Natural zeolite enhances anaerobic digestion of waste activated sludge: Insights into the performance and the role of biofilm

Anaerobic digestion is widely employed for the treatment of waste activated sludge (WAS) due to its advantages like simultaneous energy recovery and sludge stabilization, promoting carbon-neutral operation of wastewater treatment plants. Natural zeolite, a low-cost and eco-friendly additive, has the potential to improve methane production from anaerobic digestion. This study investigated the effects of natural zeolite on anaerobic digestion when the substrate was WAS. It was found that methane production potential in response to natural zeolite was dosage-dependent. The optimal dosage was 0.1 g zeolite/g volatile suspended solids (VSS), with a methane yield of 181.89 ± 6.75 mL/g VSS, which increased by 20.1% compared to that of the control. Although the methane yields with other dosages of natural zeolite were higher than that of control, they were lesser than that with 0.1 g zeolite/g VSS. Natural zeolite affected transfer and conversion of proteins much more than polysaccharides in liquid phase and extracellular polymeric substances. In anaerobic digestion, natural zeolite had with little effects on WAS solubilization, while it improved hydrolysis, acidification, and methanogenesis. The dosages of natural zeolite did have significant effects on bacterial communities in biofilm rather than suspension, while the archaeal communities in biofilm and suspension were all greatly related to natural zeolite dosages. The developed biofilms promoted richness and functionality of microbial communities. The syntrophic metabolism relationships between methanogens and bacteria were improved, which was proved by selective enrichment of Methanosarcina, Syntrophomonas, and Petrimonas. The findings of this work provided some new solutions for promoting methane production from WAS, and the roles of natural zeolite in anaerobic digestion.

Integrated microbial electrolysis with high-alkali pretreated sludge digestion: Insight into the effect of voltage on methanogenesis and substrate metabolism

Integrated microbial electrolysis with anaerobic digestion is proved to be an effective way to improve methanogenesis efficiency of waste activated sludge (WAS). WAS requires pretreatment for efficient improvement of acidification or methanogenesis efficiency, but excessive acidification may inhibit the methanogenesis. In order to balance these two stages, a method for efficient WAS hydrolysis and methanogenesis has been proposed in this study by high-alkaline pretreatment integrated with microbial electrolysis system. The effects of pretreatment methods and voltage on the normal temperature digestion of WAS have also been further investigated with emphasis on the effects of voltage and substrate metabolism. The results show that compared to low-alkaline pretreatment (pH = 10), high-alkaline pretreatment (pH > 14) can double the SCOD release and promote the VFAs accumulation to 5657 ± 392 mg COD/L, but inhibit the methanogenesis process. Microbial electrolysis can alleviate this inhibition effectively through the rapid consumption of VFAs and speeding up of the methanogenesis process. The optimal methane yield of the integrated system is 120.4 ± 8.4 mL/g VSS at the voltage of 0.5 V. Enzyme activities, high-throughput and gene function prediction analysis reveal that the cathode and anode maintain the activity of methanogens under high substrate concentrations. Voltage positively responded to improved methane yield from 0.3 to 0.8 V, but higher than 1.1 V is found to be unfavorable for cathodic methanogenesis and results in additional power loss. These findings provide a perspective idea for rapid and maximum biogas recovery from WAS.

Evaluation of the effect of biofilm formation on the reductive transformation of triclosan in cathode-modified electrolytic systems

The performance of electrochemical reduction is often enhanced by electrode modification techniques. However, there is a risk of microbial colonization on the electrode surface to form biofilms in the treatment of actual wastewater with modified electrodes. In this work, the effects of biofilm formation on modified electrodes with reduced graphene oxide (rGO), platinum/carbon (Pt/C), and carbon nanotube (CNT) were investigated in triclosan (TCS) degradation. With biofilm formation, the TCS degradation efficiencies of carbon cloth (CC), rGO@CC, Pt/C@CC, and CNT@CC decayed to 54.53 %, 59.77 %, 69.19 %, and 53.97 %, respectively, compared to the raw electrodes. Confocal laser scanning microscopy and microbial community analysis revealed that the difference in biofilm thickness and activity were the major influencing factors on the discrepant TCS degradation rather than the microbial community structure. The electrochemical performance tests showed that the biofilm formation increased the ohmic resistance by an order of magnitude in rGO@CC, Pt/C@CC, and CNT@CC, and the charge transfer resistance was increased by 2.45, 3.78, and 7.75 times, respectively. The dechlorination and hydrolysis governed the TCS degradation pathway in all electrolysis systems, and the toxicity of electrochemical reductive products was significantly decreased according to the Toxicity Estimation Software Tool analysis. This study presented a systematic assessment of the biofilm formation on modified electrodes in TCS reduction, and the undisputed experimental outcomes were obtained to enrich the knowledge of implementing modified electrodes for practical applications.

Removal of antibiotic resistance genes and mobile genetic elements in a three-stage pig manure management system: The implications of microbial community structure

In this work, the removal of antibiotic resistance genes (ARGs) in the industrial-scale pig manure management system has been investigated. Additionally, the implications of mobile genetic elements (MGEs) and microbial community structure have been discussed. During the whole period of manure management, 19 ARGs and 7 MGEs were obtained from the system. The results identified that the 9 ARGs and 2 MGEs were removed from the pig manure-based materials after composting, while 5 ARGs and 2 MGEs were still remained, indicating that the ARGs/MGEs could not be removed completely as contaminants by composting. The pig farm without additional antibiotics in-feed was still faced with the risk of ARGs/MGEs from outside. Microbial community analysis illuminated that a greater decrease in the abundance of norank_f__JG30-KF-CM45, Corynebacterium, Terrisporobacter, Truepera, Salinispora and Clostridium, was responsible for the removal of ARGs/MGEs. The genes, including tnpA-01, tnpA-02, tnpA-05, Tp614, tetQ, tetM-01, tetR-02, tetX, cfxA, floR, dfrA1 and ermF exhibited significantly positive correlation with fungal communities. Fungal community analysis verified that a remarkable decrease in the abundance of Aspergillus and Thermomyces after composting was responsible for the ARGs/MGEs removal. The results elucidated the crucial roles of the related bacterial and fungal communities in the removal of ARGs/MGEs. The compound microbial agent assisted the temperature rise of composting, thereby changing the related microbial community structure and resulting in ARGs/MGEs removal.

An emerging unrated mobile reservoir for antibiotic resistant genes: Does transportation matter to the spread

The regional distribution of antibiotic resistance genes has been caused by the use and preference of antibiotics. Not only environmental factors, but also the population movement associated with transportation development might have had a great impact, but yet less is known regarding this issue. This research study has investigated and reported that the high-speed railway train was a possible mobile reservoir of bacteria with antibiotic resistance, based on the occurrence, diversity, and abundance of antibiotic resistant bacteria (ARB), antibiotic resistance genes (ARGs), and mobile gene elements (MGEs) in untreated train wastewater. High-throughput 16S rRNA sequencing analyses have indicated that opportunistic pathogens like Pseudomonas and Enterococcuss were the predominant bacteria in all samples, especially in cultivable multi-antibiotic resistant bacteria. The further isolated Enterococcus faecalis and Enterococcus faecium exhibited multi-antibiotic resistance ability, potentially being an indicator for disinfection proficiency. Positive correlations amongst ARGs and MGEs were observed, such as between intI1 and tetW, tetA, blaTEM, among Tn916/154 and mefA/F, qnrS, implying a broad dissemination of multi-ARGs during transportation. The study findings suggested that the high-speed railway train wastewater encompassed highly abundant antibiotic-resistant pathogens, and the wastewater discharge without effective treatment may pose severe hazards to human health and ecosystem safety.

Causality and correlation analysis for deciphering the microbial interactions in activated sludge

Time series data has been considered to be a massive information provider for comprehending more about microbial dynamics and interaction, leading to a causality inference in a complex microbial community. Granger causality and correlation analysis have been investigated and applied for the construction of a microbial causal correlation network (MCCN) and efficient prediction of the ecological interaction within activated sludge, which thereby exhibited ecological interactions at the OTU-level. Application of MCCN to a time series of activated sludge data revealed that the hub species OTU56, classified as the one belonging to the genus Nitrospira, was responsible for nitrification in activated sludge and interaction with Proteobacteria and Bacteroidetes in the form of amensal and commensal relationships, respectively. The phylogenetic tree suggested a mutualistic relationship between Nitrospira and denitrifiers. Zoogloea displayed the highest ncf value within the classified OTUs of the MCCN, indicating that it could be a foundation for activated sludge through the formation of characteristic cell aggregate matrices where other organisms embed during floc formation. Inclusively, the research outcomes of this study have provided a deep insight into the ecological interactions within the communities of activated sludge.

Tracking the diversity and interaction of methanogens in the energy recovery process of a full-scale wastewater treatment plant

Methanogens have been significant for the achievement of carbon neutrality in wastewater treatment plants due to their crucial roles in the anaerobic digestion of sludge. Nevertheless, the phylogenetic diversity of methanogens and their versatile metabolism have been continuously investigated, the current scientific knowledge regarding these microbes appears inadequate and requires more evaluations. This study is considered an endeavor in which functional genes sequencing was used to reveal the diversity of methanogens in the sludge process of the wastewater treatment plant. The information obtained was substantially more than that employing 16s sequencing. The methanogenic microbial resources were appropriate to sustain a self-inoculated energy recovery with a potential ability to boost methane production. A constancy was observed in 16 S rRNA gene and mcrA gene sequencing results, where the bacterial or Methanosaeta concilii dominated community of DS (digest sludge) was distinct from the inoculum sources TS (total sludge), CTS (concentrated total sludge), and HTS (hydrolysis total sludge), indicating the independent development of DS. A quantitative cross-network was constructed by coupling the absolute quantify of 16 S rRNA and mcrA sequences. The Methanobacterium petrolearium actively interacted with bacteria in the DS community rather than the dominant species (Methanosaeta concilii). Moreover, the unclassified methanogens were identified to be significantly prevalent in all communities, suggesting that unknown methanogenic taxa might be imperative in accomplishing community functions. Collectively, the findings of this research study will shed light on the comprehensive knowledge of microbial communities, especially the methanogenic microbiota. This will further enhance the exploration of the phylogenetic diversity of methanogens and their corresponding impacts in energy recovery from wastewater treatment plants.

Efficiency of Coriandrum sativum (Linn.) and Petroselinum crispum (Mill.) in Enhancing Iron Absorption: An In Silico and In Vitro Approach

Coriandrum sativum (Linn.) and Petroselinum crispum (Mill.) are the common herbs used for culinary purposes in daily life. The chlorophyll pigment in plants is being identified with various medicinal values, whereas iron is an essential micronutrient for the proper metabolism of the human body. The current research has been aimed at predicting the role of C. sativum and P. crispum in enhancing iron absorption via an in vitro approach. C. sativum and P. crispum have been analyzed for their capability of being a source of chlorophyll and iron concentration. The extracts prepared from solvents like carbinol, petroleum ether, and water were subjected to the identification of phytoconstituents through gas chromatography-mass spectrometry analysis, and the identified compounds were subjected to in silico studies against the iron-binding receptor, transferrin, to depict the binding affinity of the identified compounds. The carbinol extract was then put through in vitro analytical studies in Caco2 cell lines with a concentration of 500 µg/ml. Current research has shown that the leaves of C. sativum and P. crispum are an excellent source of chlorophyll and iron and has also suggested that these herbs efficiently enhance the absorption of iron in human intestinal cells.

Efficient methane production from waste activated sludge and Fenton-like pretreated rice straw in an integrated bio-electrochemical system

Integrated microbial electrolysis cell-anaerobic digestion (MEC-AD) systems have demonstrated potential advantages for methane production in the presence of small amounts of residual inhibitors. In this study, a series of tests were conducted to analyse the acidification and methanogenesis performance of pretreated rice straw (RS) in anaerobic digestion (AD) and MEC-AD systems after the addition of Fenton-like reagents. The results indicated that the short-chain acids (SCFAs) accumulations reached 2284.64 ± 21.57 mg COD/L with a dosage ratio of 1/4 (g RS/g VSS sludge) in the MEC-AD system and that methane production increased by 63.8% compared with that of an individual AD system. In the interim, the net energy output reached 1.09 × 10³ J/g TCOD, which was 1.23 times higher than that of the AD system. The residual Fe³⁺/Fe²⁺ in the pretreatment reagent was capable of promoting acidification and methanogenesis in sludge and RS fermentation. The RS hydrolysis products could constrain methanogenesis, which can be mitigated by introducing an MEC. The microbiological analyses revealed that the MEC strongly increased the enrichment of hydrogenotrophic methanogens, especially Methanobacterium (61.16%). Meanwhile, the Syntrophomonas and Acetobacterium abundances increased to 2.81% and 2.65%, respectively, which suggested the reinforcement of acetogenesis and methanogenesis. Therefore, the enhanced hydrogenotrophic methanogens might have served as the key for enhancing the efficiency of methanogenesis due to the introduction of an MEC.

PCCAMN—Path Constancy Based Channel Assignment in Mobile ADHOC Network for Healthcare Data Transmission

A MANET is a self-governing network for mobile devices in many crucial domains, including health care, for transmitting health data of the patients. The key challenge in MANETS is maintaining the links between devices under mobility; it creates limitless network disconnections and path loss frequently. Such issues, raises network delay and minimize packet delivery ratio (PDR) and entire set-up throughput brings reduced quality of services (QOS). To get better QoS, stable path selection and link disconnection count based nearby device selection carried out in this work. It’s on this basis that the thesis is exploring the design and the analysis of the FPC. The FPC is designed in network simulator with the support of optimized fuzzy logic (FL). It has obtained three inputs which is fallout to 27 set of laws. This law sets (LS) direct in the fortitude of the precedence to select best path set to transmit a packets from sender to destination. The analyses are with previous protocols of Distributed Admission Control Protocol (DACP) and Call Admission Protocol of MANET. The outcome results monitored with delay, Packet Delivery Ratio (PDR), throughput and overheads as the QOS metrics of network.

Revealing hydrodynamics and energy efficiency of mixing for high-solid anaerobic digestion of waste activated sludge

Anaerobic digestion is a feasible and promising technique to deal with emerging waste activated sludge issues. In this work, the hydrodynamics and digestion performance of horizontal anaerobic systems equipped with double-bladed impeller and ribbon impeller were investigated. Simulation using computational fluid dynamics technique visually showcased the favorable mixing status implementing ribbon impeller. The mixing modes were considered as the major motivation for the difference of mixing efficiencies. Tracing experiment indicated that the minimum thorough mixing time with ribbon impeller was 20 min at a rotation speed of 50 rpm, whereas it was 360 min for the double-bladed impeller under similar conditions. The superior mixing performance of ribbon impeller resulted in better anaerobic digestion and energy efficiency outputs. The digester employing ribbon impeller obtained an ultimate biogas yield of 340.38 ± 15.91 mL/g VS (corresponding methane yield of 210.34 ± 7.55 mL/g VS) and produced a surplus energy of 16.23 ± 0.76 MJ/(m³·d). This study thus ascertained that ribbon impeller was proficient for high-solid anaerobic digestion and it will prominently benefit future system designs.

Methane production in a bioelectrochemistry integrated anaerobic reactor with layered nickel foam electrodes

Towards the regulation and enhancement of inter-species electron transfer in sludge anaerobic digestion system, microbial electrolysis technology has become one of the effective ways to accelerate both fermentation and methanogenesis. In this study, the reactor performances and microbial activities related to biocathode formation are evaluated when the role of biocathode is regulated by series of layered cathodes. The results show the abundance of the cathodic methanogens decreased when enlarges the cathode area due to the lower current density. The biocathode evolution is directly related to the spatial methane distribution, which can further determine 25% increase of methane production rate compared to control without biocathode. Ultimately, the maximum methane production yield of 145.79 mL·d^-1 is achieved by the optimal cathode area with a current density of 5.3 mA/cm³. The spatially methanogens distribution in suspended sludge and electrodes regulated by the layered cathodes is regarded to be the key to increase methanogenesis.

Electrochemical polarization analysis for optimization of external operation parameters in zinc fuel cells

Zinc-air flow fuel cells utilizing zinc particles as fuel possess the potential to evolve as efficient distributed grid generators. In this research study, electrochemical impedance analysis was employed to determine the optimum design and operational parameters for the feasible maneuver and enhanced energy generation from zinc fuel cells. Polarization resistance (R _p), ohmic resistance (R _s), and mass transfer resistance (R _m) were used as the indicators for determination of the optimum parameters of fuel cell performance. Experimental conditions optimized from previous studies like potassium hydroxide electrolyte with temperature of 25 °C and concentration of 40 wt% zinc powder quantity of 20 g, electrode reaction surface area of 48 cm² were followed in the fuel cells used in the present study. Parameters like collector plate material, air flow velocity and cell operating temperature were augmented and finally were all implemented in the fuel cell and operated. Plain nickel or nickel-plated copper were both advantageous as collector plate materials whereas an air flow velocity ranging from 1-3 m s^-1 and a cell operating temperature of 25 °C to 45 °C were beneficial for the stability and performance of the zinc fuel cells. Finally, based on the optimized parameters obtained from the above experiments, performance tests of zinc fuel cells were investigated. The maximum power produced was 16.5 W, along with a corresponding voltage of 0.8 V, maximum current density of 430 mA cm^-2 and peak power density of 364.6 mW cm^-2. Thus it can be concluded that the fuel cells designed and operated in this study were capable for feasible and efficient future applications.

Hydrodynamics of up-flow hybrid anaerobic digestion reactors with built-in bioelectrochemical system

Understanding the electrode configuration is vital for the successful application of bioelectrochemical system (BES) in recalcitrant wastewater treatment. Especially in those traditional anaerobic processes that integrate with BES to construct effective hybrid bioreactors. Hybrid bioreactors employed granular graphite as electrode material achieved 86.62 ± 1.83% decolorization efficiency of azo dye acid orange 7 (AO7) at influent AO7 loading rate of 800 g/(m³∙d) and it was about 6% higher than that with carbon fiber brush electrodes. Such electrodes were positioned above the anaerobic sludge layer and higher efficiency (8%) than the reactors with electrodes placed beneath the sludge layer was observed. Tracer experiments and modeling of residence time distribution indicated that the fluid pattern in hybrid bioreactors was modified to plug flow pattern and had a better consummate mixing ability compared to the conventional anaerobic reactor. Simulation using computational fluid dynamics technique showcased favorable mass transfer near electrode modules. The hydrodynamics of simulation and experimental results were connected by simplifying electrode module as a porous media model. This study thus proved that hybrid bioreactors can effectively enhance wastewater treatment comprehensively through the analysis of decolorization performance and hydrodynamics.

FTIR studies, DFT calculations and time domain reflectometry studies on tetrahydrofuran - methanol binary solutions

FTIR signature of neat tetrahydrofuran (THF), methanol (MeOH) and their binary solutions at various molefractions (0.8:0.2 (THF:MeOH), 0.6:0.4, 0.4:0.6 and 0.2:0.8) have been recorded. Density Functional Theory (DFT) calculations have also been carried out on THF, MeOH multimers and possible THF-MeOH complex molecules. The results of FTIR studies and DFT calculations confirm the formation of 1:3 (THF:MeOH) and 1:4 complex structures with (MeOH)O - H⋯O(THF), (MeOH methyl)C - H⋯O(THF) and (THF methylene)C - H⋯O(MeOH) H-bond interactions. (MeOH)O - H⋯O(MeOH) homointeractions among the MeOH trimers and tetramers are stronger than the THF-MeOH heterointeractions in complexes. But, the stability of 1:4 complexes is more than that of the trimers and tetramers as inferred from the interaction energy values obtained by DFT calculations. Time Domain Reflectometry (TDR) study has also been carried out on the THF-MeOH binary solutions in the frequency range 10 MHz-30 GHz at 298 K. The results of dielectric studies have been correlated with that of FTIR studies and DFT calculations.

Efficient azo dye wastewater treatment in a hybrid anaerobic reactor with a built-in integrated bioelectrochemical system and an aerobic biofilm reactor: Evaluation of the combined forms and reflux ratio

A combined process that consisted of a hybrid anaerobic reactor (HAR) with an integral bioelectrochemical system and aerobic biofilm reactor (ABFR) was established for simulated azo dye wastewater treatment (domestic wastewater containing dye acid orange 7). The split combination form that separated HAR and ABFR into two individual reactors recorded a decolorization efficiency of 81.23 ± 0.12%, which was about 8% higher than that HAR and ABFR were stacked together into a single up-flow reactor. Implementation of reflux improved the decolorization and chemical oxygen demand (COD) removal in both the processes. Decolorization efficiency achieved 97.52 ± 0.66% in split process at a reflux ratio of 1 and the COD was 89 ± 2 mg/L in the final effluent. Further increasing the reflux ratio to 3 did not have any significance in treatment performance of the reactors. This study comprehensively revealed the influence of combination forms and reflux ratio on the performance of combined process.

Application of interface material and effects of oxygen gradient on the performance of single-chamber sediment microbial fuel cells (SSMFCs)

Single-chamber sediment microbial fuel cells (SSMFCs) have received considerable attention nowadays because of their unique dual-functionality of power generation and enhancement of wastewater treatment performance. Thus, scaling up or upgrading SSMFCs for enhanced and efficient performance is a highly crucial task. Therefore, in order to achieve this goal, an innovative physical technique of using interface layers with four different pore sizes embedded in the middle of SSMFCs was utilized in this study. Experimental results showed that the performance of SSMFCs employing an interface layer was improved regardless of the pore size of the interface material, compared to those without such layers. The use of an interface layer resulted in a positive and significant effect on the performance of SSMFCs because of the effective prevention of oxygen diffusion from the cathode to the anode. Nevertheless, when a smaller pore size interface was utilized, better power performance and COD degradation were observed. A maximum power density of 0.032mW/m² and COD degradation of 47.3% were obtained in the case of an interface pore size of 0.28μm. The findings in this study are of significance to promote the future practical application of SSMFCs in wastewater treatment plants.

Novel bufferless photosynthetic microbial fuel cell (PMFCs) for enhanced electrochemical performance

Photosynthetic microbial fuel cells (PMFCs) are novel bioelectrochemical transducers that employ microalgae to generate oxygen, organic metabolites and electrons. Conventional PMFCs employ non-eco-friendly membranes, catalysts and phosphate buffer solution. Eliminating the membrane, buffer and catalyst can make the MFC a practical possibility. Therefore, single chambered (SPMFC) were constructed and operated at different recirculation flow rates (0, 40 and 240 ml/min) under bufferless conditions. Furthermore, maximum power density of 4.06 mW/m², current density of 46.34 mA/m² and open circuit potential of 0.43 V and low internal resistance of 611.8 Ω were obtained at 40 ml/min. Based on the results it was decided that SPMFC was better for operation at 40 ml/min. Therefore, these findings provided progressive insights for future pilot and industrial scale studies of PMFCs.

Performance of low temperature Microbial Fuel Cells (MFCs) catalyzed by mixed bacterial consortia

Microbial Fuel Cells (MFCs) are a promising technology for treating wastewater in a sustainable manner. In potential applications, low temperatures substantially reduce MFC performance. To better understand the effect of temperature and particularly how bioanodes respond to changes in temperature, we investigated the current generation of mixed-culture and pure-culture MFCs at two low temperatures, 10°C and 5°C. The results implied that the mixed-culture MFC sustainably performed better than the pure-culture (Shewanella) MFC at 10°C, but the electrogenic activity of anodic bacteria was substantially reduced at the lower temperature of 5°C. At 10°C, the maximum output voltage generated with the mixed-culture was 540-560mV, which was 10%-15% higher than that of Shewanella MFCs. The maximum power density reached 465.3±5.8mW/m² for the mixed-culture at 10°C, while only 68.7±3.7mW/m² was achieved with the pure-culture. It was shown that the anodic biofilm of the mixed-culture MFC had a lower overpotential and resistance than the pure-culture MFC. Phylogenetic analysis disclosed the prevalence of Geobacter and Pseudomonas rather than Shewanella in the mixed-culture anodic biofilm, which mitigated the increase of resistance or overpotential at low temperatures.

Erratum to: Enhanced short chain fatty acids production from waste activated sludge conditioning with typical agricultural residues: carbon source composition regulates community functions

[This corrects the article DOI: 10.1186/s13068-015-0369-x.].

Decolorization enhancement by optimizing azo dye loading rate in an anaerobic reactor

An up-flow anaerobic sludge blanket (UASB) reactor was developed to investigate the effect of azo dye loading rate on the decolorization performance and microbial community.

Polymorphism Study on SLC30A8 and Its Association with Type 2 Diabetes

Type 2 diabetes mellitus (T2DM) is one of the threatening disorders in the world. It affects people of all ages. Type 2 diabetes mellitus is a condition in which the glucose level in the blood is elevated due to improper function of the secretion of insulin from beta cells of the pancreas. It is a multifactorial disease because it is caused by both environmental and hereditary factors. One of the genes which play an important role in type 2 diabetes mellitus is SLC30A8 which encodes for zinc transporter ZnT8. The common polymorphic site for SLC30A8 is rs13266634. This single-nucleotide polymorphism leads to type 2 diabetes mellitus by replacing the arginine residue with tryptophan residue. This review mainly focuses on the polymorphic studies in the gene SLC30A8 and its association with type 2 diabetes mellitus.

Enhanced short chain fatty acids production from waste activated sludge conditioning with typical agricultural residues: carbon source composition regulates community functions

BACKGROUND

A wide range of value-added by-products can be potentially produced from waste activated sludge (WAS) through anaerobic fermentation, among which short-chain fatty acids (SCFAs) are versatile green chemicals, but the conversion yield of SCFAs is usually constrained by the low carbon-to-nitrogen ratio of the original WAS. Conditioning of the WAS with cellulose-containing agricultural residues (ARs) has been reported to be an efficient and economical solution for balancing its nutrient components. However, contributions of different ARs to SCFAs production are still not well understood.

RESULTS

To optimize SCFAs production through carbon conditioning of WAS, we investigated the effects of two typical ARs [straws and spent mushroom substrates (SMSs)] on WAS hydrolysis and acidification in semi-continuous anaerobic fermentation. Straw-conditioning group showed a threefold increase in short-chain fatty acids yield over blank test (without conditioning), which was 1.2-fold higher than that yielded by SMS-conditioning. The maximum SCFAs yield in straw-conditioning groups reached 486.6 mgCOD/gVSS (Sludge retention time of 8 d) and the highest volumetric SCFAs productivity was 1.83 kgCOD/([Formula: see text]) (Sludge retention time of 5 d). In batch WAS fermentation tests, higher initial SCFAs production rates were achieved in straw-conditioning groups [49.5 and 52.2 mgCOD/(L·h)] than SMS-conditioning groups [41.5 and 35.2 mgCOD/(L·h)]. High-throughput sequencing analysis revealed that the microbial communities were significantly shifted in two conditioning systems. Carbohydrate-fermentation-related genera (such as Clostridium IV, Xylanibacter, and Parabacteroides) and protein-fermentation-related genus Lysinibacillus were enriched by straw-conditioning, while totally different fermentation genera (Levilinea, Proteiniphilum, and Petrimonas) were enriched by SMS-conditioning. Canonical correlation analysis illustrated that the enrichment of characteristic genera in straw-conditioning group showed positive correlation with the content of cellulose and hemicellulose, but showed negative correlation with the content of lignin and humus.

CONCLUSIONS

Compared with SMSs, straw-conditioning remarkably accelerated WAS hydrolysis and conversion, resulting in higher SCFAs yield. Distinct microbial communities were induced by different types of ARs. And the communities induced by straw-conditioning were verified with better acid production ability than SMS-conditioning. High cellulose accessibility of carbohydrate substrates played a crucial role in enriching bacteria with better hydrolysis and acidification abilities.

Preventive effect of S-allyl cysteine sulphoxide (Alliin) on mitochondrial dysfunction in normal and isoproterenol induced cardiotoxicity in male Wistar rats: a histopathological study

This study was undertaken to evaluate the preventive role of S-allyl cysteine sulphoxide (SACS) in isoproterenol (ISO)-induced cardiotoxicity in male Wistar rats. Myocardial infarction was induced by subcutaneous injection of ISO (150 mg/kg) once a day for 2 days. SACS (40 and 80 mg/kg) was given as pretreatment orally daily for a period of 35 days using an intragastric tube. SACS pretreatment significantly lowered thiobarbituric acid reactive substances (TBARS) and increased the activities of mitochondrial superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx), glutathione S-transferase (GST), and the concentration of reduced glutathione (GSH) in myocardial infarcted rats. SACS pretreatment also increased significantly the levels of mitochondrial phospholipids and decreased the levels of mitochondrial cholesterol, free fatty acids (FFAs), triglycerides (TGs) and calcium, and the activity of xanthine oxidase (XOD) in heart. Further, the activities of isocitrate dehydrogenase (ICDH), succinate dehydrogenase (SDH), alpha-ketoglutarate dehydrogenase (alpha-KGDH), NADH-dehydrogenase, and cytochrome C-oxidase were significantly elevated in the mitochondrial fraction of the heart in the SACS-pretreated ISO-induced rats. Oral administration of SACS for a period of 35 days to the normal control rats did not show any significant effect. Histopathological studies of the myocardial tissue showed a protective role of SACS in the myocardial-infarcted rats. The effect at a dose of SACS 80 mg/kg was more effective than the dose 40 mg/kg. The results of the study conclude that SACS protect the mitochondria of the ISO-induced myocardial-infarcted rats.

Protective effect of S-allyl cysteine sulphoxide (alliin) on glycoproteins and hematology in isoproterenol induced myocardial infarction in male Wistar rats

The antihyperlipidemic, antilipoperoxidative and antioxidant effects of S-allyl cysteine sulphoxide (SACS) in myocardial infarcted rats were reported previously. The present study was undertaken to evaluate the preventive role of SACS on some biochemical parameters, glycoproteins and hematology in experimentally induced myocardial infarction in rats. Myocardial infarction was induced in rats by subcutaneous injection of isoproterenol (ISO) (150 mg kg(-1)) at an interval of 24 h for 2 days. ISO-treated rats showed a significant increase in the levels of serum iron, uric acid and blood glucose, Na(+) and Ca(2+) in the heart and a significant decrease in the levels of plasma iron binding capacity, serum total protein, albumin/globulin ratio, heart K(+) and heart glycogen. The levels/concentrations of glycoproteins in serum and the heart were increased in myocardial infarcted rats. Myocardial infarcted rats also showed a significant increase in red blood cells, hemoglobin, packed cell volume, white blood cells, neutrophils, platelet count and fibrinogen level and a significant decrease in erythrocyte sedimentation rate, eosinophils, lymphocytes, bleeding, clotting and prothrombin time. Oral pretreatment with SACS (40 and 80 mg kg(-1)) daily for a period of 35 days showed a positive effect on all the biochemical parameters studied in ISO-induced rats. Thus, the study showed the protective effect of SACS on ISO-induced cardiotoxicity in male Wistar rats.

Preventive effect ofS-allyl cysteine sulfoxide (alliin) on lysosomal hydrolases and membrane-bound atpases in isoproterenol-induced myocardial infarction in wistar rats

In this study, S-allyl cysteine sulfoxide (SACS) was used to evaluate its preventive effect in isoproterenol (ISO)-induced myocardial ischemia in male Wistar rats. Rats were pretreated with SACS (40 and 80 mg kg(-1)) orally for 5 weeks. After the treatment period, ISO (150 mg kg(-1)) was administered subcutaneously to rats at an interval of 24 h for 2 days. The activities of beta-D-N-acetyl-glucosaminidase, beta-galactosidase, beta-glucosidase, and acid phosphatase increased in serum and heart in ISO-induced rats. In addition, these rats showed a significant (p < 0.05) increase in the activities of beta-glucuronidase and cathepsin-D in serum and heart and a significant (p < 0.05) decrease in their activities in lysosomal fraction of the heart. The activity of Na(+)K(+)-ATPase declined, while those of Ca(2+)- and Mg(2+)-ATPases significantly (p < 0.05) elevated in the heart of ISO-induced rats. Pretreatment with SACS (40 and 80 mg kg(-1)) showed a significant (p < 0.05) effect in all the biochemical parameters studied. The effect at a dose of 80 mg kg(-1) body weight was more effective than that at 40 mg kg(-1) body weight and brought back all the biochemical parameters to near normal levels. Hereby, our study shows the membrane-stabilizing as well as antioxidant effects of SACS in ISO-induced rats.

Preventive effect of S-allyl cysteine sulfoxide (alliin) on cardiac marker enzymes and lipids in isoproterenol-induced myocardial injury

The present study was designed to evaluate the preventive effect of S-allyl cysteine sulfoxide (SACS) in isoproterenol (ISO)-induced myocardial ischaemia in male Wistar rats. Rats were pretreated with SACS (40 and 80 mg kg(-1) body-weight) for 5 weeks. After the treatment period, ISO (150 mg kg(-1) body-weight) was administered subcutaneously to rats at intervals of 24 h for 2 days. The activities of creatine kinase, creatine kinase-MB, lactate dehydrogenase, aspartate transaminase and alanine transferase were significantly increased in serum and significantly decreased in the hearts of ISO-treated rats. Pretreatment with SACS decreased the activities of these enzymes significantly in serum and significantly increased the activities in heart in ISO-treated rats. The levels of cholesterol, triglycerides and free fatty acids increased in serum and heart, while the levels of phospholipids increased in serum and decreased in heart in ISO-treated rats. SACS pretreatment showed a significant effect on the lipids studied. The activity of 3-hydroxy 3-methyl glutaryl coenzyme A (HMG CoA) reductase was significantly increased and the activity of lecithin cholesterol acyl transferase (LCAT) was significantly reduced in ISO-induced rats. Oral pretreatment with SACS significantly decreased the activity of HMG CoA reductase and significantly increased the activity of LCAT in ISO-induced rats. The levels of plasma thiobarbituric acid reactive substances and hydroperoxides were increased in ISO-treated rats. Pretreatment with SACS significantly decreased the levels of lipidperoxides in ISO-treated rats. The effect at a dose of 80 mg kg(-1) body-weight was more effective than at a dose of 40 mg kg(-1) body-weight and brought back all the biochemical parameters to near normal levels. Thus our study shows that SACS has a lipid-lowering effect in ISO-induced rats. Our study may have clinical relevance.

Antilipoperoxidative and antioxidant effects of S-allyl cysteine sulfoxide on isoproterenol-induced myocardial infarction in wistar rats

Our study evaluates the preventive effect of S-allyl cysteine sulfoxide (SACS) on lipid peroxidative products and enzymic and nonenzymic antioxidants in isoproterenol (ISO) induced myocardial infarction in rats. The male Wistar rats were rendered myocardial infarction by ISO (150 mg kg(-1), once a day for two days). The concentrations of thiobarbituric acid reactive substances and lipid hydroperoxides were increased in hearts from ISO-treated rats, whereas the content of enzymic and nonenzymic antioxidants were declined in rats administered ISO. Oral pretreatment with SACS (40 mg kg(-1) and 80 mg kg(-1) daily for a period of 35 days) significantly (p < 0.05) decreased the lipid peroxidative products and significantly (p < 0.05) increased antioxidants in ISO-induced rats. Oral administration of SACS (40 mg kg(-1) and 80 mg kg(-1)) did not show any significant effect in normal rats. Thus, the present study shows that SACS exhibits antilipoperoxidative and antioxidant effects in experimental myocardial infarction.