A pan-cancer single-cell transcriptional analysis of antigen-presenting cancer-associated fibroblasts in the tumor microenvironment.

Background: Cancer-associated fibroblasts (CAFs) are the primary stromal cells found in tumor microenvironment, and display high plasticity and heterogeneity. By using single-cell RNA-seq technology, researchers have identified various subpopulations of CAFs, particularly highlighting a recently identified subpopulation termed antigen-presenting CAFs (apCAFs), which are largely unknown. Methods: We collected datasets from public databases for 9 different solid tumor types to analyze the role of apCAFs in the tumor microenvironment. Results: Our data revealed that apCAFs, likely originating mainly from normal fibroblast, are commonly found in different solid tumor types and generally are associated with anti-tumor effects. apCAFs may be associated with the activation of CD4+ effector T cells and potentially promote the survival of CD4+ effector T cells through the expression of C1Q molecules. Moreover, apCAFs exhibited highly enrichment of transcription factors RUNX3 and IKZF1, along with increased glycolytic metabolism. Conclusions: Taken together, these findings offer novel insights into a deeper understanding of apCAFs and the potential therapeutic implications for apCAFs targeted immunotherapy in cancer.

The predictive significance of chromobox family members in prostate cancer in humans.

PURPOSE: The Chromobox (CBX) family proteins are crucial elements of the epigenetic regulatory machinery and play a significant role in the development and advancement of cancer. Nevertheless, there is limited understanding regarding the role of CBXs in development or progression of prostate cancer (PCa). Our objective is to develop a unique prognostic model associated with CBXs to improve the accuracy of predicting outcomes of patients with PCa. METHODS: Data from TCGA and GEO databases were analyzed to assess differential expression, prognostic value, gene pathway enrichment, and immune cell infiltration. COX regression analysis was utilized to identify the independent prognostic factors that impact disease-free survival (DFS). The expression of CBX2 and FOXP3+ cells infiltration was verified by immunohistochemical staining of clinical tissue sections. In vitro proliferation, migration and invasion assay were conducted to examine the function of CBX2. RNA-seq was employed to examine the CBX2 related pathway enrichment. RESULTS: CBX2, CBX3, CBX4, and CBX8 were upregulated, while CBX6 and CBX7 were downregulated in PCa tissues. CBXs expression varied by stage and grade. Elevated expression of CBX1, CBX2, CBX3, CBX4 and CBX8 is correlated with poor outcome. CBX2 expression, T stage, and Gleason score were independent prognostic factors. The expression level of CBX2 in PCa tissues was significantly higher than that in adjacent normal tissues. More Treg infiltration was observed in the group with high CBX2 expression. CBX2 expression affected PCa cell growth, migration, and invasion. CONCLUSIONS: CBX2 is involved in the development and advancement of PCa, suggesting its potential as a reliable prognostic indicator for PCa patients.

Nonionic surfactant Tween 80-facilitated bacterial transport in porous media: A nonmonotonic concentration-dependent performance, mechanism, and machine learning prediction.

The surfactant-enhanced bioremediation (SEBR) of organic-contaminated soil is a promising soil remediation technology, in which surfactants not only mobilize pollutants, but also alter the mobility of bacteria. However, the bacterial response and underlying mechanisms remain unclear. In this study, the effects and mechanisms of action of a selected nonionic surfactant (Tween 80) on Pseudomonas aeruginosa transport in soil and quartz sand were investigated. The results showed that bacterial migration in both quartz sand and soil was significantly enhanced with increasing Tween 80 concentration, and the greatest migration occurred at a critical micelle concentration (CMC) of 4 for quartz sand and 30 for soil, with increases of 185.2% and 27.3%, respectively. The experimental results and theoretical analysis indicated that Tween 80-facilitated bacterial migration could be mainly attributed to competition for soil/sand surface sorption sites between Tween 80 and bacteria. The prior sorption of Tween 80 onto sand/soil could diminish the available sorption sites for P. aeruginosa, resulting in significant decreases in deposition parameters (70.8% and 33.3% decrease in KD in sand and soil systems, respectively), thereby increasing bacterial transport. In the bacterial post-sorption scenario, the subsequent injection of Tween 80 washed out 69.8% of the bacteria retained in the quartz sand owing to the competition of Tween 80 with pre-sorbed bacteria, as compared with almost no bacteria being eluted by NaCl solution. Several machine learning models have been employed to predict Tween 80-faciliated bacterial transport. The results showed that back-propagation neural network (BPNN)-based machine learning could predict the transport of P. aeruginosa through quartz sand with Tween 80 in-sample (2 CMC) and out-of-sample (10 CMC) with errors of 0.79% and 3.77%, respectively. This study sheds light on the full understanding of SEBR from the viewpoint of degrader facilitation.

Henna plant biomass enhanced azo dye removal: Operating performance, microbial community and machine learning modeling.

The bio-reduction of azo dyes is significantly dependent on the availability of electron donors and external redox mediators. In this study, the natural henna plant biomass was supplemented to promote the biological reduction of an azo dye of Acid Orange 7 (AO7). Besides, the machine learning (ML) approach was applied to decipher the intricate process of henna-assisted azo dye removal. The experimental results indicated that the hydrolysis and fermentation of henna plant biomass provided both electron donors such as volatile fatty acid (VFA) and redox mediator of lawsone to drive the bio-reduction of AO7 to sulfanilic acid (SA). The high henna dosage selectively enriched certain bacteria, such as Firmicutes phylum, Levilinea and Paludibacter genera, functioning in both the henna fermentation and AO7 reduction processes simultaneously. Among the three tested ML algorithms, eXtreme Gradient Boosting (XGBoost) presented exceptional accuracy and generalization ability in predicting the effluent AO7 concentrations with pH, oxidation-reduction potential (ORP), soluble chemical oxygen demand (SCOD), VFA, lawsone, henna dosage, and cumulative henna as input variables. The validating experiments with tailored optimal operating conditions and henna dosage (pH 7.5, henna dosage of 2 g/L, and cumulative henna of 14 g/L) confirmed that XGBoost was an effective ML model to predict the efficient AO7 removal (91.6%), with a negligible calculating error of 3.95%. Overall, henna plant biomass addition was a cost-effective and robust method to improve the bio-reduction of AO7, which had been demonstrated by long-term operation, ML modeling, and experimental validation.

A variety of death modes of neutrophils and their role in the etiology of autoimmune diseases.

Neutrophils are important in the context of innate immunity and actively contribute to the progression of diverse autoimmune disorders. Distinct death mechanisms of neutrophils may exhibit specific and pivotal roles in autoimmune diseases and disease pathogenesis through the orchestration of immune homeostasis, the facilitation of autoantibody production, the induction of tissue and organ damage, and the incitement of pathological alterations. In recent years, more studies have provided in-depth examination of various neutrophil death modes, revealing nuances that challenge conventional understanding and underscoring their potential clinical utility in diagnosis and treatment. This review explores the multifaceted processes and characteristics of neutrophil death, with a focus on tailored investigations within various autoimmune diseases. It also highlights the potential interplay between neutrophil death and the landscape of autoimmune disorders. The review encapsulates the pertinent pathways implicated in various neutrophil death mechanisms across diverse autoimmune diseases while also charts possible avenues for future research.

UCHL1 aggravates skin fibrosis through an IGF-1-induced Akt/mTOR/HIF-1α pathway in keloid.

Keloid is a heterogeneous disease featured by the excessive production of extracellular matrix. It is a great challenge for both clinicians and patients regarding the exaggerated and uncontrolled outgrowth and the therapeutic resistance of the disease. In this study, we verified that UCHL1 was drastically upregulated in keloid fibroblasts. UCHL1 had no effects on cell proliferation and migration, but instead promoted collagen I and α-SMA expression that was inhibited by silencing UCHL1 gene and by adding in LDN-57444, a pharmacological inhibitor for UCHL1 activity as well. The pathological process was mediated by IGF-1 promoted Akt/mTOR/HIF-1α signaling pathway because inhibition of any of them could reduce the expression of collagen I and α-SMA driven by UCHL1 in fibroblasts. Also, we found that UCHL1 expression in keloid fibroblasts was promoted by M2 macrophages via TGF-ß1. These findings extend our understanding of the pathogenesis of keloid and provide potential therapeutic targets for the disease.

Preferential, synergistic sorption and reduction of Cr(VI) from chromium-rhodamine B mixed wastewater by magnetic porous biochar derived from wasted Myriophyllum aquaticum biomass.

Eradication of heavy metals and dyes simultaneously from wastewater is urgently needed to safeguard public and environmental health. In this study, magnetic porous biochar derived from wasted Myriophyllum aquaticum (MPMaB) was synthesized by KOH-activation and co-precipitation method to treat chromate and rhodamine B (RhB)-bearing wastewater. The KOH activation significantly improved the pore structure of biochar with a high specific surface area of 937.1 m2 g-1. The sorption performance of MPMaB for Cr(VI) and RhB in single and co-solutes conditions was evaluated. In single system, a pH-dependent sorption pattern for Cr(VI) by MPMaB was revealed and the estimated sorption capability reached 175.4 mg g-1, whereas the Langmuir-based sorption capacity of RhB was 175.4 mg g-1 pH-independently. MPMaB partially transformed Cr(VI) to less toxic Cr(III) (approximately 59.3%). Synergistic sorption of Cr(VI) with the coexistence of RhB was observed, where synergistic effect ranged from 119% to 527% depending on pH. For example, the sorption capacity of Cr(VI) on MPMaB, at pH 2, augmented from 175.4 mg g-1 (single system) to 208.3 mg g-1 (binary system). Preferential sorption of Cr(VI) was found and was further confirmed by the post-sorption of Cr(VI) (or RhB) by MPMaB pre-sorbed with RhB (or chromate). Chromate sorption mechanisms mainly include electrostatic interactions and complexation, while the sorption of RhB is ascribed to π-π interactions, pore filling and hydrogen bonding. Additionally, MPMaB showed excellent reusability and maintained high removal efficiency after 5 cycles. In short, MPMaB can efficiently treat chromium and dyes-containing wastewater as sustainable and environmentally friendly adsorbent.

Valorisation of food waste for valuable by-products generation with economic assessment.

This study assessed the techno-economic feasibility of a biorefinery for valuable by-products (mainly hydrogen, ethanol and fertilizer) generation from food waste. The plant was designed to be built in Zhejiang province (China) with a processing capacity of 100 t food waste per day. It was found that the total capital investment (TCI) and annual operation cost (AOC) of the plant were US$ 7625549 and US$ 2432290.7 year-1, respectively. After the tax, US$ 3141867.6 year-1 of net profit could be reached. The payback period (PBP) was 3.5 years at a 7% discount rate. The internal rate of return (IRR) and return on investment (ROI) were 45.54% and 43.88%, respectively. Shutdown condition could happen with the feed of food waste less than 7.84 t day-1 (2587.2 t year-1) for the plant. This work was beneficial for attracting interests and even investment for valuable by-products generation from food waste in large scale.

Gut microbiota and risk of five common cancers: A univariable and multivariable Mendelian randomization study.

BACKGROUND: Previous studies have linked gut microbiota with cancer etiology, but the associations for specific gut microbiota are causal or owing to bias remain to be elucidated. METHODS: We performed a two-sample Mendelian randomization (MR) analysis to assess the causal effect of gut microbiota on cancer risk. Five common cancers, including breast, endometrial, lung, ovarian, and prostate cancer as well as their subtypes (sample sizes ranging from 27,209 to 228,951) were included as the outcomes. Genetic information for gut microbiota was obtained from a genome-wide association study (GWAS) comprising 18,340 participants. In univariable MR (UVMR) analysis, the inverse variance weighted (IVW) method was conducted as the primary method, with the robust adjusted profile scores, weighted median, and MR Egger used as supplementary methods for causal inference. Sensitivity analyses including the Cochran Q test, Egger intercept test, and leave-one-out analysis were performed to verify the robustness of the MR results. Multivariable MR (MVMR) was performed to evaluate the direct causal effects of gut microbiota on the risk of cancers. RESULTS: UVMR detected a higher abundance of genus Sellimonas predicted a higher risk of estrogen receptor-positive breast cancer (OR = 1.09, 95% CI 1.05-1.14, p = 2.01 × 10-5 ), and a higher abundance of class Alphaproteobacteria was associated with a lower risk of prostate cancer (OR = 0.84, 95% CI 0.75-0.93, p = 1.11 × 10-3 ). Sensitivity analysis found little evidence of bias in the current study. MVMR further confirmed that genus Sellimonas exerted a direct effect on breast cancer, while the effect of class Alphaproteobacteria on prostate cancer was driven by the common risk factors of prostate cancer. CONCLUSION: Our study implies the involvement of gut microbiota in cancer development, which provides a novel potential target for cancer screening and prevention, and might have an implication for future functional analysis.

Surfactant recovery and efficient separation of PAHs from surfactant solutions by low-cost waste activated sludge and two-stage design optimization.

The treatment and surfactant recovery of soil washing/flushing effluent containing high levels of surfactants and organic pollutants are critical for the surfactant-assisted remediation of soils and waste management due to their complexity and high-potential risks. Combination of waste activated sludge material (WASM) and a kinetic-based two-stage system design was introduced in this study as a novel strategy for the separation of phenanthrene and pyrene from Tween 80 solutions. The results showed that WASM can effectively sorb phenanthrene and pyrene with high affinities (Kd) of 2325.5 L·kg-1 and 9911.2 L·kg-1, respectively. This allowed a high-level recovery of Tween 80 of 90.47 ± 1.86%, with selectivity of up to 69.7. In addition, a two-stage design was constructed, and the results showed an improved reaction time (approximately 5% of equilibrium time in conventional single-stage process) and increased the separation levels of phenanthrene or pyrene from Tween 80 solutions. For instance, the minimal total operating time for the sorption of 99% pyrene from 1.0 g·L-1 Tween 80 was only 23.0 min in the two-stage process compared to that of 480 min with a 71.9% removal level in the single-stage system. Results indicated that the combination of low-cost waste WASH and two-stage design was a high-efficiency and time-saving way to recover surfactants from soil washing effluents.

Demulsification Performance and Mechanism of Tertiary Amine Polymer-Grafted Magnetic Nanoparticles in Surfactant-Free Oil-in-Water Emulsion.

Numerous cationic magnetic nanoparticles (MNPs) have previously been developed for demulsifying oil-in-water (O/W) emulsion, and results showed that the cationic MNPs could effectively flocculate and remove the negatively charged oil droplets via charge attraction; however, to the best of our knowledge, there are no research reports regarding the synergetic influence of both the positive charge density and interfacial activity of MNPs on the demulsification performance. In this study, three tertiary amine polymer-grafted MNPs, namely, poly(2-dimethylaminoethyl acrylate)-grafted MNPs (M-PDMAEA), poly(2-dimethylamino)ethyl methacrylate)-grafted MNPs (M-PDMAEMA), and poly(2-diethylaminoethyl methacrylate)-grafted MNPs (M-PDEAEMA), were synthesized and evaluated for their demulsification performance. Results demonstrated that a high positive charge density and superior interfacial activity of MNPs could cause partial oil droplet re-dispersion when excessive MNPs were introduced, leading to a lower magnetic separation efficiency and narrower demulsification window. Herein, a demulsification window is defined as a range of nanoparticle dosages in which the MNPs can effectively demulsify the O/W emulsion under certain conditions. For highly positively charged MNPs, their good interfacial activity could aggravate the formation of a narrower demulsification window. When tertiary amine polymer-grafted MNPs carried a lower positive charge density or weak interfacial activity, that is, M-PDMAEA at pH 4.0, M-PDMAEMA at pH 5.0-9.0, and M-PDEAEMA at pH 9.0-10.0, wide demulsification windows were observed. Additionally, a recycling experiment suggested that MNPs could maintain high demulsification efficiency up to at least five cycles, indicating their satisfactory recyclability. The three tertiary amine polymer-grafted MNPs can be potentially used for efficient demulsification from surfactant-free O/W emulsion in various pH ranges.

Spatiotemporal distribution of opportunistic pathogens and microbial community in centralized rural drinking water: One year survey in China.

Centralized water supply in rural areas, supported by small waterworks (small-central mode) and by municipal water treatment plants (urban-extension mode), is an important guarantee to implement the Rural Revitalization Strategy Plan (2018-2022) in China. Opportunistic pathogens (OPs) could not be evaluated by the national drinking water sanitation standards in China (GB 5749-2022), posing potential microbial risks in rural drinking water. In this study, the spatiotemporal distribution of OPs, microbial community and the associated functional composition under two central water supply modes were investigated by molecular approaches. The results indicated that OPs were widely presented in the rural drinking water regardless of water supply modes, and were more abundant than those in the urban tap water. The insufficient residual chlorine and higher turbidity triggered more microbial proliferation, posing a seasonal variation of OPs gene copy numbers and bacterial community compositions. In warm seasons of summer and autumn, the gene copies of E. coli, M. avium, Pseudomonas spp. and the amoeba host Acanthamoeba spp. achieved up to 4.92, 3.94, 6.75 and 3.74 log10 (gene copies/mL), respectively. Potential functional prediction indicated higher relative abundance of pathogenic genes and infectious risks associated with the rural drinking water under small-central water supply mode. This one-year survey of the spatiotemporal distribution of OPs and microbial community provided scientific insights into microbial safety of rural drinking water, prompting attention on small-central water supply mode against OPs risks.

Process design and techno-economic analysis of fuel ethanol production from food waste by enzymatic hydrolysis and fermentation.

In this study, fuel ethanol production from food waste using enzymatic hydrolysis and fermentation was evaluated from techno-economic viewpoint. The plant was designed with a capacity of 10 t/d food waste and a lifetime of 15-year. The total capital cost, annual operation cost and annual net profits of the plant were US$ 367,552, US$ 155,959 and US$ 74,995.57, respectively. The plant was economically viable as long as the internal rate of return remained below 29.8%. The shortest payback time was 5 years with discount rate of 5%. The price of fuel ethanol and food waste treatment fee were the most important variables for the economic performance of the plant by sensitivity analysis. This work could provide the basic knowledge for techno-economic analysis of food waste treatment and promote the industrial production of fuel ethanol.

Coupled process of in-situ sludge fermentation and riboflavin-mediated nitrogen removal for low carbon wastewater treatment.

Volatile fatty acid recovery from waste activated sludge (WAS) was highly suggested to supplement carbon source for nitrogen removal. However, it was not easy to separate them from the metabolites under the ex-situ fermentation. In this study, in-situ WAS fermentation combined in the denitrification system was established to treat low carbon wastewater (COD/TN = 4), and riboflavin was employed as a redox mediator. This coupled process could simultaneously enhance the WAS fermentation and nitrogen removal, and riboflavin could significantly enrich the fermentative bacteria (Firmicutes phylum), denitrifying bacteria (Denitratisoma genus) and related functional genes (narGHJI, napABC, nirKS, nosZ, norBC), generating more available carbon sources for efficient nitrogen removal. This resulted in the effluent TN (<15 mg/L) satisfying the required discharge standard in China. This study provided new insights into the efficient nitrogen removal from low carbon wastewater, realizing the carbon-neutral operation of new concept wastewater treatment plant in China.

Identification of CXCL10 and CXCL11 as the candidate genes involving the development of colitis-associated colorectal cancer.

Background: Ulcerative colitis (UC) is a well-known risk factor for developing colitis-associated colorectal cancer (CAC). However, the molecular mechanism of the pathogenesis of CAC remains unclear. This study aimed to explore candidate genes involved in the tumorigenesis of CAC. Methods: GSE75214 and the Cancer Genome Atlas Program (TCGA) dataset were used to analyze the differentially expressed genes (DEGs) in UC and colorectal cancer (CRC), respectively. Survival-hub genes were identified from these DEGs by sequentially constructing a protein-protein interaction network, selecting hub genes, and conducting survival analysis. Regulatory signatures were also predicted on these genes through the online database. Apc min/+ and UC mice models were used to validate the expression of the above-predicted molecules. Gene set enrichment analysis and CIBERSORT were performed to explore the enriched molecular pathways and associated tissue-infiltrating immune cells of genes. Results: Here, 376 common DEGs were identified from the GSE75214 and TCGA datasets. Through survival-hub gene selection and in vivo experiments, we confirmed that CXCL10 and CXCL11 were significantly upregulated in UC and CRC. We also proved that miR-34a-5p and miR-203a-5p were potential regulators of CXCL10 and CXCL11. Meanwhile, CXCL10 and CXCL11 may activate the JAK-STAT signaling pathway via the interaction with cytokine receptors in UC. Furthermore, CXCL10 and CXCL11 were positively associated with the tissue infiltration of proinflammatory M1 macrophages in UC and CRC. Conclusion: CXCL10 and CXCL11 may act as the candidate genes involved in the tumorigenesis of CAC and potential therapeutic targets to prevent the development of CAC from UC.

Ethanol Production from the Mixture of Waste French Fries and Municipal Wastewater via Separate Hydrolysis and Fermentation.

The potential of bioethanol generation using the mixture of waste French fries (WFF) and municipal wastewater (MWW) via separate hydrolysis and fermentation (SHF) was evaluated in this study. The effect of WFF substrate loading (SL, 10%, 16%, and 20%, w/v) on the SHF was also examined. Both glucose production and hydrolysis efficiency increased with increasing of SL from 10 to 16% and the maximum glucose yield of 0.236 g glucose/g WFF and hydrolysis efficiency of 91.9% were obtained at SL of 16%. However, the glucose production and hydrolysis efficiency decreased when the SL further increased to 20% due to the inhibition on enzyme caused by higher glucose production. The mixture hydrolysate was then used as feedstock for ethanol fermentation. The maximum ethanol production of 22.69 g/L was obtained from SL of 16%. The highest rate of glucose conversion to ethanol was 84.2%. The results demonstrated that the mixture of WFF and MWW could be used for ethanol production by the SHF.

Bioethanol production from expired cookies and economic analysis for practical application.

This work examined the potential of bioethanol production from expired cookies (EC) by the separate hydrolysis and fermentation process. EC was hydrolyzed by glucoamylase with different enzyme addition (3.5 U/g to 140 U/g) to produce the EC hydrolysate. The glucose concentration increased with enzyme addition from 3.5 U/g to 14 U/g and the highest glucose concentration of 21.2 g/L was obtained. The EC hydrolysate was used by Saccharomyces cerevisiae for bioethanol production. The optimal ethanol production obtained from this study was 40.1 g/L in term of economics and efficiency. According to the mass balance, the highest ethanol yield from EC was 0.4 g/g. Techno-economic analysis of the plant with capacity of 5 tons EC/day was also assessed in this study. The total capital cost and annual operation cost were US$540400.7 and US$144543.9/y, respectively. The revenue of the plant was US$390522/y with the sales of 660 t/y ethanol and 412.5 t/y oils. The plant should feed the EC more than 1.04 t/d (334.2 t/y) to avoid the shutdown point. This is the first study to demonstrate the bioethanol production from EC and assess the economic feasibility for industrial application.

Age-associated B cells contribute to the pathogenesis of rheumatoid arthritis by inducing activation of fibroblast-like synoviocytes via TNF-α-mediated ERK1/2 and JAK-STAT1 pathways.

OBJECTIVES: Age-associated B cells (ABCs) are a recently identified B cell subset, whose expansion has been increasingly linked to the pathogenesis of autoimmune disorders. This study aimed to investigate whether ABCs are involved in the pathogenesis and underlying mechanisms of rheumatoid arthritis (RA). METHODS: ABCs were assessed in collagen-induced arthritis (CIA) mice and patients with RA using flow cytometry. Transcriptomic features of RA ABCs were explored using RNA-seq. Primary fibroblast-like synoviocytes (FLS) derived from the synovial tissue of patients with RA were cocultured with ABCs or ABCs-conditioned medium (ABCsCM). IL-6, MMP-1, MMP-3 and MMP-13 levels in the coculture supernatant were detected by ELISA. Signalling pathways related to ABCs-induced FLS activation were examined using western blotting. RESULTS: Increased ABCs levels in the blood, spleen and inflammatory joints of CIA mice were observed. Notably, ABCs were elevated in the blood, synovial fluid and synovial tissue of patients with RA and positively correlated with disease activity. RNA-seq revealed upregulated chemotaxis-related genes in RA ABCs compared with those in naive and memory B cells. Coculture of FLS with RA ABCs or ABCsCM led to an active phenotype of FLS, with increased production of IL-6, MMP-1, MMP-3 and MMP-13. Mechanistically, ABCsCM-derived TNF-α promoted the upregulation of interferon-stimulated genes in FLS, with elevated phosphorylation of ERK1/2 and STAT1. Furthermore, blockage of ERK1/2 and Janus Kinase (JAK)-STAT1 pathways inhibited the activation of FLS induced by ABCsCM. CONCLUSIONS: Our results suggest that ABCs contribute to the pathogenesis of RA by inducing the activation of FLS via TNF-α-mediated ERK1/2 and JAK-STAT1 pathways.

Effect of temperature on fermentative VFAs production from waste sludge stimulated by riboflavin and the shifts of microbial community.

Fermentative volatile fatty acids (VFAs) production from waste activated sludge (WAS) under moderate temperature is a promising way for resource and energy regeneration in municipal wastewater treatment plants (MWTPs). In this study, the effect of temperature on VFAs production and the associated microbial community from riboflavin-assisted WAS fermentation were investigated. Three fermentative reactors under 25, 35 and 55 °C were operated for 30 days, respectively. The results indicated that riboflavin enhanced VFAs production from WAS fermentation under moderate temperatures (25 °C, 35 °C), increasing conversion of organic matters to bioavailable substrates for the subsequent acidification process. Although a small dosage of riboflavin (1.0 ± 0.05 mM) hardly inhibited the methanogenic process, it could mediate the electron sink for VFAs under lower temperatures. This in turn increased the accumulation of acetic and propionic acids (up to 234 mg/g of volatile suspended solids) and their proportions relative to the total VFAs, being efficient electron donors and carbon sources for nutrient removal in MWTPs. Furthermore, microbial communities were shifted in response to temperature, and riboflavin stimulated the special fermentative bacteria under room temperature and mesophilic conditions. The study suggested a feasible and eco-friendly method to improve VFAs production from crude WAS at a relatively lower temperature.

Stromal Protein Chloroplast Development and Biogenesis1 Is Essential for Chloroplast Development and Biogenesis in Arabidopsis thaliana.

Although numerous studies have been carried out on chloroplast development and biogenesis, the underlying regulatory mechanisms are still largely elusive. Here, we characterized a chloroplast stromal protein Chloroplast Development and Biogenesis1 (CDB1). The knockout cdb1 mutant exhibits a seedling-lethal and ivory leaf phenotype. Immunoblot and RNA blot analyses show that accumulation of chloroplast ribosomes is compromised in cdb1, resulting in an almost complete loss of plastid-encoded proteins including the core subunits of the plastid-encoded RNA polymerase (PEP) RpoB and RpoC2, and therefore in impaired PEP activity. Orthologs of CDB1 are found in green algae and land plants. Moreover, a protein shows high similarity with CDB1, designated as CDB1-Like (CDB1L), is present in angiosperms. Absence of CDB1L results in impaired embryo development. While CDB1 is specifically located in the chloroplast stroma, CDB1L is localized in both chloroplasts and mitochondria in Arabidopsis. Thus, our results demonstrate that CDB1 is indispensable for chloroplast development and biogenesis through its involvement in chloroplast ribosome assembly whereas CDB1L may fulfill a similar function in both mitochondria and chloroplasts.