Additional Carbon Source Research Articles

Production, characterisation and immobilization of laccase for an efficient aniline-based dye decolourization

Laccase was produced by cultivation of Trametes versicolor on non-expensive substrates, barley husk and eggshell, in solid-state conditions. An efficiency of crude laccase extract in free and immobilized form for the degradation of aniline-based dye was investigated in batch experiments. Up to 91 % of dye conversion was achieved using free crude enzyme, while the use of partially purified enzyme led to 60.9 % of conversion. Crude laccase was immobilized on calcium alginate beads and used in 10 cycles-repetitive batch experiments where complete decolourization was achieved. The results of this study suggest that a) barley husk and eggshell can be used for laccase production without the need to add additional carbon and nitrogen sources or mineral compounds; b) crude laccase entrapped in alginate beads can be applied in aniline-based dye decolourization in repetitive batch experiments.

Trophic diversity and carbon sources supporting fish communities along a pollution gradient in a tropical river

Anthropogenic activities can have a great influence on water quality and in the availability of habitat and food resources, which can promote changes in the trophic diversity and carbon sources sustaining aquatic communities. The objective of this study was to evaluate if the trophic diversity and the main carbon sources sustaining fish communities change along a pollution gradient. The study was carried out at eight sites distributed along the Rio das Velhas, a Brazilian river highly impacted by anthropogenic activities, in which the discharge of domestic and industrial sewage from the Metropolitan Region of Belo Horizonte (MRBH) presents a major source of pollution. Using carbon (δ13C) and nitrogen (δ15N) isotope ratios, we identified the major carbon sources/food sources of common fish species and calculated six metrics of trophic diversity. Autochthonous primary producers (algae, periphyton, and macrophytes) were the main carbon sources for all trophic guilds at all sites, but notably, sewage-derived organic matter was an additional significant carbon source to the fish community in the most polluted testing site. Here, the community was composed mainly by detritivorous and omnivorous fishes and exhibited greater ranges of carbon and nitrogen isotopic values, large total areas, high trophic diversity, small trophic redundancy, and less even distribution of trophic niches than the less polluted sites. We conclude that the trophic guilds, trophic diversity metrics, and carbon sources sustaining fish communities in the Rio das Velhas are highly influenced by the presence of pollution. Besides favoring omnivorous and detritivorous fishes, the input of sewage also provided an important food source to sustain the fish community from sites close to the MRBH.

Metabolic Cooperation among Commensal Bacteria Supports Drosophila Juvenile Growth under Nutritional Stress.

SummaryThe gut microbiota shapes animal growth trajectory in stressful nutritional environments, but the molecular mechanisms behind such physiological benefits remain poorly understood. The gut microbiota is mostly composed of bacteria, which construct metabolic networks among themselves and with the host. Until now, how the metabolic activities of the microbiota contribute to host juvenile growth remains unknown. Here, using Drosophila as a host model, we report that two of its major bacterial partners, Lactobacillus plantarum and Acetobacter pomorum, engage in a beneficial metabolic dialogue that boosts host juvenile growth despite nutritional stress. We pinpoint that lactate, produced by L. plantarum, is utilized by A. pomorum as an additional carbon source, and A. pomorum provides essential amino acids and vitamins to L. plantarum. Such bacterial cross-feeding provisions a set of anabolic metabolites to the host, which may foster host systemic growth despite poor nutrition.

Effective Removal of Lead from Solution by Sulfate Reducing Bacteria Cultured with Sugar Byproducts

Sulfate reducing bacteria (SRB) are widely used to remove heavy metals because of their high efficiency. However, the metabolic processes of SRB require additional carbon sources, and the development of low-cost carbon sources has gradually attracted attention. The utilization of sugar byproduct resources, as the low-cost carbon sources, has great practical significance for environmentally sustainable development in Guangxi, China. This study aims to cultivate SRB with low-cost sugar byproducts, apply them to controlling a lead-polluted environment, and study the effects and mechanisms of controlling lead pollution. The research results show that the best culture effect of SBR can be obtained by mixing the filter mud and vinasse in a ratio of 1:1 to 3:1. SRB have average lead removal rates of more than 96.97% in solutions with different lead concentration of 10∼100 mg/L, and SRB have a higher tolerance to high concentrations of lead due to factors such as the organic substance composition of sugar byproducts and the porosity of filter mud. Scanning electron microscopy combined with energy dispersive spectrometry and X-ray diffraction analysis show that SRB mainly cause Pb2+ to form PbS precipitate through redox reactions to remove lead from the solution. Therefore, low-cost filters of a mud and vinasse mixture can be used as a medium for SRB and exhibit high heavy metal removal efficiency, thus providing a new utilization of filter mud and vinasse.

Dye reduction-based electron-transfer activity monitoring assay for assessing microbial electron transfer activity of microbial fuel cell inocula

Microbial fuel cells (MFC) utilize microbes as catalysts to convert chemical energy to electricity. Inocula used for MFC operation must therefore contain active microbial population. The dye reduction-based electron-transfer activity monitoring (DREAM) assay was employed to evaluate different inocula used in MFCs for their microbial bioelectrical activity. The assay utilizes the redox property of Methylene Blue to undergo color change from blue to colorless state upon microbial reduction. The extent of Methylene Blue reduction was denoted as the DREAM assay coefficient. DREAM assay was initially performed on a microbial culture along with the growth curve and estimation of colony forming units (CFUs). DREAM coefficient correlated to the CFU/mL obtained over time as growth progressed. The assay was then extended to water samples (domestic sewage, lake and a man-made pond) serving as inocula in MFCs. Domestic wastewater gave the highest DREAM coefficient (0.300 ± 0.05), followed by pond (0.224 ± 0.07) and lake (0.157 ± 0.04) water samples. Power density obtained conformed to the DREAM coefficient values, with the three samples generating power densities of 46.45 ± 5.1, 36.12 ± 3.2 and 25.08 ± 4.3 mW/m2 respectively. We have also studied the role of addition of various carbon sources and their concentrations towards improving the sensitivity of the assay. The DREAM assay is a rapid, easy-to-perform and cost-effective method to assess inocula for their suitability as anolytes in terms of electron transfer potential in MFCs.

Nanoporous Carbon Prepared with MOF-5 as a Template and Activated using KOH for Hydrogen Storage

A series of nanoporous carbon was prepared with MOF-5 as a template and furfuryl alcohol as an additional carbon source by carbonation at temperatures of 550 °C and 900 °C, respectively, with and without activation using KOH. XRD patterns of the obtained carbons before and after the activation process showed characteristic peaks at the same 2θ values, which corresponded to the XRD pattern of a ZnO. The Surface morphology of the MOF-5 templated carbon with a carbonation temperature of 550 °C was in the form of a cube. In contrast, the one carbonated at 900 °C had a cubic and circular morphology. The N2 adsorption-desorption isothermal showed that MOF-5 templated carbon had a larger specific surface area, pore diameter, and pore volume than those of the original MOF-5. Activation of the MOF-5 templated carbon using KOH resulted in a decrease in surface area and pore volume. All the materials were measured for their hydrogen adsorption at room temperature and atmospheric pressure using a gravimetric method.

A Honeycomb-Like Bulk Superstructure of Carbon Nanosheets for Electrocatalysis and Energy Storage.

Superstructures have attracted extensive attention because of their potential applications in materials science and biology. Herein, we fabricate the first centimeter-sized porous superstructure of carbon nanosheets (SCNS) by using metal-organic framework nanoparticles as a template and polyvinylpyrrolidone as an additional carbon source. The SCNS shows a honeycomb-like morphology with wall-sharing carbon cages, in each cavity of which a porous carbon sphere is encapsulated. A single piece of SCNS is directly used as the electrode for a two-electrode symmetrical supercapacitor cell without any binders and supports, benefiting from its advantage in ultra-large geometric size, and the Fe-immobilized SCNS exhibits excellent catalytic performances for oxygen reduction reaction and in a Zn-air battery. This synthetic strategy presents a facile approach for preparing functional SCNS at centimetric scale with controllable morphologies and compositions favoring the fabrication of energy devices.

A Honeycomb‐Like Bulk Superstructure of Carbon Nanosheets for Electrocatalysis and Energy Storage

AbstractSuperstructures have attracted extensive attention because of their potential applications in materials science and biology. Herein, we fabricate the first centimeter‐sized porous superstructure of carbon nanosheets (SCNS) by using metal–organic framework nanoparticles as a template and polyvinylpyrrolidone as an additional carbon source. The SCNS shows a honeycomb‐like morphology with wall‐sharing carbon cages, in each cavity of which a porous carbon sphere is encapsulated. A single piece of SCNS is directly used as the electrode for a two‐electrode symmetrical supercapacitor cell without any binders and supports, benefiting from its advantage in ultra‐large geometric size, and the Fe‐immobilized SCNS exhibits excellent catalytic performances for oxygen reduction reaction and in a Zn–air battery. This synthetic strategy presents a facile approach for preparing functional SCNS at centimetric scale with controllable morphologies and compositions favoring the fabrication of energy devices.

Nutrient metabolism, mass balance, and microbial structure community in a novel denitrifying phosphorus removal system based on the utilizing rules of acetate and propionate

The effect of acetate (HAc) and propionate (HPr) on denitrifying phosphorus removal (DPR) was evaluated in a novel two-sludge A2/O - MBBR (anaerobic/anoxic/oxic - moving bed biofilm reactor) system. Results showed that it was the carbon source transformation and utilization especially the composition of poly-β-hydroxyalkanoates (PHA) (mainly poly-β-hydroxybutyrate (PHB) and poly-bhydroxyvalerate (PHV)) decided DPR performance, where the co-exist of HAc and HPr promoted the optimal nitrogen (85.77%) and phosphorus (91.37%) removals. It facilitated the balance of PHB and PHV and removing 1 mg NO3− (PO43−) consumed 3.04–4.25 (6.84–9.82) mgPHA, where approximately 40–45% carbon source was saved. Mass balance revealed the main metabolic pathways of carbon (MAn,C (consumed amount in anaerobic stage) and MA-O,C (consumed amount in anoxic and oxic stages): 66.38–76.19%), nitrogen (MDPR,N (consumed amount in DPR): 57.01–65.75%), and phosphorus (MWS,P (discharged amount in waste sludge): 81.05–85.82%). Furthermore, the relative abundance and microbial distribution were assessed to elucidate DPR mechanism (e.g. Accumulibacter, Acinetobacter, Dechloromonas, Competibacter, and Defluviicoccus) in the A2/O reactor and nitrification performance (e.g. Nitrosomonas, Nitrosomonadaceae and Nitrospira) in the MBBR. Carbon source was demonstrated as the key point to stimulate the biodiversity and bioactivity related to DPR potential, and the operational strategy of carbon source addition was proposed based on the utilizing rules of HAc and HPr.

Effect of CNT impregnation on the mechanical and thermal properties of C/C-SiC composites

The present study investigates the effect of additional carbon source, in the form of carbon nanotubes (CNTs), on mechanical and thermal properties of carbon fiber reinforced silicon carbide (C/C-SiC) ceramic matrix composites (CMC) produced by liquid silicon infiltration (LSI) technique. The CNTs used in this study were impregnated into the C/C preforms before the liquid silicon infiltration stage. The results showed that the addition of excess carbon to the C/C preforms in the form of CNTs enhanced Si infiltration efficiency significantly resulting in C/C-SiC composites with higher density and microstructural uniformity. Accordingly, the addition of CNTs improved the flexural strength of the composites by 40% with respect to no-CNT-containing composites due to a lower amount of residual porosity and additional reinforcement effect of the unreacted CNTs. The thermal conductivity of the resulting C/C-SiC composites has been also increased by 31% and 18% parallel and perpendicular to the carbon fiber–woven fabric surface, respectively, by CNT addition.

Evaluation of Step Feeding Strategy in One-Stage Simultaneous Partial Nitritation, Anammox and Denitrification (SPNAD) Process

Fast start-up of simultaneous partial nitritation, anaerobic ammonium oxidation (anammox) and denitrification (SPNAD) process was achieved within a month by applying step feeding strategy without carbon source addition in the acclimation period. The decreasing cycle number of step feeding strategy successfully improved the SPNAD process performance and enhanced nitrogen and organic removal performance for treating sidestream wastewater. The 3-cycle step feeding strategy obtained higher average values of nitrogen loading rate (NLR), nitrogen removal rate (NRR), ammonium removal rate (ARR) and COD removal rate (CRR) of 0.50, 0.31, 0.45, and 0.18 kg/m3/day, respectively, than 10-cycle and 5-cycle step feeding strategy. The step feeding strategy also contributes in maintaining DO, pH and ORP sensors performance stability even after being operated in long-term duration.

Effect of Organic Carbon Source on Pyrite Biooxidation by Moderately Thermophilic Acidophilic Microorganisms

Iron- and sulfur-oxidizing auto-, mixo- and heterotrophic bacteria and archaea dominate in the bioleaching of pyrite from sulfide ores and concentrates both in natural conditions and in biohydrometallurgical processes. The goal of the present work was to study the oxidation of pyrite, the most widespread sulfide mineral, by representatives of microbial groups predominant in biohydrometallurgical processes (mixotrophic iron- and sulfur-oxidizing bacterial strain Sulfobacillus thermosulfidooxidans VKMB1269T, autotrophic sulfur-oxidizing bacterial strain Acidithiobacillus caldus MBC-1, and heterotrophic iron- and sulfur-oxidizing strain of archaea Acidiplasma sp. MBA-1) to evaluate the potential importance of different groups of microorganisms, and to determine the role of interspecies interactions in the population during pyrite oxidation. It was shown that pyrite was most actively leached by the strain of the mixotrophic bacterium S. thermosulfidooxidans VKMB 1269T, in the case when the medium was supplemented with organic substrates. In the experiment with a pure culture of strain VKMV 1269T in a medium with 0.02% yeast extract, 17% of pyrite was leached in 30 days, while in experiments with pure cultures of A. caldus MBC-1 and Acidiplasma sp. MBA-1, less than 1.5% of pyrite were leached. Significantly better results were obtained using mixed cultures of iron-oxidizing strains and A. caldus MBC-1: the rate of pyrite leaching was 26–28%. Moreover, in experiments with a mixed culture of S. thermosulfidooxidans VKMB 1269T and A. caldus MBC-1, addition of an organic carbon source (yeast extract) did not affect the rate of pyrite leaching (25–26%). The highest (38%) leaching rate was in the experiments with a pure culture of S. thermosulfidooxidans VKMV 1269T with periodic addition of yeast extract to the medium: 0.02% at the beginning of the experiment, as well as on days 10 and 20. Thus, in laboratory conditions it was shown that the greatest role in the process of pyrite oxidation was played by the bacterial strain of the genus Sulfobacillus, but its activity was largely dependent on availability of an organic carbon source in the medium, which may be represented by yeast extract or exometabolites of autotrophic bacteria present in the community of microorganisms performing pyrite leaching from sulfide ores and concentrates.

Decolourisation and detoxification of CI Direct Blue 201 textile dye by two fungal strains of genus Aspergillus

Two fungal strains capable of decolourisation of CI Direct Blue 201 textile dye were isolated from textile wastewater effluent sites in Sri Lanka and they were identified as Aspergillus aculeatus and Aspergillus nomius using 18s rRNA analysis. A. nomius and A. aculeatus showed 98 % decolourisation of CI Direct Blue 201 textile dye (50 mg/L) at 3rd day of incubation with the supplement of modified Kirk’s medium. Both fungal strains were found to be more effective for dye decolourisation at temperatures ranging from 24 ˚C to 36 ˚C. Further, it was found that the decolourisation potential increased at pH 5 and 10 under shaking condition (100 rpm) with the presence of glucose and nitrate as additional carbon and nitrogen sources. Seed germination assay showed less germination (22.2 ± 5.0 % and 10.0 ± 3.3 % for Oryza sativa and Vigna radiata, respectively) when seeds were exposed to the original dye in comparison to 100 % seed germination observed when exposed to fungal treated dye effluent, showing the detoxification of dye by the fungal isolates.

Nitrogen removal efficiency of surface flow constructed wetland for treating slightly polluted river water.

Restoration and water quality improvement of malodorous as well as slightly polluted rivers have been the global focus for environmental protection research and the development and construction of sponge cities. To date, constructed wetlands have been proven to be one of efficient methods to improve water quality. Nitrogen removal efficiency is a crucial indicator for the performance evaluation in slightly polluted river water treatment. Therefore, current study aimed to investigate the N removal efficiency of 3-stage surface flow constructed wetlands for water treatment. Results show that after a prolonged operation period, constructed wetlands were able to remove NH4+-N, NO3--N, and TN by 38.4%, 22.3%, and 29.1%, respectively. Further investigations were carried out to investigate the removal efficiency of various N species in the 3-stage wetlands. Findings reveal that NH4+-N was mainly treated in wetland #1 (W1) and wetland #2 (W2), while NO3--N and TN were in wetland #2 (W2) and wetland #3 (W3). Results also reveal that the influencing factors such as hydraulic retention time (HRT), water temperature (WT), and additional carbon source have significant effect on the removal performance of constructed wetlands.

Nano-porous carbon wrapped SiC nanowires with tunable dielectric properties for electromagnetic applications

In this work, SiC nanowires core and nano-porous carbon shell (SiC@C) was synthesized successfully via direct surface carbonization of SiC without any additional carbon source. The thickness of the carbon shell which can induce a remarkable improvement of dielectric properties can be modulated in range of 34‐75 nm by controlling the time and temperature of the carbonization process. An abvious amorphous structure characteristic for the carbon shell was demonstrated mainly by XRD, Raman and TEM technique. By optimizing the carbonization process, SiC@C can be used in both microwave absorption in which the minimum refection loss (RLmin) is −56.34 dB and the effective absorption bandwidth (EAB) is 7.20 GHz and electromagnetic interference shielding in which the electromagnetic interference shielding effective (EMI SE) can reach 60 dB. This work provides a new strategy of SiC@C for electromagnetic applications in microelectronics, aircraft and spacecraft.

Effects of carbon source addition on microbial community and water quality in recirculating aquaculture systems for Litopenaeus vannamei

In order to study the effects of carbon source addition on the bacterial community, water quality and shrimp growth in the recirculating aquaculture system of Litopenaeus vannamei, sucrose with 50% of the daily feed was added daily to the system from the middle stage of culture. The bacterial communities in biofilters, aquaculture waters and shrimp intestines were measured using an Illumina MiSeq platform. The addition of sucrose did not significantly improve the regulation of nitrogen in the water, although there was a tendency to increase shrimp production. The addition of sucrose also had little effect on the bacterial community of water and intestine, but had significant effects on the bacterial community in the biofilter. Carbon addition transformed the dominant bacterial taxa of the biofilter from the Proteobacteria dominated by Rhodobacteraceae to the Planctomycetes dominated by Planctomycetaceae. In this study, the characteristics of the bacterial community and the effects of carbon source addition in the recirculating aquaculture system of L. vannamei are presented, which provides a basis for microbial management in the recirculating aquaculture system of L. vannamei. In view of the unknown role of numerous bacterial groups, the function of the bacterial community needs further study.

Optimation of <i>Spirulina</i> sp. Growth in Walne Media with Variation of Urea and NaHCO3 Supplements

One alternative biofuel to substitute fossil fuels is bioethanol. Microalgae Spirulina sp. contains high carbohydrates, which has 17-25% potential to produce bioethanol. Urea and NaHCO3 can be used as additional nutrients sources of nitrogen and carbon to Spirulina sp. cultivation. Deficiency of nitrogen causing the cell’s enzymes change that shown through decreased lipid and chlorophyll synthesis. While deficiency of carbon can affect the growth rate. In this research, the growth rate of Spirulina sp. is analyzed using Optical Density (OD) method. The growth rate calculation is used to measure the growth of microalgae cells shown in the growth curve. This was a laboratory-scale method using CRD with 4 treatments and 5 replications namely treatment A addition of 0.36 g/500 ml urea without addition of NaHCO3, treatment B addition of 0.043 g/500 ml NaHCO3 without addition of urea, treatment C addition of 0.36 g/500 ml urea and 0.043 g/500 ml NaHCO3, and control without addition of urea or NaHCO3. The results indicated that addition of urea and NaHCO3 didn’t affect to OD and Spirulina sp. growth rate. The highest growth rate was treatment A with 0.00906/day of growth rate followed by treatment C which has 0.00865/day of growth rate. Treatment B and control treatment (K) showed a low growth rate. The maximum OD value obtained in treatment C was 0.674 cells/ml on the 10th day. This research can be used as the reference to larger scale of Spirulina sp. cultivation in the field of bioethanol production.

Separating and Characterizing Functional Nitrogen Degraders via Magnetic Nanoparticle-Mediated Isolation

Magnetic nanoparticle-mediated isolation (MMI) is a new method for isolating active functional microbes from complex microorganisms without substrate labeling. In this study, the composition and properties of magnetic nanoparticles (MNPs) were characterized by a number of techniques, indicating that MNPs have characteristics such as microinterfaces and can be efficiently fixed on the surface of microbial cells. It also introduced the MMI technology in activated sludge after stable long-term treatment. With further addition of promotor carbon sources, the enrichment of the functional nitrogen degraders in MMI was significantly higher than in samples without MNPs, showing the advantages of MMI in identifying the active degraders. Redundancy analysis (RDA) also showed that the functional nitrogen degraders such as Comamonadaceae_unclassified and Thiobacillus absolutely dominated in situ ammonia degradation, and the change in dominant genera had the same trend as the degradation rate of ammonia nitrogen. In the magnetically functionalized system, the separated functional nitrogen degraders significantly improved ammonia nitrogen degradation efficiency, making it basically stable at more than 80%, up to 91.6%. These results prove that the complex flora created after the addition of MNPs is more adaptable to newly introduced pollutants, and MMI is a powerful tool for studying pollutant-degrading microorganisms under in situ conditions.

Biofloc technology with addition of different carbon sources altered the antibacterial and antioxidant response in Macrobrachium rosenbergii to acute stress

The objective of this study was to evaluate the immune response of Macrobrachium rosenbergii to acute stress, including the pathogen challenge, acute H2O2 and pH stress, to explore the application of biofloc systems in prawn farming. All 780 prawns (0.19 ± 0.01 g) were randomly distributed into one control group with 1/3 water changed daily (no carbon source addition) and three biofloc groups with glucose, sucrose and molasses addition (limited-exchanged water), respectively. The biofloc volume dynamics in the water showed that carbon addition significantly promoted the biofloc formation in all biofloc groups (P < .05), meanwhile, during the 45-day rearing period, biofloc improved water quality by consuming the element N accumulated in the water, then leading to the decrease in the concentration of TAN and NO2−-N. However, no significant difference was found in the survival and the growth of prawns between the biofloc groups and the control group (P > .05). Furthermore, the relative gene expression levels of prophenoloxidase (ProPO), catalase (CAT) and superoxide dismutase (SOD) of prawns in the biofloc groups were significantly higher than that in the control group during the acute H2O2 and pH stress (P < .05), as well as the relative gene expression of crustin (CRU) in the biofloc groups was higher than that in the control group during the H2O2 stress (P < .05), which exhibited a stronger adaptive antioxidant and antibacterial response in prawns reared with biofloc, thereby a higher relative percent survival of prawns was recorded in the biofloc groups during pathogen challenge test. Taken together, biofloc system appeared to help prawns to better resist the environment stress.

Addition of insoluble fiber to isolation media allows for increased metabolite diversity of lab-cultivable microbes derived from zebrafish gut samples

ABSTRACT There is a gap in measured microbial diversity when comparing genomic sequencing techniques versus cultivation from environmental samples in a laboratory setting. Standardized methods in artificial environments may not recapitulate the environmental conditions that native microbes require for optimal growth. For example, the intestinal tract houses microbes at various pH values as well as minimal oxygen and light environments. These microbes are also exposed to an atypical source of carbon: dietary fiber compacted in fecal matter. To investigate how the addition of insoluble fiber to isolation media could affect the cultivation of microbes from zebrafish intestines, an isolate library was built and analyzed using the bioinformatics pipeline IDBac. While all isolation media encouraged the growth of species from several phyla, the extent of growth was greater with the addition of fiber allowing for easier isolation. Furthermore, fiber addition altered the metabolism of the cultivated gut-derived microbes and induced the production of unique metabolites that were not produced when microbes were otherwise grown on standard isolation media. Addition of this inexpensive carbon source to the media supported the cultivation of a diverse community whose secondary metabolite production may more closely replicate their metabolite production in vivo.