A metallo-β-lactamase is responsible for the degradation of ceftiofur by the bovine intestinal bacterium Bacillus cereus P41.

Ceftiofur is a highly effective veterinary cephalosporin, yet it is rapidly degraded by bacteria in the gut. The goal of this work was to directly determine the mechanism of ceftiofur degradation by the bovine intestinal isolate Bacillus cereus P41. B.

Comparison of the effects of antimicrobial agents from three different classes on metabolism of isoflavonoids by colonic microflora using Etest strips.

Daidzein (4',7-dihydroxyisoflavone), a phytoestrogen found in soybeans mainly in the form of its glycoside daidzin, is metabolized by colonic bacteria to compounds with altered estrogenic activities, which may affect human health. Antibacterial agents used for the treatment of infections can alter the composition of bacterial populations in the colon and therefore can affect daidzein metabolism. To rapidly detect the effects of different concentrations of antibiotics on daidzein metabolism by colonic bacteria of monkeys and identify the subpopulation involved in daidzein metabolism, Etest strips containing antibacterial agents from three classes (tetracyclines, fluoroquinolones, and β-lactams) were used to eliminate the colonic bacteria that were susceptible to 0-32 μg/ml of each antibacterial agent and test the surviving bacteria for their ability to metabolize daidzein.

Modification of norfloxacin by a Microbacterium sp. strain isolated from a wastewater treatment plant.

Antimicrobial residues found in municipal wastewater may increase selective pressure on microorganisms for development of resistance, but studies with mixed microbial cultures derived from wastewater have suggested that some bacteria are able to inactivate fluoroquinolones. Medium containing N-phenylpiperazine and inoculated with wastewater was used to enrich fluoroquinolone-modifying bacteria. One bacterial strain isolated from an enrichment culture was identified by 16S rRNA gene sequence analysis as a Microbacterium sp.

Biotransformation of quinazoline and phthalazine by Aspergillus niger.

Cultures of Aspergillus niger NRRL-599 in fluid Sabouraud medium were grown with quinazoline and phthalazine for 7 days. Metabolites were purified by high-performance liquid chromatography and identified by mass spectrometry and proton nuclear magnetic resonance spectroscopy. Quinazoline was oxidized to 4-quinazolinone and 2,4-quinazolinedione, and phthalazine was oxidized to 1-phthalazinone.

Acrylamide formed at physiological temperature as a result of asparagine oxidation.

Acrylamide is a probable human carcinogen that is neurotoxic to both humans and animals. It is known to be formed during cooking of foods at temperatures higher than 120 degrees C. The present study demonstrates that acrylamide can also be formed at physiological conditions (37 degrees C, pH 7.

Metabolism of azo dyes by human skin microbiota.

Reduction of Methyl Red (MR) and Orange II (Or II) by 26 human skin bacterial species was monitored by a rapid spectrophotometric assay. The analysis indicated that skin bacteria, representing the genera Staphylococcus, Corynebacterium, Micrococcus, Dermacoccus and Kocuria, were able to reduce MR by 74-100 % in 24 h, with only three species unable to reduce completely the dye in that time. Among the species tested, only Corynebacterium xerosis was unable to reduce Or II to any degree by 24 h, and only Staphylococcus delphini, Staphylococcus sciuri subsp.

Decolorization of water and oil-soluble azo dyes by Lactobacillus acidophilus and Lactobacillus fermentum.

The capability of Lactobacillus acidophilus and Lactobacillus fermentum to degrade azo dyes was investigated. The bacteria were incubated under anaerobic conditions in the presence of 6 microg/ml Methyl Red, Ponceau BS, Orange G, Amaranth, Orange II, and Direct Blue 15; 5 microg/ml Sudan I and II; or 1.5 microg/ml Sudan III and IV in deMann-Rogosa-Sharpe broth at 37 degrees C for 36 h, and reduction of the dyes was monitored.

Sudan azo dyes and Para Red degradation by prevalent bacteria of the human gastrointestinal tract.

Sudan azo dyes have genotoxic effects and ingestion of food products contaminated with Sudan I, II, III, IV, and Para Red could lead to exposure in the human gastrointestinal tract. In this study, we examined thirty-five prevalent species of human intestinal bacteria to evaluate their capacity to degrade Sudan dyes and Para Red. Among these tested bacterial strains, 23, 13, 33, 30, and 29 out of 35 species tested were able to reduce Sudan I, II, III, IV, and Para Red, respectively, to some extent.

Interaction of dietary resveratrol with animal-associated bacteria.

Resveratrol (3,5,4'-trihydroxy-trans-stilbene), an antifungal phytoalexin produced by grapes, peanuts, and Japanese knotweeds, is thought to be a beneficial dietary phytochemical in red wine and grape juice. Information on its antibacterial properties and biotransformation, however, is limited. We surveyed the interactions of resveratrol with 43 strains of bacterial species that are often animal- or human-associated.

Isolation of bacterial strains from bovine fecal microflora capable of degradation of ceftiofur.

Ceftiofur, a third-generation cephalosporin used to treat bacterial infections in animals, is degraded in bovine feces but the specific bacteria involved are unknown. To find the bacteria involved in ceftiofur metabolism, the bovine fecal microflora was screened. Twenty-one nonidentical strains of bovine fecal bacteria were isolated on media containing 1-32 microg ml(-1) of ceftiofur.

Biotransformation of acridine by Mycobacterium vanbaalenii.

Cultures of Mycobacterium vanbaalenii strain PYR-1 in a liquid medium were exposed to the toxic environmental contaminant acridine (260 microM). After incubation for 7 d, the cultures were extracted with ethyl acetate. Metabolites were purified using high-performance liquid chromatography and analyzed by mass spectrometry and 1H nuclear magnetic resonance spectroscopy.

Transformation of N-phenylpiperazine by mixed cultures from a municipal wastewater treatment plant.

Samples from a wastewater treatment plant were used as inocula for mixed cultures dosed with N-phenylpiperazine (NPP), a model compound containing the piperazine ring found in many fluoroquinolones. Chemical analyses showed that NPP (50 mg liter(-1)) disappeared in 12 days, with the appearance of a transient metabolite and two nitrosated compounds.

Synthesis and characterization of DNA adducts from the HIV reverse transcriptase inhibitor nevirapine.

Nevirapine (NVP) is a non-nucleoside reverse transcriptase inhibitor used against the human immunodeficiency virus type 1 (HIV-1), mostly to prevent mother-to-child HIV transmission in developing countries. One of the limitations of nevirapine use is severe hepatotoxicity, which raises concerns about its administration, particularly in the perinatal and pediatric settings. Nevirapine metabolism involves oxidation of the 4-methyl substituent to 12-hydroxy-NVP and the formation of phenolic derivatives.

Anaerobic metabolism of 1-amino-2-naphthol-based azo dyes (Sudan dyes) by human intestinal microflora.

The rates of metabolism of Sudan I and II and Para Red by human intestinal microflora were high compared to those of Sudan III and IV under anaerobic conditions. Metabolites of the dyes were identified as aniline, 2,4-dimethylaniline, o-toluidine, and 4-nitroaniline through high-performance liquid chromatography and liquid chromatography electrospray ionization tandem mass spectrometry analyses. These data indicate that human intestinal bacteria are able to reduce Sudan dyes to form potentially carcinogenic aromatic amines.

Metabolism of daidzein by fecal bacteria in rats.

Daidzein (4',7-dihydroxyisoflavone), a soy phytoestrogen, is a weakly estrogenic compound that may have potential health benefits. Biotransformation of daidzein by the human gut microflora after ingestion converts it to either the highly estrogenic metabolite equol or to nonestrogenic metabolites. We investigated the metabolism of daidzein by colonic microflora of rats.

Acetylation and nitrosation of ciprofloxacin by environmental strains of mycobacteria.

To determine the ability of environmental bacteria to metabolize the frequently prescribed fluoroquinolone drug ciprofloxacin, eight Mycobacterium spp. cultures were grown for 4 days in a medium containing sorbitol and yeast extract with 100 mg x L(-1) ciprofloxacin. After the cultures had been centrifuged and the supernatants extracted with ethyl acetate, two metabolites were purified by using high-performance liquid chromatography.

Biotransformation of flumequine by the fungus Cunninghamella elegans.

The metabolism of the antibacterial fluoroquinolone drug flumequine by Cunninghamella elegans was investigated using cultures grown in Sabouraud dextrose broth with 308microM flumequine. The cultures were extracted with ethyl acetate; metabolites were separated by high-performance liquid chromatography and identified by mass spectrometry and proton nuclear magnetic resonance spectroscopy. Flumequine was transformed to two diastereomers of 7-hydroxyflumequine (23 and 43% of the total chromatographic peak area at 280nm) and 7-oxoflumequine (11% of the total peak area).

Transformation of the antibacterial agent norfloxacin by environmental mycobacteria.

Because fluoroquinolone antimicrobial agents may be released into the environment, the potential for environmental bacteria to biotransform these drugs was investigated. Eight Mycobacterium sp. cultures in a sorbitol-yeast extract medium were dosed with 100 microg ml(-1) of norfloxacin and incubated for 7 days.

Improved cell typing by charge-state deconvolution of matrix-assisted laser desorption/ionization mass spectra.

Robust, specific, and rapid identification of toxic strains of bacteria and viruses, to guide the mitigation of their adverse health effects and optimum implementation of other response actions, remains a major analytical challenge. This need has driven the development of methods for classification of microorganisms using mass spectrometry, particularly matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS), that allows high-throughput analyses with minimum sample preparation. We describe a novel approach to cell typing based on pattern recognition of MALDI mass spectra, which involves charge-state deconvolution in conjunction with a new correlation analysis procedure.

In vitro cytotoxicity of nonpolar constituents from different parts of kava plant (Piper methysticum).

Kava (Piper methysticum), a perennial shrub native to the South Pacific islands, has been used to relieve anxiety. Recently, several cases of severe hepatotoxicity have been reported from the consumption of dietary supplements containing kava. It is unclear whether the kava constituents, kavalactones, are responsible for the associated hepatotoxicity.

Stability of black tea polyphenol, theaflavin, and identification of theanaphthoquinone as its major radical reaction product.

In the current study, we have focused on isolation and detection of major radical oxidation products from theaflavin in order to better understand antioxidation mechanisms of this compound. Theanaphthoquinone was identified as a major oxidation product of theaflavin from two different oxidant model systems: DPPH and peroxidase/hydrogen peroxide. This result indicated that the benzotropolone moiety in theaflavin may play an important role in its antioxidant properties.

Fungal biotransformation of benzo[f]quinoline, benzo[h]quinoline, and phenanthridine.

Cultures of Umbelopsis ramanniana (=Mucor ramannianus) were grown in fluid Sabouraud medium for 3 days, dosed with 0.23 mM benzo[f]quinoline, benzo[h]quinoline, or phenanthridine (benzo[c]quinoline), and incubated for another 18 days. Cultures were extracted and metabolites (66-75% of the UV absorbance) were separated by high-performance liquid chromatography.

Instability of St. John's wort (Hypericum perforatum L.) and degradation of hyperforin in aqueous solutions and functional beverage.

Several bioactive botanicals including St. John's wort (SJW; Hypericum perforatum L.) have been used to formulate functional foods and beverages.

Sample preparation and determination of ginkgo terpene trilactones in selected beverage, snack, and dietary supplement products by liquid chromatography with evaporative light-scattering detection.

Ginkgo biloba leaf extract has been widely used in dietary supplements and more recently in some foods and beverages. Sample preparation procedures for determination of ginkgo terpene trilactones (including bilobalide and ginkgolides A, B, C, and J) in various sample matrixes were developed in this study. Ginkgo leaves and capsules were extracted with 5% KH2PO4 aqueous solution under sonication.