Facile Synthesis of 2D/2D Ti2C3/ZnIn2S4 Heterostructure for Enhanced Photocatalytic Hydrogen Generation.

ZnIn2S4, a novel two-dimensional visible light-responsive photocatalyst, has attracted much attention in the photocatalytic evolution of H2 under visible light irradiation due to its attractive intrinsic photoelectric properties and geometric configuration. However, ZnIn2S4 still has severe charge recombination, which results in moderate photocatalytic performance. Herein, we report the successful synthesis of 2D/2D ZnIn2S4/Ti3C2 nanocomposites by a facile one-step hydrothermal method. The efficiency of the nanocomposites in photocatalytic hydrogen evolution under visible light irradiation was also evaluated for different ratios of Ti3C2, and the optimal photocatalytic activity was achieved at 5% Ti3C2. Importantly, the activity was significantly higher than that of pure ZnIn2S4, ZnIn2S4/Pt, and ZnIn2S4/graphene. The enhanced photocatalytic activity is mainly due to the close interfacial contact between Ti3C2 and ZnIn2S4 nanosheets, which amplifies the transport of photogenerated electrons and enhances the separation of photogenerated carriers. This research describes a novel approach for the synthesis of 2D MXenes for photocatalytic hydrogen production and expands the utility of MXene composite materials in the fields of energy storage and conversion.

CdS Nanoparticles Supported by Cobalt@Carbon-Derived MOFs for the Improved Adsorption and Photodegradation of Ciprofloxacin.

The design and synthesis of efficient photocatalysts that promote the degradation of organic pollutants in water have attracted extensive attention in recent years. In this work, CdS nanoparticles are grown in situ on Co@C derived from metal-organic frameworks. The resulting hierarchical CdS/Co@C nanostructures are evaluated in terms of their adsorption and photocatalytic ciprofloxacin degradation efficiency under visible-light irradiation. The results show that, apart from offering a large surface area (55.69 m2·g-1), the prepared material can effectively suppress the self-agglomeration of CdS and enhance the absorption of visible light. The CdS/Co@C-7 composite containing 7% wt Co@C has the highest photodegradation rate, and its activity is approximately 4.4 times greater than that of CdS alone. Moreover, this composite exhibits remarkable stability after three successive cycles of photocatalysis. The enhanced photocatalytic performance is largely ascribed to the rapid separation of electron-hole pairs and the effective electron transfer between CdS and Co@C, which is confirmed via electrochemical experiments and photoluminescence spectra. The active substance capture experiment and the electron spin resonance technique show that h+ is the main active entity implicated in the degradation of CIP, and accordingly, a possible mechanism of CIP photocatalytic degradation over CdS/Co@C is proposed. In general, this work presents a new perspective on designing novel photocatalysts that promote the degradation of organic pollutants in water.

Poly-γ-glutamic acid production by simultaneous saccharification and fermentation using corn straw and its fertilizer synergistic effect evaluation.

Agricultural wastes rich in lignocellulosic biomass have been used in the production of poly-γ-glutamic acid (γ-PGA) through separate hydrolysis and fermentation (SHF), but this process is complicated and generates a lot of wastes. In order to find a simpler and greener way to produce γ-PGA using agricultural wastes, this study attempted to establish simultaneous saccharification and fermentation (SSF) with citric acid-pretreated corn straw. The possibility of Bacillus amyloliquefaciens JX-6 using corn straw as substrate to synthesize γ-PGA was validated, and the results showed that increasing the proportion of glucose in the substrate could improve the γ-PGA yield. Based on these preliminary results, the corn straw was pretreated using citric acid. Then, the liquid fraction (xylan-rich) was used for cultivation of seed culture, and the solid fraction (glucan-rich) was used as the substrate for SSF. In a 10-L fermenter, the maximum cumulative γ-PGA concentration in batch and fed-batch SSF were 5.08 ± 0.78 g/L and 10.78 ± 0.32 g/L, respectively. Moreover, the product from SSF without γ-PGA extraction was used as a fertilizer synergist, increasing the yield of pepper by 13.46% (P < 0.05). Our study greatly simplified the production steps of γ-PGA, and each step achieved zero emission as far as possible. The SSF process for γ-PGA production provided a simple and green way for lignocellulose biorefinery and sustainable cultivation in agriculture.

Microbiologically induced calcite precipitation technology for mineralizing lead and cadmium in landfill leachate.

As a new bioremediation technology for toxic metals, microbiologically induced calcite precipitation (MICP) is gradually becoming a research focus. This study investigated the application of MICP to mineralize toxic metals (lead and cadmium) in landfill leachate for the first time. In the experiment of remediating synthetic landfill leachate (SLL) contaminated by Pb2+, 100% of the 20 mg/L Pb2+ was removed when the maximum urease activity was only 20.96 U/ml. Scanning electron microscopy and energy dispersive spectroscopy (SEM-EDS) and laser particle size characterizations of the precipitates indicate the formation of agglomerated square particles, 76.9% of which had sizes that ranged from 33.93 to 57.06 µm. Fourier transform infrared spectroscopic and X-ray diffraction analyses confirmed that the precipitates consisted predominantly of calcite crystals, and the unit cell lattice constants of the precipitates (a = b = 4.984 Å, c = 17.171 Å) matched those of calcite, while lead was fixed as hydrocerussite. In addition, the Pb-MICP precipitates were stable under continuous acid degradation (pH = 5.5), and only 1.76% of the lead was released after 15 days. In the verification test of toxic metals remediation in a real landfill leachate (RLL), all of the Pb2+ and Cd2+ (initial concentrations: Pb2+ = 25 mg/L; Cd2+ = 5.6205 mg/L) was mineralized simultaneously, which further confirmed the feasibility of MICP for toxic metal remediation in landfill leachate. However, optimizing the urea dosage and combining the ammonium recovery are necessary strategies required for improving the economic and environmental benefits of the MICP process.

Deodorization of pig manure using lignin peroxidase with different electron acceptors.

UNLABELLED: Odor pollution is a big environmental problem caused by large-scale livestock production in China, and developing a practical way to reduce these odors is pressing. In this study, a combination of 0.2-1.0 U/mL lignin peroxidase (LiP) and one of three peroxides (H2O2, CaO2, 2Na3CO3·3H2O2) was examined for its efficiency in reducing the release of eight chemicals (propionic acid, isobutyric acid, isocaproic acid, isovaleric acid, phenol, p-cresol, indole, and skatole), NH3, H2S, and odor intensity from pig manure. The results showed an approximately 90% reduction in p-cresol, 40-60% reduction in odor intensity, 16.5-40% reduction in indolic compounds, and 25-40% reduction in volatile fatty acids. Being the electron acceptors of LiP, 2Na3CO3·3H2O2 and CaO2 performed better than H2O2 in reducing the concentration of eight chemicals, NH3, H2S, and odor intensity from pig manure. The effect of deodorization can last for up to 72 hr. IMPLICATIONS: In China, one of the major environmental problems caused by confined feeding is odor pollution, which brings a major threat to the sustainability, profitability, and growth of the livestock industry. To couple the LiP with the electron acceptors, a low-cost, simple, and feasible method for odor removal was established in this study. Based on the study results, a practical treatment method was provided for odor pollution and supply the farm operators a more flexible time to dispose treated manure.

Enhanced methane production in an anaerobic digestion and microbial electrolysis cell coupled system with co-cultivation of Geobacter and Methanosarcina.

The anaerobic digestion (AD) and microbial electrolysis cell (MEC) coupled system has been proved to be a promising process for biomethane production. In this paper, it was found that by co-cultivating Geobacter with Methanosarcina in an AD-MEC coupled system, methane yield was further increased by 24.1%, achieving to 360.2 mL/g-COD, which was comparable to the theoretical methane yield of an anaerobic digester. With the presence of Geobacter, the maximum chemical oxygen demand (COD) removal rate (216.8 mg COD/(L·hr)) and current density (304.3A/m(3)) were both increased by 1.3 and 1.8 fold compared to the previous study without Geobacter, resulting in overall energy efficiency reaching up to 74.6%. Community analysis demonstrated that Geobacter and Methanosarcina could coexist together in the biofilm, and the electrochemical activities of both were confirmed by cyclic voltammetry. Our study observed that the carbon dioxide content in total gas generated from the AD reactor with Geobacter was only half of that generated from the same reactor without Geobacter, suggesting that Methanosarcina may obtain the electron transferred from Geobacter for the reduction of carbon dioxide to methane. Taken together, Geobacter not only can improve the performance of the MEC system, but also can enhance methane production.

Straw- and slurry-associated prokaryotic communities differ during co-fermentation of straw and swine manure.

Anaerobic co-fermentation of straw and manure is widely used for waste treatment and biogas production. However, the differences between the straw- and slurry-associated prokaryotic communities, their dynamic changes throughout the co-fermentation process, and their correlations with bioreactor performance are not fully understood. To address these questions, we investigated the prokaryotic community compositions and the dynamics of prokaryotes attached to the straw and in the slurry during co-fermentation of wheat straw and swine manure using pyrosequencing technique. The results showed that straw- and slurry-associated prokaryotes were different in their structure and function. Straw-associated prokaryotic communities were overrepresented by the phyla Spirochaetes and Fibrobacteres, while Synergistetes and Euryarchaeota were more abundant in the slurry. The straw-associated candidate class TG3, genera Fibrobacter, Bacteroides, Acetivibrio, Clostridium III, Papillibacter, Treponema, Sedimentibacter, and Lutispora may specialize in substrate hydrolysis. Propionate was the most abundant volatile fatty acid in the slurry, and it was probably degraded through syntrophic oxidation by the genera Pelotomaculum, Methanoculleus, and Methanosaeta. The protein-fermenting bacteria Aminobacterium and Cloacibacillus were much abundant in the slurry, indicating that proteins are important substrates in the co-fermentation. This study provided a better understanding of the anaerobic co-fermentation process that is driven by spatially differentiated microbiota.

Biogenic C-doped titania templated by cyanobacteria for visible-light photocatalytic degradation of Rhodamine B.

Cyanobacteria, which occurred in eutrophic water harvest solar light to carry out photosynthesis with high efficiency. In this work, cyanobacteria (Microcystis sp.) were used as biotemplate to synthesize titania structure. The synthesized titania sample had similar morphology to that of the original template in spite of the fragile unicellular structures and extremely high water content of cyanobacterial cells. Incorporation of biogenic C, as well as the morphology inherited from biotemplate improved visible-light absorbance of the titania structure. The sample exhibited higher visible-light photocatalytic activity than commercial titania photocatalyst Degussa P25 for Rhodamine B (RhB) degradation. Compared with those C-doped titania photocatalysts prepared by other methods, cyanobacteria templated titania photocatalyst offer some potential for competitive advantages. The reported strategy opened up a new use for the cyanobacteria. It could also be used for titania in applications such as treatment of polluted water, dye-sensitized solar cells, or other regions.

Analysis of latrine fecal odor release pattern and the deodorization with composited microbial agent.

As an important source of malodor, the odor gases emitted from public toilet significantly interfered the air quality of living surroundings, resulting in environmental problem which received little attention before. Thus, this paper explored the odor release pattern of latrine feces and deodorization effect with composited microbial agent in Chengdu, China. The odor release rules were investigated in sealed installations with a working volume of 9 L for 20 days. The odor units (OU), ammonia (NH3), hydrogen sulfide (H2S) and total volatile organic compounds (TVOC) were selected to assess the release of malodorous gases under different temperature and humidity, while the highest malodor release was observed under 45℃, with OU and TVOC concentration was 643.91 ± 2.49 and 7767.33 ± 33.50 mg/m3, respectively. Microbes with deodorization ability were screened and mixed into an agent, which composited of Bacillus amyloliquefaciens, Lactobacillus plantarum, Enterococcus faecalis and Pichia fermentans. The addition of microbial deodorant could significantly suppress the release of malodor gas during a 20-day trial, and the removal efficiency of NH3, H2S, TVOC and OU was 81.50 %, 38.31 %, 64.38 %, and 76.86 %, respectively. The analysis of microbial community structure showed that temperature was the main environmental factor driving the microbial variations in latrine feces, while Firmicutes, Actinobacteria, Proteobacteria and Bacteroidetes were the main bacteria phyla involved in the formation and emission of malodorous gases. However, after adding the deodorant, the abundance of Bacteroidetes, Proteobacteria and Actinobacteria were decreased, while the abundance of Firmicutes was increased. Furthermore, P. fermentans successfully colonized in fecal substrates and became the dominant fungus after deodorization. These results expanded the understanding of the odor release from latrine feces, and the composited microbial deodorant provided a valuable basis to the management of odor pollution.

Microbiologically induced calcite precipitation (MICP) in situ remediated heavy metal contamination in sludge nutrient soil.

Microbiologically induced calcite precipitation (MICP), as a newly developing bioremediation technology, could redeem heavy metal contamination in diverse scenarios. In this study, MICP bacterium Sporosarcina ureilytica ML-2 was employed to suppress the pollution of Pb, Cd and Zn in municipal sludge nutrient soil. After MICP remediation, the exchangeable Cd and Zn in sludge nutrient soil were correspondingly reduced by 31.02 % and 6.09 %, while the carbonate-bound Pb, Cd and Zn as well as the residual fractions were increased by 16.12 %, 6.63 %, 13.09 % and 6.10 %, 45.70 %, 3.86 %, respectively. In addition, the extractable Pb, Cd and Zn either by diethylenetriaminepentaacetic acid (DTPA) or toxicity characteristic leaching procedure (TCLP) in sludge nutrient soil were significantly reduced. These results demonstrated that the bio-calcite generated via MICP helped to immobilize heavy metals. Furthermore, MICP treatment improved the abundance of functional microorganisms related to urea cycle, while reduced the overall abundance of metal resistance genes (MRGs) and antibiotic resistance genes (ARGs). This work confirmed the feasibility of MICP in remediation of heavy metal in sludge nutrient soil, which expanded the application field of MICP and provided a promising way for heavy metal pollution management.

Microbiologically induced calcite precipitation for in situ stabilization of heavy metals contributes to land application of sewage sludge.

Microbiologically induced calcite precipitation (MICP) has shed new light on solving the problem of in situ stabilization of heavy metals (HMs) in sewage sludge before land disposal. In this study, we examined whether MICP treatment can be integrated into a sewage sludge anaerobic digestion-land application process. Our results showed that MICP treatment not only prevented the transfer of ionic-state Cd from the sludge to the supernatant (98.46 % immobilization efficiency) but also reduced the soluble exchangeable Pb and Cd fractions by up to 100 % and 48.54 % and increased the residual fractions by 22.54 % and 81.77 %, respectively. In addition, the analysis of the stability of HMs in MICP-treated sludge revealed maximum reductions of 100 % and 89.56 % for TCLP-extractable Pb and Cd, respectively. Three-dimensional fluorescence, scanning electron microscopy-energy-dispersive X-ray spectroscopy, X-ray diffraction, and Fourier-transform infrared spectroscopy analyses confirmed the excellent performance of the ureolytic bacteria Sporosarcina ureilytica ML-2 in the sludge system. High-throughput sequencing showed that the relative abundance of Sporosarcina sp. reached 53.18 % in MICP-treated sludge, and the urease metabolism functional genes unit increased by a maximum of 239.3 %. The MICP technology may be a feasible method for permanently stabilizing HMs in sewage sludge before land disposal.

LncRNA-NEAT1 inhibits the occurrence and development of pancreatic cancer through spongy miR-146b-5p/traf6.

To investigate the inhibitory effect of LNCNA-NEA1 on pancreatic cancer development and progression via spongiosa miR-146b-5p/TRAF6, 60 pancreatic cancer patients diagnosed from December 2017 to December 2019 were selected as a general source of information. Real-time fluorescence quantitative polymerase chain reaction (RTFQ-PCR) was used to detect the expression level of NEAT1 in cancerous and adjacent non-cancerous tissues. Cell counting kit-8 (CCK-8) and transwell were used to determine the effect of LNCNA-NEA1 on the proliferation and migration of pancreatic cancer cells (Panc-1). The results of dual luciferase reporter gene assay showed that nea 1 could target and regulate the expression of spongy miR-146b-5p/TRAF6, and reducing the expression of spongy miR-146b-5p/TRAF6 could reverse the inhibitory effects of nea 1-siRNA on proliferation, migration and invasion of pancreatic cancer cells. Therefore, it was concluded that knockdown of nea 1 could inhibit the proliferation, migration and invasion of pancreatic cancer cells by upregulating the level of miR-146b-5p/TRAF6, and the expression of lnc RNA-nea 1 could be used as an indicator for preoperative diagnosis and postoperative prognosis of pancreatic cancer patients. .

Performance evaluation of H2S and NH3 removal by biological trickling filter reactors with various fillers under heterotrophic conditions.

A pilot-scale biological trickling filter (BTF) reactor (13.5 L) packed with different fillers (Pine bark, Cinder, Straw, and MBBR (mobile bed biofilm reactor) filler was employed to evaluate their removal performance of H2S and NH3 after heterotrophic bacterium addition, and some parameters, including different packing heights, empty bed residence time (EBRT), inlet titers, loading ratios, and restart trial, were investigated in this study. According to the experimental results, BTF filled with pine bark exhibited better removal efficiency than other reactors under a variety of conditions. The removal efficiency of H2S and NH3 reached to as high as 81.31 % and 91.72 %, respectively, with the loading range of 3.29-67.70 g/m3·h. Moreover, due to the addition of heterotrophic bacterium, the removal efficiency was enhanced and capable to eliminate majority of H2S and NH3 even though the packing height was reduced to 400 mm. After 15 days of idle, the BTF reactor was able to resume rapidly and execute deodorization with high efficiency. The degradation mechanism was further explored by a thorough examination of microbial species which degraded contaminants, as well as by functional prediction and correlation analyses. In a word, these results laid a foundation for the application of heterotrophic microorganisms in BTF, which could improve the removal efficiency of biological deodorization.

Biotemplated CdS Nano-Aggregate Networks for Highly Effective Visible-Light Photocatalytic Hydrogen Production.

In the last few decades, many new synthesis techniques have been developed in order to obtain an effective visible-light responsive photocatalyst for hydrogen production by water splitting. Among these new approaches, the biotemplated synthesis method has aroused much attention because of its unique advantages in preparing materials with special morphology and structure. In this work, Hydrilla verticillata (L. f.) Royle was used as a biotemplate to synthesize a CdS photocatalyst. The as-synthesized sample had the microstructure of nano-scaled aggregate networks and its activity for photocatalytic hydrogen production was six times higher than that of CdS synthesized without a template in an Na2S-Na2SO3 sacrificial system. The use of Pt and PdS as cocatalysts further improved the hydrogen production rate to 14.86 mmol/g·h under visible-light (λ ≥ 420 nm) irradiation, so the hydrogen production can be directly observed by the naked eye. The results of characterization showed that the as-synthesized CdS photocatalyst has a high specific surface area and narrow band gap, which is favorable for light absorption and photocatalytic reaction. This work provides a new way to search for efficient visible-light catalysts and confirms the uniqueness of a biotemplated synthesis method in obtaining specially structured materials.

Mechanism of microbiologically induced calcite precipitation for cadmium mineralization.

Microbiologically induced calcite precipitation (MICP) technology shows potential for remediating heavy metal pollution; however, the underlying mechanism of heavy metal mineralization is not well-understood, limiting the application of this technology. In this study, we targeted Cd contamination (using 15:1, 25:1, and 50:1 Ca2+/Cd2+ molar ratios) and showed that the ureolytic bacteria Sporosarcina ureilytica ML-2 removed >99.7 % Cd2+ with a maximum fixation capacity of 75.61 mg-Cd/g-CaCO3 and maximum precipitation production capacity of 135.99 mg-CaCO3/mg-cells. Quantitative PCR analysis showed that Cd2+ inhibited the expression of urease genes (ureC, ureE, ureF, and ureG) by 70 % in the ML-2 strain. Additionally, the pseudo-first-order kinetics model (R2 = 0.9886), intraparticle diffusion model (R2 = 0.9972), and Temkin isotherm model (R2 = 0.9828) described the immobilization process of Cd2+ by bio calcite in MICP-Cd system. The three Cd2+ mineralization products generated by MICP were attributed to surface precipitation (Cd2+ → Cd(OH)2), direct binding with the CO32-/substitution calcium site of calcite (Cd2+ → CdCO3, otavite), and calcite lattice vacancy anchors (Cd2+ → (CaxCd1-x)CO3). Our findings improve the understanding of the mechanisms by which MICP can achieve in situ stabilization of heavy metals.

Study on anaerobic co-digestion of municipal sewage sludge and fruit and vegetable wastes: Methane production, microbial community and three-dimension fluorescence excitation-emission matrix analysis.

Constantly increased sewage sludge (SS) and fruit and vegetable wastes (FVW) are becoming the major organic solid wastes in human society. Thus, anaerobic digestion is employed as a low carbon energy strategy to reduce their environmental pollution risk. Anaerobic co-digestion system was developed based on the carbon to nitrogen ratio strategy. Results showed that the daily biogas production was higher in co-digester, and the volumetric biogas production rate (VBPR) significantly enhanced for 1.3 âˆ¼ 3 folds, and the highest VBPR was 2.04 L/L • day with optimal OLR of 2.083 Kg L-1 d-1. Analytic results indicated that co-digestion could improve the biodegradable of feedstocks, which transforming to more VFAs and biogas. Compared with mono SS digester, mixed substrates relieved ammonia nitrogen inhibition and enhanced the hydrolytic acidification and methanogenesis. Meanwhile, the excessive humification of organics was suppressed. This study supported the concepts of improving carbon recovery from SS and FVW.

Modular configurations of living biomaterials incorporating nano-based artificial mediators and synthetic biology to improve bioelectrocatalytic performance: A review.

Currently, the industrial application of bioelectrochemical systems (BESs) that are incubated with natural electrochemically active microbes (EABs) is limited due to inefficient extracellular electron transfer (EET) by natural EABs. Notably, recent studies have identified several novel living biomaterials comprising highly efficient electron transfer systems allowing unparalleled proficiency of energy conversion. Introduction of these biomaterials into BESs could fundamentally increase their utilization for a wide range of applications. This review provides a comprehensive assessment of recent advancements in the design of living biomaterials that can be exploited to enhance bioelectrocatalytic performance. Further, modular configurations of abiotic and biotic components promise a powerful enhancement through integration of nano-based artificial mediators and synthetic biology. Herein, recent advancements in BESs are synthesized and assessed, including heterojunctions between conductive nanomaterials and EABs, in-situ hybrid self-assembly of EABs and nano-sized semiconductors, cytoprotection in biohybrids, synthetic biological modifications of EABs and electroactive biofilms. Since living biomaterials comprise a broad range of disciplines, such as molecular biology, electrochemistry and material sciences, full integration of technological advances applied in an interdisciplinary framework will greatly enhance/advance the utility and novelty of BESs. Overall, emerging fundamental knowledge concerning living biomaterials provides a powerful opportunity to markedly boost EET efficiency and facilitate the industrial application of BESs to meet global sustainability challenges/goals.

Improvement of sewage sludge anaerobic digestion through synergistic effect combined trace elements enhancer with enzyme pretreatment and microbial community response.

In this study, a double E strategy (enzymes and enhancer) characterized by high efficiency for enhancing sewage sludge anaerobic digestion (AD) is proposed. This strategy combines addition of trace elements (TEs) enhancer and enzyme pretreatment, inducing a synergistic effect on AD, and it is more effective and economical compared with TEs addition or enzyme pretreatment in isolation. When adding 400 U/g cocktail enzymes and 1.24% trance elements enhancers, the cumulative methane production and the maximum daily methane increased yield by 45.29% and 84.7%, respectively. According to microbial community analysis, the double E strategy significantly motivate the growth of acetogens and protein fermenting bacterium. The relative abundance of Fermentimonas and Lutispora increased by 6.15% and 5.4%, respectively. Archaeal community analysis and changes in the mcrA gene abundance demonstrate enrichment of hydrogenotrophic methanogens, with the methanogens exhibiting high vitalities and stress resistance. The double E strategy could be a promising way to improve industrial sewage sludge AD efficiency.

Inward-to-outward assembly of amine-functionalized carbon dots and polydopamine to Shewanella oneidensis MR-1 for high-efficiency, microbial-photoreduction of Cr(VI).

A novel photosensitized living biohybrid was fabricated by inward-to-outward assembly of amine-functionalized carbon dots (NCDs) and polydopamine (PDA) to Shewanella oneidensis MR-1 and applied for high-efficiency, microbial-photoreduction of Cr(VI). Within a 72 h test period, biohybrids achieved a pronounced catalytic reduction capacity (100%) for 100 mg/L Cr(VI) under visible illumination, greatly surpassing the poor capacity (only 2.5%) displayed by the wild strain under dark conditions. Modular configurations of NCDs and PDA afforded biohybrids with a large electron flux by harvesting extracellular photoelectrons generated from illuminated NCDs and increasing reducing equivalents released from an enlarged intracellular NADH/NAD+ pool. Further, increased production of intracellular c-type cytochromes and extracellular flavins resulting from the modular configuration enhanced the biohybrid electron transport ability. The enhancement of electron transport was also attributed to more conductive conduits at NCDs-PDA junction interfaces. Moreover, because NCDs are highly reductive, the enhanced Cr(VI) reduction was also attributed to direct reduction by the NCDs and the direct Cr(VI) reduction by sterile NCDs-assembled biohybrid was up to 20% in the dark. Overall, a highly efficient strategy for removal/transformation of Cr(VI) by using NCD-assembled photosensitized biohybrids was proposed in this work, which greatly exceeded the performance of Cr(VI)-remediation strategies based on conventional microbial technologies.

Nitrogen removal characteristics of efficient heterotrophic nitrification-aerobic denitrification bacterium and application in biological deodorization.

A heterotrophic nitrifying aerobic denitrifying (HN-AD) strain HY-1 with excellent capacity, identified as Paracoccus denitrificans, was isolated from activated sludge. HY-1 was capable of removing NH4+, NO2-, and NO3- with the corresponding rate of 17.33 mg-N L-1 h-1, 21.83 mg-N L-1 h-1, and 32.37 mg-N L-1 h-1, as well as the mixture of multiple nitrogen sources. Meanwhile, HY-1 could execute denitrification function under anaerobic conditions with a rate of 14.56 mg-N L-1 h-1. HY-1 required less energy investment, which exhibited average denitrification rate of 5.19 mg-N L-1 h-1 at carbon-nitrogen ratio was 1. After nitrification-denitrification metabolic pathway analysis, HY-1 was applied in a biological trickling filter reactor for compost deodorization. The results showed that adding of HY-1 greatly reduced the ionic concentration of NH4+ and NO3- in the circulating liquid without impairing the deodorization effect (NH3 removal rate＞98.07%). These findings extend the field of application of HN-AD and provide new insights for biological deodorization.