Chemical composition and antimicrobial activity of some oleogum resin essential oils from Boswellia spp. (Burseraceae)

The chemical composition of Boswellia carteri (Somalia), B. papyrifera (Ethiopia), B. serrata (India) and B. rivae (Ethiopia) oleogum resin essential oils was investigated using GC-MS to identify chemotaxonomy marker components. Total ion current peak areas gave good approximations to relative concentrations based on GCMS peak areas. B. carteri and B. serrata oleogum resin oils showed similar chemical profiles, with isoincensole and isoincensole acetate as the main diterpenic components. Both n-octanol and n-octyl acetate, along with the diterpenic components incensole and incensole acetate, were the characteristic compounds of B. papyrifera oleogum resin oil. Hydrocarbon and oxygenated monoterpenes were the most abundant classes of compounds identified in the B. rivae oleogum resin oil. The antimicrobial activities of the essential oils were individually evaluated against different microorganisms including fungi, Gram-positive and Gram-negative bacteria strains. The essential oils with the best activity against fungal str ains were those obtained from B. carteri and B. papyrifera with MIC values as low as 6.20 \u3bcg/ml. The essential oil of B. rivae resin showed the best activity against C. albicans with a MIC value of 2.65 \u3bcg/ml

Microbiologically influenced corrosion capability of bacteria isolated from Yucca Mountain

Microorganisms, implicated in microbiologically influenced corrosion, were isolated from the deep subsurface at Yucca Mountain. Corrosion rates of iron-oxidizing, sulfate-reducing, and exopolysaccharide (EPS)-producing bacteria were examined in constructed electrochemical corrosion cells for periods up to 109 days. The test system consisted of a 1020 carbon steel (CS) coupon immersed in soft R2A agar prepared with simulated groundwater. A 1% potassium chloride (KCl) bridge was used to connect the test to a reference calomel electrode and a potential was applied with a platinum counter electrode. The corrosion process was measured by polarization resistance methodology. Average corrosion rates were measured in milli-inches per year (mpy) against time. Purified cultures of EPS-producing bacteria and enrichment cultures of iron-oxidizing and sulfate-reducing bacteria were tested separately and in various combinations. An uninoculated control cell was prepared to assess abiotic corrosion. The corrosion rates peaked at 35 days at 1.2 mpy (control), 2.3 mpy (iron-oxidizing bacteria), 3.30 mpy (sulfate-reducing bacteria), and 2.8 mpy (EPS-producing bacteria) before stabilizing. Various microbial combinations demonstrated higher corrosion rates (3.1 mpy to 4.8 mpy) than single groups and peaked at 30 days. The results indicate that Yucca Mountain microorganisms, alone and in combination, are capable of causing corrosion of 1020 CS. Upon completion of these experiments, phospholipid fatty acid analysis detected all of the bacterial groups inoculated into the individual test systems, suggesting that biofilm development had occurred. The examination of mineralized biofilms on the CS surface with light microscopy and scanning electron microscopy/energy-dispersive x-ray analysis (SEM/EDXA) demonstrated that all of the bacterial groups promoted a generalized corrosion process; however, the corrosion experiments containing SRB were particularly effective in biofilm development and pitting

Triacylglycerols in edible oils: Determination, characterization, quantitation, chemometric approach and evaluation of adulterations

Vegetable oils are a dietary source of lipids that constitute an essential component of a healthy diet. The commonly used vegetable oils differ significantly for their triacylglycerol (TAG) profile. TAGs represent the principal components of oils and may contain different fatty acids (FA) esterified with glycerol leading to several positional isomers. To differentiate individual TAGs species in edible oils, advanced analysis systems and innovative methods are therefore required. TAGs can be considered as good fingerprints for quality control and many studies have been performed to develop rapid and low cost analytical methods to determinate the authenticity, origin and eventually evidence frauds or adulterations. The present manuscript provides a general overview on the most common vegetable oils TAGs compositions and on the related analytical methodologies recently used. Finally, the chemometric applications developed to assess the authenticity, quality and botanical origin of various edible oils are discussed

First report on the presence of Alloxan in bleached flour by LC-MS/MS method

In this work the presence of Alloxan in bread, pastry and cake bleached flour was investigate in order to verify possible risk for consumers related to the use of chemicals for flour bleaching. A selective UHPLC-MS/MS method has been developed and validated for the purpose. Alloxan is one of the possible minor side products of oxidation after chemical bleaching of wheat flours, when several chemical agents are used. One hundred and seventy-five flour samples were analyzed for Alloxan determination. The validation of the method was performed in accordance with the ISO/IEC/EN 17025 for linearity, detection limit, quantification limit, accuracy, precision and ruggedness determination. Satisfactory performances were obtained for the analyte, with a Limit of Detection (LOD) of 0.73 mg kg(-1), a Limit of Quantification (LOQ) of 0.85 mg kg(-1) and recovery values between 94% and 102%. The present work report for the first time the presence of trace levels of Alloxan in 24% of the analyzed samples, with mean values of 0,95 +/- 0,04 mg kg(-1). The presence of Alloxan was detected only in cake flour samples. Further studies on toxicological levels of Alloxan are needed in order to evaluate possible risks for consumers linked to the consumption of bakery product

Sequence-specific Retention and Regulated Integration of a Nascent Membrane Protein by the Endoplasmic Reticulum Sec61 Translocon

A defining feature of eukaryotic polytopic protein biogenesis involves integration, folding, and packing of hydrophobic transmembrane (TM) segments into the apolar environment of the lipid bilayer. In the endoplasmic reticulum, this process is facilitated by the Sec61 translocon. Here, we use a photocross-linking approach to examine integration intermediates derived from the ATP-binding cassette transporter cystic fibrosis transmembrane conductance regulator (CFTR) and show that the timing of translocon-mediated integration can be regulated at specific stages of synthesis. During CFTR biogenesis, the eighth TM segment exits the ribosome and enters the translocon in proximity to Sec61α. This interaction is initially weak, and TM8 spontaneously dissociates from the translocon when the nascent chain is released from the ribosome. Polypeptide extension by only a few residues, however, results in stable TM8-Sec61α photocross-links that persist after peptidyl-tRNA bond cleavage. Retention of these untethered polypeptides within the translocon requires ribosome binding and is mediated by an acidic residue, Asp924, near the center of the putative TM8 helix. Remarkably, at this stage of synthesis, nascent chain release from the translocon is also strongly inhibited by ATP depletion. These findings contrast with passive partitioning models and indicate that Sec61α can retain TMs and actively inhibit membrane integration in a sequence-specific and ATP-dependent manner