Removal of chloramphenicol in aqueous solutions by modified humic acid loaded with nanoscale zero-valent iron particles.

As a natural organic carbon skeleton, humic acid (HA) was loaded with nanoscale zero-valent iron (nZVI) Particles to remove chloramphenicol (CAP) from aqueous solution. The pore morphology and structure, the type, the distribution and valence state of element, and the class of functional groups on the surface of the material were shown by SEM/EDS, XPS, BET and FTIR. When the load ratio of nZVI on HA was 1:30, the iron content in the material was minimized, the specific gravity of the economic material-HA was increased, and the removal efficiency of CAP was 80.0% or higher. In addition, the mass ratio of nZVI on HA, the dosage of nZVI/HA-30, the initial pH and CAP concentration of the solution, these four general factors, played an important role in the efficiency and equilibrium time of the CAP removal. The removal efficiency of CAP by nZVI/HA-30 was 84.2% when the dosage was 1.0 g (100 mL)-1, the initial concentration of CAP was 30 mg L-1 and the pH was 3. The reaction pathway and removal mechanism of ZVI/HA-30 were studied by the concentration of total and ferrous iron ions in the solution, UV-Vis and MS. The CAP was continuously denitrified and dechlorinated, decomposed into easily degradable substances by nZVI particles supported on HA, which was consistent with the first-order kinetic model within 5 min. This newly synthesized material was economical and efficient, easy to store, effectively prevented agglomeration and passivation of nZVI, and had a good application prospect for removing contaminants from water.

Insecticidal Activities of Chloramphenicol Derivatives Isolated from a Marine Alga-Derived Endophytic Fungus, Acremonium vitellinum, against the Cotton Bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae).

A great deal of attention has been focused on the secondary metabolites produced by marine endophytic fungi, which can be better alternatives to chemicals, such as biopesticides, for control of polyphagous pests. On the basis of its novel biocontrol attributes, chemical investigation of a marine alga-derived endophytic fungus, Acremonium vitellinum, resulted in the isolation of three chloramphenicol derivatives (compounds 1⁻3). Their chemical structures were elucidated by detailed analysis of their nuclear magnetic resonance spectra, high-resolution electrospray ionization mass spectrometry, and by comparison with the data available in the literature. In this paper, compound 2 was firstly reported as the natural origin of these fungal secondary metabolites. The insecticidal activities of compounds 1⁻3 against the cotton bollworm, Helicoverpa armigera, were evaluated. The natural compound 2 presented considerable activity against H. armigera, with an LC50 value of 0.56 ± 0.03 mg/mL (compared to matrine with an LC50 value of 0.24 ± 0.01 mg/mL). Transcriptome sequencing was used to evaluate the molecular mechanism of the insecticidal activities. The results presented in this study should be useful for developing compound 2 as a novel, ecofriendly and safe biopesticide.

Multiplexed site-specific genome engineering for overproducing bioactive secondary metabolites in actinomycetes.

Actinomycetes produce a large variety of pharmaceutically active compounds, yet production titers often require to be improved for discovery, development and large-scale manufacturing. Here, we describe a new technique, multiplexed site-specific genome engineering (MSGE) via the 'one integrase-multiple attB sites' concept, for the stable integration of secondary metabolite biosynthetic gene clusters (BGCs). Using MSGE, we achieved five-copy chromosomal integration of the pristinamycin II (PII) BGC in Streptomyces pristinaespiralis, resulting in the highest reported PII titers in flask and batch fermentations (2.2 and 2g/L, respectively). Furthermore, MSGE was successfully extended to develop a panel of powerful Streptomyces coelicolor heterologous hosts, in which up to four copies of the BGCs for chloramphenicol or anti-tumour compound YM-216391 were efficiently integrated in a single step, leading to significantly elevated productivity (2-23 times). Our multiplexed approach holds great potential for robust genome engineering of industrial actinomycetes and novel drug discovery by genome mining.

Bacterial microbiota present in the gallbladder of cattle and antimicrobial resistance of Staphylococcus isolates / Microbiota bacteriana presente na vesícula biliar de bovinos e resistência antimicrobiana de isolados de Staphyloccocus

Pathogenic microorganisms can reside transiently or permanently in the gallbladder of cattle. Thus, during slaughter, more attention should be given to the gastrointestinal tract, especially to the accessory organ, the gallbladder. The main aim of this study was to characterize the bacterial microbiota present in bile and gallbladder epithelium of cattle slaughtered in a slaughtering plant under sanitary conditions and to evaluate the antimicrobial resistance in strains of the genus Staphylococcus. Thirty intact gallbladders were collected and the in bile and epithelium were researched for the presence of Aerobic Mesophilic Heterotrophic Bacteria (AMHB), Staphylococcus spp., total Enterobacteriaceae, Enterococcus spp. and Salmonella spp.The frequency of isolation of the microorganism mentioned above were, respectively: 23.02 percent, 14.39 percent, 13.67 percent, 24.46 percent, 0 percent and 24.46 percent. Concerning both gallbladder environments, the frequency of isolation of the microorganisms in the epithelium was 64.03 percent, and in the bile 35.97 percent, with no statistical difference, but with significant difference between the population averages. In antimicrobial susceptibility testing, strains of Staphylococcus from both bile and gallbladder epithelium showed sensitivity to the antimicrobials: penicillin G, ceftriaxone, chloramphenicol and gentamicin. The observation that the gallbladder supports a high frequency of microorganisms brings us to the possible fact that cattle might be a persistent carrier of pathogens of great importance to public health...

Microrganismos patogênicos podem residir temporariamente ou permanentemente na vesícula biliar de bovinos. Assim, durante o abate, maior atenção deve ser dada ao trato gastrointestinal, especialmente para o órgão acessório, a vesícula biliar. O principal objetivo deste estudo foi caracterizar a microbiota bacteriana presente na bile e no epitélio de vesículas biliares de bovinos abatidos em matadouro frigorífico sob inspeção sanitária e avaliar a resistência antimicrobiana de estirpes do gênero Staphyloccocus. Foram coletadas 30 vesículas biliares íntegras e foi pesquisada na bile e no epitélio do órgão a presença de bactérias heterotróficas aeróbias mesófilas (BHAM), Staphylococcus spp. e Enterobacteriaceae totais, Escherichia coli, Enterococcus spp. e Salmonella spp. A frequência de isolamento dos microrganismos citados acima foi, respectivamente: 23,02 por cento, 14,39 por cento, 13,67 por cento, 24,46 por cento, 0por cento e 24,46 por cento. Em relação aos dois ambientes da vesícula, a frequência de isolamento dos microrganismos no epitélio foi de 64,03 por cento, e na bile 35,97 por cento, não sendo diferente estatisticamente, mas com diferença significativa entre as médias populacionais.No teste de susceptibilidade aos antimicrobianos, as estirpes de Staphylococcus isoladas a partir da bile e do epitélio da vesícula biliar apresentaram sensibilidade a: penicilina G, ceftriaxona, cloranfenicol e gentamicina. A observação de que a vesícula biliar comporta microrganismos em elevadas frequências atenta para o fato de que o bovino possa ser um portador persistente de patógenos de grande importância em saúde pública...

Interactions between surfactants and biomass during liquid-liquid extraction.

Fermentation systems can contain may surface-active compounds that can interfere with downstream separation processes. This work examines the interactions that can occur between surfactants and biomass during solute mass transfer in a liquid-liquid extraction system. Adding the surfactants sodium dodecyl sulfate and dodecyl trimethyl ammonium bromide to the aqueous phase caused a substantial increase in the mass transfer of chloramphenicol between water and octanol. Further investigation of the interfacial region using an optical Schlieren apparatus revealed that these increases were due to interfacial turbulence that gave rise to a rapid surface renewal convective mass transfer mechanism. When microbial biomass was present with sodium dodecyl sulfate, an increase in the mass transfer rate was again found, however, to a lesser extent. In contrast, dodecyl trimethyl ammonium bromide did not promote mass transfer and it is postulated that electrical interactions between the surfactant and the cell surface prevented adsorption of either at the interface. The interaction between the antifoaming agent polypropylene glycol 2000 and extraction system components was also investigated, with both positive and negative effects being recorded under varying conditions.

Modifications and adaptations of the Charm II rapid antibody assay for chloramphenicol in honey.

The Charm II screening method for the presence of chloramphenicol in honey has a sensitivity of 0.3 ppb. This screening method is a simple, rapid antibody assay using [3H]chloramphenicol and a binding reagent. Analysis of different types of honey revealed considerable differences in results. Honey can be liquid, crystallized (creamed), or partially crystallized and is classified by the U.S. Department of Agriculture into seven color categories: water white, extra white, white, extra light amber, light amber, amber, and dark amber. Fortified and nonfortified liquid amber honey tested appropriately with the Charm II unit and the negative control provided with the unit after slight modifications were made. However, approximately 70% of creamed honey samples fortified at 0.6 ppb did not test positive for the presence of chloramphenicol using the provided negative control. Matrix quenching effects were evaluated, and these effects were accounted for by establishing different assay conditions for different honey types.

Determinación simultánea de la susceptibilidad a los antimicrobianos en aerobiosis y anaerobiosis / Simultaneous determination to antimicrobians in aerobiosis and anaerobiosis susceptibility

Se determina y compara la susceptibilidad aerobia y anaerobia de zocepas de E.coli anteropatógenos, anaerobios facultativas, aisladas de alimentos, a los antimicrobianos, ampicilina, cloranfenicol, gentamicina, tetraciclina y sulfalmetoxazol/trimetoprin (SMZ/TMP), mediante la determinación simultánea de la CMI en medio sólido de agar inclinado. Las CMIs resultantes se compararon con el fin de observar si las condiciones de crecimiento afectaba la susceptibilidad de los microorganismos ensayados. No se hallaron diferencias estadísticamente significativas para la ampicilina, cloranfenicol y tetraciclina; en cambio hubo un significativo incremento de la CMI anaerobio de la gentamicina fue 15 veces menos activa y la actividad del SMZ/TMP decreció en 237 veces o más. Al evaluar el efecto de los medios de cultivo, no hubieron diferencias significativas estadísticamente entre los CMIs aerobio y anerobio promedios. Se compararon los resultados de esta técnica con el método de difusión con discos, con el cual los diámetros de inhibición fueron mas grandes en condiciones anarobios, excepto con la gentamicina.

Glutathione-dependent dechlorination of chloramphenicol by cytosol of rat liver.

The 100,000 g supernatant fraction (cytosol) of rat liver converts chloramphenicol (CAP, RNHCOCHCl2) into two products. Most of the enzyme activity is lost during dialysis of the enzyme preparation overnight, but is restored by addition of glutathione (GSH). Other thiols are not as effective as GSH in restoring the enzyme activity. The formation of the metabolites is not inhibited when incubations are performed under anaerobic conditions. The major metabolite was identified as CAP aldehyde (RNHCOCHO) whereas the minor metabolite was identified as an alkali-unstable derivative of CAP oxamic acid (RNHCOCOOH). Plausible pathways are discussed for the formation of these metabolites.

Quantitative gas-chromatographic flame-ionization method for chloramphenicol in human serum.

We describe a flame-ionization gas-chromatographic procedure for determination of the potentially toxic antibiotic, chloramphenical, in serum. The serum (500 mul) is extracted into ethyl acetate and nonpolar impurities are subsequently partitioned into hexane. The drug is chromatographed as its bis-trimethylsilyl derivative, with the analog thiamphenicol as the internal standard. Within-run precision (CV) is 4.4% at a serum concentration of 41 mg/liter and 9.2% at a concentration of 5 mg/liter. Over a six-month period, the run-to-run variation was 5.1% at 40 mg/liter (n = 24). Results by the gas-chromatographic method compared well with those by an established colorimetric procedure; mean concentrations for the comparison samples in the two procedures were 18.4 mg/liter and 17.6 mg/liter, respectively (n = 27), with a coefficient of correlation of 0.998. The gas-chromatographic method is more precise and specific than classical microbiological procedures and is suitable for routine therapeutic monitoring of serum chloramphenicol concentrations.