Abundance Of Microorganisms Research Articles

Global metagenomic survey identifies sewage-derived hgcAB+ microorganisms as key contributors to riverine methylmercury production

Methylmercury (MeHg) in aquatic systems poses a serious public health risk through bioaccumulation in the aquatic food web. In recent years, MeHg has been observed to increase to concerning levels globally in rivers near cities; however, the causes of this increase are not well understood. Here, we demonstrate the significant role of sewage contamination by analyzing over 1,300 publicly available metagenomes in urban rivers worldwide, and conducting experiments with water samples across China. We find that sewage contamination significantly increases the abundance of mercury (Hg)-methylating microorganisms in urban rivers globally. This increase is primarily attributed to the high abundance of active Hg-methylating microorganisms in sewage, which migrate to rivers via direct discharge or combined sewer overflows (CSOs), becoming key contributors to elevated riverine MeHg levels. Our findings underscore the importance of effectively eliminating Hg-methylating microorganisms from sewage to mitigate the public health risks associated with MeHg in urban rivers.

Characteristics of Water Environment and Intestinal Microbial Community of Largemouth Bass (Micropterus salmoides) Cultured Under Biofloc Model

To investigate the effects of biofloc mode on the water environment and intestinal microbial community structure of largemouth bass, a 60-day culture experiment was conducted without water replacement in 300-L glass tanks. The experiment included a control group and a biofloc group, each with three replicates. The results showed the following: (i) the richness and diversity of the water environment and fish intestinal microbial community increased under the biofloc model; (ii) Proteobacteria, Patescibacteria, and Bacteroidota were the dominant phyla in the water environment of largemouth bass, while Proteobacteria, Firmicutes, Bacteroidota, Patescibacteria, and Actinobacteriota were the dominant phyla in the gut of largemouth bass. However, differences in the relative abundance and community structure of microorganisms were observed between the two groups, suggesting that the biofloc system impacts both the water environment and intestinal microbial community structure in largemouth bass culture. (iii) A correlation analysis between water quality indices and enzyme activity with microbial abundance revealed that microbial community composition could effectively reflect water quality and fish physiological health. Based on the analysis of microbial community structure, this study offers a theoretical foundation for integrating largemouth bass culture with the biofloc system, and provides valuable data for future health management and water quality control in largemouth bass production.

Gut and intraocular fluid dysbiosis in people with type 2 diabetes-related retinopathy in India: A case for further research.

To explore the relationship between gut microbiome, gut mycobiome, and intraocular (aqueous humor) microbiome dysbiosis in people with type 2 diabetes (T2DM) and diabetic retinopathy (DR). Multiple case-control studies. We evaluated three groups of people: healthy controls (HC), people with T2DM without retinopathy, and those with DR. The study samples included fecal matter (30-50 g) and aqueous humor (0.05-0.1 mL). After amplicon sequencing, we analyzed microbiome profiles (V3-V4 region of bacterial 16S rRNA gene) and mycobiome (ITS2 region of fungal rRNA gene). The main outcome measures were relative abundance, α and β diversity, and dysbiotic bacteria and fungi, analyzed based on the inferred functions of the taxa. We recruited 82 people for gut microbiome (30 HC, 24 DM, and 28 DR); 75 people for gut mycobiome (30 HC, 21 DM, and 24 DR); and 12 people for aqueous humor microbiome (4 each HC, DM, and DR) studies. Generally, there was an increased abundance of pro-inflammatory and pathogenic microorganisms and a decreased abundance of anti-inflammatory and probiotic microorganisms. The differences were higher between HC and DM/DR than between DM and DR. In aqueous humor, there was a wider separation in microbiome profiles of people with DR than their gut microbiome. The gut and aqueous humor microbiota of people with diabetes and DR may differ from those without diabetes. Given these unique observations in individuals living in one region of India, further research involving people from different regions is required to identify indices for possible regional or global use.

The impact of pine wilt disease on the endophytic microbial communities structure of Pinus koraiensis

Pine Wilt Disease (PWD) is a devastating pine tree disease characterized by rapid onset, high mortality rate, quick spread, and difficulty in control. Plant microbiome plays a significant role in the development of PWD. However, the endophytic microbial communities of Pinus koraiensis infected by pine wood nematode (PWN) Bursaphelenchus xylophilus remain largely unexplored. In this study, we analyzed the structural changes of endophytic communities of P. koraiensis after infection by the PWN using high-throughput sequencing technology. The results showed that the community structure underwent significant changes as the degree of PWN infection intensified. The diversity and abundance of endophytic fungi in P. koraiensis increased, while those of endophytic bacteria in P. koraiensis decreased during the infection process. Meanwhile, the abundance of some dominant microorganisms has also changed, including species such as Graphilbum and Pseudoalteromonas. Functional prediction analysis showed that the functional composition of endophytic fungi in P. koraiensis was significantly different across the development of PWD, while the composition of endophytic bacteria remained essentially similar. The results indicated that PWN infection had a significant impact on the structure, diversity, abundance, and functional gene composition of endophytic microbial communities in P. koraiensis, and most of the main endophytic microbial groups tended to coordinate with each other. This work provides a better understanding of the changes in endophytic community structure and function caused by PWD infection of P. koraiensis, which may benefit the exploration of potential endophytes for PWN biocontrol.

Host–microbe interaction-mediated resistance to DSS-induced inflammatory enteritis in sheep

BackgroundThe disease resistance phenotype is closely related to immunomodulatory function and immune tolerance and has far-reaching implications in animal husbandry and human health. Microbes play an important role in the initiation, prevention, and treatment of diseases, but the mechanisms of host–microbiota interactions in disease-resistant phenotypes are poorly understood. In this study, we hope to uncover and explain the role of microbes in intestinal diseases and their mechanisms of action to identify new potential treatments.MethodsFirst, we established the colitis model of DSS in two breeds of sheep and then collected the samples for multi-omics testing including metagenes, metabolome, and transcriptome. Next, we made the fecal bacteria liquid from the four groups of sheep feces collected from H-CON, H-DSS, E-CON, and E-DSS to transplant the fecal bacteria into mice. H-CON feces were transplanted into mice named HH group and H-DSS feces were transplanted into mice named HD group and Roseburia bacteria treatment named HDR groups. E-CON feces were transplanted into mice named EH group and E-DSS feces were transplanted into mice in the ED group and Roseburia bacteria treatment named EDR groups. After successful modeling, samples were taken for multi-omics testing. Finally, colitis mice in HD group and ED group were administrated with Roseburia bacteria, and the treatment effect was evaluated by H&E, PAS, immunohistochemistry, and other experimental methods.ResultsThe difference in disease resistance of sheep to DSS-induced colitis disease is mainly due to the increase in the abundance of Roseburia bacteria and the increase of bile acid secretion in the intestinal tract of Hu sheep in addition to the accumulation of potentially harmful bacteria in the intestine when the disease occurs, which makes the disease resistance of Hu sheep stronger under the same disease conditions. However, the enrichment of harmful microorganisms in East Friesian sheep activated the TNFα signalling pathway, which aggravated the intestinal injury, and then the treatment of FMT mice by culturing Roseburia bacteria found that Roseburia bacteria had a good curative effect on colitis.ConclusionOur study showed that in H-DSS-treated sheep, the intestinal barrier is stabilized with an increase in the abundance of beneficial microorganisms. Our data also suggest that Roseburia bacteria have a protective effect on the intestinal barrier of Hu sheep. Accumulating evidence suggests that host–microbiota interactions are associated with IBD disease progression.2GpPdtDdh9Lk52sebv8JARVideo

Effects of graphene oxide composite additive on the species abundance and diversity of microorganisms in saline-alkali soil

Saline-alkali soil is common in north China, especially in the Datong district in north Shanxi province. Improving the soil will benefit the environment and society. Graphene oxide (GO) has been shown to benefit agricultural and forest soils. Herein we explore three different experimental conditions of CK (CK means irrigated with tap water), CJ (CJ means 0.2 g of bacteria addition and irrigated with tap water) and CJ25 (CJ25 means 0.2 g of composited bacteria plus 25.0 mg/L of graphene oxide added and irrigated with tap water) for saline-alkali soil by the addition of optimized amounts of graphene oxide and external bacteria. Our results show that the addition of 25.0 mg/L graphene oxide and microbial agents increases the number of bacteria and fungi in the soil and improves the species abundance of bacteria and fungi in the saline-alkali soil, while having little effect on species richness. The graphene oxide and bacterial treatment increased the abundance of Proteobacteria, Actinobacteriota, Chloroflexi, Pseudomonas, Ascomycota, Mortierella and Fusarium. These bacteria have been shown to produce proteolytic enzymes and cellulases that decompose lignin and cellulose in litter, and thus play important roles in carbon and nutrient cycling. The addition of graphene oxide and microorganisms provide a viable way to improve saline-alkali soils.

Rhizosphere effect: microbial and enzymatic dynamics in the rhizosphere of various shrub species

Abstract Aims The aim of our research was to compare the properties of the rhizosphere soil of different shrub species. We assumed that the physicochemical properties and microbiome of the rhizosphere differ from bulk soil and the species of shrub is important in their formation. Methods The study involved determining the abundance and diversity of microorganisms in the rhizosphere, along with assessing the basic chemical properties and enzymatic activity. Samples were collected from both rhizosphere and bulk soil in pine stands with an understory of shrubs forming biogroups. Results The enzymatic activity in the rhizosphere was significantly higher than in bulk soil. At the same time enzymatic activity in the rhizosphere differed between the shrub species tested. Both intracellular and extracellular enzymes exhibited a positive correlation with basic biochemical parameters. The number of bacteria and fungi correlated with physicochemical and biochemical properties. The number of bacteria and fungi was notably higher in the rhizosphere of the examined shrub species compared to bulk soil, at the same time, we noted a significant influence of the shrub species on microorganisms in the rhizosphere zone. Among the bacteria in the rhizosphere of shrubs, genera Edaphobaculum, Gemmatimonas, Bdellovibrio, Jorgensenbacteria, Rhodoplanes, and Acidocella were more abundant. Regarding fungi, Mortierella longigemmata, Didymella viburnicola, Trichoderma stellatum, and Phacidium pseudophacidioides were found to be more abundant in the rhizosphere. Conclusions The findings from our research may have practical applications in shaping the species composition of tree stands, with potential implications for future soil health condition.

Irradiance level and elevation shape the soil microbiome communities of Coffea arabica L.

BackgroundThe nexus plant-microbe-environment is essential to understand the ecosystem processes shaping plant health and fitness. Within this triangle, soils and associated microflora are among the key ecosystem’s drivers, underpinning plant productivity and evolution. In this study, we conducted a comprehensive analysis (physicochemical properties, enzyme activities, and taxonomic diversity) of soils under the canopy projection of Coffea arabica trees along a gradient of elevation (600, 800, and 900 m) and shade (0, 50, 100%).ResultsWhile shade had no influence on most parameters, altitude shaped the dynamics of microbial communities. Available phosphorus, soil organic carbon, and nitrate were significantly higher at 800 m, likely due to the higher activities of β-glucosidase and phosphatases at this altitude. Microbial biomass (carbon and nitrogen) and moisture were significantly higher at 600 and 900 m, which might be attributed to the abundance and richness of soil microorganisms. Indeed, metabarcoding analysis revealed a complex pattern of microbial consortia (bacteria, archaea, fungi) at the three altitudes, with the lowest index of richness recorded at 800 m. The highest number of Amplicon Sequence Variants was observed in bacteria, whose functional analysis revealed distinct metabolic adaptations across different altitudes. At 900 m, the main functional attributes favored the responses to environmental stimuli and microbial interactions; at 800 m, the predominant metabolic pathways were related to organic matter, fermentation, and bioremediation; and at the lower 600 m, the pathways shifted towards the breakdown of plant-derived compounds (e.g. geraniol, limonene, and pinene degradation).ConclusionOverall, the results indicate a higher effectiveness of the microbial consortium at 800 m, which might result in better nutrient cycling. The study highlights the importance of canopy shade species and elevation for the composition of microbial consortia in C. arabica, unveiling ecological functions beyond plant health, with implications for bio-based solutions and biotechnology.

Absence of measurable quantities of Candida auris and Cryptococcus spp. in the gut microbiota of Ghanaian individuals with and without HIV infection as confirmed by applying multiple real-time PCR assays.

Introduction. Fungal infections are relevant health risks for individuals with acquired immunodeficiency in the resource-limited tropics, but available surveillance data are scarce. For Candida auris and Cryptococcus spp., the evolution from environmental reservoirs to human pathogens causing life-threatening diseases is currently discussed as a public health concern in the context of climate change and limited treatment options.Gap statement. Uncovering the gastrointestinal tract as an epidemiological niche of fungi emerging from the environment into individuals for whom fungal infections are not diagnosed.Aim. To contribute to data on the local epidemiology of C. auris and Cryptococcus spp. in Western African Ghana by analysing gastrointestinal samples of Ghanaian individuals.Methodology. Four real-time PCR assays targeting C. auris and five real-time PCR assays targeting Cryptococcus spp. were applied with stool samples of 875 non-age-stratified Ghanaian HIV patients and 30 Ghanaian control individuals without known HIV infection. Also, 664 samples from Ghanaian children under 2 years of age were investigated. The true abundance of the target micro-organism was considered as unlikely in the case of one or fewer positive signals, likely in the case of two to three positive signals and highly likely in the case of four or more positive signals per sample in the real-time PCR assays.Results. The combined application of sensitive, target-specific real-time PCR assays indicates that neither C. auris, Cryptococcus neoformans complex nor Cryptococcus gattii complex were part of the gut microbiota of Ghanaian individuals with or without HIV infection.Conclusion. Despite the significant disease burden from these pathogens in immunosuppressed Ghanaian individuals, detection from gastrointestinal samples was unlikely, which should be taken into account when discussing screening strategies for these fungi of public health concern. In contrast, the detection of these fungi from such samples should not routinely be considered as commensal colonization flora.

Thermodynamics-driven metabolic and microbial preference for lactate methanization at different operational temperatures

Lactate-dominant organic acids released from acidified feedstocks inhibit anaerobic digestion processes, which can result in decreased biomethane (CH4) yield or even complete process failure. Herein, this study focus on exploring the effects of temperature (35 °C, 38 °C, 41 °C, 44 °C, 47 °C, 50 °C, and 55 °C) on the thermodynamics of microbial communities to assess the thermodynamics or microbial flora in driving the concurrent bioreactions involved in organic acid degradation. The findings revealed a prevalence of species such as Syntrophaceticus schinkii, DTU014, and Methanosarcina at 38 °C-44 °C. These species are known for their abilities in propionate and butyrate degradations, acetate oxidation, and methanation, respectively. Conversely, at thermophilic temperatures (47 °C, 50 °C, and 55 °C), this study observed higher abundance of thermophilic microorganisms like Defluviitoga and Methanoculleus, although these organisms are adapted to higher temperatures, their lactate utilization and methane production were less efficient than mesophilic species. Despite higher ΔG values for lactate, propionate, and butyrate degradation at 38 °C–44 °C compared with thermophilic temperatures, the relative abundance of functional enzymes (specifically, propionate and butyrate degrading enzymes) was found to be marginally higher than 47 °C–55 °C. As a result, 41 °C–44 °C induced remarkable thermodynamic effects that not only facilitated organic acid degradation but also promoted subsequent methanation, indicating the suitability of these temperatures for the methanation of biowaste acidified by lactate. Overall, this study provides insight into the temperature-dependent response of organic acid degradation, specifically focusing on the mechanisms involved in overcoming energy barriers, shaping the microbial flora, and ultimately improving the efficiency and stability of anaerobic digestion, especially for lactate-acidified feedstock.

Dietary Conversion from All-Concentrate to All-Roughage Alters Rumen Bacterial Community Composition and Function in Yak, Cattle-Yak, Tibetan Yellow Cattle and Yellow Cattle.

The experiment was to compare the effects of switching all-concentrate to all-roughage diets on rumen microflora and functional metabolism of yak, cattle-yak, Tibetan yellow cattle and yellow cattle living in different altitudes. A total of 24 yaks, cattle-yaks, Tibetan yellow cattle and yellow cattle with a similar weight and good body condition aged 3.5 years were selected and divided into four groups according to species. They were fed a concentrate diet with 40% soybean meal and 60% corn meal for the first month (C group) and a roughage diet with dry corn stalks (100%) for the second month (R group); the formal experimental period was 60 d. These results showed that the conversion had a significant effect on the rumen microflora structure of the four herds, and the biggest difference between concentrate and roughage diets was yak and cattle-yak, followed by Tibetan yellow cattle and yellow cattle. At the phylum level, Bacteroidetes and Firmicutes still predominate in all groups. Compared with the C groups, the relative abundance of Lentisphaerae and Kiritimatiellaeota increased in all R groups, and Lentisphaerae was significantly increased in yak and cattle-yak (p < 0.05). At the genus and species levels, Prevotella had the highest abundance, and the relative abundances of Prevotella, Ruminococcus, Sarcina and Ruminobacter in R groups were lower, while the abundances of other differential genera, including Methanobrevibacter, Fibrobacter, Treponema, Eubacterium, Butyrivibrio, Succinivibrio and Succinimonas, were all higher. Roughage diets increased the number of unique genes and functional genes encoding different CAZymes in rumen microorganisms in all four herds. In the functional contribution analysis, with the exception of ABC transporters and methane metabolism, Prevotella was the main contributor to almost all of these functions. In methane metabolism, Methanobrevibacter had the highest relative abundance, followed by Prevotella, Clostridia and Bacteroidales in all groups. Compared with Tibetan yellow cattle and yellow cattle, yaks and cattle-yaks have better adaptability to roughage, and its utilization rate can be fully improved to reduce methane emission. The study indicates that when four herds are converted to high roughage at the later stage of feeding, the growth and reproduction of rumen microorganisms are affected, and the abundance and diversity of rumen microorganisms are increased to varying degrees. The transformation of concentrate to roughage diet can change the metabolic pathways of rumen microorganisms in yaks and finally affect the fermentation mode of rumen. The above results provide a theoretical basis for the research and development of fattening feeds for yaks, cattle-yaks, Tibetan yellow cattle and yellow cattle and the intensive feeding of livestock on the plateau.

Effects of Paecilomyces lilacinus and Bacillus pumilus on stem nematode and rhizosphere bacterial communities of sweet potato

Stem nematode (Ditylenchus destructor Thorne) is considered one of the most economically devastating species affecting sweet potato production. Biocontrol offers a sustainable strategy for nematode control. This study conducted a pot experiment to evaluate the biocontrol efficacy of Paecilomyces lilacinus CS-Z and Bacillus pumilus Y-26 against the stem nematode, as well as to examine their influence on the bacterial communities in the sweet potato rhizosphere. The findings indicated that B.pumilus Y-26 and P.lilacinus CS-Z exhibited respective suppression rates of 82.9% and 85.1% against the stem nematode, while also stimulating sweet potato plant growth. Both high-throughput sequencing and Biolog analysis revealed distinct impacts of the treatments on the bacterial communities. At the phylum level, B.pumilus Y-26 enhanced the abundance of Actinobacteria but reduced the abundance of Cyanobacteria, with P.lilacinus CS-Z exhibiting similar effects. Additionally, the treatment with B.pumilus Y-26 resulted in increased abundances of Crossiella, Gaiella, Bacillus, and Streptomyces at the genus level, while the treatment with P.lilacinus CS-Z showed increased abundances of Crossiella and Streptomyces. In contrast, the abundance of Pseudarthrobacter was reduced in the treatment with B.pumilus Y-26. Conversely, the application of the nematicide fosthiazate exhibited minor influence on the bacterial community. The findings indicated that the application of P.lilacinus CS-Z and B.pumilus Y-26 led to an increase in the relative abundances of beneficial microorganisms, including Gaiella, Bacillus, and Streptomyces, in the rhizosphere soil. In conclusion, P.lilacinus CS-Z and B.pumilus Y-26 demonstrated their potential as environmentally friendly biocontrol agents for managing stem nematode disease of sweet potato.

Aeration treatment promotes transformation of soil phosphorus fractions to plant-available phosphorus by modulating rice rhizosphere microbiota

Microorganisms play an important role in affecting the content of available phosphorus (P) in plant rhizosphere soil. However, the effect of aeration on available P in rice rhizosphere soil and its microbial mechanism remain unclear. This study aimed to elucidate the effects of aeration strategies on available P and P-solubilizing microorganisms in rhizosphere soil, employing three different aeration methods (continuous flooding (CF), continuous flooding and aeration (CFA), and alternate wetting and drying (AWD)). We analyzed the bacterial and fungal community structures in rice rhizosphere soil via Illumina sequencing techniques and quantified the abundance of P transformation functional genes related to inorganic P solubilization (pqqC) and organic P mineralization (phoC, phoD, and appA) through quantitative PCR. Our findings revealed that the AWD treatment significantly increased soil pH and Eh; Both AWD and CFA treatments markedly increased soil Olsen-P content at the tillering and heading stages, as well as the microbial carbon-to-phosphorus ratio (MBC/MBP) at the heading and maturity stages. Cluster analysis showed distinct bacterial communities at the heading and maturity stages under AWD, which differed from those in other treatments. Fungal communities at the tillering and heading stages under CFA and AWD grouped together. AWD and CFA treatments consistently enhanced labile-P in the rhizosphere soil throughout the entire growth stages, while reducing moderately labile-P during the tillering and heading stages. Compared to CF, at the heading and maturity stages, the copy numbers of pqqC, phoD, phoC, and appA were higher under AWD compared to other treatments. In conclusion, this study posits that the increase in Olsen-P in paddy fields due to aeration results from improved oxygen conditions in the rhizosphere, alterations in pH and Eh, effects on microbial stoichiometry, and adjustments in the abundance and composition of P-solubilizing microorganisms, thereby promoting P transformation. This conclusion provides new insights into the conversion of soil P Fractions into plant-available forms.

The construction of double short-cut sulfur autotrophic denitrification and PN/Anammox partition and its effect on the coupling performance of nitrogen and sulfur removal

How to reduce NO3--N from partial nitrification /Anammox (PN/Anammox) for low carbon emissions, thus achieve deep nitrogen removal, is a significant issue when applying PN/Anammox to treatment inorganic high-ammonia wastewater. This study designed a prepositioned double short-cut sulfur autotrophic denitrification (DSSADN) system integrated with PN/Anammox, achieving simultaneous sulfur recovery and complete autotrophic denitrification. It also examined the impact of reflux changes on the nitrogen and sulfur transformation characteristics in the coupled system when treating ammonia and sulfur-containing wastewater. Results indicate that the coupling of DSSADN zone (zone C1) enhanced TN removal by PN/Anammox, with the TN removal rate (TNRRT), TN removal efficiency (TNRET), and S2- removal rate reaching 0.54 kg/(m³·d), 95.1%, and 100%, respectively. The NO2--N accumulation efficiency (NiAEC1) of DSSADN reached 87.1%, with ΔSO42--S consistently less than 11.8 mg/L, and the S0 accumulation efficiency (S0AEC1) reaching 82.4%. A small amount of O2 carried in the reflux can effectively reduce residual S2- in zone C1, preventing its entry into the PN/Anammox zone (zone C2) and mitigating its toxic effects on Anammox. However, O2 also increases the expression of soxB in zone C1, causing more S2- to be oxidized to SO42-, and reducing S0AEC1. When DOC1 was between 0.05 mg/L and 0.34 mg/L, nirK expression was significantly increased, and the abundance of related functional microorganisms changed, led to more NO3--N being reduced to N2. When DOC1 exceeds 0.34 mg/L, it inhibits the denitrification process, leading to elevated NiAE. Therefore, when regulating reflux in DSSADN+PN/Anammox partitioned integrated coupling system, attention should be given to changes in DOC1, controlling it within 0.05 mg/L.

Study on the Remediation of Groundwater Nitrate Pollution by Pretreated Wheat Straw and Woodchips

Groundwater nitrate contamination poses a threat to both the ecological environment and human health. This study investigated the potential of using saturated Ca(OH)2 to pretreat wheat straw and woodchips, aiming to enhance their efficacy as carbon sources for denitrification. The optimization of pretreatment conditions, and the elucidation of underlying mechanisms were explored. The pretreatment process involved the dissolution of lignin and hemicellulose, exposure of the cellulose structure, reduction of hydrogen bonds within cellulose, hydrolysis of polymerized cellulose, and the formation of cracks and hierarchical structures on the surface of the carbon source. These alterations improved the attachment and utilization of microorganisms. The maximum enzymatic reducing sugar yields for wheat straw and woodchips were achieved at solid-liquid ratios of 1:40 and soaking times of 5 and 2 days, respectively. The response surface predicted the optimal pretreatment conditions for wheat straw to be a solid-liquid ratio of 1:88.1 and a soaking time of 8.2 hours. Alkaline treatment increased the denitrification rate of woodchips by fivefold and prevented the initial organic matter leaching rate of wheat straw, thereby reducing the risk of secondary pollution. The predominant microbial communities in all samples exhibited functions related to lignocellulose degradation and denitrification. The community composition of solid-phase carbon sources was found to be richer than that of liquid-phase carbon sources, and the pretreatment increased the abundance of lignocellulose degradation and denitrification functional microorganisms. The pretreatment liquid of wheat straw achieved the highest denitrification rate constant (0.43 h-1). Our result validated the feasibility of using the pretreatment liquid as a denitrification carbon source and presenting a novel approach for waste resource utilization.

In-Situ Algal Control by Two-stage Nanobubble Technology in Taihu Lake: Efficacy and Ecological Impact

Hydrodynamic cavitation and ozone nanobubble-coupled hydrodynamic cavitation have demonstrated effective algae control in laboratories, but their in-situ potential, especially impact on nutrient salt degradation and microbial communities remain unclear. This study applied two-stage nanobubble technology, combining hydrodynamic cavitation and ozone nanobubbles, in a 3300 m2 semi-enclosed area of Taihu Lake to address these gaps. Results show that the technology efficiently controls algae, reduces odors, improves anaerobic conditions, and lowers ammonia nitrogen. Over 20 days, chlorophyll-a concentration reduced by 77.46% and cyanobacterial phycocyanin by 89.47%. Additionally, the concentrations of 2-MIB, GSM, and DMTS fell below threshold values. Notably, the relative abundance of Cyanobacteria in sediment dropped from 8.53% in the control area to only 1.59% ∼ 3.65% in the experimental area. The technology also achieved a significant reduction in ammonia nitrogen, with removal efficiencies of 78.53% in the water column and 39.17% in sediments, though the removal of total phosphorus was limited. Furthermore, the two-stage nanobubble system enhanced the abundance of nitrogen-cycling microorganisms and genes in the water, while promoting nitrogen- and phosphorus-related microbial communities in sediments and inhibiting the cyanobacteria-associated genus Cyanobium PCC-6307. Thus, Two-stage nanobubble technology can be employed for in-situ algal control in aquatic ecosystems.

Ralstonia solanacearum Infection Drives the Assembly and Functional Adaptation of Potato Rhizosphere Microbial Communities.

Bacterial wilt caused by Ralstonia solanacearum is a destructive disease that affects potato production, leading to severe yield losses. Currently, little is known about the changes in the assembly and functional adaptation of potato rhizosphere microbial communities during different stages of R. solanacearum infection. In this study, using amplicon and metagenomic sequencing approaches, we analyzed the changes in the composition and functions of bacterial and fungal communities in the potato rhizosphere across four stages of R. solanacearum infection. The results showed that R. solanacearum infection led to significant changes in the composition and functions of bacterial and fungal communities in the potato rhizosphere, with various microbial properties (including α,β-diversity, species composition, and community ecological functions) all being driven by R. solanacearum infection. The relative abundance of some beneficial microorganisms in the potato rhizosphere, including Firmicutes, Bacillus, Pseudomonas, and Mortierella, decreased as the duration of infection increased. Moreover, the related microbial communities played a significant role in basic metabolism and signal transduction; however, the functions involved in soil C, N, and P transformation weakened. This study provides new insights into the dynamic changes in the composition and functions of potato rhizosphere microbial communities at different stages of R. solanacearum infection to adapt to the growth promotion or disease suppression strategies of host plants, which may provide guidance for formulating future strategies to regulate microbial communities for the integrated control of soil-borne plant diseases.

Recent trends and open questions regarding the effects of microplastics on soil, plants and soil microorganisms

In recent years, microplastics have been extensively detected in sea, freshwater, soils and organisms. The microplastics pollution is of increasing concerns for soil health. Microplastics are considered as an emerging threat to the agroecosystems, where soils may represent a reservoir for plastics pollution. Microplastics in soils could alter soil properties, plant growth, soil invertebrate, abundance and activity of soil microorganisms. Further investigations are needed to evaluate the overall effect of microplastics on soil ecosystems services.

Constructed wetland coupled microbial fuel cell (CW-MFC) with Phragmites australis planted for hexavalent chromium removal and electricity generation

Hexavalent chromium (Cr(VI)) in aqueous solution is characterized by strong mobility, high solubility, and significant biological toxicity. In this study, four constructed wetland combined with microbial fuel cell (CW-MFC) systems were established to explore the changes in electricity generation, water purification, and microbial community structure under the influence of plant, bioelectrochemical, and Cr(VI) stress. The planted CW-MFC (total Cr: 97.5 %, Cr(VI): 99.2 %) and non-planted CW-MFC (total Cr: 95.3 %, Cr(VI): 97.3 %) showed significantly higher Cr removal efficiency than open circuit CW-MFC (total Cr: 86.9 %, Cr(VI): 84.8 %). The presence of plants and Cr(VI) increased the average voltage and power density of CW-MFC. Additionally, plants, bioelectrochemistry, and Cr(VI) improved COD removal and significantly enhanced the abundance and diversity of microorganisms in the system during long-term domestication. The Cr(VI)-reducing bacterium Exiguobacterium was least abundant in non-Cr(VI) containing CW-MFC system. The abundance of the electrochemically active bacteria (EAB) Geobacter increased under bioelectrochemistry and Cr(VI).

Effect of Harvest Maturity and Lactiplantibacillus plantarum Inoculant on Dynamics of Fermentation Characteristics and Bacterial and Fungal Community of Triticale Silage

(1) Background: Suitable harvest maturity stage selection and microbial inoculation during anaerobic fermentation are effective strategies for improving the quality of triticale (×Triticosecale) silage for ruminant nutrition. (2) Methods: In the present study, the fermentation characteristics, microbial communities, and their correlations were evaluated for triticale silages, as affected by Lactiplantibacillus plantarum (LP) inoculation at the heading, flowering, filling, milk-ripening, and wax-ripening stages. (3) Results: The results indicate that the filling and milk-ripening stages without LP inoculation resulted in lower pH and higher lactic acid than other harvest maturity stages (p &lt; 0.05). Inoculating with LP decreased the pH at each harvest maturity stage, except for the filling stage, and increased the lactic acid concentration at the heading and filling stages (p &lt; 0.05). The bacterial dynamics indicated that the abundances of Lactiplantebacilli and Monascus of the triticale silages without the LP inoculation were different between the harvest maturity stages (p &lt; 0.05), and the abundance of Enterobacters was different between the harvest maturity stages in the triticale silage (p &lt; 0.05). Remarkably, negative correlations were found between the Lactiplantebacillus, Monascus, and pH and positive correlations were found between the Lactiplantebacillus, Monascus, and lactic acid content (p &lt; 0.05). (4) Conclusions: The filling and milk-ripening stages were the most suitable harvest maturity stages for the triticale silage. Inoculation with LP could enhance the fermentation quality, increase the abundances of beneficial microorganisms, and inhibit harmful microorganisms in triticale silage.