Mixed Culture System Research Articles

Effect of Sinonovacula constricta on sediment microbial numbers and easily degradable organics in shrimp-crab polyculture systems

To explore the influence of different densities of Sinonovacula constricta on the composition of easily degradable organic matter and related functional bacteria, four experimental ecosystems were established: three polyculture systems (PMB1, PMB2, and PMB3) of Portunus trituberculatus and Marsupenaeus japonicus with different stocking densities of S. constricta (11.6, 23.1, and 34.7×104 ind./hm2, respectively) and a polyculture system with only P. trituberculatus and M. japonicus (PM). Among the easily degradable organic components in all aquaculture systems, protein content was the highest (0.74%~0.86%), followed by carbohydrates (0.16%~0.21%) and lipids (0.06%~0.13%). In the high-density (34.7×104 ind./hm2) S. constricta mixed culture system, the contents of carbohydrates, lipids, and proteins in the sediment were significantly lower than those of the other polyculture systems. The number of cellulose-decomposing bacteria in PMB3 was 3.79×106 cfu/g, which was significantly higher than that in the other systems. The number of starch-degrading bacteria and glutin-degrading bacteria was the lowest in PMB3, 1.26×104 cfu/g, and 160.00 cfu/g, respectively. The number of lipid-degrading bacteria in PMB3 was 0.77×104 cfu/g, which was significantly lower than that in the other systems. The easily degradable organics content in sediment was significantly positively correlated with the corresponding functional bacteria. The results showed that mixed culture of S. constricta could reduce the content of easily degradable organics in the sediment of mariculture ponds and change the number of functional bacteria in the sediment and the availability of degradable organic sediments may determine the abundance of corresponding degradable bacteria.

Platelets correlate with false negative T-SPOT.TB results by inhibiting interferon-γ production in T cells via degranulation.

BackgroundT-SPOT.TB (T-SPOT) is widely used for the detection of Mycobacterium tuberculosis infection by detecting interferon-gamma (IFN-γ) release in T lymphocytes. This assay is performed on peripheral blood mononuclear cells (PBMCs) separated by Ficoll density gradient centrifugation, which often contain some residual platelets. Here, we investigated the impact of platelets on T-SPOT assay and related mechanisms.MethodsThe correlation between platelet count, platelet-to-lymphocyte ratio (PLR), and the IFN-γ secreting T cells (ISCs) in positive control wells of T-SPOT assay were retrospectively analyzed. T-SPOT assay was performed with un-treated PBMCs, platelets-removed PBMCs, and platelets-enriched PBMCs to confirm the impact of platelets on T-SPOT assay. The activation of platelets and their impact on IFN-γ production in T cells were detected by flow cytometry (FCM). Platelets and T cells were cultured in a mixed culture system and co-culture system respectively, followed by detection of the frequencies of IFN-γ-producing T cells and the levels of intracellular IFN-γ in T cells by FCM. Moreover, the effect of platelet releasate on the T-SPOT assay was evaluated.ResultsThe ISCs in positive control wells of the T-SPOT assay showed a significant decrease with the increase in platelet count. The PLR of the peripheral blood were negatively correlated with the ISCs in positive control wells of the T-SPOT assay. Removal or enrichment of platelets significantly increased or decreased the ISCs and the positive rate of T-SPOT. Inhibition of platelet activation significantly increased the ISCs of T-SPOT. The frequencies of IFN-γ-producing T cells in PBMCs and the levels of intracellular IFN-γ were significantly reduced by the addition of platelets, both in the mixed culture system and the co-culture system. Platelet releasate upon thrombin activation significantly decreased the ISCs of T-SPOT.ConclusionsPlatelets correlate with negative T-SPOT results by inhibiting IFN-γ production in T cells via degranulation.

From Organic Wastes and Hydrocarbons Pollutants to Polyhydroxyalkanoates: Bioconversion by Terrestrial and Marine Bacteria

The use of fossil-based plastics has become unsustainable because of the polluting production processes, difficulties for waste management sectors, and high environmental impact. Polyhydroxyalkanoates (PHA) are bio-based biodegradable polymers derived from renewable resources and synthesized by bacteria as intracellular energy and carbon storage materials under nutrients or oxygen limitation and through the optimization of cultivation conditions with both pure and mixed culture systems. The PHA properties are affected by the same principles of oil-derived polyolefins, with a broad range of compositions, due to the incorporation of different monomers into the polymer matrix. As a consequence, the properties of such materials are represented by a broad range depending on tunable PHA composition. Producing waste-derived PHA is technically feasible with mixed microbial cultures (MMC), since no sterilization is required; this technology may represent a solution for waste treatment and valorization, and it has recently been developed at the pilot scale level with different process configurations where aerobic microorganisms are usually subjected to a dynamic feeding regime for their selection and to a high organic load for the intracellular accumulation of PHA. In this review, we report on studies on terrestrial and marine bacteria PHA-producers. The available knowledge on PHA production from the use of different kinds of organic wastes, and otherwise, petroleum-polluted natural matrices coupling bioremediation treatment has been explored. The advancements in these areas have been significant; they generally concern the terrestrial environment, where pilot and industrial processes are already established. Recently, marine bacteria have also offered interesting perspectives due to their advantageous effects on production practices, which they can relieve several constraints. Studies on the use of hydrocarbons as carbon sources offer evidence for the feasibility of the bioconversion of fossil-derived plastics into bioplastics.

Microbial co-culturing of Chlorella sp. And Rhodotorula toruloides for the enhanced microbial lipid production

A microbial co-culture system composed of Chlorella sp. and Rhodotorula. toruloides was established to improve the microbial lipid production in this study. Within this mixed culture, Chlorella sp. acts as oxygen emitters to provide a constant supply of oxygen and regulate the pH, leading to higher biomass and lipid production. Subsequently, a series of culture conditions were optimized to improve the suitability and stability of the cocultivation system, including the C/N ratio, temperature, inoculation time and inoculation ratio. Under the optimal conditions, the accumulation of biomass and lipid content was improved 26.9 g/L and 70.94%, which was 1.8-fold and 2.13-fold than that of pure culture, respectively. Interestingly, the composition of fatty acids was significantly changed under different temperatures in mixed culture systems. The enhancement of unsaturated fatty acids will contribute to high value-added applications. In addition, the highest biomass of 31.9 g/L was obtained from molasses, indicating the great potential for industrial application.

Transcriptomic mechanisms for the promotion of cyanobacterial growth against eukaryotic microalgae by a ternary antibiotic mixture

This study evaluated the responses of a mixed culture of two cyanobacterial species (Microcystis aeruginosa and Synechocystis sp.) and two eukaryotic microalgal species (Raphidocelis subcapitata and Tetradesmus obliquus) to a mixture of three frequently detected antibiotics (tetracycline, ciprofloxacin and sulfamethoxazole) at environmentally relevant exposure doses of 60-300ng/L. Mixed antibiotics selectively stimulated (p < 0.05) the growth and photosynthetic activity as well as generated transcriptomic responses in cyanobacteria without disrupting co-existing eukaryotic microalgae. Mixed antibiotics stimulated the growth of M. aeruginosa through the regulation of genes related to ribosome, photosynthesis, redox homeostasis, quorum sensing and nutrient metabolism. The proportion of M. aeruginosa among the four phytoplankton species in the mixed-culture system was increased from 33% to 38-44% under antibiotic exposure, which promoted the dominance of M. aeruginosa. Up-regulation of carbon catabolism-related genes contributed to the increased growth of Synechocystis sp. under antibiotic exposure. Since the antibiotic-stimulated growth rate of Synechocystis sp. was still lower than that of M. aeruginosa, the proportion of Synechocystis sp. in the mixed-culture system remained stable. Synechocystis sp. was less adaptive to antibiotic exposure than M. aeruginosa, due to a lower number of up-regulated ribosomal genes and photosynthesis-related genes. Antibiotic exposure reduced the proportions of two eukaryotic microalgal species in the mixed-culture system through a selective promotion of cyanobacterial competitiveness against eukaryotic microalgae, which may facilitate the formation of cyanobacteria bloom.

Stabilization and mechanism of uranium sequestration by a mixed culture consortia of sulfate-reducing and phosphate-solubilizing bacteria

In this study, a highly efficient phosphate-solubilizing bacteria (PSB) (Pantoea sp. grinm-12) was screened out from uranium (U) tailings, and the carbon and nitrogen sources of mixed culture with sulfate-reducing bacteria (SRB) were optimized. Results showed that the functional expression of SRB-PSB could be promoted effectively when glucose + sodium lactate was used as carbon source and ammonium nitrate + ammonium sulfate as nitrogen source. The concentration of PO43− in the culture system could reach 107.27 mg·L−1, and the sulfate reduction rate was 81.72%. In the process of biological stabilization of U tailings by mixed SRB-PSB culture system, the chemical form of U in the remediation group was found to transfer to stable state with the extension of remediation time, which revealed the effectiveness of bioremediation on the harmless treatment of U tailings. XRD, FT-IR, SEM-EDS, high-throughput sequencing, and metagenomics were also used to assist in revealing the microstructure and composition changes during the biological stabilization process, and explore the microbial community/functional gene response. Finally, the stabilization mechanism of U was proposed. In conclusion, the stabilization of U in U tailings was realized through the synergistic effect of bio-reduction, bio-precipitation, and bio-adsorption.

Evaluation of N doped rGO-ZnO-CoPc(COOH)8 nanocomposite in cyanide degradation and its bactericidal activities

In the present study, an attempt has been made to design a solar light driven N-rGO-ZnO- CoPc(COOH)8 nanocomposite for the degradation of cyanide. The morphological and structural characterization of the synthesized nanocomposite was performed by XRD, FT-IR, XPS, UV–vis DRS, FESEM, TEM, EDS, PL spectra and BET surface area. The results revealed that almost 91% degradation and 86% toxicity removal occurred at 25 mgL−1 of initial cyanide concentration by the N-rGO-ZnO-CoPc(COOH)8 nanocomposite under illumination of solar light within 120 min. Analysis of free radicals reveals that the generation of OH. radicals was the predominant species in the photocatalytic degradation process. The cyanide degradation follows pseudo-first order kinetics. The estimated apparent rate constant (Kapp) of the above nanocomposite was 3 times higher than that of the ZnO photocatalyst alone together with a very good recycle activities. This might be due to the application of metallpthalocyanine photosensitizer CoPc(COOH)8 which enhances the rate of visible light absorption efficiency and activates the higher band gap ZnO photocatalyst under visible light. In addition, the presence of residual oxygen in N-rGO also promotes nucleation and anchor sites for interfacial contact between ZnO and N-rGO for effective charge transfer. Further, the N-rGO-ZnO-CoPc(COOH)8 photocatalytic system showed significant antibacterial activities against mixed culture systems. Therefore, the N-rGO-ZnO-CoPc(COOH)8 nanocomposite may be an alternative solar light driven photocatalyst system for the removal of cyanide from the wastewater along with its strong disinfectant activities.

Treatment of Synthetic Ammonium Sulfate Wastewater by Mixed Culture of Chlorella pyrenoidosa and Enriched Nitrobacteria.

Ammonium sulfate wastewater can cause eutrophication and black odor of water body. Although ammonia nitrogen can be used as nutrient of microalgae, high ammonia nitrogen levels could inhibit the growth of microalgae. Nitrobacteria can transform ammonia nitrogen into nitrate nitrogen. In this study, mono Chlorella pyrenoidosa culture (mono-C.py), synchronous mixed culture (mixed-a), and asynchronous mixed culture (mixed-b) systems were examined for their ability to treat ammonium sulfate wastewater. Nitrogen removal rate of mixed-b at the end of culture (52.96%) was higher than that of the mono-C.py (46.37%) and the mixed-a (39.11%). Higher total suspended solid concentration (2.40g/L), crude protein yield (0.76g/L), and heating value yield (35.73kJ/L) were obtained in mixed-b, meanwhile with excellent settlement performance (91.43 ± 0.51%). Mechanism analysis of settlement showed that the relative abundance of floc-forming-related bacteria Sphingopyxis and Acidovorax were increased generally, while nitrification/denitrifying members were decreased in mixed-b along with the culture proceeding.

Inflammatory Environment Promotes the Adhesion of Tumor Cells to Brain Microvascular Endothelial Cells.

Cancer patients usually suffer from unfavorable prognosis, particularly with the occurrence of brain metastasis of lung cancer. The key incident of brain metastasis initiation is crossing of blood-brain barrier (BBB) by cancer cells. Although preventing brain metastasis is a principal goal of cancer therapy, the cellular mechanisms and molecular regulators controlling the transmigration of cancer cells into the brain are still not clearly illustrated. We analyzed the mRNA expression profiles of metastatic brain tissues and TNF-α treated cancer cells to understand the changes in adhesion molecule expression during the tumor phase. To imitate the tumor microenvironment, an in vitro model was developed and the low or high metastatic potential lung tumor cells (A549 or H358) were cultured with the human brain microvascular endothelial cells (hBMECs) under TNF-α treatment. The analysis of online database indicated an altered expression for adhesion molecules and enrichment of their associated signaling pathways. TNF-α treatment activated hBMECs via up-regulating several adhesion molecules, including ICAM1, CD112, CD47, and JAM-C. Meanwhile, TNF-α induced an increased expression of adhesion molecule ligands such as ALCAM and CD6 in both A549 and H358. Moreover, the expression of adhesion molecules and the ligands were also increased both in A549- or H358-hBMECs mixed culture system, which promoted tumor cells adhesion to endothelial cells. These results suggested that the enhanced interaction between tumor cells and brain microvascular endothelium might facilitate the incidence of metastatic brain tumors and further offer a better comprehension of brain metastasis prevention and treatment.

Amlexanox enhances the antitumor effect of anti-PD-1 antibody

Cancer immunotherapy, especially treatment with monoclonal antibodies (mAbs) that block programmed cell death-1 (PD-1)/programmed cell death-ligand 1 (PD-L1) signaling, has attracted attention as a new therapeutic option for cancer. However, only a limited number of patients have responded to this treatment approach. In this study, we searched for compounds that enhance the efficacy of anti-PD-1 mAb using mixed lymphocyte reaction (MLR), which is a mixed culture system of the two key cells (dendritic and T cells) involved in tumor immunity. We found that amlexanox enhanced production of interferon (IFN)-γ, an indicator of T cell activation, by anti-PD-1 mAb. Amlexanox also induced PD-L1 expression in dendritic cells in MLR, whereas it did not stimulate interleukin-2 production by Jurkat T cells. These results suggest that amlexanox acts on dendritic cells, not T cells, in MLR. Furthermore, it enhanced the antitumor effect of the anti-PD-1 mAb in vivo in a mouse tumor-bearing model. The combination of amlexanox and anti-PD-1 mAb increased the expression of Ifng encoding IFN-γ, IFN-γ-related genes, Cd274 encoding PD-L1, and cytotoxic T cell-related genes in tumors. In conclusion, amlexanox stimulates the antitumor effect of anti-PD-1 mAb by acting on dendritic cells, which in turn activates cytotoxic T cells in tumors.

518 New In Vitro Model of Traumatic Brain Injury to Assess Biomaterial Based Regenerative Strategies

Abstract Introduction Penetrating traumatic brain injury (pTBI) management is largely supportive, with no clinically established regenerative therapies. Neurocompatible biomaterials offer a high potential to promote regenerative mechanisms but facile, high throughput, pathomimetic in vitro pTBI models for the developmental testing of neuro-materials is lacking. Method A mouse mixed glial culture system was utilised within which penetrating injuries could be induced. DuraGen PlusTM – an FDA approved neurosurgical grade biomaterial could be implanted into lesions to assess cell-biomaterial responses. Reactive gliosis (astrocytic morphological responses/GFAP expression) and microglial infiltration (Iba1 expression) were assessed/quantified. Results Key pathological features of pTBI were observed in the model, with the ability to (i) introduce reproducible lesions (diameter 949 ± 26 μm) and (ii) for DuraGen PlusTM to be implanted into lesions. Peri-lesional astrocytes displayed hypertrophic palisading morphologies and GFAP upregulation, analogous to gliosis in vivo. Significant microglial numbers infiltrated the DuraGen PlusTM implant at 7 days post-lesion (132.41 ± 15.83 cells/mm2) versus lesion only (82.04 ± 5.11 cells/mm2), p &amp;lt; 0.05). Conclusions We have developed a novel, neuropathomimetic pTBI model, wherein biomaterial implantation enables investigation of neural cell-biomaterial responses. This model can facilitate early-stage evaluation of novel biomaterials as high throughput, inexpensive and facile screening tool.

Farmers’ perception to climate change and adaptation to sustain black pepper production in North Lampung, Indonesia

Lampung Province is the largest black pepper production area in Indonesia mainly in North Lampung District. However, in the last decade the area and production is declining. This research aims to study farmers’ perceptions of climate change and challenge to sustain black pepper production in North Lampung. The study was carried out in North Lampung District using survey method at two sub-districts of major producing area of black pepper that purposively sampled namely Abung Barat and Abung Tengah sub-district in March-June 2019. A total of 93 respondent farmers from 4 villages were randomly sampled. The conclusions are: (1) Sustainability of black pepper production in North Lampung faces challenges regarding declining of planting areal, low productivity, climate change, and low interest of the younger generation in black pepper farming; (2) Farmers in the two sub-districts mostly agree that the current climate is different from the climate 10 years ago and they have perception that as impact of climate change pepper yield is decreased by 25-49%; (3) To sustain black pepper production and to adapt climate change, farmers are practicing mixed culture system of pepper-coffee-and other cash crops, using live support of legume tree, and continuing rehabilitation or replanting of black pepper plantation

Study on the effect of synergy effect between the mixed cultures on the power generation of microbial fuel cells

ABSTRACT Microbial fuel cells (MFC) can use microorganisms to directly convert the chemical energy of organic matter into electrical energy, and generate electrical energy while pollutants degradation. To solve the critical problem of lower power yield of power production, this study selected Saccharomyces cerevisiae, Escherichia coli, Pseudomonas aeruginosa, and Bacillus subtilis as the anodic inoculums. The influence of the mixed bacteria on the power-producing effect of MFC and the synergy effect between the electrochemically active bacteria in mixed cultures were discussed. The results showed that among the mixed culture system, only the mixed cultures MFC composed of Saccharomyces cerevisiae and Bacillus subtilis had a significant increase in power generation capacity, which could reach to 554 mV. Further analysis of the electrochemical and microbiological performance of this system was conducted afterward to verify the synergy effect between Saccharomyces cerevisiae and Bacillus subtilis. The riboflavin produced by Bacillus subtilis could be utilized by Saccharomyces cerevisiae to enhance the power generation capacity. Meanwhile, Saccharomyces cerevisiae could provide carbon source and electron donor for Bacillus subtilis through respiration. Finally, in the experiment of adding exogenous riboflavin in the mixed bacterial MFC, the result indicated that the mixed bacterial MFC chose the self-secreting riboflavin over the exogenous riboflavin as the electron mediator, and the excess riboflavin might hinder the electron trasfer.

Increased myeloid-derived suppressor cells in patients with myelodysplastic syndromes suppress CD8+ T lymphocyte function through the STAT3-ARG1 pathway

MDSCs, which are defined as a kind of negatively regulatory cells, could suppress T cell immune response in many tumor-bearing animal models and cancer patients. We supposed that MDSCs also contributed to the impaired antitumor immunity in MDS. Here we demonstrated that STAT3-ARG1 pathway could be a critical signal transduction pathway that regulated MDSCs-mediated immunosuppression. Increased MDSCs was revealed in MDS patients when compared to healthy controls. Especially, MDSCs performed higher activated STAT3 and CCR2 expression in high-risk MDS patients. The CCL2 and IL-6 levels in MDS patients were also higher than in healthy controls, which could drive recruitment and activation of MDSCs. Meanwhile, lower expression levels of CD3ζ chain, perforin and granzyme B were demonstrated in MDS patients, which were associated with downregulated activation of CD8+ T lymphocytes. The results were supported by the decreased perforin, granzyme B and IFN-γ levels in the mixed-culture system of MDSCs and CD8+ T lymphocytes in vitro. Notably, targeting STAT3 pathway by selective inhibitor could decrease ARG1 expression in MDSCs and partially reverse the lower expression levels of effector molecules on CD8+ T lymphocytes. Therefore, this study revealed the potential STAT3-ARG1 mechanism behind MDSCs and provided a promising STAT3 targeting strategy in MDS.

HMGB1 A box protects neurons by potently inhibiting both microglia and T cell-mediated inflammation in a mouse Parkinson's disease model.

In the subacute Parkinson's disease (PD) mice model of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP), injection of HMGB1 competitive inhibitor protein HMGB1 A box and the ethyl pyruvate (EP) that inhibit the release of HMGB1 from cells restored the number of dopaminergic neurons and TH+ fibers in the SN and striatum. Our data show that A box up-regulated CD200-CD200R signal of microglia inhibited the activation of microglia mediated by HMGB1, and the production of TNF-α, IL-1β and IL-6 in vivo and in vitro mixed culture system. Microglia overexpressing CD200R produced less inflammatory chemokines and reduced the loss of TH+ neurons. In addition, HMGB1 A box decreased the level of CCL5 and significantly inhibited the infiltration of almost all T cells including Th17 and the proportion of Th17 in CD4+ T cells. In vitro MPP+ induced model and HMGB1-stimulated mesencephalic cell system activated microglia induced the differentiation of naïve T cells to Th17, and A box significantly inhibited this process. To sum up, our results show that HMGB1 A box targeting HMGB1, which effectively reduces the activation of microglia in MPTP PD model by restoring CD200-CD200R signal inhibit microglia mediated neuroinflammation and the differentiation of T cells to Th17.

Microbial synergistic interactions enhanced power generation in co-culture driven microbial fuel cell

An understanding of the inter-species relationships, especially their metabolic network in a mixed-culture system, is crucial to design an effective inoculum for enhancing the power generation of wastewater fed microbial fuel cell (MFC). In the present study, the influence of microbial mutualistic interactions on the power generation of palm oil mill effluent fed MFCs has been widely investigated by designing several co-culture and mixed culture inoculums. Among the different inoculum compositions, the highest power density of 14.8 W/m3 was achieved by Pseudomonas aeruginosa and Klebsiella variicola co-culture inoculum due to their synergistic relationships which were inter-linked via fermentation-based metabolites. Besides, the interaction of K. variicola and Bacillus cereus positively influenced the power generation resulting in a maximum power density of 11.8 W/m3 whereas the antagonistic relationship between B. cereus and P. aeruginosa resulted in a lower power generation of 1.9 W/m3. The microbial mutualistic interactions were investigated with polarization, cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), as well as by using metabolite and biofilm analysis. It was observed that the synergism between bacteria enhanced power generation through the production of higher electron shuttling mediators and efficient biofilm formation as evidenced by polarization, CV and EIS analysis. In contrast, the antagonistic relationship resulted in production of cell inhibiting metabolites leading to the formation of ineffective biofilm. These findings demonstrate that the synergistic interaction between or within microorganisms is emergent in designing co-culture or mixed-culture inoculum for achieving maximum power generation in MFCs.

Characterisation of microalgae-based monocultures and mixed cultures for biomass production and wastewater treatment

Microalgae-based systems have been increasingly considered to remediate wastewater, while producing valued biomass. While microalgal monocultures are difficult to maintain in wastewater, mixed cultures have the potential to offer improved system stability and robustness. This research aims to provide a detailed comparison of microalgal monoculture and mixed culture photobioreactors (PBRs) in terms of microalgae growth, biomass harvesting potential, nutrient removal and organic characteristics. Some of the PBRs were further tested for their responses to the presence of wastewater-derived bacteria. Monocultures (containing species from Chlorophyta, Cyanophyta and Eustigmatophyta, respectively) and mixed cultures (mixing two or three species) were evaluated using advanced characterisation techniques including flow cytometry, liquid chromatography – organic carbon detection and excitation−emission matrix fluorescence spectroscopy. The impact of bacteria on system performance was explored by co-culturing some of the cultures with activated sludge. In general, mixed culture systems showed more stable biomass growth and improved nutrient removal uptake (by 20%), as compared to monocultures. However, overyielding (higher biomass production) was not observed in the mixed cultures. Mixing different microalgae tended to increase the concentrations of soluble extracellular materials (e.g. biopolymers) that were able to retain water within the biomass, leading to a lower biomass harvesting potential, as indicated by the capillary suction time. Adding activate sludge significantly increased reduction of measurable dissolved organic carbon concentration (particularly biopolymers and low molecular weight compounds) and nitrogen by >250%. However, wastewater-derived bacteria reduced the yield of all the cultures substantially (by 63–76%) and lowered the dewaterability of the cultures.

The mixotrophic denitrification characteristics of Zoogloea sp. L2 accelerated by the redox mediator of 2-hydroxy-1,4-naphthoquinone

Denitrification in mixed culture system has been extensively researched to date, but few studies have focused on accelerating the process using redox mediators to promote electron transfer. Strain L2, an iron-reducing bacteria, can remove 75.44% of nitrate under temperature of 30.60 °C, pH of 6.75 and Fe2+ concentration of 27.86 mg·L−1. Additionally, the removal rate of nitrate reached 1.516 mg·L−1·h−1 in 8 h with the addition of 0.030 mmol·L−1 2-hydroxy-1,4-naphthoquinone (HNQ), which increased by 1.38 times than control group. Furthermore, analysis by fluorescence spectroscopy, flow cytometer and gas chromatography demonstrated that HNQ positively stimulated denitrification. This study provides a reference for enhancing denitrification in mixed culture and lays the foundation for the practical application of redox mediators in groundwater treatment.

A simple and accurate method for specific quantification of biomass in mixed cultures of filamentous fungi by quantitative PCR

Production of lignocellulolytic enzymes by filamentous fungi have a great potential at industrial level due to their widespread applications. Mixed fungal cultures and particularly mixed fungal biofilms constitute a promising fermentation system for an enhanced enzyme production. However, it has not been addressed how much of this enhancement depends on the mixed biomass proportion. In this sense, the aim of this study was to develop a method to specifically and accurately quantify mixed fungal biomass. For this purpose, mixed biofilm cultures composed of Aspergillus niger and Trichoderma reesei, two filamentous fungi used industrially for cellulase production, were collected from 48 to 120 h of growth; mycelia were pulverized, and DNA was extracted for qPCR assays with specific primers for each fungus. Primers were designed from non-conserved regions of sequences of actin and β-tubulin genes of both A. niger and T. reesei. Specificity of these primers was tested in silico and experimentally. A statistically significant correlation was obtained between qPCR-calculated biomass and dry weight biomass data. By this method, it was possible to detect changes on mycelia proportions in biofilms over time, suggesting a competitive interaction between these two fungi. In conclusion, this method allows a specific and accurate quantification of mixed fungal biomass and could be also applied to different mixed culture systems for studying microbial interactions.

Partial FMRP expression is sufficient to normalize neuronal hyperactivity in Fragile X neurons.

Fragile X syndrome (FXS) is the most common genetic form of intellectual disability caused by a CGG repeat expansion in the 5′‐UTR of the Fragile X mental retardation gene FMR1, triggering epigenetic silencing and the subsequent absence of the protein, FMRP. Reactivation of FMR1 represents an attractive therapeutic strategy targeting the genetic root cause of FXS. However, largely missing in the FXS field is an understanding of how much FMR1 reactivation is required to rescue FMRP‐dependent mutant phenotypes. Here, we utilize FXS patient‐derived excitatory neurons to model FXS in vitro and confirm that the absence of FMRP leads to neuronal hyperactivity. We further determined the levels of FMRP and the percentage of FMRP‐positive cells necessary to correct this phenotype utilizing a mixed and mosaic neuronal culture system and a combination of CRISPR, antisense and expression technologies to titrate FMRP in FXS and WT neurons. Our data demonstrate that restoration of greater than 5% of overall FMRP expression levels or greater than 20% FMRP‐expressing neurons in a mosaic pattern is sufficient to normalize a FMRP‐dependent, hyperactive phenotype in FXS iPSC‐derived neurons.