Microbial Community Function Research Articles

Effects of different stocking density start-up conditions on water nitrogen and phosphorus use efficiency, production, and microbial composition in aquaponics systems

Controlling environmental parameters, including nitrogen and phosphorus use efficiency, is a crucial aspect of maintaining effective aquaponic systems. In this study, we evaluated the impact of start-ups under high (20 kg/m3) and low (5 kg/m3) stocking density conditions on water quality, productivity, nitrogen use efficiency (NUE), phosphorus use efficiency (PUE), microbial community compositions, and functional genes in the aquaponics system. Six experimental units (three replications per treatment) were categorized into two groups. The experimental process was divided into two phases: Phase I (Days 1–40) and Phase II (Days 41–145). During Phase I, the two system groups were initiated under high and low stocking densities. Phase II constituted the fish and vegetable production phase, with all aquaponics systems standardized at a stocking density of 10 kg/m3 and a planting density of 12 plants/m2. The results indicated superior water quality in the low aquaponics systems than that in the high aquaponics systems during Phase I, whereas the opposite was observed during Phase II. The final weight, specific growth rate, and fish weight gain of jade perch (Scortum barcoo), as well as the plant weight gain of tomato plants, were significantly higher in the high aquaponics system than those in the low aquaponics system. The NUE and PUE of the high aquaponics system were 49.55 ± 1.02% and 60.12 ± 1.28%, respectively, surpassing those of the low aquaponics system (43.41 ± 2.16% and 49.06 ± 1.59%). The microbial diversity in the moving bed biofilm reactor and roots of the high aquaponics system was lower than in the low aquaponics system. However, the relative abundances of nitrifying and denitrifying bacteria were higher than those in the low aquaponics system. The number of copies of functional genes for nitrification and denitrification, including amoA, nxrB, nirS, nirK, and nosZ, was higher in the high aquaponics systems. Overall, the results indicated that high aquaponics systems initiated with high stocking density yield more products, improved water quality, and higher NUE and PUE by altering the composition of microbial communities. This study presents a method for enhancing the functional microbial community of a system by optimizing conditions during the initiation period.

Effects of Reduced Seawater pH and Oil Contamination on Bacterial Communities and Biochemical Markers of Estuarine Animal Hosts

Ecosystem functioning depends on complex interactions between microorganisms, hosts, and the environment. Changes in environmental conditions (e.g., ocean acidification) in combination with anthropogenic pollution have been shown to affect the composition and function of free-living microbial communities, but little is known about the effects these stressors on host-associated communities. This study aims to characterize the response of host-associated bacterial communities of the bottom-dwelling polychaete Hediste diversicolor and the epibenthic gastropod Peringia ulvae to oil contamination and reduced seawater pH. The independent and interactive effects of both stressors were simulated under controlled conditions. The response of host-associated bacterial communities was assessed using the high-throughput sequencing of the 16S rRNA gene and several biochemical markers related to host metabolic pathways, e.g., neurotransmission, anaerobic metabolism, biotransformation, oxidative stress, and energy consumption. In H. diversicolor, reduced seawater pH was associated with a high relative abundance of Cyanobacteria, while in P. ulvae oil contamination was associated with a reduction in the relative abundance of Chitinophagales. In P. ulvae, enrichment with oil hydrocarbon-degrading bacteria suggests a possible role of these organisms in the dispersion of oil hydrocarbon degraders. Furthermore, oil supplementation shifted some specific biochemical markers of gastropods related to oxidative stress and energy consumption, which suggests host stress. In general, the bacterial communities and biochemical markers of the gastropod were more affected by stressors than those of the polychaete. Overall, this study contributes to a better understanding of the response of host-associated bacterial communities of benthic macrofauna to anthropogenic contamination and environmental change.

Effects of non-pelleted or pelleted low-native grass and pelleted high-native grass diets on meat quality by regulating the rumen microbiota in lambs.

Diet modulates the gut microbiome, which in turn impact the meat quality, yet few studies investigate the correlation between the rumen microbiome and the fatty acid profile of meat. Here, the current study develops an experiment to investigate the correlation of the rumen microbiome and fatty acid profile of meat: rumen microbiome responses to feed type and meat quality. The results indicated a unique microbiota in the rumen of lamb in response to diets and meat quality. Associations between utilization and production were widely identified among the affected microbiome and meat quality, and these findings will contribute to the direction of future research in lamb.

Distinct microbial communities under different rock-associated microhabitats in the Qaidam Desert

Hypolithic communities, which occupy highly specialised microhabitats beneath translucent rocks in desert and arid environments, have assembly mechanisms and ecosystem functions are not fully understood. Thus, in this study, we aimed to examine the microbial community structure, assembly, and function of light-accessible (under quartz, calcite, and hypolithic lichen-dominated biocrusts) and light-inaccessible microhabitats (under basalt and adjacent soil) in the Qaidam Desert, China. The results showed that hypolithic communities have different characteristics compared with microbial communities of light-inaccessible microhabitats. Notably, hypolithic bacterial communities were dominated by Cyanobacteria, whereas light-inaccessible microhabitats showed a predominance of Bacteroidetes and Proteobacteria. Although the class Dothideomycetes (phylum: Ascomycota) dominated the fungal communities between the two microhabitat types, Sordariomycetes were more prevalent in light-accessible microhabitats. Network and robustness analyses showed that hypolithic communities were less complex and more resilient than microbial communities in light-inaccessible microhabitats. Our results indicated that deterministic processes, specifically homogeneous selection, govern the establishment of bacterial and fungal communities in light-accessible and light-inaccessible microhabitats. The hypolithic community showed an increased frequency of phylotypes that exhibited increased tolerance to functional stress response pathways. In contrast to light-inaccessible microhabitats, light-accessible microhabitats showed a slight decrease and a notable increase in the prevalence of carbon fixation pathways in prokaryotes and carbon fixation in photosynthetic organisms, respectively. For fungi, light-accessible microhabitats enriched saprotrophic and ectomycorrhizal groups. These results highlight the importance of complex and diverse microhabitats in desert regions, which serve as vital shelters for microbes. Combining future research on interactions between hypolithic communities and environments may enhance our current understanding of their pivotal roles in sustaining desert ecosystems. This knowledge then be applied to design and implement informed conservation efforts to preserve these unique rock-associated microhabitats in desert ecosystems.

Non-mercury methylating microbial taxa are integral to understanding links between mercury methylation and elemental cycles in marine and freshwater sediments

The goal of this study was to explore the role of non-mercury (Hg) methylating taxa in mercury methylation and to identify potential links between elemental cycles and Hg methylation. Statistical approaches were utilized to investigate the microbial community and biochemical functions in relation to methylmercury (MeHg) concentrations in marine and freshwater sediments. Sediments were collected from the methylation zone (top 15 cm) in four Hg-contaminated sites. Both abiotic (e.g., sulfate, sulfide, iron, salinity, total organic matter, etc.) and biotic factors (e.g., hgcA, abundances of methylating and non-methylating taxa) were quantified. Random forest and stepwise regression were performed to assess whether non-methylating taxa were significantly associated with MeHg concentration. Co-occurrence and functional network analyses were constructed to explore associations between taxa by examining microbial community structure, composition, and biochemical functions across sites. Regression analysis showed that approximately 80% of the variability in sediment MeHg concentration was predicted by total mercury concentration, the abundances of Hg methylating taxa, and the abundances of the non-Hg methylating taxa. The co-occurrence networks identified Paludibacteraceae and Syntrophorhabdaceae as keystone non Hg methylating taxa in multiple sites, indicating the potential for syntrophic interactions with Hg methylators. Strong associations were also observed between methanogens and sulfate-reducing bacteria, which were likely symbiotic associations. The functional network results suggested that non-Hg methylating taxa play important roles in sulfur respiration, nitrogen respiration, and the carbon metabolism-related functions methylotrophy, methanotrophy, and chemoheterotrophy. Interestingly, keystone functions varied by site and did not involve carbon- and sulfur-related functions only. Our findings highlight associations between methylating and non-methylating taxa and sulfur, carbon, and nitrogen cycles in sediment methylation zones, with implications for predicting and understanding the impact of climate and land/sea use changes on Hg methylation.

Impact of wine-grape continuous cropping on soil enzyme activity and the composition and function of the soil microbial community in arid areas.

Continuous cropping affected the stability of soil enzyme activity and the structural characteristics of microbial community. Owing to challenges in the study of complex rhizosphere microbial communities, the composition and function of these microbial communities in farmland ecosystems remain elusive. Here, we studied the microbial communities of the rhizosphere of wine grapes with different years of continuous cropping and investigated their relationships with soil enzyme activity. Metagenomic sequencing was conducted on the rhizosphere soils from one uncultivated wasteland and four vineyards with varying durations of continuous cropping. The predominant microbial were bacteria (98.39%), followed by archaea (1.15%) and eukaryotes (0.45%). Continuous cropping caused a significant increase in the relative abundance of Rhizobiales and Micrococcales but a marked decrease in Solirubrobacterales. At the genus level, 75, 88, 65, 132, and 128 microbial genera were unique to uncultivated wasteland, 5, 10, 15, and 20 years of continuous cropping, respectively. The relative abundance of genes with signal transduction function was the highest. The activity of all enzymes measured in this study peaked at 5 years of continuous cropping, and then decreased with 10 to 15 year of continuous cropping, but increased at 20 years again. In addition, soil enzyme activity, especially of alkaline phosphatase was significantly correlated with the diversity of the dominant microorganisms at the genus level. Moreover, the coupled enzyme activities had a greater impact on the diversity of the microbial community than that of individual enzymes. Our findings reveal the composition and function of the soil microbial communities and enzymes activity in response to changes in cropping years, which has important implications for overcoming continuous cropping obstacles and optimizing land use.

Assessing the impact of biofertilizer on soil microbial dynamics and metabolic activity in a controlled maize pot-grown experiment

Biofertilizers, consisting of carefully selected microorganisms across various species and genera, exhibit distinct features that enhance soil fertility and promote plant growth. Embracing the principles of eco-friendly agriculture, the use of biofertilizers emerges as a pivotal strategy for sustainable farming, contributing to environmental preservation and the overall health and biodiversity of the soil. In this study, a commercially available biofertilizer, containing a specialized strain of Priestia megatherium with nitrogen-fixing capabilities, was employed alongside chemical fertilizers at two different doses (30 and 40 mg per kg of soil). The primary objective was to evaluate the impact of biofertilizer on the metabolic activity and structure of microbial communities in a short-term experiment involving potted maize plants, utilizing the BIOLOG® EcoPlates technique. Parameters such as average well-color development (AWCD) and substrate utilization across six guilds (SAWCD) were assessed to gauge microbial metabolic activity. Additionally, functional indexes, including Shannon diversity, Shannon evenness, and Simpson diversity, were calculated as indicators of soil microbial community functionality. While statistically significant differences in AWCD among the studied variants were not observed, all estimated functional indexes consistently revealed heightened microbial diversity and evenness following the application of biofertilizer. This noteworthy finding, achieved within a relatively short period of plant cultivation, underscores the necessity for further research to explore the biofertilizer's enduring effects on soil communities, both in controlled laboratory environments and under real-world field conditions.

Whole community shotgun metagenomes of two biological soil crust types from the Mojave Desert.

We present six whole community shotgun metagenomic sequencing data sets of two types of biological soil crusts sampled at the ecotone of the Mojave Desert and Colorado Desert in California. These data will help us understand the diversity and function of biocrust microbial communities, which are essential for desert ecosystems.

Microbial community succession of cow manure and tobacco straw composting

Composting livestock manure using microorganisms is a safe and resourceful practice. The continual fluctuations in physicochemical parameters during composting are intricately linked to the composition of microbial communities. This study investigated the dynamics of microbial communities during the composting of cow manure and tobacco straw using amplicon sequencing and shotgun metagenomics. The sequencing results revealed major genera such as Sphaerobacter, Actinomadura, Thermomonospora, Flavobacterium, Bacillus, Hydrogenophaga, Pseudomonas, Lysinibacillus, Aneurinibacillus, and Azotobacter. Metagenomic analysis highlighted that the phylum Proteobacteria constituted the largest proportion. Furthermore, the presence of the genus Rhodococcus, known to cause human and animal diseases, gradually decreased over time. These findings offer initial insights into the microbial community composition and function during cow manure and tobacco straw composting.

Farmland Microhabitat Mediated by a Residual Microplastic Film: Microbial Communities and Function.

How the plastisphere mediated by the residual microplastic film in farmlands affects microhabitat systems is unclear. Here, microbial structure, assembly, and biogeochemical cycling in the plastisphere and soil in 33 typical farmland sites were analyzed by amplicon sequencing of 16S rRNA genes and ITS and metagenome analysis. The results indicated that residual microplastic film was colonized by microbes, forming a unique niche called the plastisphere. Notable differences in the microbial community structure and function were observed between soil and plastisphere. Residual microplastic film altered the microbial symbiosis and assembly processes. Stochastic processes significantly dominated the assembly of the bacterial community in the plastisphere and soil but only in the plastisphere for the fungal community. Deterministic processes significantly dominated the assembly of fungal communities only in soil. Moreover, the plastisphere mediated by the residual microplastic film acted as a preferred vector for pathogens and microorganisms associated with plastic degradation and the nitrogen and sulfur cycle. The abundance of genes associated with denitrification and sulfate reduction activity in the plastisphere was pronouncedly higher than that of soil, which increase the potential risk of nitrogen and sulfur loss. The results will offer a scientific understanding of the harm caused by the residual microplastic film in farmlands.

Functional diversity of microbial communities in herbaceous vegetation patches in coal mine heaps

AbstractCoal mine heaps represent unique novel environments, suitable for studying plant succession and its influence on the activity of microbes inhabiting the rhizosphere. Our aim was to verify if the functional diversity and catabolic activity of soil microorganisms would increase along with the plant succession from non‐vegetated and forbs‐dominated to grass‐dominated communities. The study was conducted on coal mine heaps located in Upper Silesia (Southern Poland), focusing on non‐vegetated patches, patches dominated by forbs–Tussilago farfara and Daucus carota (in the early stages of succession), and by grasses–Poa compressa and Calamagrostis epigejos (in later stages of primary succession). The catabolic activity and functional diversity of soil microbial communities were analyzed based on community‐level physiological profiles using BIOLOG EcoPlatesTM and the activity of dehydrogenase, alkaline phosphatase, acid phosphatase, and urease. Our results showed that spontaneous vegetation on coal mine heaps strongly affects the physicochemistry of the substrate and the functional diversity of soil microbial communities. Grasses' rhizosphere was hosting more active and functional diversified microbial communities, while non‐vegetated and T. farfara‐vegetated patches were accompanied by a reduced development of soil microbiota. Furthermore, grasses were mainly associated with a substantial delivery of plant litter to the substrate, providing a source of carbon for microorganisms.

Time-Course Responses of Apple Leaf Endophytes to the Infection of Gymnosporangium yamadae.

Apple rust, caused by Gymnosporangium yamadae, poses a significant challenge to apple production. Prior studies have underscored the pivotal role played by endophytic microbial communities, intimately linked with the host, in influencing plant diseases and their pathogenic outcomes. The objective of this study is to scrutinize alternations in endophytic microbial communities within apple leaves at different stages of apple rust using high-throughput sequencing technology. The findings revealed a discernible pattern characterized by an initial increase and subsequent decrease in the alpha diversity of microbial communities in diseased leaves. A microbial co-occurrence network analysis revealed that the complexity of the bacterial community in diseased leaves diminished initially and then rebounded during the progression of the disease. Additionally, employing the PICRUSt2 platform, this study provided preliminary insights into the functions of microbial communities at specific disease timepoints. During the spermogonial stage, endophytic bacteria particularly exhibited heightened activity in genetic information processing, metabolism, and environmental information processing pathways. Endophytic fungi also significantly enriched a large number of metabolic pathways during the spermogonial stage and aecial stage, exhibiting abnormally active life activities. These findings establish a foundation for comprehending the role of host endophytes in the interaction between pathogens and hosts. Furthermore, they offer valuable insights for the development and exploitation of plant endophytic resources, thereby contributing to enhanced strategies for managing apple rust.

Optimization of operating parameters and microbiological mechanism of a low C/N wastewater treatment system dominated by iron-dependent autotrophic denitrification

Ferrous iron (Fe2+) reduces the amount of external carbon source used for the denitrification of low-C/N wastewater. The effects of key operating parameters on the efficiency of ferrous-dependent autotrophic denitrification (FDAD) and the functioning mechanism of the microbiome can provide a regulatory strategy for improving the denitrification efficiency of low C/N wastewater. In this study, the response surface method (RSM) was used to explore the influence of four important parameters–the molar ratio of Fe2+ to NO3−-N (Fe/N), total organic carbon (TOC), the molar ratio of inorganic carbon to NO3−-N (IC/N) and sludge volume (SV, %)–on the FDAD efficiency. Functional prediction and molecular ecological networks based on high-throughputs sequencing techniques were used to explore changes in the structure, function, and biomarkers of the sludge microbial community. The results showed that Fe/N and TOC were the main parameters affecting FDAD efficiency. Higher concentrations of TOC and high Fe/N ratios provided more electron donors and improved denitrification efficiency, but weakened the importance of biomarkers (Rhodanobacter, Thermomonas, Comamonas, Thauera, Geothrix and unclassified genus of family Gallionellaceae) in the sludge ecological network. When Fe/N > 4, the denitrification efficiency fluctuated significantly. Functional prediction results indicated that genes that dominated N2O and NO reduction and the genes that dominated Fe2+ transport showed a slight decrease in abundance at high Fe/N levels. In light of these findings, we recommend the following optimization ranges of parameters: Fe/N (3.5–4); TOC/N (0.36–0.42); IC/N (3.5–4); and SV (approximately 35%).

Biochars assisted phytoremediation of polycyclic aromatic hydrocarbons contaminated agricultural soil: Dynamic responses of functional genes and microbial community

A biochar-intensified phytoremediation experiment was designed to investigate the dynamic effects of different biochars on polycyclic aromatic hydrocarbon (PAH) removal in ryegrass rhizosphere contaminated soil. Maize and wheat straw biochar pyrolyzed at 300 °C and 500 °C were amended into PAH-contaminated soil, and then ryegrass (Lolium multiflorum L.) was planted for 90 days. Spearman's correlations among PAH removal, enzyme activity, abundance of PAH-ring hydroxylating dioxygenase (PAH-RHDα), and fungal and bacterial community structure were analyzed to elucidate the microbial degradation mechanisms during the combined remediation process. The results showed that 500 °C wheat straw biochar had higher surface area and more nutrients, and significantly accelerated the phytoremediation of PAHs (62.5 %), especially for high molecular weight PAH in contaminated soil. The activities of urease and dehydrogenase and the abundance of total and PAH-degrading bacteria, which improved with time by biochar and ryegrass, had a positive correlation with the removal rate of PAHs. Biochar enhanced the abundance of gram-negative (GN) PAH-RHDα genes. The GN PAH-degraders, Sphingomonas, bacteriap25, Haliangium, and Dongia may play vital roles in PAH degradation in biochar-amended rhizosphere soils. Principal coordinate analysis indicated that biochar led to significant differences in fungal community structures before 30 days, while the diversity of the bacterial community composition depended on planting ryegrass after 60 days. These findings imply that the structural reshaping of microbial communities results from incubation time and the selection of biochar and ryegrass in PAH-contaminated soils. Applying 500 °C wheat straw biochar could enhance the rhizoremediation of PAH-contaminated soil and benefit the soil microbial ecology.

Wekemo Bioincloud: A user-friendly platform for meta-omics data analyses.

The increasing application of meta-omics approaches to investigate the structure, function, and intercellular interactions of microbial communities has led to a surge in available data. However, this abundance of human and environmental microbiome data has exposed new scalability challenges for existing bioinformatics tools. In response, we introduce Wekemo Bioincloud-a specialized platform for -omics studies. This platform offers a comprehensive analysis solution, specifically designed to alleviate the challenges of tool selection for users in the face of expanding data sets. As ofnow, Wekemo Bioincloud has been regularly equipped with 22 workflows and 65 visualization tools, establishing itself as a user-friendly and widely embraced platform for studying diverse data sets. Additionally, the platform enables the online modification of vector outputs, and the registration-independent personalized dashboard system ensures privacy and traceability. Wekemo Bioincloud is freely available at https://www.bioincloud.tech/.

Evolution of the functionality of microbial communities in patients with metastatic renal cell carcinoma (mRCC) receiving cabozantinib (cabo)/nivolumab (nivo) with or without CBM588: A randomized clinical trial.

460 Background: Our team has previously demonstrated in two prospective studies that the live bacterial product CBM588 may enhance clinical outcomes in patients with mRCC (Ebrahimi et al ASCO 2023, Dizman et al Nature Med 2022). In the current study, we sought to determine if gut microbial functionality is associated with clinical outcomes in patients with mRCC treated with cabo/nivo with or without CBM588. Methods: Pts ≥18 yrs old with histologically verified (clear-cell, papillary, or sarcomatoid component) mRCC and no prior systemic therapy for metastatic disease were enrolled and randomized 1:2 to receive either cabo/nivo at the standard dose/schedule alone or with CBM588 dosed at 80mg PO BID. Whole metagenome sequencing was performed on stool specimens collected at baseline and week 12 of treatment. Taxonomic profiling was conducted using MetaPhlAn 4, and functional profiling was performed using HUMAnN 3. HUMAnN 3 annotates open reading frames and provides highly accurate information on metabolic pathways and other molecular functions from metagenomic or metatranscriptomic sequencing data. The ANCOM-BC was used to detect the taxonomic/genetic features with differential abundance between two time-points within the same treatment arm. Results: A total of 30 (20:10 M:F) pts were enrolled with a median age of 65 (36-84). 5 pts (17%) had sarcomatoid features, and 2 pts (7%) had predominant papillary histology. Objective response was achieved in 20% and 65% of the pts in the cabo/nivo and cabo/nivo/CBM588 arm, respectively. Significant changes in 9 metabolic pathways (1 upregulation, 8 downregulation) in the control arm and 7 metabolic pathways (2 upregulation, 5 with downregulation) in the experimental arm were identified. Superpathways of biosynthesis of different forms of menaquinole, a reversible redox component of the electron transfer chain, were depleted with cabo/nivo treatment. In contrast, the biosynthesis of menaquinol-8 and 1,4 dihydroxy-6-naphthoate (an intermediate of the menaquinone pathway) were upregulated in cabo/nivo/CBM588 arm. Conclusions: Our interrogation of metabolic dynamics and pathways in patients receiving CBM588 suggests key differences in biosynthesis pathways of menaquinone between control and experimental arms. Menaquinones (vitamin K2 derivatives) have been previously reported to induce apoptosis in many cancer cell types and also increase the objective response rate to sorafenib in patients with hepatocellular carcinoma. Our findings provide mechanistic evidence for the effect of the addition of CBM588 to cabo/nivo on gut microbiome function and the resultant improvement in clinical outcomes in mRCC, potentially through enhancing the enteric production of vitamin K2. Clinical trial information: NCT05122546 .

Illegal dumping of oil and gas wastewater alters arid soil microbial communities.

The Permian Basin, underlying southeast New Mexico and west Texas, is one of the most productive oil and gas (OG) provinces in the United States. Oil and gas production yields large volumes of wastewater with complex chemistries, and the environmental health risks posed by these OG wastewaters on sensitive desert ecosystems are poorly understood. Starting in November 2017, 39 illegal dumps, as defined by federal and state regulations, of OG wastewater were identified in southeastern New Mexico, releasing ~600,000 L of fluid onto dryland soils. To evaluate the impacts of these releases, we analyzed changes in soil geochemistry and microbial community composition by comparing soils from within OG wastewater dump-affected samples to unaffected zones. We observed significant changes in soil geochemistry for all dump-affected compared with control samples, reflecting the residual salts and hydrocarbons from the OG-wastewater release (e.g., enriched in sodium, chloride, and bromide). Microbial community structure significantly (P < 0.01) differed between dump and control zones, with soils from dump areas having significantly (P < 0.01) lower alpha diversity and differences in phylogenetic composition. Dump-affected soil samples showed an increase in halophilic and halotolerant taxa, including members of the Marinobacteraceae, Halomonadaceae, and Halobacteroidaceae, suggesting that the high salinity of the dumped OG wastewater was exerting a strong selective pressure on microbial community structure. Taxa with high similarity to known hydrocarbon-degrading organisms were also detected in the dump-affected soil samples. Overall, this study demonstrates the potential for OG wastewater exposure to change the geochemistry and microbial community dynamics of arid soils.IMPORTANCEThe long-term environmental health impacts resulting from releases of oil and gas (OG) wastewater, typically brines with varying compositions of ions, hydrocarbons, and other constituents, are understudied. This is especially true for sensitive desert ecosystems, where soil microbes are key primary producers and drivers of nutrient cycling. We found that releases of OG wastewater can lead to shifts in microbial community composition and function toward salt- and hydrocarbon-tolerant taxa that are not typically found in desert soils, thus altering the impacted dryland soil ecosystem. Loss of key microbial taxa, such as those that catalyze organic carbon cycling, increase arid soil fertility, promote plant health, and affect soil moisture retention, could result in cascading effects across the sensitive desert ecosystem. By characterizing environmental changes due to releases of OG wastewater to soils overlying the Permian Basin, we gain further insights into how OG wastewater may alter dryland soil microbial functions and ecosystems.

Effect of long-term in-row branch covering on soil microorganisms in pear orchards.

Branches covering (BC) is a way to reuse the pruned branches and save the cost of ground cloth. This study investigated the effects of BC and ground-cloth covering on the soil microcosm environment by measuring the chemical properties and microbial communities at different soil depths for 6 years. The results revealed that BC significantly improved soil chemical properties, increased the abundance of bacterial microbial communities and the diversity and homogeneity of bacteria and fungi, while decreased the abundance of fungal microbial communities. There was a threshold value for the regulation of microbial communities by BC, which decreased the high-abundance communities (Proteobacteria, Ascomycota, etc.) and increased the low-abundance communities (Acidobacteriota, Basidiomycota, etc.). Fungi were more sensitive to BC than bacteria. The stability and homogeneity of microorganisms were stronger in the 15-25 cm soil layer. The bacterial phyla were dominated by Proteobacteria, with the top 10 phyla accounting for more than 80% of the relative abundance; the genera were dominated by MND1, with the top 10 genera accounting for about 10%. The fungal phyla were dominated by Ascomycota, with the top 10 phyla accounting for 50-90%; the genera were dominated by unidentified Pyronemataceae sp., with the top 10 genera accounting for 30-60%. The phyla that differed significantly between treatments were mainly Proteobacteria, Ascomycota, Acidobacteriota, and Basidiomycota. In addition, metabolism was the predominant function in bacteria, while Saprotroph was the predominant function in fungi. Bacteroidota correlated strongly with soil chemical properties and bacterial functions, while Chytridiomycota correlated strongly with soil chemical properties and Pathogen-Saprotroph-Symbiotroph. In conclusion, BC can improve soil nutrient content and optimize microbial community structure and function. Through initially assessing the effects of BC on soil nutrients and microorganisms in pear orchard rows, this study provides a reference for excavating key microorganisms and updating the soil row management model.

Comparison of distinctive diversities, co-occurrence patterns and potential ecological functions of microbial communities in heterogeneous soil areas in typical subtropical forests, southeast China

Although microbes are crucial in ecological cycling in forest soil, the response of the network structure and ecological functions of these microorganisms to soil heterogeneity remains elusive. Here, we analyzed the composition and co-occurrence network patterns of microorganisms in heterogeneous soil areas and evaluated their potential ecological functions, taking the scenic area (SA) and nature reserve (NR) of Wuyishan National Park as examples. Our results showed that the soil properties of SA and NR could almost be clustered separately, and soil heterogeneity between them has been found. Prokaryotic communities in both areas were also divided and showed higher similarities individually than those of eukaryotes. The prokaryotic community composition in both areas was mainly affected by pH and ammonia, while the eukaryotic community composition was mainly affected by total carbon and the carbon to nitrogen ratio. Both the microbial network and ecological function network in SA were more complex than those of NR, while those of NR were more stable than those of SA. The keystone taxa of pro- and eukaryotes with important ecological functions were enriched in SA and NR, respectively. Moreover, significant discrepancies between SA and NR were found in the prokaryotic functions related to nitrogen cycling, sulfur cycling, and compound degradation. Our study illuminated that the soil heterogeneity in subtropical areas changed microbial community diversity, interaction patterns, and keystone taxa composition, and might further affect their ecological functions.

Comparative Metagenomic Analysis of Bacteriophages and Prophages in Gnotobiotic Mouse Models.

Gnotobiotic murine models are important to understand microbiota-host interactions. Despite the role of bacteriophages as drivers for microbiome structure and function, there is no information about the structure and function of the gut virome in gnotobiotic models and the link between bacterial and bacteriophage/prophage diversity. We studied the virome of gnotobiotic murine Oligo-MM12 (12 bacterial species) and reduced Altered Schaedler Flora (ASF, three bacterial species). As reference, the virome of Specific Pathogen-Free (SPF) mice was investigated. A metagenomic approach was used to assess prophages and bacteriophages in the guts of 6-week-old female mice. We identified a positive correlation between bacteria diversity, and bacteriophages and prophages. Caudoviricetes (82.4%) were the most prominent class of phages in all samples with differing relative abundance. However, the host specificity of bacteriophages belonging to class Caudoviricetes differed depending on model bacterial diversity. We further studied the role of bacteriophages in horizontal gene transfer and microbial adaptation to the host's environment. Analysis of mobile genetic elements showed the contribution of bacteriophages to the adaptation of bacterial amino acid metabolism. Overall, our results implicate virome "dark matter" and interactions with the host system as factors for microbial community structure and function which determine host health. Taking the importance of the virome in the microbiome diversity and horizontal gene transfer, reductions in the virome might be an important factor driving losses of microbial biodiversity and the subsequent dysbiosis of the gut microbiome.