Effect of Working Atmospheres on the Detection of Diacetyl by Resistive SnO2 Sensor

Nanostructured metal oxide semiconductors (MOS) are considered proper candidates to develop low cost and real-time resistive sensors able to detect volatile organic compounds (VOCs), e.g., diacetyl. Small quantities of diacetyl are generally produced during the fermentation and storage of many foods and beverages, conferring a typically butter-like aroma. Since high diacetyl concentrations are undesired, its monitoring is fundamental to identify and characterize the quality of products. In this work, a tin oxide sensor (SnO2) is used to detect gaseous diacetyl. The effect of different working atmospheres (air, N2 and CO2), as well as the contemporary presence of ethanol vapors, used to reproduce the typical alcoholic fermentation environment, are evaluated. SnO2 sensor is able to detect diacetyl in all the analyzed conditions, even when an anaerobic environment is considered, showing a detection limit lower than 0.01 mg/L and response/recovery times constantly less than 50 s.

Insights into the Anaerobic Hydrolysis Process for Extracting Embedded EPS and Metals from Activated Sludge

The amount of sewage sludge generated from wastewater treatment plants globally is unavoidably increasing. In recent years, significant attention has been paid to the biorefinery concept based on the conversion of waste streams to high-value products, material, and energy by microorganisms. However, one of the most significant challenges in the field is the possibility of controlling the microorganisms’ pathways in the anaerobic environment. This study investigated two different anaerobic fermentation tests carried out with real waste activated sludge at high organic loading rate (10 g COD L−1d−1) and short hydraulic retention time (HRT) to comprehensively understand whether this configuration enhances extracellular polymeric substance (EPS) and metal solubilisation. The quantity of EPS recovered increased over time, while the chemical oxygen demand to EPS ratio remained in the range 1.31–1.45. Slightly acidic conditions and sludge floc disintegration promoted EPS matrix disruption and release, combined with the solubilisation of organically bound toxic metals, such as As, Be, Cu, Ni, V, and Zn, thereby increasing the overall metal removal efficiency due to the action of hydrolytic microorganisms. Bacteroidetes, Firmicutes, and Chloroflexi were the most abundant phyla observed, indicating that the short HRT imposed on the systems favoured the hydrolytic and acidogenic activity of these taxa.

The Destruction of the Anaerobic Environment Caused by Rumen Fistula Surgery Leads to Differences in the Rumen Microbial Diversity and Function of Sheep

This experiment was to study the impact of rumen fistula surgery on the rumen microbios in sheep. Six male adult Hu sheep (48.8 ± 0.23 kg, 0.5 years) were fed at 0700 and 1,800 with ad libitum access to water. The rumen fistula was installed in the same batch from 0600 to 0900. Monitoring the dry mater intake and the output of dry mater faces 1, 2, 4, 6, 8, 10, 12, 14 days after fistulated surgery. The collection of rumen fluid was arranged at 1d during rumen surgery (DRS1), 3d after rumen surgery (ARS3), and 14d after rumen surgery (ARS14) for volatile fatty acid (VFA) and DNA extraction for sequencing and bioinformatics analysis. There was no difference in DMI, the pH apparent digestibility of dry matter, organic matter, neutral detergent fiber, acid detergent fiber both before and 14 days after surgery. Increases were observed in the acetate and total VFA at ARS3. There was no difference in digestion of dry material, organic material, neutral detergent fiber, and acid detergent fiber before and after surgery. The relative abundance of Bacteroides decreased from 61.96% at DRS1 to 28.85% at ARS3. In comparison with the DRS1 and ARS3, the relative abundance of Firmicutes in the ARS14 increased to 44.58% (P < 0.01). Proteobacteria increased from 11.33% at DRS1 to 51.66% at ARS3 and then decreased to 11.39% at ARS14. Prevotella decreased form 61.06% at DRS1 to 28.04% in the ARS3. Succinivibrio increased from 8.32% at DRS1 to 48.58% at ARS3, but decreased to 10.43% in the ARS14. Compared with DRS1 and ARS3, the ARS14 was higher in the Simpson and Shannon index. As for the BugBase function prediction, rumen fistula surgery increased the microorganism abundance of aerobic and facultative anaerobic phenotype, and anaerobic phenotype was decreased in the ARS3. There was higher microorganism abundance of aerobic phenotype in the ARS14 than before fistula installation. In conclusion, the rumen fistula surgery destroys the anaerobic environment of rumen, leading to differences in rumen microbial diversity and function, but the apparent digestibility and total VFA were not affected.

Assessment of Changes in the Oral Microbiome That Occur in Dogs with Periodontal Disease

The oral microbiome in dogs is a complex community. Under some circumstances, it contributes to periodontal disease, a prevalent inflammatory disease characterized by a complex interaction between oral microbes and the immune system. Porphyromonas and Tannerella spp. are usually dominant in this disease. How the oral microbiome community is altered in periodontal disease, especially sub-dominant microbial populations is unclear. Moreover, how microbiome functions are altered in this disease has not been studied. In this study, we compared the composition and the predicted functions of the microbiome of the cavity of healthy dogs to those with from periodontal disease. The microbiome of both groups clustered separately, indicating important differences. Periodontal disease resulted in a significant increase in Bacteroidetes and reductions in Actinobacteria and Proteobacteria. Porphyromonas abundance increased 2.7 times in periodontal disease, accompanied by increases in Bacteroides and Fusobacterium. It was predicted that aerobic respiratory processes are decreased in periodontal disease. Enrichment in fermentative processes and anaerobic glycolysis were suggestive of an anaerobic environment, also characterized by higher lipopolysaccharide biosynthesis. This study contributes to a better understanding of how periodontal disease modifies the oral microbiome and makes a prediction of the metabolic pathways that contribute to the inflammatory process observed in periodontal disease.

Alteration of Fractionation and Bioavailability of Arsenic (As) in Paddy Soil under Transition from Aerobic to Anaerobic Conditions

The impact of the change from aerobic to anaerobic immersed soil conditions on arsenic (As) fractionation (Tessier’s method) and its bioavailability (ethylene diamine tetraacetic acid extractable) were assessed. As-contaminated paddy soils were tested by laboratory simulation experiments. The samples were aerobic, with 35-49 mg/kg of As at low bioavailability (<2%). Most As was distributed in the stable fraction (77%), followed by As bound to ferric and manganese oxide (17%) and organic compounds (5%), while the mobile fraction (exchangeable and mildly acid-soluble) was limited (1%). After one month under anaerobic simulation, redox potential reduced to less than zero (-32 to -124 mV). The stable fraction of As decreased (-17%), while the mobile fraction increased (+16%) and As bioavailability also increased (+26% total As). Increase in the As mobile fraction was associated with freshly precipitated compounds. The As content in the soil altered from a stable fraction to an available fraction when confined in an anaerobic environment for a long period. Results indicated that agricultural methods which promoted anaerobic conditions in As-contaminated soil should be avoided.

Effects of Drying-Rewetting Cycles on Ferrous Iron-Involved Denitrification in Paddy Soils

Soil moisture status has an important effect on the process of denitrification in paddy soils. However, it is unclear how it affects the ferrous iron-involved denitrification. Here, the influence of drying-rewetting cycles on ferrous iron-involved denitrification in paddy soil were studied with batch experiments. The dynamics of nitrate, ammonia, Fe2+, Fe3+ and total organic carbon (TOC), as well as nitrous oxide (N2O) were investigated using the iron-rich paddy soil in Jiangxi province, South China. Results demonstrated that the denitrification rate dropped while ammonia nitrogen content (NH4+-N) showed a rapid accumulation in the drying period. In the rewetting period, organic carbon played two-side roles. Organic carbon and ferrous iron together provided electron donors to denitrification, and organic carbon simultaneously reduced ferric iron under anaerobic environment. There were complex interactions among organic carbon, nitrate and Fe2+/Fe3+ under drying-rewetting cycles. Soil rewetting led to denitrification flush, especially after a moderately long drying period, while excessively frequent drying-rewetting alternation was not favorable to nitrate denitrification.

Microbial redox interplay enhances biodiversity and ecosystem productivity

A significant portion of the Earth’s biodiversity and biomass is from the subsurface biosphere, where chemotrophic microbial species harness diverse inorganic oxidation-reduction reactions (redox reactions) as a major source of metabolic energy while driving biogeochemical cycles. Given the limited availability of energy in the anaerobic environment, a fundamental question concerns what interplay between the chemical environment and chemotrophic community enables the persistence of whole biogeochemical systems. Here, using a thermodynamics-based mechanistic model that maps the interplay between diverse chemotrophic species and chemical compounds onto a redox network, we show that cycles of redox reactions mediate chemotrophic interactions in a way that increases the complexity of both redox reaction networks and microbial communities and enhances the community-level efficiency of energy metabolism. The high efficiency and complexity of biogeochemical systems arises from the self-organised ecological niche segmentation of microbes. More specifically, a consortium of chemotrophic species that subdivide a long-reaction pathway into shorter-reaction segments enhance each other’s population growth, replaces the species that monopolises the long-reaction pathway, and increases ecosystem productivity. An ecologically driven ‘division of metabolic labour’ in the chemotrophic community provides a novel mechanism through which an intimate life-environment interplay concurrently enhances biodiversity and ecosystem productivity.

Spinal Tuina Improves Cognitive Impairment in Cerebral Palsy Rats through Inhibiting Pyroptosis Induced by NLRP3 and Caspase-1

Cerebral palsy (CP) is a severe cerebral disease with high mortality and morbidity, which leads to great challenges for the suffering children and their families. Hence, the need for the efficacious and safe treatments is urgent. As a physical therapy arising from traditional Chinese medicine (TCM), Tuina has shown multiple effects on various diseases, including cerebral palsy. Nevertheless, the detailed mechanisms of Tuina on CP remain unknown, which impedes its further clinical application. Herein, we explored the effects of Tuina on CP and its potential mechanisms. Thirty Sprague Dawley (SD) male rats were randomly divided into sham, model, and Tuina groups (model + Tuina). CP rat model was established by hypoxia-ischemia via permanent occlusion of left common carotid artery and hypoxia for 2.5 hours caused by anaerobic environment, which was subsequently followed by onset of Tuina treatment from postnatal day 7 (P7) to P49. After completion of Tuina treatment, the behavioral tests showed that Tuina treatment not only improved the retarded body weight and impaired motor balance function, but also ameliorated weakened learning and memory function of CP rats. Moreover, immunohistochemistry and western blot also revealed a reduced expression of NLRP3 inflammasome and corresponding pyroptosis-related molecules induced by NLRP3 in CP rats after Tuina treatment. Therefore, our study indicated that Tuina treatment may improve impaired neurocognitive function of CP rats, which was possibly realised via inhibiting NLRP3-induced pyroptosis.