PubMed · 13618014
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C E BALLOU. 1958. Glycolaldehyde phosphate.. https://doi.org/10.1016/0003-9861(58)90356-4
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We have addressed critical challenges in probiotic design to develop a commercially viable bacterial strain capable of removing the intestinal toxin, acetaldehyde. In this study, we report the engineering of the hag locus, a σD-dependent flagellin expression site, as a stable location for robust enzyme production. We demonstrate constitutive gene expression in relevant conditions driven by the endogenous hag promoter, following a deletion of the gene encoding a post-translational regulator of σD, FlgM, and a point mutation to abrogate the binding of the translational inhibitor CsrA. Reporter constructs demonstrate activity at the hag locus after germination, with a steady increase in heterologous expression throughout outgrowth and vegetative growth. To evaluate the chassis as a spore-based probiotic solution, we identified the physiologically relevant ethanol metabolic pathway and the subsequent accumulation of gut-derived acetaldehyde following alcohol consumption. We integrated a Cupriavidus necator aldehyde dehydrogenase gene (acoD) into the hag locus under the control of the flagellin promoter and observed a rapid reduction in acetaldehyde levels in gut-simulated conditions post-germination. This work demonstrates a promising approach for the development of genetically engineered spore-based probiotics.
Although millions of individuals are exposed to emissions from articles inside cars, relatively little has been published about possible adverse health effects and about exposure levels that can be considered safe or "acceptable". Xylene, formaldehyde and acetaldehyde represent typical examples of relevant volatile organic substances (VOC) released from articles inside cars. Recently, a concept for derivation of maximum exposure levels for volatile organic substances in cars has been published. In the present study we applied this concept to derive maximum exposure levels for xylene, formaldehyde and acetaldehyde and compared the resulting concentrations to exposure levels usually found inside of cars. We derived Short Term Exposure Levels Inside Automotive Vehicles (STELIA) of 29, 0.125 and 15.3 mg/m(3) for xylene, formaldehyde and acetaldehyde, respectively. These STELIAs should not be exceeded during short-term exposures, for instance when starting a car that had been heated up during parking in the sun. Exposure Levels Inside Automotive Vehicles (ELIA, chronic) for chronic exposure to non-genotoxic substances were 8.8, 0.125 and 0.635 mg/m(3) for systemic as well as 17.6, 0.125 and 1.7 mg/m(3) for local exposure to xylene, formaldehyde and acetaldehyde, respectively. Although, it is known that exposure limits for carcinogenic substances should be treated with caution, encouraged by the well documented threshold mechanisms we nevertheless derived ELIAs for Carcinogenic and Mutagenic Substances (ELIA, cm) resulting in 0.125 and 0.635 mg/m(3) for formaldehyde and acetaldehyde. If these ELIAs are matched against average concentrations of xylene, formaldehyde and acetaldehyde found in cars at 23 degrees C (1.22, 0.048 and 0.042 mg/m(3)), there is no reason for concern. With respect to STELIAs and extrapolated concentrations at 65 degrees C (14.7, 1.47 and 1.68 mg/m(3), for xylene, formaldehyde and acetaldehyde, respectively), however, a reduction of the concentration of formaldehyde may be necessary.
In order to be able to fully understand the vibrational dynamics of monosaccharide sugars, we started with hydroxyacetone CH2OHCOCH3, and glycolaldehyde CH2OHCOH, which are among the smallest molecules that contain hydroxyl and carbonyl group on neighboring carbon atoms. This sterical configuration is characteristic for saccharides and determines their biochemical activity. In this work vibrational analysis of hydroxyacetone was undertaken by performing the normal coordinate analysis for glycolaldehyde first, and transferring these force constants to hydroxyacetone. The observed Raman and infrared bands for 90 wt.% solution of hydroxyacetone in water (acetol) were used as a first approximation for the bands of free hydroxyacetone. The number of observed Raman and infrared bands for acetol exceeds the number of calculated values for the most stable hydroxyacetone conformer with Cs symmetry, which suggests more than one conformer of hydroxyacetone in water solution. In particular, there are two bands both in infrared (1083 and 1057 cm(-1)) and in Raman spectrum (1086.5 and 1053 cm(-1)) that are assigned to the CO stretching mode and this is one of the indicators of several hydroxyacetone conformers in the solution. Additional information was obtained from low temperature Raman spectra: at 240 K a broad asymmetric band centered around 280 cm(-1) appears, suggesting a disorder in the orientation of hydroxyl groups. Glassy state forms at approximately 150K. The broad band at 80 cm(-1) is assigned to frozen torsions of hydroxymethyl groups.