Ethanol is indispensable for virucidal hand antisepsis and without toxic risks in daily use

The approval of ethanol by the Biocidal Products Regulation has been under evaluation since 2007 due to controversial opinions on the risk assessment. Because of this critical situation, 2022 a memorandum was published to verify whether the use of ethanol for hand antisepsis poses any hazard. On the basis of the memorandum a toxicological evaluation of ethanol-based hand rubs is given.

Improving 1-propanol force field: a new methodology

A new force field for 1-propanol, in the united and all atom models, has been obtained by combining two different empirical methodologies. The first was developed by scaling atom charges and Lennard-Jones parameters to fit the dielectric constant, surface tension, and density; this methodology is named three steps systematic parameterization procedure (3SSPP), as reported by Pérez de la Luz et al. (J Chem Theory Comput 14:5949-5958, 2018). The second methodology consists of moving these parameters and together with the bond distance to obtain the liquid-vapor phase diagram of the CO₂ molecule as discussed by Harris and Yung (J Phys Chem 99:12021-12024, 1995). The last methodology is used to obtain the self-diffusion coefficient, which was not consider in the 3SSPP. The 3SSPP/bond methodology is the 3SSPP plus the bond distance scaling. With this new methodology, the experimental density, dielectric constant, surface tension, and self-diffusion coefficient at ambient temperature could be achieved. Furthermore, we show the temperature dependence of the aforementioned properties. The static structure factors are in accordance with the experimental spectrum. Solubility is increased to the experimental value for the united atom (UA) model after applying this methodology and for all atom (AA) scheme, the experimental solubility value is maintained. Graphical abstract The reduction in bond distance of the 1-propanol molecule does not modify the structure factor.

A Critical Review on the Economically Feasible and Sustainable Poly(3-Hydroxybutyrate-co-3-hydroxyvalerate) Production from Alkyl Alcohols

Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (P(3HB-co-3HV)) is the most studied short-chain-length polyhydroxyalkanoates (PHA) with high application importance in various fields. The domination of high-cost propionate and valerate over other 3-hydroxyvalerate (3HV) precursors owing to their wide preference among PHA-producing bacteria has hindered the development of diverse production processes. As alkyl alcohols are mainly produced from inexpensive starting materials through oxo synthesis, they contribute a cost-effective advantage over propionate and valerate. Moreover, alkyl alcohols can be biosynthesized from natural substrates and organic wastes. Despite their great potential, their toxicity to most PHA-producing bacteria has been the major drawback for their wide implementation as 3HV precursors for decades. Although the standard PHA-producing bacteria Cupriavidus necator showed promising alcohol tolerance, the 3HV yield was discouraging. Continuous discovery of alkyl alcohols-utilizing PHA-producing bacteria has enabled broader choices in 3HV precursor selection for diverse P(3HB-co-3HV) production processes with higher economic feasibility. Besides continuous effort in searching for promising wild-type strains, genetic engineering to construct promising recombinant strains based on the understanding of the mechanisms involved in alkyl alcohols toxicity and tolerance is an alternative approach. However, more studies are required for techno-economic assessment to analyze the economic performance of alkyl alcohol-based production compared to that of organic acids.

Frequency of postmortem ethanol formation in blood, urine and vitreous humor - Improving diagnostic accuracy with the use of ethylsulphate and putrefactive alcohols

PURPOSE

This study aimed to compare the frequency of postmortem ethanol formation in blood, urine and vitreous humor according to negative ethylsulphate (EtS) in blood or positive putrefactive alcohols (PA's) in either medium. Furthermore, it aimed to evaluate the interpretational value of calculated ethanol ratios in relation to EtS and PA results.

METHODS

Blood ethanol positive forensic cases were included; one dataset consisting of 2504 cases with EtS analysed in blood and another dataset with 8001 cases where PA's were analysed.

RESULTS

PA's were found in 24.4% of cases. EtS was negative in 15.3%, 9.4% and 7.4% of cases that were positive for ethanol in blood, urine and vitreous humor, respectively. In EtS negative cases, the concentrations of ethanol in blood, urine and vitreous humor were lower than 0.20 g/kg in 51.3%, 67.4% and 77.8%, respectively. It was 1.0 g/kg or higher in blood in 4.2% of cases. More EtS negative and PA positive cases were seen in central compared to peripheral blood. Ethanol ratios between urine or vitreous humor and blood were significantly lower in both EtS negative and PA positive cases, but large variations were observed.

CONCLUSION

EtS and PA analysis improve the diagnostic accuracy of ethanol in postmortem cases. Postmortem ethanol formation in vitreous humor and urine were both more frequent than expected and we recommend the analysis of ethanol primarily in peripheral blood if available.

Assay of ethanol and congener alcohols in serum and beverages by headspace gas chromatography/mass spectrometry

The analysis of ethanol and of its congeners in blood plays an important role in forensic cases, especially when allegations are made that alcohol has been consumed after an accident. In alcoholic beverages, congener alcohols are by-products and are generated during fermentation. The assay of these compounds in serum samples and beverages has been previously performed using headspace-gas chromatography-flame ionization detection methods (HS-GC-FID). As an alternative, a robust headspace-gas chromatography-mass spectrometry (HS-GC-MS) procedure was developed and validated, which has the following advantages:•Simultaneous determination of ethanol, congener alcohols and other endogenous substances.•Reduction of matrix interference by increasing selectivity and specificity.•Clear separation of the positional isomers 3-methyl-1-butanol and 2-methyl-1-butanol.

Reaction Behaviors of S-, O-, and N-containing Aliphatic Molecules with a Propyl Moiety on Ge(100) Surface

The reaction pathways of 1-propanethiol, 1-propanol, and propylamine molecules, containing a propyl moiety, on a Ge(100) surface were investigated using high-resolution photoemission spectroscopy (HRPES) experiments and density functional theory (DFT) calculations. Upon analysis of the HRPES data, the adsorption of 1-propanethiol and 1-propanol was found to occur through a dissociation reaction, whereas that of propylamine took place via N dative bonding at room temperature. On the basis of our DFT results, adsorption geometries and transition states for each of these molecules on the Ge(100) surface were confirmed. Systematic studies of S-, O-, and N-containing molecules, composed of an identical propyl moiety, on the Ge(100) surface provide insight into the adsorption mechanism of aliphatic molecules containing alkyl chains on the Ge(100) surface.

Endogenous formation of 1-propanol and methanol after consumption of alcoholic beverages

INTRODUCTION

In cases of drunk-driving, allegations that alcohol has been consumed after the incident, are proved by analyzing congener alcohols in the blood sample. 1-Propanol, one of the main congener compounds, was tested, whether it is also endogenously formed when a person has consumed alcoholic beverages.

METHODS

Eleven male and 13 female volunteers consumed congener-free vodka (37.5 vol% ethanol, individual doses: 0.15-0.32 l) within one hour. Blood samples were taken up to 10 h and analyzed for ethanol and congener alcohols by headspace gas chromatography-mass spectrometry.

RESULTS

Ethanol concentrations reached in blood a maximum of 0.65-1.23 g/l and decreased by 0.18 g/l/h (median values). Of the congener alcohols analyzed, only methanol and 1-propanol were detected in the plasma samples of all subjects. The endogenous methanol concentration increased from 0.66 mg/l by 0.22 mg/l/h to 2.19 mg/l (medians). 1-Propanol was not detected prior to alcohol consumption. Maximum concentrations of 0.10-0.32 mg/L were measured after 1.0-4.5 h. A plateau of the 1-propanol concentration was observed in the plasma samples of the 18 subjects lasting for 0.5-4.0 h and this alcohol was completely eliminated at ethanol concentrations of 0.17 g/l (median, range 0.03-0.55 g/l).

CONCLUSION

The results of the study confirm the formation of 1-propanol after consumption of 1-propanol-free beverages, which should be taken into account when evaluating its concentration.

Modeling postmortem ethanol production by C. albicans: Experimental study and multivariate evaluation

In previous research, we modeled the ethanol production by certain bacteria under controlled experimental conditions in an attempt to quantify the production of microbial postmortem ethanol in cases where other alcohols were co-detected. This contribution on the modeling of postmortem ethanol production by Candida albicans is complementary to these previous studies. Τhis work aimed to study ethanol, higher alcohols (1-propanol, isobutanol, 2-methyl-1-butanol and 3-methyl-1-butanol), and 1-butanol production by Candida albicans: (i) in different culture media (Brain Heart Infusion, BHI and, Sabouraud Dextrose Broth, SDB), (ii) under mixed aerobic/anaerobic or strict anaerobic conditions, and (iii) at different temperatures (37 °C, 25 °C and, 4 °C), and develop simple mathematical models, resulted from fungal cultures at 25 °C, to predict the microbially produced ethanol in correlation with the other alcohols. The applicability of the models was tested in the C. albicans cultures in BHI and SDB media at 37 °C, in denatured human blood at 25 °C, acidic and neutral with different concentrations of additional glucose, in acidic denatured blood diluted with dextrose solution and in blood from autopsy cases. The received results indicated that the C. albicans models could apply in cases where yeasts have been activated in blood with elevated glucose levels. Overall, the in vitro ethanol production by C. albicans in blood depended on temperature, time, glucose (or carbohydrate) content, pH of the medium and endogenous changes in the medium composition through time. Our results showed that methyl-butanol is the most significant indicator of fungal ethanol production, followed by the equally important isobutanol and 1-propanol in qualitative and quantitative terms.

Contact sensitizations to disinfectants containing alcohols or quaternary ammonium compounds are rarely of clinical relevance

BACKGROUND

The use of disinfectants is part of the everyday life of people, especially in the medical profession. During the coronavirus disease 2019 (COVID-19) pandemic, the use of disinfectants continues to increase and is of fundamental importance in infection control.

OBJECTIVES

To determine the frequency of sensitization and the value of patch testing to didecyldimethylammonium chloride (DDAC) and the alcohols ethanol, 1-propanol, and isopropanol.

METHODS

Clinical patch test data of 145 patients with suspected contact allergy to disinfectants were retrospective analysed.

RESULTS

Among the 145 patients patch tested with the different alcohols, only one nurse was detected with a possible allergy to 1-propanol. Additional patch testing in 84 patients with DDAC 0.05% resulted in five patients with weakly positive reactions only, without clinical relevance. Patch testing with DDAC 0.03% showed no positive reactions at all on day 3 readings.

CONCLUSIONS

DDAC and alcohols are rarely responsible for allergic contact dermatitis. The accused products of the patients should be checked for other allergens and further additives with skin-irritating properties. Individual susceptibility and mishandling of the disinfectants should be considered.

Engineering Escherichia coli for propionic acid production through the Wood-Werkman cycle

Native to propionibacteria, the Wood-Werkman cycle enables propionate production via succinate decarboxylation. Current limitations in engineering propionibacteria strains have redirected attention toward the heterologous production in model organisms. Here, we report the functional expression of the Wood-Werkman cycle in Escherichia coli to enable propionate and 1-propanol production. The initial proof-of-concept attempt showed that the cycle can be used for production. However, production levels were low (0.17 mM). In silico optimization of the expression system by operon rearrangement and ribosomal-binding site tuning improved performance by fivefold. Adaptive laboratory evolution further improved performance redirecting almost 30% of total carbon through the Wood-Werkman cycle, achieving propionate and propanol titers of 9 and 5 mM, respectively. Rational engineering to reduce the generation of byproducts showed that lactate (∆ldhA) and formate (∆pflB) knockout strains exhibit an improved propionate and 1-propanol production, while the ethanol (∆adhE) knockout strain only showed improved propionate production.

Reaction of 1-propanol with Ozone in Aqueous Media

The main aim of this work is to substantiate the mechanism of 1-propanol oxidation by ozone in aqueous solution when the substrate is present in large excess. Further goals are assessment of the products, their formation yields as well as the kinetic parameters of the considered reaction. The reaction of ozone with 1-propanol in aqueous solution occurs via hydride transfer, H-abstraction and insertion. Of these three mechanisms, the largest share is for hydride transfer. This implies the extraction of an hydride ion from the activated C-H group by O₃ according to reaction: (C₂H₅)(H)(HO)C-H + O₃ → [(C₂H₅)(H)(HO)C⁺ + HO₃^-]_cage → (C₂H₅)(H)(HO)C⁺ + HO₃^-. The experimentally determined products and their overall formation yields with respect to ozone are: propionaldehyde-(60 ± 3)%, propionic acid-(27.4 ± 1.0)%, acetaldehyde-(4.9 ± 0.3)%, acetic acid-(0.3 ± 0.1)%, formaldehyde-(1.0 ± 0.1)%, formic acid-(4.6 ± 0.3)%, hydrogen peroxide-(11.1 ± 0.3)% and hydroxyl radical-(9.8 ± 0.3)%. The reaction of ozone with 1-propanol in aqueous media follows a second order kinetics with a reaction rate constant of (0.64 ± 0.02) M^-1·s^-1 at pH = 7 and 23 °C. The dependence of the second order rate constant on temperature is described by the equation: l n   k I I = ( 27.17 ± 0.38 ) - ( 8180 ± 120 ) × T - 1 , which gives the activation energy, Ea = (68 ± 1) kJ mol^-1 and pre-exponential factor, A = (6.3 ± 2.4) × 10¹¹ M^-1 s^-1. The nature of products, their yields and the kinetic data can be used in water treatment. The fact that the hydride transfer is the main pathway in the 1-propanol/ozone system can probably be transferred on other systems in which the substrate is characterized by C-H active sites only.

Metabolic pathway engineering for production of 1,2-propanediol and 1-propanol by Corynebacterium glutamicum

BACKGROUND

Production of the versatile bulk chemical 1,2-propanediol and the potential biofuel 1-propanol is still dependent on petroleum, but some approaches to establish bio-based production from renewable feed stocks and to avoid toxic intermediates have been described. The biotechnological workhorse Corynebacterium glutamicum has also been shown to be able to overproduce 1,2-propanediol by metabolic engineering. Additionally, C. glutamicum has previously been engineered for production of the biofuels ethanol and isobutanol but not for 1-propanol.

RESULTS

In this study, the improved production of 1,2-propanediol by C. glutamicum is presented. The product yield of a C. glutamicum strain expressing the heterologous genes gldA and mgsA from Escherichia coli that encode methylglyoxal synthase gene and glycerol dehydrogenase, respectively, was improved by additional expression of alcohol dehydrogenase gene yqhD from E. coli leading to a yield of 0.131 mol/mol glucose. Deletion of the endogenous genes hdpA and ldh encoding dihydroxyacetone phosphate phosphatase and lactate dehydrogenase, respectively, prevented formation of glycerol and lactate as by-products and improved the yield to 0.343 mol/mol glucose. To construct a 1-propanol producer, the operon ppdABC from Klebsiella oxytoca encoding diol dehydratase was expressed in the improved 1,2-propanediol producing strain ending up with 12 mM 1-propanol and up to 60 mM unconverted 1,2-propanediol. Thus, B12-dependent diol dehydratase activity may be limiting 1-propanol production.

CONCLUSIONS

Production of 1,2-propanediol by C. glutamicum was improved by metabolic engineering targeting endogenous enzymes. Furthermore, to the best of our knowledge, production of 1-propanol by recombinant C. glutamicum was demonstrated for the first time.

Systematically engineering Escherichia coli for enhanced production of 1,2-propanediol and 1-propanol

The biological production of high value commodity 1,2-propanediol has been established by engineering the glycolysis pathway. However, the simultaneous achievement of high titer and high yield has not been reported yet, as all efforts in increasing the titer have resulted in low yields. In this work, we overcome this limitation by employing an optimal minimal set of enzymes, channeling the carbon flux into the 1,2-propanediol pathway, increasing NADH availability, and improving the anaerobic growth of the engineered Escherichia coli strain by developing a cell adaptation method. These efforts lead to 1,2-propanediol production at a titer of 5.13 g/L with a yield of 0.48 g/g glucose in 20 mL shake flask studies. On this basis, we pursue the enhancement of 1-propanol production from the 1,2-propanediol platform. By constructing a fusion diol dehydratase and developing a dual strain process, we achieve a 1-propanol titer of 2.91 g/L in 20 mL shake flask studies. To summarize, we report the production of 1,2-propanediol at enhanced titer and enhanced yield simultaneously in E. coli for the first time. Furthermore, we establish an efficient system for the production of biofuel 1-propanol biologically.

Escherichia coli mar and acrAB mutants display no tolerance to simple alcohols

The inducible Mar phenotype of Escherichia coli is associated with increased tolerance to multiple hydrophobic antibiotics as well as some highly hydrophobic organic solvents such as cyclohexane, mediated mainly through the AcrAB/TolC efflux system. The influence of water miscible alcohols ethanol and 1-propanol on a Mar constitutive mutant and a mar deletion mutant of E. coli K-12, as well as the corresponding strains carrying the additional acrAB deletion, was investigated. In contrast to hydrophobic solvents, all strains were killed in exponential phase by 1-propanol and ethanol at rates comparable to the parent strain. Thus, the Mar phenotype does not protect E. coli from killing by these more polar solvents. Surprisingly, AcrAB does not contribute to an increased alcohol tolerance. In addition, sodium salicylate, at concentrations known to induce the mar operon, was unable to increase 1-propanol or ethanol tolerance. Rather, the toxicity of both solvents was increased in the presence of sodium salicylate. Collectively, the results imply that the resilience of E. coli to water miscible alcohols, in contrast to more hydrophobic solvents, does not depend upon the AcrAB/TolC efflux system, and suggests a lower limit for substrate molecular size and functionality. Implications for the application of microbiological systems in environments containing high contents of water miscible organic solvents, e.g., phage display screening, are discussed.