RESUMEN
BACKGROUND: Ascomycetous budding yeasts are ubiquitous environmental microorganisms important in food production and medicine. Due to recent intensive genomic research, the taxonomy of yeast is becoming more organized based on the identification of monophyletic taxa. This includes genera important to humans, such as Kazachstania. Until now, Kazachstania humilis (previously Candida humilis) was regarded as a sourdough-specific yeast. In addition, any antibacterial activity has not been associated with this species. RESULTS: Previously, we isolated a yeast strain that impaired bio-hydrogen production in a dark fermentation bioreactor and inhibited the growth of Gram-positive and Gram-negative bacteria. Here, using next generation sequencing technologies, we sequenced the genome of this strain named K. humilis MAW1. This is the first genome of a K. humilis isolate not originating from a fermented food. We used novel phylogenetic approach employing the 18 S-ITS-D1-D2 region to show the placement of the K. humilis MAW1 among other members of the Kazachstania genus. This strain was examined by global phenotypic profiling, including carbon sources utilized and the influence of stress conditions on growth. Using the well-recognized bacterial model Escherichia coli AB1157, we show that K. humilis MAW1 cultivated in an acidic medium inhibits bacterial growth by the disturbance of cell division, manifested by filament formation. To gain a greater understanding of the inhibitory effect of K. humilis MAW1, we selected 23 yeast proteins with recognized toxic activity against bacteria and used them for Blast searches of the K. humilis MAW1 genome assembly. The resulting panel of genes present in the K. humilis MAW1 genome included those encoding the 1,3-ß-glucan glycosidase and the 1,3-ß-glucan synthesis inhibitor that might disturb the bacterial cell envelope structures. CONCLUSIONS: We characterized a non-sourdough-derived strain of K. humilis, including its genome sequence and physiological aspects. The MAW1, together with other K. humilis strains, shows the new organization of the mating-type locus. The revealed here pH-dependent ability to inhibit bacterial growth has not been previously recognized in this species. Our study contributes to the building of genome sequence-based classification systems; better understanding of K.humilis as a cell factory in fermentation processes and exploring bacteria-yeast interactions in microbial communities.
Asunto(s)
Antibacterianos , Saccharomycetales , Humanos , Filogenia , Antibacterianos/metabolismo , Bacterias Gramnegativas , Bacterias Grampositivas , Saccharomycetales/genética , Levaduras/metabolismo , FermentaciónRESUMEN
Raspberry fruits are a valuable source of bioactive compounds. The study used the modification of the substrate (coconut fibre), consisting of the use of various organic and mineral additives, in the soilless cultivation of raspberries. The additives influenced the biosynthesis of bioactive compounds in the raspberry fruits by modifying the sorption properties and the abundance of the substrate. The influence of the additives on the content of polyphenols was determined as well as their profile (UPLC-MS), antioxidant potential (ABTS), vitamin C content, and the activity of selected enzymes that are markers of stress and resistance to abiotic factors. In the study, a significant effect of these additives was observed on the biosynthesis of polyphenols in raspberry fruit. The highest increase in the content of these compounds in relation to the control sample (substrate-100% coconut fibre), namely 37.7%, was recorded in the case of fruit produced on coconut substrate enriched with sheep wool. These fruits were also characterised by a significantly different profile of these compounds. These changes were caused by readily available ammonium nitrogen and free amino acids in the decomposition of proteins contained in the sheep wool. This was confirmed by the recorded content of chlorophyll SPAD in the plant leaves and the activity of selected enzymes, which proves a low level of stress and good condition of the plants.
Asunto(s)
Rubus , Rubus/química , Frutas/química , Cromatografía Liquida , Espectrometría de Masas en Tándem , Polifenoles/análisis , Antioxidantes/análisisRESUMEN
Natural products have always enjoyed great popularity among consumers. Wild tea is an interesting alternative to tea from intensive plantations. The term "wild tea" is applied to many different varieties of tea, the most desirable and valued of which are native or indigenous tea plants. Special pro-health properties of wild tea are attributed to the natural conditions in which it grows. However, there are no complex studies that describe quality and health indicators of wild tea. The aim of this research was to evaluate the quality of wild and cultivated green tea from different regions of China: Wuzhishan, Baisha, Kunlushan, and Pu'Er. The assessment was carried out by verifying the concentration of selected chemical components in tea and relating it to the health risks they may pose, as well as to the nutritional requirements of adults. Wild tea was characterized by higher micronutrient concentration. The analyzed teas can constitute a valuable source of Mn in the diet. A higher concentration of nitrates and oxalates in cultivated tea can be associated with fertilizer use. The analyzed cultivated tea was a better source of antioxidants with a higher concentration of caffeine. There were no indications of health risks for wild or cultivated teas.
Asunto(s)
Antioxidantes/análisis , Fertilizantes/análisis , Oxalatos/análisis , Extractos Vegetales/análisis , Hojas de la Planta/química , Polifenoles/química , Té/química , China , Elementos Químicos , Humanos , Nitratos/análisis , Control de CalidadRESUMEN
Bone and soft tissue infection involving the foot is a serious complication of diabetes mellitus and represents a major public health and socioeconomic burden to National Health Services worldwide. Research in the past decade has improved diagnosis and treatment of these frequent and potentially devastating complications of diabetic foot which often remain difficult to be diagnosed and treated despite the availability of various clinical, serological, and imaging modalities. Furthermore, neuropathic osteoarthropathy can share many clinical and imaging features of osteomyelitis, and infection is often superimposed in patients with neuropathic disease. Thus, distinguishing between the two abnormalities is further complicated. Although the reference standard for diagnosis remains microbiologic analysis of bone specimens, in most clinical practice, soft tissue and bone infection involving the diabetic foot is diagnosed solely on the basis of a combination of clinical evaluation, serum inflammatory markers, and imaging modalities. Correlation between imaging findings and clinical features is very important as well as a common knowledge base for treatment team members rather than a compartmentalized view. Thus, the primary purpose of this review article was to provide radiologist and clinician with important clinical knowledge and relevant radiological semiotics, respectively, in order to facilitate a prompt diagnosis and personalised treatment of diabetic foot infections.
Asunto(s)
Pie Diabético/complicaciones , Osteomielitis/diagnóstico por imagen , Osteomielitis/etiología , Infecciones de los Tejidos Blandos/diagnóstico por imagen , Infecciones de los Tejidos Blandos/etiología , Diagnóstico Diferencial , HumanosRESUMEN
BACKGROUND: Interactions between microorganisms during specific steps of anaerobic digestion determine metabolic pathways in bioreactors and consequently the efficiency of fermentation processes. This study focuses on conversion of lactate and acetate to butyrate by bacteria of dark fermentation. The recently recognized flavin-based electron bifurcation as a mode of energy coupling by anaerobes increases our knowledge of anaerobic lactate oxidation and butyrate formation. RESULTS: Microbial communities from dark fermentation bioreactors or pure culture of Clostridium butyricum are able to convert lactate and acetate to butyrate in batch experiments. The ability of C. butyricum to transform lactate and acetate to butyrate was shown for the first time, with ethanol identified as an additional end product of this process. A search for genes encoding EtfAB complexes and their gene neighbourhood in C. butyricum and other bacteria capable of lactate and acetate conversion to butyrate as well as butyrate-producers only and the lactate oxidiser Acetobacterium woodii, revealed that the Etf complexes involved in (i) lactate oxidation and (ii) butyrate synthesis, form separate clusters. There is a more extent similarity between Etf subunits that are involved in lactate oxidation in various species (e.g. A. woodii and C. butyricum) than between the different etf gene products within the same species of butyrate producers. A scheme for the metabolic pathway of lactate and acetate transformation to butyrate in C. butyricum was constructed. CONCLUSIONS: Studies on the conversion of lactate and acetate to butyrate by microbial communities from dark fermentation bioreactors or Clostridium butyricum suggest that a phenomenon analogous to cross-feeding of lactate in gastrointestinal tract also occurs in hydrogen-yielding reactors. A scheme of lactate and acetate transformation pathway is proposed, based on the example of C. butyricum, which employs flavin-based electron bifurcation. This process utilizes electron-transferring flavoprotein (Etf) complexes specific for (i) lactate oxidation and (ii) butyrate formation. Phylogenetic analysis revealed that such complexes are encoded in the genomes of other bacteria capable of lactate and acetate conversion to butyrate. These findings contribute significantly to our understanding of the metabolic pathways and symbiotic interactions between bacteria during the acidogenic step of anaerobic digestion.
Asunto(s)
Acetatos/metabolismo , Butiratos/metabolismo , Clostridium butyricum/metabolismo , Fermentación , Ácido Láctico/metabolismo , Microbiota , Bacterias Anaerobias/metabolismo , Reactores Biológicos/microbiología , Clostridium butyricum/genética , Microbiología Industrial , Redes y Vías MetabólicasRESUMEN
Fatty acids contribute to the nutritional quality of the phytoplankton and, thus, play an important role in Daphnia nutrition. One of the polyunsaturated fatty acids (PUFAs)--eicosapentaenoic acid (EPA)--has been shown to predict carbon transfer between primary producers and consumers in lakes, suggesting that EPA limitation of Daphnia in nature is widespread. Although the demand for EPA must be covered by the diet, the demand of EPA in Daphnia that differ in body size has not been addressed yet. Here, we hypothesize that the demand for EPA in Daphnia is size-dependent and that bigger species have a higher EPA demand. To elucidate this, a growth experiment was conducted in which at 20 °C three Daphnia taxa (small-sized D. longispina complex, medium-sized D. pulicaria, and large-bodied D. magna) were fed Synechococcus elongatus supplemented with cholesterol and increasing concentrations of EPA. In addition, fatty acid analyses of Daphnia were performed. Our results show that the saturation threshold for EPA-dependent growth increased with increasing body size. This increase in thresholds with body size may provide another mechanism contributing to the prevalence of small-bodied cladocera in warm habitats and to the midsummer decline of large cladocera in eutrophic water bodies.
Asunto(s)
Daphnia , Ácido Eicosapentaenoico , Animales , Tamaño Corporal , Ecosistema , FitoplanctonRESUMEN
Phaeohyphomycoses are infections caused by dark-walled dematiaceous fungi. Alternaria and Curvularia are two genera of dematiaceous molds known to cause invasive fungal rhinosinusitis, particularly in immunocompromised patients. Co-infection with two dematiaceous fungi is rarely reported in the literature. This report describes a case of biopsy proven invasive fungal rhinosinusitis with Alternaria spp. and Curvularia spp. co-infection in a neutropenic host. The infection characteristics, microbiologic findings, and treatment are described.
RESUMEN
Russia's invasion of Ukraine contributed one of the largest migration movements in the 21st century. Refugees may become a source of severe acute respiratory syndrome coronavirus 2 infections for the residents of host countries. The study aim was to assess knowledge and preventive practices regarding coronavirus disease 2019 (COVID-19) among Ukrainian refugees in Poland. The cross-sectional study was conducted between March and April 2022 among Ukrainian refugees registering consecutively in Zielona Góra, Poland. Knowledge and preventive practices were assessed by giving 1 point for each correct answer by anonymous, self-administered questionnaire. The response rate was 96%, 190 participated (mean age 37.8â ±â 15.5 years; 57.9% females); 61.6% self-reported their socio-economic status (SES) as high, 38.9% reported high level of education. The mean COVID-19 knowledge score was 3.06â ±â 1.95; 19.5% scored >50%. The knowledge level was higher among migrants with high SES (Pâ =â .003). The mean preventive practices score was 2.56â ±â 1.38; 54.0% scoredâ ≥â 60%. 40.5% declared social distancing, 62.6% followed coughing etiquette, 69.0% home isolate themselves during COVID-19. 57.9% always used masks in public space, however 74.2% wore masks with uncovered nose. Refugees with higher education, high SES and knowledge level had significantly greater preventive practices scores (Pâ =â .002; Pâ =â .02; Pâ =â .03, respectively). The knowledge and preventive practices level was insufficient. Educational campaigns oriented to raising knowledge and prevention behavior skills should be implemented, especially targeting high-risk groups to avoid spread of COVID-19.
Asunto(s)
COVID-19 , Refugiados , Femenino , Humanos , Adulto Joven , Adulto , Persona de Mediana Edad , Masculino , COVID-19/epidemiología , COVID-19/prevención & control , SARS-CoV-2 , Polonia/epidemiología , Estudios TransversalesRESUMEN
Introduction Combination antifungal regimens are frequently employed in the treatment of invasive fungal infections in patients who are immunocompromised, particularly for cancer and transplant patients. Terbinafine is a potential agent of interest for combination regimens. Methods We reviewed data over a six-year period examining patient outcomes in terms of both mortality and distribution of pathogens. The total number of patients in our study was 64. The use of terbinafine versus no terbinafine in combination therapy was assessed. Of the 64 patients analyzed, only 14 received terbinafine. Mortality was calculated for both groups, and demographics were analyzed by descriptive statistics. Results There was no statistical difference in mortality outcomes in either group. The addition of terbinafine was well tolerated and did not appear to result in any undue toxicity concerns. Discussion We wish to draw greater attention to this potential agent within our armamentarium for invasive fungal infections. To our knowledge, the total number of patients in our study, while small, represents the largest reported cohort in the literature to date. Sensitivities are crucial to be obtained for fungal pathogens as this likely undermined the utility of terbinafine in our study with larger than expected numbers of multidrug-resistant Fusarium. With limited patient numbers, a multicenter trial would be beneficial to further examine terbinafine in combination regimens.
RESUMEN
Acute appendicitis is an inflammatory process which is one of the most frequent global causes of surgical interventions in children. The goal of the study was to determine whether acute phase proteins, that is, C-reactive protein (CRP), procalcitonin (PCT) and neutrophil gelatinase-associated lipocalin (NGAL), interleukin 6 (IL-6), transforming growth factor-beta1 (TGF-ß1) and cortisol (HC) play a role in the pathomechanism of post-trauma stress response of the organism and to establish the impact of the applied surgical procedure and/or of inflammation on their concentrations. An additional purpose was to establish the clinical usefulness of the studied biomarkers in the diagnostics of appendicitis. CRP concentrations were quantified via the immunoturbidimetric method, while the levels of IL-6 and PCT were assessed using a bead-based multiplexed immunoassay system in a microplate format (Luminex xMAP technology); NGAL, TGF-ß1 and cortisol concentrations were determined via the enzyme-linked immunosorbent assay (ELISA) technique. All the investigated biomarkers were assayed twice, i.e., immediately before the surgery and 12-24 h after its completion. Significant increases in CRP, IL-6 and PCT concentrations were found in all children subjected to laparoscopic surgeries (p = 0.001, p = 0.006, and p = 0.009, respectively) and open (classic) surgeries (p = 0.001, p = 0.016, and p = 0.044, respectively) compared to the initial concentrations. The patients undergoing classical surgery moreover presented with significant (p = 0.002, and p = 0.022, respectively) increases in NGAL and TGF-ß1 levels after the procedures. In a group of children undergoing laparoscopic surgery, the appendicitis induced an increase in cortisol concentration, whereas in patients undergoing classical surgery the increase in the levels of this biomarker was caused by the type of performed surgical procedure. Simultaneously assaying the levels of CRP, NGAL and IL-6 (p = 0.008, p = 0.022, and p = 0.000, respectively) may prove useful in clinical practice, enabling the diagnosis of appendicitis in paediatric patients reporting to a hospital with abdominal pains, in addition to data from anamnesis and from clinical or ultrasound examination. The performed study confirms the participation of examined biomarkers in the pathomechanism of post-injury stress reaction of the organism to surgical trauma.
RESUMEN
A higher body mass index (BMI) before pregnancy is associated with an increased risk of maternal and perinatal complications. This study aimed to analyze selected parameters of carbohydrate and lipid metabolism, including adipokines, in obese pre-pregnant women, and their influence on the birth weight of newborns. MATERIALS AND METHODS: The study group (O) consisted of 34 pregnant women with higher BMI (obese) before pregnancy. The control group (C) was 27 pregnant women with target BMI and physiological pregnancy. The BMI index: body weight [kg]/(height [m]2 was assessed on the first obstetrical visit. The research material was the serum of pregnant women collected in the third trimester of pregnancy and umbilical cord blood collected immediately after delivery. Selected parameters of carbohydrate and lipid metabolism and adipokines were determined. RESULTS: There were no statistically significant differences between the study group and the control group concerning the concentrations of insulin, glucose, VLDL, adiponectin, TNF-α, HOMA-IR, as well as LDH and cholesterol in maternal blood serum and umbilical cord blood serum. Total cholesterol and HDL in both maternal blood serum and umbilical cord blood were statistically significantly lower than those in the control group. The concentration of triglycerides (TG) and resistin in the blood serum of obese mothers were higher than those in the control group (p < 0.05). However, no statistically significant differences were found between the two groups regarding the concentrations of TG and resistin in the umbilical cord blood. The concentration of LDL cholesterol in the umbilical blood serum in the obese group was statistically significantly lower than that in the control group. The concentration of leptin in maternal blood serum and umbilical cord blood serum in the study group was statistically significantly higher than that in the control group. CONCLUSIONS: Pregestational obesity does not substantially affect the basic parameters of carbohydrate metabolism in pregnant women, but it disturbs the lipid profile, which is manifested by a significant increase in triglycerides and a decrease in the level of HDL cholesterol in the serum. Preexisting obesity increases the concentration of leptin and resistin in the serum of pregnant women, which may be caused by the increased volume of adipose tissue. The concentrations of leptin and resistin in the blood of pregnant women correlate positively, and the concentrations of adiponectin and TNF-α negatively correlate with pre-pregnancy BMI values. There is a positive correlation between the concentration of leptin in the serum of umbilical cord blood and the birth weight of the newborn, which suggests that this parameter contributes to the pathomechanism of macrosomia.
Asunto(s)
Adipoquinas , Leptina , Recién Nacido , Embarazo , Femenino , Humanos , Resistina , Adiponectina , Metabolismo de los Lípidos , Peso al Nacer , Factor de Necrosis Tumoral alfa , Obesidad , GlucosaRESUMEN
In the scientific literature, a selected number of reports have investigated the impact of proliferative activity on the development and progression of uterine carcinosarcomas (UC). The aim of the present retrospective study was to compare the immunohistochemical proliferation markers [Ki67, proliferating cell nuclear antigen (PCNA), minichromosome maintenance complex component 3 (MCM3), and topoisomerase IIα (topoIIα)] assessment in both components of UC. A total of 30 paraffin-embedded slides of UCs, obtained from patients who underwent surgery between January 1, 2006, and December 31, 2020, were analyzed. Medical records and clinicopathological data of patients were reviewed. Formalin-fixed, paraffin-embedded tissue sections were immunostained with monoclonal antibodies against Ki67, PCNA, MCM3 and topoIIα. Ki67-positive nuclear immunoreactivity was reported in 20 (67%) and 16 (53%) UC carcinomatous and sarcomatous components, respectively. In the epithelial component, Ki67 positive staining was related to the International Federation of Gynecology and Obstetrics (FIGO) stage (P=0.025), and histological grade (G1 vs. G2/G3, P=0.031). Nuclear PCNA reactivity was observed in 18 (60%) and 16 (53%) carcinomatous and sarcomatous components, respectively. Notably, all four cases with omental metastases were PCNA-positive, and a relationship between staining pattern and the existence of metastases was of significant value (P=0.018). MCM3-positive nuclear staining was found nearly twice as high in the carcinomatous (n=19; 63%), compared with the sarcomatous (n=11; 37%) component, respectively, and MCM3 expression in the epithelial component was related to clinical stage (P=0.030), and the existence of omental metastasis (P=0.012). In addition, out of the 30 UCs, 17 (57%) and 13 (43%) showed topoIIα positivity in the carcinomatous and sarcomatous UC components, respectively. A significant relationship between protein immunoreactivity and FIGO stage (P=0.049), and omental metastasis (P=0.026) was revealed to exist. However, no significant differences between expression of proliferation markers and clinicopathological features in the sarcomatous UC component were identified. Finally, a significant correlation between each protein immunohistochemical staining was demonstrated, particularly in the sarcomatous UC component. Collectively, a combined analysis of Ki67, PCNA, MCM3, and topoIIα may provide more detailed information of cell-cycle alterations determining the heterogeneity of uterine carcinosarcomas.
RESUMEN
The utilization of municipal waste and sewage sludge as a source of energy is technically very difficult due to high variability of their physical and chemical properties. The aim of this study was to evaluate the efficiency of the conversion of biomass contained in the whitewater fraction of municipal waste and sewage sludge by means of methanogenesis. The second objective was to assess the chemical composition of the digestate in the context of its use for fertilizer purposes. The whitewater fraction of municipal waste and sewage sludge was subjected to methanogenesis under static experimental conditions, according to DIM DIN 38414 methodology. The methanogenesis of concentrated substrates used in agricultural biogas plants was taken as a reference to evaluate the efficiency of the process. The organic fraction of the municipal waste was characterized by approximately 30% lower value of the soluble COD, with a comparable level of total COD compared to other materials. The total biogas yield, i.e., 404 dm3 per 1 kg of dry weight of the batch, was measured in the facility with sewage sludge. In COD value, this is 0.232 dm3·g O2 COD. In the case of corn, these values were, respectively, 324 dm3 and 0.193, and for the organic sub-sieve fraction of municipal waste, 287 dm3·kg-1 dw or 0.178 dm3·g O2 COD, respectively. The type of fermented material did not affect the intensity of biogas production. The maximum level of biogas production occurred between the 13th and 15th day of the process. The digestate obtained in the process of methanogenesis of corn silage and the organic fraction of municipal waste was characterized by good parameters in terms of possible use for fertilization purposes.
RESUMEN
Cytokeratins (CKs) are the largest subgroup of intermediate filament proteins, preferentially expressed in epithelial tissues. CKs play a critical role in determining epithelial structural integrity under stressful conditions in addition to their various fundamental functions in cellular proliferation, apoptosis, migration, adherence and molecular signaling. Immunohistochemical CKs staining could be evaluated with a proper comprehension of their task limitations and their association with the normal morphology to avoid misdiagnosis. Herein, we critically review the CKs expression patterns in ECs in relation to clinicopathological features and patients' outcome. We also briefly discussed the recent advantage of CKs immunohistochemical staining in the detection of EC micrometastasis.
RESUMEN
There is a potential for using sulfur waste in agriculture. The main objective of this study was to design a granular fertilizer based on waste elemental sulfur. Humic acids and halloysite were used to improve the properties and their influence on soil properties. This is the first report on the use of proposed materials for fertilizer production. The following granular fertilizers were prepared (the percentage share of component weight is given in brackets): fertilizer A (waste sulfur (95%) + halloysite (5%)), fertilizer B (waste sulfur (81%) + halloysite (5%) + humic acids (14%)), fertilizer C (waste sulfur (50%) + halloysite (50%)) and fertilizer D (waste sulfur (46%) + halloysite (46%) + humic acids (8%)). Basic properties of the obtained granulates were determined. Furthermore, the effect of the addition of the prepared fertilizers on soil pH, electrolytic conductivity, and sulfate content was examined in a 90-day incubation experiment. Enrichment with humic acids and the higher amount of halloysite increased the fertilizer properties (especially the share of larger granules and bulk density). In addition, it stabilized soil pH and increased the sulfur content (extracted with 0.01 mol·L-1 CaCl2 and Mehlich 3) in the soil.
RESUMEN
Crop fertilization with sulfur is an important part of agricultural practices, as is the systematic increase in soil organic matter content. Materials of waste origin constitute a source of plant-available sulfur, as well as soil organic matter. The study was to verify the hypothesis assuming that combining waste sulfur pulp and its mixtures with organic materials enables simultaneous soil enrichment with readily available sulfur and organic matter. A 240-day incubation experiment was conducted, on two soils: very light and heavy; with two sulfur doses applied to each soil (20 and 40 mg S/kg d.m. for very light soil, and 30 and 60 mg S/kg d.m. for heavy soil). The sulfate sulfur content in the incubated soil material, treated with the addition of sulfur pulp and its mixtures with organic materials, increased significantly up to day 60 and then decreased. The application of these materials significantly increased the content of available sulfur and decreased the pH value of the incubated material. The effect of the introduced materials on dehydrogenase activity depended on soil granulometric composition (the impact of the applied materials on the activity of these enzymes in very light soil was small, and in heavy soil, their activity was usually limited by the presence of introduced materials). Application of the studied materials had little effect on the total organic carbon content in the incubated soil material (a significant change in the value of this parameter, in relation to the control soil, was recorded in some treatments of heavy soil).
RESUMEN
Proper quality assessment of ready-mixed concrete, which is currently the principal material for construction, land engineering and architecture, has an impact on the optimisation and verification of correct functioning of individual stages of the production process. According to the European Standard EN 206 "Concrete-Specification, performance, production and conformity", obligatory conformity control of concrete is carried out by the producer during its production. In order to verify the quality of concrete, investors generally commission independent laboratory units to perform quality assessment of both concrete mix and hardened concrete, which guarantees a high quality of construction works. One of the essential tools for ensuring the quality of test results is the participation of laboratories in the so-called proficiency testing (PT) or inter-laboratory comparisons (ILC). Participation in PT/ILC programmes is, on the one hand, a tool for demonstrating the laboratory's performance, on the other hand an aid for maintaining the quality of available concrete tests and validating test methods. Positive evaluation is a confirmation of the laboratory's capability for performing the tests. The paper presents the results of laboratory proficiency tests carried out by means of inter-laboratory comparisons, as shown in the example of quality assessment of ready-mixed concrete for nine participating laboratories. The tests were performed for concrete of the following parameters: strength class C30/37, consistency S3, frost resistance degree F150, and water resistance degree W8. This involved determining consistencies, air content and density of the concrete mix, and compressive strength of hardened concrete. For the evaluation of laboratory performance results, z-score, ζ-score and En-score were applied. The innovation of the proposed study lies in employing both classical and iterative robust statistical methods. In comparison with classical statistical methods, robust methods ensure a smaller impact of outliers and other anomalies on the measurement results. Following the analyses, clear differences were found between the types of detected discrepancy of test results, which occurred due to the nature of individual parameters. For two laboratories, two scores revealed unsatisfactory results for concrete mix consistency. The main reasons can be pouring into the cone-shaped form a concrete mixture that is too dry, or incorrect use of a measuring tool also creating a possibility that the obtained value can be wrongly recorded. Other possible reasons are discussed in the paper. Participation in inter-laboratory comparison programmes is undoubtedly a way to verify and raise the quality of tests performed for concrete mix and hardened concrete, whereas individual analysis of the results allows the laboratory quality system to be improved.
RESUMEN
BACKGROUND: This study focuses on the processes occurring during the acidogenic step of anaerobic digestion, especially resulting from nutritional interactions between dark fermentation (DF) bacteria and lactic acid bacteria (LAB). Previously, we have confirmed that DF microbial communities (MCs) that fed on molasses are able to convert lactate and acetate to butyrate. The aims of the study were to recognize the biodiversity of DF-MCs able and unable to convert lactate and acetate to butyrate and to define the conditions for the transformation. RESULTS: MCs sampled from a DF bioreactor were grown anaerobically in mesophilic conditions on different media containing molasses or sucrose and/or lactate and acetate in five independent static batch experiments. The taxonomic composition (based on 16S_rRNA profiling) of each experimental MC was analysed in reference to its metabolites and pH of the digestive liquids. In the samples where the fermented media contained carbohydrates, the two main tendencies were observed: (i) a low pH (pH ≤ 4), lactate and ethanol as the main fermentation products, MCs dominated with Lactobacillus, Bifidobacterium, Leuconostoc and Fructobacillus was characterized by low biodiversity; (ii) pH in the range 5.0-6.0, butyrate dominated among the fermentation products, the MCs composed mainly of Clostridium (especially Clostridium_sensu_stricto_12), Lactobacillus, Bifidobacterium and Prevotella. The biodiversity increased with the ability to convert acetate and lactate to butyrate. The MC processing exclusively lactate and acetate showed the highest biodiversity and was dominated by Clostridium (especially Clostridium_sensu_stricto_12). LAB were reduced; other genera such as Terrisporobacter, Lachnoclostridium, Paraclostridium or Sutterella were found. Butyrate was the main metabolite and pH was 7. Shotgun metagenomic analysis of the selected butyrate-producing MCs independently on the substrate revealed C.tyrobutyricum as the dominant Clostridium species. Functional analysis confirmed the presence of genes encoding key enzymes of the fermentation routes. CONCLUSIONS: Batch tests revealed the dynamics of metabolic activity and composition of DF-MCs dependent on fermentation conditions. The balance between LAB and the butyrate producers and the pH values were shown to be the most relevant for the process of lactate and acetate conversion to butyrate. To close the knowledge gaps is to find signalling factors responsible for the metabolic shift of the DF-MCs towards lactate fermentation. Video Abstract.
Asunto(s)
Butiratos , Microbiota , Reactores Biológicos , Fermentación , Ácido LácticoRESUMEN
BACKGROUND: During the acetogenic step of anaerobic digestion, the products of acidogenesis are oxidized to substrates for methanogenesis: hydrogen, carbon dioxide and acetate. Acetogenesis and methanogenesis are highly interconnected processes due to the syntrophic associations between acetogenic bacteria and hydrogenotrophic methanogens, allowing the whole process to become thermodynamically favorable. The aim of this study is to determine the influence of the dominant acidic products on the metabolic pathways of methane formation and to find a core microbiome and substrate-specific species in a mixed biogas-producing system. RESULTS: Four methane-producing microbial communities were fed with artificial media having one dominant component, respectively, lactate, butyrate, propionate and acetate, for 896 days in 3.5-L Up-flow Anaerobic Sludge Blanket (UASB) bioreactors. All the microbial communities showed moderately different methane production and utilization of the substrates. Analyses of stable carbon isotope composition of the fermentation gas and the substrates showed differences in average values of δ13C(CH4) and δ13C(CO2) revealing that acetate and lactate strongly favored the acetotrophic pathway, while butyrate and propionate favored the hydrogenotrophic pathway of methane formation. Genome-centric metagenomic analysis recovered 234 Metagenome Assembled Genomes (MAGs), including 31 archaeal and 203 bacterial species, mostly unknown and uncultivable. MAGs accounted for 54%-67% of the entire microbial community (depending on the bioreactor) and evidenced that the microbiome is extremely complex in terms of the number of species. The core microbiome was composed of Methanothrix soehngenii (the most abundant), Methanoculleus sp., unknown Bacteroidales and Spirochaetaceae. Relative abundance analysis of all the samples revealed microbes having substrate preferences. Substrate-specific species were mostly unknown and not predominant in the microbial communities. CONCLUSIONS: In this experimental system, the dominant fermentation products subjected to methanogenesis moderately modified the final effect of bioreactor performance. At the molecular level, a different contribution of acetotrophic and hydrogenotrophic pathways for methane production, a very high level of new species recovered, and a moderate variability in microbial composition depending on substrate availability were evidenced. Propionate was not a factor ceasing methane production. All these findings are relevant because lactate, acetate, propionate and butyrate are the universal products of acidogenesis, regardless of feedstock.
RESUMEN
This article presents data designed by European researchers who performed a literature review and interpreted the results to determine impact factors of many agroecological practices on a wide variety of sustainability indicators. The impact factors are represented in a matrix that connects practices to indicators. The indicators are related to environmental, economic and social sustainability of a typical European integrated crop-livestock farm. The data are included in the serious game SEGAE to learn agroecology, as described in "SEGAE: a serious game to learn agroecology" [1]. The data can be modified to adapt the game to other agricultural systems. Finally, the data can be re-used in research projects as a basis to assess impacts of agroecological practices.