Specific Pretreatments Research Articles

Analysis of the Urine Volatilome of COVID-19 Patients and the Possible Metabolic Alterations Produced by the Disease.

Alterations in metabolism caused by SARS-CoV-2 infection have been highlighted in various investigations and have been used to search for biomarkers in different biological matrices. However, the selected biomarkers vary greatly across studies. Our objective is to provide a robust selection of biomarkers, including results from different sample treatments in the analysis of volatile organic compounds (VOCs) present in urine samples from patients with COVID-19. Between September 2021 and May 2022, urine samples were collected from 35 hospitalized COVID-19 patients and 32 healthy controls. The samples were analyzed by headspace (HS) solid phase microextraction (SPME) coupled to gas chromatography-mass spectrometry (GC-MS). Analyses were conducted on untreated urine samples and on samples that underwent specific pretreatments: lyophilization and treatment with sulfuric acid. Partial Least Squares Linear Discriminant Analysis (PLS-LDA) and Subwindow Permutation Analysis (SPA) models were established to distinguish patterns between COVID-19 patients and healthy controls. The results identify compounds that are present in different proportions in urine samples from COVID-19 patients compared to those from healthy individuals. Analysis of urine samples using HS-SPME-GC-MS reveals differences between COVID-19 patients and healthy individuals. These differences are more pronounced when methods that enhance VOC formation are used. However, these pretreatments can cause reactions between sample components, creating additional products or removing compounds, so biomarker selection could be altered. Therefore, using a combination of methods may be more informative when evaluating metabolic alterations caused by viral infections and would allow for a better selection of biomarkers.

Antimicrobial properties and biocompatibility of semi-synthetic carbohydrate-based ionic hydrogels.

Hydrogels have gained significant interest in the last decades, especially in the medical sector, due to their versatile properties. While hydrogels from naturally occurring polysaccharides (e.g. cellulose) are well-known, those produced from polymerizable carbohydrate-based monomers remain underexplored. However, these semi-synthetic hydrogels offer the great advantage of having adjustable properties for customization depending on their application. The objective of this study was to characterize semi-synthetic carbohydrate-based ionic hydrogels produced from GVIM-I (glucosyl vinyl imidazolium iodide). The antimicrobial activity was evaluated using the disk diffusion method, which demonstrated that all samples exhibit inhibitory effects on the growth of Candida auris. In vitro biocompatibility was determined by cell viability studies with L929 mouse fibroblasts, and a correlation was observed between eluate concentration and cell viability. In particular, the type of initiator system employed for polymerization was found to affect cell viability. The direct contact assessments showed that specific pre-treatments of the hydrogels resulted in higher cell viability than non-treated hydrogels. The results also revealed the impact of crosslinker concentration and type and identified poly(ethylene glycol)diacrylate (PEGDA) 575 as a promising crosslinker for future medical applications. LC-MS analysis of the wash medium identified unreacted GVIM-I as the leached material, which is presumed to be the cause of the observed cytotoxicity. Overall, the study provides valuable insights into the characteristics of GVIM-I based hydrogels and sheds light on the factors that influence their cytotoxicity and potential for medical application.

Chlorine evolution and char characteristics during pyrolysis upgrading of Xinjiang high chlorine coal

Xinjiang ShaErHu (SEH) coal, characterized by a high chlorine concentration exceeding 1 %, can cause severe chlorine corrosion when directly burned. To utilize this high-chlorine coal in an effective and clean way, specific pretreatments such as low-temperature pyrolysis upgrading are required. In this paper, the changes in tar, pyrolysis gas, combustion characteristics, and chlorine evolution features were analyzed during the low-temperature pyrolysis of SEH coal. The effects of increasing temperature (350 °C, 450 °C, and 550 °C) were studied. The results show that the proportion of aromatic compounds released consistently increases with temperature, reaching a peak of 80 % at 550 °C in the tar. It is noteworthy that chlorine is hardly detected in tar. The percentage of chlorine released in the pyrolysis gas remains relatively stable as the temperature rises from 350 °C to 550 °C, accounting for approximately 17.5 % of the total chlorine. The percentages of water-soluble chlorine in raw coal, char-350 °C, char-450 °C and char-550 °C are 74.3 %, 80.4 %, 82.2 %, and 55.1 % respectively. The majority of the chlorine in the char produced at 350 °C and 450 °C is inorganic, making up 68.9 % and 69.4 %, respectively. In contrast, char generated at 550 °C has 58.4 % chlorine that is primarily organic. About 40 % of the inorganic chlorine is converted to organic chlorine when the pyrolysis temperature is raised to 550 °C. This conversion likely occurs as a result of the inorganic chlorine ions combining with carbon to form C-Cl bonds. In order to effectively prevent high temperature corrosion, high-chlorine coal can be treated by pyrolysis at temperatures between 350 and 450 °C, followed by water washing and burning. This research provides a theoretical foundation for the clean and efficient use of high-chlorine coal.

Licensing effects of inflammatory factors and TLR ligands on the regenerative capacity of adipose-derived mesenchymal stem cells.

Introduction: Adipose tissue-derived mesenchymal stem cells are promising contributors to regenerative medicine, exhibiting the ability to regenerate tissues and modulate the immune system, which is particularly beneficial for addressing chronic inflammatory ulcers and wounds. Despite their inherent capabilities, research suggests that pretreatment amplifies therapeutic effectiveness. Methods: Our experimental design exposed adipose-derived mesenchymal stem cells to six inflammatory factors for 24h. We subsequently evaluated gene expression and proteome profile alterations and observed the wound closure rate post-treatment. Results: Specific pretreatments, such as IL-1β, notably demonstrated an accelerated wound-healing process. Analysis of gene and protein expression profiles revealed alterations in pathways associated with tissue regeneration. Discussion: This suggests that licensed cells exhibit potentially higher therapeutic efficiency than untreated cells, shedding light on optimizing regenerative strategies using adipose tissue-derived stem cells.

Unravelling the effects of surface modification pre-treatments on porous hastelloy X supports for H2 selective Pd-based membranes preparation with a statistical approach

Metal-based supports require specific pre-treatments to reach the surface quality needed for achieving thin Pd layers deposition without defects. Hastelloy X supports with high surface roughness and large pore diameter are acquired and pre-treated via polishing and chemical etching. They are then asymmetrically filled with α-Al2O3 of decreasing particle size (18 μm, 5 μm and 1.5 μm) and equipped with a γ-Al2O3 interdiffusion barrier. Each pre-treatment step is thoroughly characterized and elucidated with ANalysis Of VAriance (ANOVA) as statistical tool, introducing a hybrid observational-statistical approach to infer on a population of membrane supports.The analysis allowed to set average surface roughness (Ra) < 0.8 μm, average profile height (Rz) < 7 μm, in-pore leveling (Δ) < 6 μm, as targets for support pre-treatments reproducibility. The target average pore diameter after asymmetric filling was identified as 100–500 nm, while the target average pore diameter after interdiffusion barrier deposition was below 100 nm. The most effective particle size for in-pore leveling was identified as ≤ 5 μm, and the most effective particle size for average pore diameter reduction as 18 μm.

Enzymatic Preparation and Processing Properties of DPP-IV Inhibitory Peptides Derived from Wheat Gluten: Effects of Pretreatment Methods and Protease Types.

The choice of appropriate proteases and pretreatment methods significantly influences the preparation of bioactive peptides. This study aimed to investigate the effects of different pretreatment methods on the hydrolytic performance of diverse proteases during the production of dipeptidyl peptidase-IV (DPP-IV) inhibitory peptides derived from wheat and their foaming and emulsion properties. Dry heating, aqueous heating, and ultrasound treatment were employed as pretreatments for the protein prior to the enzymatic hydrolysis of wheat gluten. FTIR analysis results indicated that all pretreatment methods altered the secondary structure of the protein; however, the effects of dry heating treatment on the secondary structure content were opposite to those of aqueous heating and ultrasound treatment. Nevertheless, all three methods enhanced the protein solubility and surface hydrophobicity. By using pretreated proteins as substrates, five different types of proteases were employed for DPP-IV inhibitory peptide production. The analysis of the DPP-IV inhibitory activity, degree of hydrolysis, and TCA-soluble peptide content revealed that the specific pretreatments had a promoting or inhibiting effect on DPP-IV inhibitory peptide production depending on the protease used. Furthermore, the pretreatment method and the selected type of protease collectively influenced the foaming and emulsifying properties of the prepared peptides.

Development of selective Pd–Ag membranes on porous metal filters

Metallic supports with sufficient surface quality to achieve highly selective thin Pd–Ag membranes require specific pre-treatments, are not readily available on the market and are generally very expensive. To reduce costs, rough and large media grade Hastelloy X filters have been acquired and pre-treated via polishing and chemical etching. The loss in gas permeance given by the polishing treatment proved fully recovered after chemical etching. A method to fill the large pores of the filters via aspiration of α-Al2O3 water-powder suspension has been applied and characterized via imaging of the filled pores, inferential statistics, and capillary flow porometry measurements. The most suitable filler particle size for pore size distribution reduction has been identified as 18 μm, while a 5 μm filler proved optimal for further pore morphology improvement. The wide pore size distribution of the filters has thus been reduced up to 200 nm by filling with α-Al2O3 particles of decreasing size, similarly to the ceramic supports used for thin Pd–Ag membranes deposition. A boehmite based interdiffusion barrier has been deposited, achieving further surface roughness reduction. A highly H2 selective membrane has been obtained via simultaneous Pd–Ag plating on the pre-treated filter.

INFLUENCE OF BIOMASS PRETREATMENT ON SUBSEQUENT PYROLYSIS AND HYDRODEOXYGENATION IN BIO-BASED TRANSPORT FUELS AND CHEMICALS PRODUCTION: A CRITICAL REVIEW

The present article aims to review the influence of various biomass pretreatments on the production of bio-based transportation fuel and chemicals via pyrolysis and hydrodeoxygenation (HDO). The article includes the influence of different thermochemical pretreatments such as dry torrefaction (DT), wet torrefaction (WT), steam explosion treatment (SET), hot water extraction (HWE), acid treatment (ACT), and alkali treatment (AKT) on bio-oil yield and bio-oil properties. HDO primarily includes dehydration, hydrogenolysis, decarbonylation, and hydrogenation. HDO can be classified based on stages (single and two-stage HDO), reaction pressure (high and low), and hydrogen presence (ex situ and in situ). The recent developments, advantages, and drawbacks associated with different types of HDO processes have been included. The article includes recent studies on designing various catalysts based on HDO conversion of different bio-oil compositions or selective model compounds to targeted bio-based products. The various biomass pretreatments impact the concentration of certain families of organic compounds present in bio-oil. Hence, the present review article also includes recommendations of specific biomass pretreatments for various HDO catalysts designed for selective model compounds or different bio-oil compositions. Few praiseworthy techno-economic analysis (TEA) studies on the influence of different biomass pretreatments on the minimum selling price (MSP) of bio-based products obtained at various production stages have been discussed.

Integrated Technology for Cereal Bran Valorization: Perspectives for a Sustainable Industrial Approach.

Current research focuses on improving the bioaccessibility of functional components bound to cereal bran cell walls. The main bioactive components in cereal bran that have major biological activities include phenolic acids, biopeptides, dietary fiber, and novel carbohydrates. Because of the bound form in which these bioactive compounds exist in the bran matrix, their bioaccessibility is limited. This paper aims to comprehensively analyze the functionality of an integrated technology comprising pretreatment techniques applied to bran substrate followed by fermentation bioprocesses to improve the bioaccessibility and bioavailability of the functional components. The integrated technology of specific physical, chemical, and biological pretreatments coupled with fermentation strategies applied to cereal bran previously-pretreated substrate provide a theoretical basis for the high-value utilization of cereal bran and the development of related functional foods and drugs.

Biobutanol production from sustainable biomass process of anaerobic ABE fermentation for industrial applications.

The growing population increases the need to develop advanced biological methods for utilizing renewable and sustainable resources to produce environmentally friendly biofuels. Currently, energy resources are limited for global demand and are constantly depleting and creating environmental problems. Some higher chain alcohols, like butanol and ethanol, processing similar properties to gasoline, can be alternate sources of biofuel. However, the industrial production of these alcohols remains challenging because they cannot be efficiently produced by microbes naturally. Therefore, butanol is the most interesting biofuel candidate with a higher octane number produced naturally by microbes through Acetone-Butanol-Ethanol fermentation. Feedstock selection as the substrate is the most crucial step in biobutanol production. Lignocellulosic biomass has been widely used to produce cellulosic biobutanol using agricultural wastes and residue. Specific necessary pretreatments, fermentation strategies, bioreactor designing and kinetics, and modeling can also enhance the efficient production of biobutanol. The recent genetic engineering approaches of gene knock in, knock out, and overexpression to manipulate pathways can increase the production of biobutanol in a user friendly host organism. So far various genetic manipulation techniques like antisense RNA, TargeTron Technology and CRISPR have been used to target Clostridium acetobutylicum for biobutanol production. This review summarizes the recent research and development for the efficient production of biobutanol in various aspects.

Investigation of the Mechanisms of Tramadol-Induced Seizures in Overdose in the Rat.

Tramadol overdose is frequently associated with the onset of seizures, usually considered as serotonin syndrome manifestations. Recently, the serotoninergic mechanism of tramadol-attributed seizures has been questioned. This study’s aim was to identify the mechanisms involved in tramadol-induced seizures in overdose in rats. The investigations included (1) the effects of specific pretreatments on tramadol-induced seizure onset and brain monoamine concentrations, (2) the interaction between tramadol and γ-aminobutyric acid (GABA)A receptors in vivo in the brain using positron emission tomography (PET) imaging and 11C-flumazenil. Diazepam abolished tramadol-induced seizures, in contrast to naloxone, cyproheptadine and fexofenadine pretreatments. Despite seizure abolishment, diazepam significantly enhanced tramadol-induced increase in the brain serotonin (p < 0.01), histamine (p < 0.01), dopamine (p < 0.05) and norepinephrine (p < 0.05). No displacement of 11C-flumazenil brain kinetics was observed following tramadol administration in contrast to diazepam, suggesting that the observed interaction was not related to a competitive mechanism between tramadol and flumazenil at the benzodiazepine-binding site. Our findings do not support the involvement of serotoninergic, histaminergic, dopaminergic, norepinephrine or opioidergic pathways in tramadol-induced seizures in overdose, but they strongly suggest a tramadol-induced allosteric change of the benzodiazepine-binding site of GABAA receptors. Management of tramadol-poisoned patients should take into account that tramadol-induced seizures are mainly related to a GABAergic pathway.

Transparent Composite Films Showing Durable Antifogging and Repeatable Self-Healing Properties Based on an Integral Blend Method.

Antifogging coatings for infrastructures and transparent objects have attracted much attention lately from the perspective of safety and visibility. We have developed a one-pot process to fabricate transparent composite films showing long-lasting antifogging and fast repeatable self-healing properties based on an integral blend (IB) method. This method does not require any specific pretreatments of inorganic fillers/particles. Thus, the precursor solutions could be prepared in a single step by simply mixing raw materials, e.g., poly(vinylpyrrolidone) (PVP) having different molecular weights (MWs: 55, 360, and 1300 k), nano-clay particles (NCPs), and amino-terminated organosilane (AOS). In this study, to control the degree of cross-linking between the PVP matrices and NCPs, addition of AOS as a cross-linker to the PVP matrices (weight percentage of AOS to the PVP matrices, α = 0.01-300%) was carefully controlled. Transparency and self-healing abilities/kinetics of the resulting samples were found to be strongly influenced by both the MWs of PVP and α values. Samples spin-coated with the lowest MW of PVP (55 k) and α values of 0.01-1% gave highly transparent and durable antifogging performance. For example, no fogging was observed for 7 days under >80% relative humidity, and scratches about 30 μm in width could be completely self-healed within a few hours. However, samples with α > 10% gave opaque/grayish films that did not show any self-healing abilities because of an increase in cross-linking of the matrices. The optimized precursor solution was also deposited directly onto the glass slides covered with a transparent porous silica nano-framework (SNF) by a spray-coating method. Due to the formation of the hard and superhydrophilic/hygroscopic SNF with a large surface area, durability of antifogging and self-healing properties of the composite films were moderately improved, compared to those on the flat glass slides.

Boosting manure biogas production with the application of pretreatments: A meta-analysis

Anaerobic digestion (AD) is a versatile manure management approach that can combine waste treatment , energy generation and nutrient recovery, thus playing a central role in circular economy . The AD process is highly influenced by manure composition which, depending on the source, may contain high loads recalcitrant materials (e.g., lignocellulosic and fibers) or lead to the formation of toxic compounds (e.g., NH 3 ), decreasing the energetic potential of the waste and requiring specific pretreatments to increase its degradability and biogas production. Although there are distinctions in the chemical composition of manure according to animal diets, different manure sources are usually grouped together, leading to a suboptimal performance of both the pretreatment and the AD process. Here, we performed a meta-analysis of 54 studies to evaluate the effects of different pretreatments on different manure types and their effect on methane (CH 4 ) yield and we estimated the energy potential if the appropriate pretreatment is applied to largest manure producing countries. The results showed that chemical and/or biological pretreatments were more effective for omnivore manure (e.g., swine, chicken), while physical and a combination of chemical and physical pretreatments negatively affected CH 4 production. Physical and/or chemical pretreatments had a positive effect on CH 4 yield from herbivore manure (e.g., cattle, horses), while biological pretreatments had a negative effect. The application of the adequate pretreatment can more than double the energy recovered from manure, allowing for an important substitution of fossil fuels, while decreasing operational costs and environmental risks and ultimately improving profitability . The development of pretreatment technologies and their application are strongly related to public policies for sustainable manure management and biogas use and production. • CH 4 production from different manure sources varies with different pretreatments. • Chemical and biological pretreatments increase CH 4 production from omnivore manure. • Physical and chemical pretreatments increase CH 4 production from herbivore manure. • The appropriate pretreatment can increase CH 4 yield up to ten times.

Experimental Study of the Influence of the Surface Preparation on the Fatigue Behavior of Polyamide Single Lap Joints.

The low quality of adhesion performance on polymeric surfaces has forced the development of specific pretreatments able to toughen the interface between substrate and adhesive. Among these methods, atmospheric pressure plasma treatment (APPT) appears particularly suitable for its environmental compatibility and its effectiveness in altering the chemical state of the surface. In this work, an experimental study on adhesively bonded joints realized using polyamide as substrates and polyurethane as the structural adhesive was carried out with the intent to characterize their fatigue behavior, which represents a key issue of such joints during their working life. The single lap joint (SLJ) geometry was chosen and several surface pretreatments were compared with each other: degreasing, abrasion (alone and followed by APPT) and finally APPT. The results show that the abrasion combined with APPT presents the most promising behavior, which appears consistent with the higher percentage of life spent for crack propagation found by means of DIC on this class of joints with respect to the others. APPT alone confers a good fatigue resistance with respect to the simple abrasion, especially at a low number of cycles to failure.

The impacts of altitude and seed pretreatments on seedling emergence of Syrian juniper (Juniperus drupacea (Labill.) Ant. et Kotschy)

BackgroundSyrian juniper is an economically important species and in danger of extinction. For these reasons, the best seedling production methods of the species should be determined and its plantations should be established. The aim of the study is to examine the impacts of altitude and different pretreatment combinations of cold and warm stratifications, citric acid, shaking seeds in bottles with crushed glass, and different stimulating agents including Baikal EM1, Biohumus, Polystimulin A6 and K hormones (PS-A6 and PS-K) on seed germination of Syrian juniper. To conduct the study, the cones of the Syrian junipers were collected from three different altitudes (1000, 1200, and 1400 m a.s.l.) within the boundaries of Forest Management Directorate of Bozyazı, Mersin in Turkey. The seeds were subjected to three replicates per one treatment (altitude in interaction with pretreatment). There were 100 seeds per replicate.ResultsTwo-way ANOVA revealed significant effects of altitude, pretreatment, and their interaction on seedling emergence of Syrian juniper. Seeds from higher altitudes had higher germination rates in all pretreatments. The highest percent emergence (85%) was recorded in the combination consisting of shaking with crushed glass, both cold and warm stratification, and successive application of stimulators PS-A6 and PS-K. All the treatments with most germinating seeds encompassed shaking in crushed glass or soaking in citric acid, both warm and cold stratifications, and application of stimulating agents.ConclusionsThe use of seeds from higher altitudes should be considered for seedling production of Syrian juniper due to their higher germination potential. Beyond altitudinal differences, specific pretreatments can rise germination potential more than twofold.

Lignocellulosic Biomass as a Substrate for Oleaginous Microorganisms: A Review

Microorganisms capable of accumulating lipids in high percentages, known as oleaginous microorganisms, have been widely studied as an alternative for producing oleochemicals and biofuels. Microbial lipid, so-called Single Cell Oil (SCO), production depends on several growth parameters, including the nature of the carbon substrate, which must be efficiently taken up and converted into storage lipid. On the other hand, substrates considered for large scale applications must be abundant and of low acquisition cost. Among others, lignocellulosic biomass is a promising renewable substrate containing high percentages of assimilable sugars (hexoses and pentoses). However, it is also highly recalcitrant, and therefore it requires specific pretreatments in order to release its assimilable components. The main drawback of lignocellulose pretreatment is the generation of several by-products that can inhibit the microbial metabolism. In this review, we discuss the main aspects related to the cultivation of oleaginous microorganisms using lignocellulosic biomass as substrate, hoping to contribute to the development of a sustainable process for SCO production in the near future.

Recycling contaminated marine sediments as filling materials by pilot scale stabilization/solidification with lime, organoclay and activated carbon

Nowadays, stabilization/solidification (S/S) applied to the treatment of contaminated marine sediments (CMSs) represents a key technology for the production of new materials for civil engineering. Literature has shown the feasibility of CMSs recycling, although sediment needs pre-treatments for the removal of organic matter and to improve the mechanical properties of the product post S/S. In view of the full-scale applicability where it is essential to reduce any additional phase (i.e., pre-treatments), this study is aimed at demonstrating the technical feasibility of recycling CMSs as filling materials by S/S treatments with lime, organoclay and activated carbon. The original sediments are contaminated with heavy metals, PCBs, and PAHs, exceeding limits values prescribed by law. Different mixtures were tested on the STABSOL-P pilot scale plant. The absence of specific CMSs pre-treatments resulted in failure to comply with the 28-days leaching test only for copper; greater air curing with 56-days allowed it to be complied with for all the investigated metals. The organic contamination, while slowing down the process of chemical stabilization, allowed in any case to get a product environmentally compatible. The unconfined compression strength tests showed values (>28 kPa) that would allow potential CMSs recycling for environmental enhancement. The mass balance of the case study of the Mar Piccolo of Taranto (Southern Italy) showed potential recycling of marine sediments (the production of 974 kg filling materials per 1000 kg of dredged sediment) with a consequent missed disposal in landfills of 0.65 m3/1000 kg of sediment.

Determination of the target population in early benefit assessments in Germany: challenges for non-small-cell lung cancer

ObjectivesDossiers submitted for early benefit assessments in Germany also provide information on the precise determination of the target population (patients eligible for a drug). The situation is complex for non-small-cell lung cancer (NSCLC) due to highly specific therapeutic indications. Our aim was to compare the different methodological steps applied to determine the target population in dossiers on drugs for NSCLC.MethodsWe analysed NSCLC dossiers assessed by the German Institute for Quality and Efficiency in Health Care (IQWiG) between 01.01.2011 and 31.12.2017. Methodological details regarding the determination of the target population were extracted and compared.ResultsWe analysed 23 NSCLC dossiers. In all dossiers, the target population was determined using the number of all patients with lung cancer as the basis for calculations. This patient population was further reduced in several successive steps by assuming proportions of patients with a specific characteristic (e.g. disease stage). The most important calculation steps were patients with NSCLC (n = 23 dossiers), with a specific disease stage (n = 23), with a specific tumour mutation (n = 14), with a specific tumour histology (n = 7), without prior treatment (n = 15), with pretreatment in second or further treatment lines (n = 17), and/or with specific pretreatments (n = 9). The proportions of patients determined within the same calculation step varied considerably between dossiers.DiscussionThe calculation methods applied and the target population sizes reported in NSCLC dossiers vary considerably. A consensus with regard to the databases and calculation methods used to determine the target population in NSCLC would be helpful to reduce variations.

Changes in Microbiota Profiles After Prolonged Frozen Storage of Stool Suspensions.

Introduction: Fecal microbiota transplantation (FMT) is recommended as safe and effective treatment for recurrent Clostridioides difficile infections. Freezing the FMT preparation simplifies the process, allowing a single stool sample to be used for multiple receivers and over an extended period of time. We aimed to assess the effect of long-term frozen storage on bacterial taxonomic profiles of a stool suspension prepared for FMT.Methods: DNA was extracted from a stool suspension before freezing and sequentially during the 18-month storage period at −80°C. Two different protocols were used for DNA extraction. The first relied on a classical mechanical and chemical cell disruption to extract both intra- and extracellular DNA; the second included specific pre-treatments aimed at removing free DNA and DNA from human and damaged bacterial cells. Taxonomic profiling of bacterial communities was performed by sequencing of V3–V4 16S rRNA gene amplicons.Results: Microbiota profiles obtained by whole DNA extraction procedure remained relatively stable during frozen storage. When DNA extraction procedure included specific pre-treatments, microbiota similarity between fresh and frozen samples progressively decreased with longer frozen storage times; notably, the abundance of Bacteroidetes decreased in a storage duration-dependent manner. The abundance of Firmicutes, the main butyrate producers in the colon, were not much affected by frozen storage for up to 1 year.Conclusion: Our data show that metataxonomic analysis of frozen stool suspensions subjected to specific pre-treatments prior to DNA extractions might provide an interesting indication of bacterial resistance to stress conditions and thus of chances of survival in FMT recipients.

The deficiency of organic matter 14C dating in Chinese Loess-paleosol sample

Abstract In the absence of reliable charcoal, wood or plant macrofossils, organic matter in loess-paleosols is often used for 14C dating. However, organic matter can be contaminated by a variety of carbon sources within the sediments, and this may affect the radiocarbon dating results. Specific chemical pretreatments can be applied to minimize such effects, and comparisons with optically stimulated luminescence (OSL) dates from the same sediments allows us to assess potential open system effects on organic matter. Here we present comparisons of the two geochronometers from loess-paleosol deposits in the Chinese Loess Plateau. Our results show that loess -paleosol samples from the past 25 cal kyr BP generally yield reliable 14C dates, however, beyond this range, specifically ~25–59 cal kyr BP, we observe a steady increase in OSL ages with depth, but no consistent increase in corresponding AMS 14C ages. We suggest that relatively old samples from loess-paleosols should be studied using techniques such as compound-specific radiocarbon dating, ramped pyrolysis or stepped-temperature combustion.