinum and P. viridicatum, citrinin; P. urticae, patulin and griseofulvin. Sterigmatocystin production by A. unguis is reported for the first time.

Aflatoxins↗
PubMed1970

Partial purification and properties of D-desthiobiotin synthetase from Escherichia coli.

d-Desthiobiotin synthetase, an enzyme that catalyzes the synthesis of d-desthiobiotin from dl-7,8-diaminopelargonic acid and HCO(3) (-), was purified 100-fold from cells of a biotin mutant strain of Escherichia coli. Adenosine triphosphate and Mg(2+) were shown, especially in purified extracts, to be obligatory for enzyme activity, although concentrations higher than 5 mm caused severe inhibition of the reaction with unpurified cell-free extracts. Adenosine diphosphate and adenosine monophosphate were shown to inhibit the reaction, but fluoride (up to 50 mm) had no detectable effect. The product of the enzyme reaction was identical to d-desthiobiotin on the basis of biological activity and chromatography. Furthermore, when H(14)CO(3) (-) was used as a substrate, the radioactive product was shown to be (14)C-desthiobiotin labeled exclusively in the ureido carbon.

Adenine Nucleotides↗
PubMed1972

A 3,5-diaminohexanoate-decomposing Brevibacterium.

An obligately aerobic bacterium that grows on dl-erythro-3, 5-diaminohexanoate as a sole carbon, nitrogen, and energy source was isolated by the enrichment culture method. The organism utilizes only the l isomer by means of an inducible enzyme system. The organism has been tentatively identified as a member of the genus Brevibacterium.

Aerobiosis↗