Mixed Culture Research Articles

Dark Fermentation of Fruit Juice Effluents: Effects of Substrate Concentration

This study explores the impact of initial substrate concentrations on biomass growth, hydrogen production, and acid generation during acidogenic fermentation of a synthetic fruit juice wastewater. Four substrate concentrations, within the range 0.30–2.12 C mol·L−1, were tested using a mixed acidogenic bacterial culture. Batch reactors were employed to conduct the study, and the results were analyzed to determine inhibition effects. The highest hydrogen production (6.1 L H2·substrate C mol−1) and hydrogen percentage in the gas phase (57%) were achieved at a substrate concentration of 0.30 C mol·L−1. Higher substrate concentrations reduced the hydrogen production due to substrate and product inhibition events. The maximum H2 potential production was 4.15 Nm3/m3 reactor at a substrate concentration of 0.91 C mol·L−1. Biomass growth and VFA production followed exponential trends at low substrate concentrations, 0.30 and 0.091 C mol·L−1, while high concentrations resulted in linear trends due to inhibition effects caused by the substrate. The main acids produced were lactic at low concentrations, and acetic when dealing with high concentrations. The highest final acid concentrations were obtained with the highest initial substrate concentration, but their yields were significantly lower due to the substrate and product inhibitions experienced by the biomass.

Two types of microorganisms isolated from petroleum hydrocarbon pollutants: Degradation characteristics and metabolic pathways analysis of petroleum hydrocarbons.

The petroleum hydrocarbons in seawater have been worldwide concern contaminants. Biological method, with the advantages of low cost, minimal environmental impact, and no secondary pollution, is a promising method for petroleum hydrocarbon treatment. In this study, two strains, identified as Stenotrophomonas acidaminiphila and Ochrobactrum, were demonstrated to possess the ability to degrade petroleum hydrocarbons. The mixed culture composed of Stenotrophomonas acidaminiphila and Ochrobactrum at a 2:1 ratio was able to achieve 79.41% degradation of the total petroleum hydrocarbons after 5 days. Besides, the average removal efficiencies of C10-C30 components in petroleum hydrocarbons by Stenotrophomonas acidaminiphila, Ochrobactrum, and mixed culture were 62.98%, 59.14% and 73.30%, respectively. The possible degradation pathways of petroleum hydrocarbons had been speculated through gas chromatography-mass spectrometry (GC-MS) and differential gene expression metabolomics analyses. The toxicity of products from the biodegradation of petroleum hydrocarbons was greatly reduced.

Presence of lactic acid bacteria in hydrogen production by dark fermentation: competition or synergy.

Dark fermentation in mixed cultures has been extensively studied due to its great potential for sustainable hydrogen production from organic wastes. However, microbial composition, substrate competition, and inhibition by fermentation products can affect hydrogen yield and production rates. Lactic acid bacteria have been identified as the key organisms in this process. On one hand, lactic acid bacteria can efficiently compete for carbohydrate rich substrates, producing lactic acid and secreting bacteriocins that inhibit the growth of hydrogen-producing bacteria, thereby decreasing hydrogen production. On the other hand, due to their metabolic capacity and synergistic interactions with certain hydrogen-producing bacteria, they contribute positively in several ways, for example by providing lactic acid as a substrate for hydrogen generation. Analyzing different perspectives about the role of lactic acid bacteria in hydrogen production by dark fermentation, a literature review was done on this topic. This review article shows a comprehensive view to understand better the role of these bacteria and their influence on the process efficiency, either as competitors or as contributors to hydrogen production by dark fermentation.

Nitrifying bacteria for the remediation of organic nitrogen‐contaminated waters: a review

AbstractThe rapid growth of the world's population and its environmental impact has increased the demand for effective water treatment methods. Surface water systems, including rivers, streams, lakes, and ponds, have suffered contamination, leading to the urgent need for effective contaminant removal. Organic nitrogen compounds and nitrates are of particular concern because they pose risks to health and can cause environmental damage. However, traditional water‐treatment methods often prove ineffective for addressing these issues. For this reason, this research focuses on harnessing the capabilities of nitrifying bacteria to denitrify organic nitrogen compounds in water, exploring various bacterial strains, their functions, and their ability to obtain sources of carbon. The study also investigates innovative approaches such as biofilm systems, mixed cultures, and combined processes, which have shown stronger potential for nitrogen removal. Overall, it provides valuable insights into the use of nitrifying bacteria‐based technologies for water remediation in the face of growing environmental challenges.

Quorum sensing in Vibrio controls carbon metabolism to optimize growth in changing environmental conditions.

Bacteria sense population density via the cell-cell communication system called quorum sensing (QS). The evolution of QS and its maintenance or loss in mixed bacterial communities is highly relevant to understanding how cell-cell signaling impacts bacterial fitness and competition, particularly under varying environmental conditions such as nutrient availability. We uncovered a phenomenon in which Vibrio cells grown in minimal medium optimize expression of the methionine and tetrahydrofolate (THF) synthesis genes via QS. Strains that are genetically "locked" at high cell density grow slowly in minimal glucose media and suppressor mutants accumulate via inactivating-mutations in metF (methylenetetrahydrofolate reductase) and luxR (the master QS transcriptional regulator). In mixed cultures, QS mutant strains initially coexist with wild type, but as glucose is depleted, wild type outcompetes the QS mutants. Thus, QS regulation of methionine/THF synthesis is a fitness benefit that links nutrient availability and cell density, preventing accumulation of QS-defective mutants.

Identification of plasmids from thermophilic Streptomyces strains and development of a gene cloning system for thermophilic Streptomyces species.

To develop a host-vector system for use in thermophilic Streptomyces, multi-copy plasmids were screened for thermophilic Streptomyces species using data from public bioresource centers (JCM and NBRC). Of 27 thermophilic Streptomyces strains, three harbored plasmids. One plasmid (pSTVU1), derived from S. thermovulgaris NBRC 16615 (= JCM 4520, ATCC 19284, DSM 40444, ISP 5444, NRRL B-12375, NCIMB 10078), was multi-copy and relatively small in size. Analysis of the sequence of this multi-copy plasmid revealed that it was 7 838bp and contained at least 10 predicted open reading frames (ORFs). The plasmid was introduced into 14 thermophilic Streptomyces strains (of 18 strains examined) and several mesophilic Streptomyces strains (S. lividans, S. parvulus, and S. avermitilis). pSTVU1 can be transferred by mixed culture because the plasmid encodes the ORF that regulates the transfer function. Plasmid transfer was observed not only between strains within the same species but also between mesophilic Streptomyces and thermophilic Streptomyces (and vice versa); however, the efficiency of this transfer was extremely low. We also confirmed that a derivative of pSTVU1 can be used as a multi-copy vector in the gene expression system that is expected to exhibit gene-dosage effects, establishing a method for efficient production of thermophilic α-amylase.

Variable bioenergetic sensitivity of neurons and astrocytes to insulin and extracellular glucose

Energy flow within cellular elements of the brain is a well-orchestrated, tightly regulated process, however, details underlying these functions at the single-cell level are still poorly understood. Studying hypometabolism in aging and neurodegenerative diseases may benefit from experimentation on unicellular bioenergetics. Here, we examined energy status in neurons and astrocytes using mixed hippocampal cultures and PercevalHR, an ATP:ADP nanosensor. We assessed exposures of several compounds including KCl, glutamate, FCCP, insulin, and glucose. A mitochondrial stress test was performed, and PercevalHR’s fluorescence was corrected for pH using pHrodo. Results demonstrate that PercevalHR can reliably report on the energetic status of two cell types that communicate in a mixed-culture setting. While KCl, glutamate, and FCCP showed clear changes in PercevalHR fluorescence, insulin and glucose responses were found to be more subtle and sensitive to extracellular glucose. These results may highlight mechanisms that mediate insulin sensitivity in the brain.

Assessing Process Conditions on Xylose Fermentation in Spathaspora passalidarum: Effects of pH, Substrate-to-Inoculum Ratio, Temperature, and Initial Ethanol Concentration.

Bioethanol represents a clean and renewable alternative to fossil fuels, offering a significant reduction in environmental impact. Second-generation ethanol (2G) is produced using lignocellulosic biomass, which presents additional challenges due to the presence of hemicellulose. The pentose sugars within hemicellulose cannot be efficiently metabolized by conventional yeast strains like Saccharomyces cerevisiae. Consequently, the yeast Spathaspora passalidarum has emerged as a promising candidate for mixed fermentation processes, given its ability to utilize xylose. This study presents an in-depth metabolic, stoichiometric, and kinetic analysis of the fermentation performance of Sp. passalidarum NRRL Y-27907 in mixed glucose and xylose cultures. Emphasis was placed on examining variables from a novel perspective compared to existing literature. Specifically, the impacts of initial inoculum-substrate ratios, substrate composition, pH, temperature, and ethanol sensitivity were analyzed using a mathematical bioprocess approach. Sp. passalidarum NRRL Y-27907 exhibited sequential sugar consumption, with xylose being utilized only after glucose was exhausted. Ethanol yields in mixed cultures were comparable to those in individual-sugar cultures. The best fermentative performance was observed at 30°C, with 25g/L of xylose and an inoculum of 0.50g/L. The strain exhibited significant robustness at pH 4.0 and was notably affected by initial ethanol concentrations up to 20g/L. These findings provide crucial insights into the metabolic and fermentative behavior of Sp. passalidarum NRRL Y-27907, offering valuable information for the design of consolidated bioprocesses from lignocellulosic materials.

New approach to agro-industrial solid and liquid waste management: Performance of an EGSB reactor at different hydraulic retention times for methane production

This study investigated the removal of agro-industrial wastes (5 g COD L⁻1 from coffee and 0.5 g COD L⁻1 from brewery wastewater, plus 1 g L⁻1 of coffee pulp and husk) in a continuous Expanded Granular Sludge Bed (EGSB) reactor at 35 °C. The effect of Hydraulic Retention Times (HRTs) of 72h, 48h, and 24h on CH₄ yield was examined using a mixed culture of cattle manure and granular sludge. Methane yields were 201, 124.5, and 113.8 mL CH₄ g⁻1 COD for the 1st, 2nd, and 3rd phases, respectively. Volatile fatty acids, particularly acetic acid, increased at lower HRTs. Sequencing of the 16S rRNA gene on the Illumina HiSeq platform revealed a syntrophic relationship between Syntrophorhabdus, Syntrophobacter, and Pseudomonas with methanogens Methanomassiliicoccus, Methanospirillum, and Methanobacterium, aiding in the removal of phenolic compounds. The study suggests that an HRT of 72h is optimal for maximizing CH₄ production in the EGSB reactor.

Targeted volatile fatty acid production based on lactate platform in mixed culture fermentation: Insights into carbon conversion and microbial metabolic traits

Targeted volatile fatty acid production based on lactate platform in mixed culture fermentation: Insights into carbon conversion and microbial metabolic traits

Influence of starter cultures of lactic acid bacteria on microbiological parameters and shelf life of sausages

The main spoilage microorganisms of the vacuum-packaged sausages on the first day of chilled storage are the bacteria of the following families: Enterobacteriaceae (Raoultella planticola, Raoultella ornithinolytica, and Citrobacter freundii), Morganellaceae (Morganella morganii) and Staphylococcaceae (Macrococcus caseolyticus), and at the end of the shelf life (on the twenty-first day) - Enterobacteriaceae (Proteus mirabilis, Moellerella wisconsensis and Serratia liquefaciens). An appearance of cloudy juice, surface slime and delamination of the vacuum packaging characterises the sausage spoilage. QMAFAnM in the sausages was increased by 1.09 lg CFU/g and 1.53 lg CFU/g on the first day of storage, by 1.18 lg CFU/g and 1.54 lg CFU/g on the twelfth day, by 0.92 lg CFU/g and 1.96 lg CFU/g on the eighteenth day, respectively, compared to the control sample, because “Vienna sausages with chicken fillet” were treated with starter culture SafePro BLC-48 (Lactobacillus curvatus) or the mixture of starter cultures SafePro BLC-48 (Lactobacillus curvatus) + Bactoferm Rubis (Lactococcus lactis subsp. Lactis) before vacuum packaging. Because the sausages were treated with the mixture of starter cultures SafePro BLC-48 + Bactoferm Rubis, the lactic-acid microorganisms were increased by 0.63 lg CFU/g and 0.53 lg CFU/g on the twenty-fifth and thirtieth days, respectively, compared to the sausages that were treated with SafePro BLC-48. During the entire shelf life, no pathogenic and opportunistic pathogenic bacteria, in particular S. aureus, L. monocytogenes, Salmonella spp., E. coli, coliform bacteria, as well as yeast and mold, were detected in the sausages under all treatment options. The use of starter culture SafePro BLC-48 (Lactobacillus curvatus) or the mixture of starter cultures SafePro BLC-48 (Lactobacillus curvatus) + Bactoferm Rubis (Lactococcus lactis subsp. Lactis) increases the shelf life of the vacuum-packaged sausages if they are kept in a refrigerator for up to 30 days, which is 12 days longer than their shelf life without treatment. The sausage treatment with the mixed starter cultures of the lactic-acid microorganisms may be promising if the development of the aerobic spoilage bacteria is confirmed.

Sustainable Abiotic-Biotic Dechlorination of Perchloroethene with Sulfidated Nanoscale Zero-Valent Iron as Electron Donor Source.

Combining organohalide-respiring bacteria with nanoscale zero-valent iron (nZVI) represents a promising approach for remediating chloroethene-contaminated aquifers. However, limited information is available regarding their synergistic dechlorinating ability for chloroethenes when nZVI is sulfidated (S-nZVI) under the organic electron donor-limited conditions typically found in deep aquifers. Herein, we developed a combined system utilizing a mixed culture containing Dehalococcoides (Dhc) and S-nZVI particles, which achieved sustainable dechlorination with repeated rounds of spiking with 110 μM perchloroethene (PCE). The relative abundance of Dhc considerably increased from 5.2 to 91.5% after five rounds of spiking with PCE, as evidenced by 16S rRNA gene amplicon sequencing. S-nZVI corrosion generated hydrogen as an electron donor for Dhc and other volatile fatty acid (VFA)-producing bacteria. Electron balance analysis indicated that 68.1% of electrons from Fe0 consumed in S-nZVI were involved in dechlorination, and 6.2, 1.1, and 3.2% were stored in formate, acetate, and other VFAs, respectively. The produced acetate possibly served as a carbon source for Dhc. Metagenomic analysis revealed that Desulfovibrio, Syntrophomonas, Clostridium, and Mesotoga were likely involved in VFA production. These findings provide valuable insights into the synergistic mechanisms of biotic and abiotic dechlorination, with important implications for sustainable remediation of electron donor-limited aquifers contaminated by chloroethenes.

Bioremediation of metal cyanide complexes from electroplating wastewater for long-term application using Agrobacterium tumefaciens SUTS 1 and Pseudomonas monteilii SUTS 2.

The purpose of this study was to investigate the optimum conditions, including aerobic and anoxic conditions, for operating a long-term bioreactor system to decrease the toxicity of industrial electroplating wastewater effluents containing metal cyanide using Agrobacterium tumefaciens SUTS 1 and Pseudomonas monteilii SUTS 2. The initial results revealed that bacteria performed better under aerobic conditions than under anoxic conditions. An aerobic bioreactor system was subsequently set up in a long-term study lasting 30days under optimum operating conditions. Both mixed-culture bacteria and indigenous bacteria promoted the high-efficiency treatment of cyanide and metals in the first 7days of the study. When the system had high removal rates, cyanide removal was greater than that of zinc, copper, nickel, and chromium (CN- > Zn > Cu > Ni > Cr), with removal efficiencies of 96.67%, 93.93%, 74.17%, 63.43%, and 44.65%, respectively, with residual concentrations of 0.15 ± 0.01, 0.24 ± 0.005, 0.03 ± 0.002, 18.41 ± 0.06 and 14.26 ± 0.15mg/L, respectively. The cell concentration in the bioreactor increased to approximately 107CFU/mL over 30days from initial cell concentrations of 6.15 × 105 CFU/mL and 1.05 × 103CFU/mL for the mixed culture and indigenous inoculation, respectively. These results implied that the bacteria were resistant to heavy metal toxicity. The addition of an appropriate carbon source with sufficient aeration to a bioreactor resulted in increased cyanide degradation.

Neuropeptide FF Promotes Neuronal Survival and Enhances Synaptic Protein Expression Following Ischemic Injury.

This study explores the neuroprotective effects of neuropeptide FF (NPFF, FLFQPQRFamide) in the context of ischemic injury. Based on transcriptomic analysis in stroke models treated with 5-Aza-dC and task-specific training, we identified significant gene expression changes, particularly involving NPFF. To further explore NPFF's role in promoting neuronal recovery, recombinant NPFF protein (rNPFF) was used in primary mixed cortical cultures subjected to oxygen-glucose deprivation and reoxygenation. Our results demonstrated that rNPFF significantly reduced lactate dehydrogenase release, indicating decreased cellular damage. It also significantly increased the expression of TUJ1 and MAP2, markers of neuronal survival and dendritic integrity. Additionally, rNPFF significantly upregulated key synaptic proteins, including GAP43, PSD95, and synaptophysin, which are essential for synaptic repair and plasticity. Post-injury rNPFF treatment led to a significant upregulation of pro-brain-derived neurotrophic factor (BDNF) and mature BDNF, which play critical roles in neuronal survival, growth, and synaptic plasticity. Moreover, rNPFF activated the protein kinase Cε isoform, Sirtuin 1, and peroxisome proliferator-activated receptor gamma pathways, which are crucial for regulating cellular stress responses, synaptic plasticity, and energy homeostasis, further promoting neuronal survival and recovery. These findings suggest that rNPFF may play a pivotal role in enhancing neuronal survival and synaptic plasticity after ischemic injury, highlighting its potential as a therapeutic target for stroke recovery.

Cultivation of Microalgae Mixed Culture from Mahoni Small Lake UI Campus Depok using Zeolite Substrate with Varying Pb Concentration

Research on the cultivation of mixed cultures of Situ (small lake) Mahoni UI Campus Depok has been done. This research was a preliminary study to measure and compare the growth of Situ Mahoni mixed cultures microalgae grown in Bold's Basal Medium (BBM) with addition of zeolite and without addition of zeolite, and varying concentrations of heavy metal Pb. The concentrations of heavy metal Pb used were 0 ppm, 20 ppm, 40 ppm, 60 ppm, 80 ppm, and 100 ppm for two treatments. The results of this research were that the growth of mixed cultures with the addition of zeolite had the highest abundance of 8.800 cells/mL on day 5 (T5) at a Pb concentration of 40 ppm. Meanwhile, the growth of mixed culture without the addition of zeolite had the highest abundance of 21.700 cells/mL on day 10 (T10) at a Pb concentration of 60 ppm. The growth of microalgae mixed cultures in the medium without addition of zeolite was higher than using zeolite. The activation of zeolite pores causes the microalgae growth is relatively lower. This work aimed to study the growth of a mixed cultures microalgae in varying concentrations of Pb with and without the addition of zeolite

Mixed and membrane-separated culturing of synthetic cyanobacteria-yeast consortia reveals metabolic cross-talk mimicking natural cyanolichens

Metabolite exchange mediates crucial interactions in microbial communities, significantly impacting global carbon and nitrogen cycling. Understanding these chemically-mediated interactions is essential for elucidating natural community functions and developing engineered synthetic communities. This study investigated membrane-separated bioreactors (mBRs) as a novel tool to identify transient metabolites and their producers/consumers in mixed microbial communities. We compared three co-culture methods (direct mixed, 2-chamber mBR, and 3-chamber mBR) to grow a synthetic binary community of the cyanobacterium Synechococcus elongatus PCC 7942 and the fungus Rhodotorula toruloides NBRC 0880, as well as axenic S. elongatus. Despite not being natural lichen constituents, these organisms exhibited interactions resembling those in cyanolichens. S. elongatus fixed CO2 into sugars as the primary shared metabolite, while R. toruloides secreted various biochemicals, predominantly sugar alcohols, mirroring the metabolite exchange observed in natural lichens. The mBR systems successfully captured metabolite gradients and revealed rapidly consumed compounds, including TCA cycle intermediates and amino acids. Our approach demonstrated that the 2-chamber mBR optimally balanced metabolite exchange and growth dynamics. This study provides insights into cross-species metabolic interactions and presents a valuable tool for investigating and engineering synthetic microbial communities with potential applications in biotechnology and environmental science.

Skeletal myotubes expressing ALS mutant SOD1 induce pathogenic changes, impair mitochondrial axonal transport, and trigger motoneuron death

Amyotrophic lateral sclerosis (ALS) is a fatal neurodegenerative disease characterized by the loss of motoneurons (MNs), and despite progress, there is no effective treatment. A large body of evidence shows that astrocytes expressing ALS-linked mutant proteins cause non-cell autonomous toxicity of MNs. Although MNs innervate muscle fibers and ALS is characterized by the early disruption of the neuromuscular junction (NMJ) and axon degeneration, there are controversies about whether muscle contributes to non-cell-autonomous toxicity to MNs. In this study, we generated primary skeletal myotubes from myoblasts derived from ALS mice expressing human mutant SOD1G93A (termed hereafter mutSOD1). Characterization revealed that mutSOD1 skeletal myotubes display intrinsic phenotypic and functional differences compared to control myotubes generated from non-transgenic (NTg) littermates. Next, we analyzed whether ALS myotubes exert non-cell-autonomous toxicity to MNs. We report that conditioned media from mutSOD1 myotubes (mutSOD1-MCM), but not from control myotubes (NTg-MCM), induced robust death of primary MNs in mixed spinal cord cultures and compartmentalized microfluidic chambers. Our study further revealed that applying mutSOD1-MCM to the MN axonal side in microfluidic devices rapidly reduces mitochondrial axonal transport while increasing Ca2 + transients and reactive oxygen species (i.e., H2O2). These results indicate that soluble factor(s) released by mutSOD1 myotubes cause MN axonopathy that leads to lethal pathogenic changes.

Bioleaching of Industrial Metallic Steel Waste by Mixed Cultures of Thermoacidophilic Archaea

Different mixed cultures of extremely thermoacidophilic microorganisms were used for bioleaching of metalliferous industrial dust waste derived from the basic oxygen furnace (BOF) steelmaking process. Such mixed cultures can extract various metals from multi-metallic BOF-dust waste, improving the metal dissolution and bioleaching performance in frames of metal recycling processes to assist circular economies and waste management. The results of the investigation showed that mixed cultures of thermoacidophilic archaea of the order Sulfolobales (Acidianus spp., Sulfolobus spp., and Metallosphaera sedula) during their growth in laboratory glass bioreactors provided a superior bioleaching system to Acidianus manzaensis alone. Depending on the composition of mixed thermoacidophilic cultures, extraction of various metals from BOF-dust could be achieved. Among the three different types of mixed cultures tested, the mixed culture system of A. manzaensis, A. brierleyi, and S. acidocaldarius was most effective for extraction of major elements (Fe, Ca, Zn, Mn, and Al). The mixed culture of A. manzaensis, A. brierleyi, and M. sedula showed high performance for bioleaching of most of the minor elements (Cu, Ni, Pb, Co, Mo, and Sr). The efficient ability of mixed cultures to colonise the mineral matrix of the metal waste product was observed via scanning electron microscopy, while their metal extraction capacities were analysed by inductively coupled plasma mass spectrometry. These investigations will promote the further design of microbial consortia in order to break down the solid matrix and efficiently extract metals from metalliferous waste materials.

Artemisiae Iwayomogii Herba mitigates excessive neuroinflammation and Aβ accumulation by regulating the pro-inflammatory response and autophagy-lysosomal pathway in microglia in 5xFAD mouse model of Alzheimer's disease.

Alzheimer's disease (AD) presents a growing societal challenge, driven by an aging population. It is characterized by neurodegeneration linked to β-amyloid (Aβ) and tau protein aggregation. Reactive glial cell-mediated neuroinflammation exacerbates disease progression by facilitating the accumulation of Aβ and impairing its clearance, thus highlighting potential therapeutic targets. Aerial parts of Artemisia iwayomogi (AIH), a kind of mugwort, has been consumed as a medicinal herb in East Asia for relieving inflammation-related diseases. Previously, AIH was found to exert potent inhibitory effects on neuroinflammation. This study aimed to examine whether AIH mitigates AD pathogenesis by regulating neuroinflammation and reducing Aβ deposition. AIH treatment to primary mixed glial cultures attenuated the pro-inflammatory responses evoked by Aβ stimulation. When treated to 5 × familial AD (5xFAD) mice, AIH improved learning and cognitive ability and reduced Aβ burden in the brain. AIH suppressed glial overactivation, as well as inhibited the expressions of pro-inflammatory mediators in the brain. Moreover, AIH regulated AKT signaling and elevated the expression of autophagy-lysosomal mediators in vitro. It was confirmed that lysosome-associated membrane protein 1 (LAMP1) was increased in the Aβ-associated microglia in the mouse hippocampus. Finally, it was observed that tau phosphorylation was alleviated, and synaptic protein expression was increased in AIH-treated 5xFAD mice. Overall, this study demonstrated that AIH ameliorated excessive neuroinflammation and Aβ accumulation by regulating microglial activation and autophagy-lysosomal pathway, thereby suggesting AIH as a promising therapeutic candidate for AD treatment.

Environmental dependency of ectomycorrhizal fungi as soil organic matter oxidizers.

Forest soils play a pivotal role as global carbon (C) sinks, where the dynamics of soil organic matter (SOM) are significantly influenced by ectomycorrhizal (ECM) fungi. While correlations between ECM fungal community composition and soil C storage have been documented, the underlying mechanisms behind this remain unclear. Here, we conducted controlled experiments using pure cultures growing on naturally complex SOM extracts to test how ECM fungi regulate soil C and nitrogen (N) dynamics in response to varying inorganic N availability, in both monoculture and mixed culture conditions. ECM species dominant in N-poor soils exhibited superior SOM decay capabilities compared with those prevalent in N-rich soils. Inorganic N addition alleviated N limitation for ECM species but exacerbated their C limitation, reflected by reduced N compound decomposition and increased C compound decomposition. In mixed cultures without inorganic N supplementation, ECM species with greater SOM decomposition potential facilitated the persistence of less proficient SOM decomposers. Regardless of inorganic N availability, ECM species in mixed cultures demonstrated a preference for C over N, intensifying relatively labile C compound decomposition. This study highlights the complex interactions between ECM species, their nutritional requirements, the nutritional environment of their habitat, and their role in modifying SOM.