Fungal Phyla Research Articles

Soil microbiota impact on Boletus edulis mycelium in chestnut orchards of different ages

Biotic factors (host plant age and soil microbiota) influencing Boletus edulis mycelium frequency and concentration have been investigated. The study was carried out in September, October and November 2018 and 2020, using six orchards of chestnut hybrid Castanea × coudercii of 40-, 10- and 3-years-old. Taxonomical identity of bacterial and fungal species was ascertained by DNA metabarcoding. Mycelium frequency and concentration of B. edulis were studied through quantitative PCR (qPCR) of soil samples. It was hypothesized that mature plants (40-years-old) have a greater soil microbiota associated at the rhizosphere, in comparison with young plants (10- and 3-years-old). This situation may reverberate on B. edulis mycelium that should be more abundant in 40-years-old orchards, also thanks to the higher number of beneficial interactions whit soil microbiota. It was found that host plant age significantly altered bacterial and fungal assemblages in both years. Bacterial fraction was dominated by the phylum Proteobacteria, Acidobacteria and Actinobacteria and showed a higher species richness and diversity in orchards of 10- and 3-years-old. Fungal phylum such as Basidiomycota was more abundant in 40- and 10-years-old orchards, whereas Ascomycota and Mortierellomycota were more abundant in the 10- and 3-years-old orchards. Mycelium frequency of B. edulis in soil samples was higher in 2020 (97 %) than in 2018 (19 %), although without differences between plant age and sampling month in each year. Boletus edulis mycelium concentration was higher in 2020 than in 2018, and in September 2020, whereas plant age did not have any effect. Of 173 bacterial taxa considered, the 12 %, 54 % and 82 % of the significant correlations with B. edulis mycelium concentration were found in 40-, 10- and 3-years-old orchards, respectively. On the other hand, of 180 fungal taxa, the 12 %, 24 % and 42 % of the significant correlations occurred in 40-, 10- and 3-years-old orchards, respectively. This investigation represents the first report about the role of soil microbiota on the ecology of B. edulis in Castanea agro-ecosystem.

Litter, Root, and Mycorrhiza Input Affected Soil Microbial Community Structure in Schima superba Pure Forest in Subtropical China

During forest vegetation rehabilitation, changes in aboveground litter and underground root inputs affect soil microbial communities. Clarifying the effects of forest ecosystem carbon inputs on soil microbial community structure can provide a theoretical basis for the microbial driving mechanism of soil fertility evolution and ecosystem rehabilitation of vegetation rehabilitation in degraded red soil. Our research focuses on a Schima superba pure forest recovered from eroded and degraded red soil in a subtropical region. Five treatments were set as follows: control treatment (CT), mycorrhiza (M), root + mycorrhiza (RM), litter + root + mycorrhiza (LRM), and double litter + root + mycorrhiza (DLRM). We used Illumina HiSeq technology to study the effects of different organic carbon inputs on soil microbial community structure. The results showed that all organic carbon input treatments reduced the total population of soil bacteria by 55–79%; M, RM, and DLRM treatments increased the quantity of operational taxonomic units (OTUs) by 25–37%, ACE index by 25–34%, and Chao1 index by 28–39%. Acidobacteria, Proteobacteria, and Actinobacteria were the dominant bacteriophyta in the Schima superba pure forest soil. The relative abundance of Alphaproteobacteria decreased by 55% under LRM treatment, and Thermoleophilia increased by 81% under M treatment. The dominant fungal phyla were Basidiomycota and Ascomycota. RM, LRM, and DLRM treatments reduced the relative abundance of Sordariomycetes by 46–64% and increased the relative abundance of Mortierellomycetes by 251–615%. The order of effects of different organic carbon inputs on the bacterial community composition at the phylum level was LRM > RM > M > DLRM and that on the fungal community composition was DLRM > LRM and RM > M. Alphaproteobacteria, Thermoleophilia, Sordariomycetes, and Mortierellomycetes were the main microbial groups affected by changes in organic carbon inputs. Soil organic carbon and total nitrogen were the key factors affecting the change of Mortierellomycetes. The bacterial community mainly affected the activity of soil acid invertase, while the fungal community affected the activities of various enzymes, with positive or negative effects. We concluded that the organic carbon inputs changed the species and quantity of soil microorganisms in the Schima superba forest, and the influence of organic carbon input on the fungal community structure was greater than that of bacteria.

Effect of disease severity on the structure and diversity of the phyllosphere microbial community in tobacco.

Tobacco target spot is a serious fungal disease and it is important to study the similarities and differences between fungal and bacterial community under different disease severities to provide guidance for the biological control of tobacco target spot. In this study, tobacco leaves at disease severity level of 1, 5, 7 and 9 (S1, S5, S7, and S9) were collected, both healthy and diseased leaf tissues for each level were sampled. The community structure and diversity of fungi and bacteria in tobacco leaves with different disease severities were compared using high-throughput sequencing technology. The results indicated that there was a significant differences in the community structure of fungi and bacteria for both healthy and diseased samples depending on the disease severity. In both healthy and diseased tobacco leaves for all four different disease severities, the most dominant fungal phylum was Basidiomycota with a high prevalence of genus Thanatephorus. The relative abundance of Thanatephorus was most found at S9 diseased samples. Proteobacteria represent the most prominent bacterial phylum, with Pseudomonas as predominant genus, followed by Pantoea. The relative abundance of Pseudomonas was most found at S7 healthy samples. In fungal community, the Alpha-diversity of healthy samples was higher than that of diseased samples. In contrast, in bacterial community, the Alpha-diversity of healthy samples was lower than that of diseased samples. LEfSe analysis showed that the most enrich fungal biomarker was Thanatephorus cucumeris in diseased samples. Clostridium disporicum and Ralstonia pickettii were the most enrich bacterial biomarker in healthy samples. FUNGuild analysis showed that the pathotroph mode was the most abundant trophic modes. The relative abundance of pathotroph mode in diseased samples changes insignificantly, but a peak at S5 was observed for healthy samples. PICRUSt analysis showed that most bacterial gene sequences seem to be independent of the disease severity. The results of this study provide scientific references for future studies on tobacco phyllosphere microecology aiming at prevention and control of tobacco target spot.

Effects of ensiling sugarcane tops with bacteria-enzyme inoculants on growth performance, nutrient digestibility, and the associated rumen microbiome in beef cattle.

Major challenges when ensiling sugarcane tops include fermentation that results in high quantities of alcohol and decrease in nutrient digestibility due to the accumulation of fiber components. Increased efforts to apply bacteria-enzyme inoculants in silage have the potential to improve nutrient digestibility. This study aimed to evaluate the effects of ensiling sugarcane tops with bacteria-enzyme inoculants or mixed bacterial inoculants on growth performance, nutrient digestibility, and rumen microbiome in beef cattle. Chopped sugarcane tops were ensiled in plastic bags for 60 d after application of 1) no inoculant (control check, CK); 2) bacteria-enzyme inoculants containing Pediococcus acidilactici, Saccharomyces cerevisiae, cellulase, and xylanase (T1, viable colony-forming units of each bacterial strain ≥108 CFU/g; enzyme activity of each enzyme ≥200 U/g); or 3) mixed bacterial inoculants containing Lactobacillus plantarum, Bacillus subtilis, and Aspergillus oryzae (T2, viable colony-forming units of each bacterial strain ≥107 CFU/g). Silages were fed to eighteen Holstein bull calves (n = 6/treatment) weighing 163.83 ± 7.13 kg to determine intake in a 49-d experimental period. The results showed that beef cattle-fed T1 silage or T2 silage had a significantly higher (P < 0.05) average daily gain than those fed CK silage, but the difference in dry matter intake was not significant (P > 0.05). The apparent digestibility of crude protein (CP) and acid detergent fiber (ADF) were higher (P < 0.05) for beef cattle-fed T1 silage or T2 silage than for those fed CK silage. The rumen bacterial community of beef cattle-fed T1 silage or T2 silage had a tendency to increase (P > 0.05) abundance of Firmicutes and Rikenellaceae_RC9_gut_group than those fed CK silage. Rumen fungal communities of beef cattle-fed T1 or T2 silage had a tendency to increase (P > 0.05) abundance of Mortierellomycota and of Mortierella than those fed CK silage. Spearman's rank correlation coefficient showed that the apparent digestibility of ADF for beef cattle was positively correlated with unclassified_p_Ascomycota of the fungal genera (P < 0.05). Neocalimastigomycota of the fungal phyla was strongly positively correlated with the apparent digestibility of neutral detergent fiber (NDF) (P < 0.05). Ruminococcus was positively correlated with the apparent digestibility of CP (P < 0.05). It was concluded that both T1 and T2 improved the growth performance of beef cattle by improving the ruminal apparent digestibility of CP and ADF, and had no significant impact on major rumen microbial communities in beef cattle.

Assessment of Fungal Diversity in Minqin County, a Typical Arid Region in Northwestern China.

Minqin County is located in the Shiyang River Basin. As a typical arid area, it is eroded by the Badain Jaran and Tengger Desert all year round, and knowledge of the fungal diversity in this area is limited. Therefore, fungal community structure and distribution in the soil of the artificial forest, desert transition zone, farmland, and desert were investigated using amplicon sequencing of the fungal ITS gene. Ten fungal phyla and 23 classes were identified, including 1131 fungi OTUs, Sordariomycetes, Dothideomycetes, Pezizomycetes, and Agaricomycetes were the most abundant classes. Although most OTUs are shared among habitats, fungal community composition among samples was highly variable, which may influence the design of restoration practices in this area.

Characteristics of Soil Physicochemical Properties and Microbial Community of Mulberry (Morus alba L.) and Alfalfa (Medicago sativa L.) Intercropping System in Northwest Liaoning

Medicinal plant intercropping is a new intercropping method. However, as a new intercropping model, the influence of intercropping of alfalfa on microorganisms has not been clarified clearly. In this study, the composition and diversity of microbial communities in alfalfa intercropping were studied, and the differences of bacterial and fungal communities and their relationships with environmental factors are discussed. Intercropping significantly decreased soil pH and significantly increased soil total phosphorus (TP) content, but did not increase soil total carbon (TC) and total nitrogen (TN). Intercropping can increase the relative abundance of Actinobacteria and reduce the relative abundance of Proteobacteria in soil. The relative abundance and diversity of bacteria were significantly correlated with soil pH and TP, while the diversity of fungi was mainly correlated with TC, TN and soil ecological stoichiometry. The bacterial phylum was mainly related to pH and TP, while the fungal phylum was related to TC, TN, C: P and N: P. The present study revealed the stoichiometry of soil CNP and microbial community characteristics of mulberry-alfalfa intercropping soil, clarified the relationship between soil stoichiometry and microbial community composition and diversity, and provided a theoretical basis for the systematic management of mulberry-alfalfa intercropping in northwest Liaoning.

Rhizosphere Soil Fungal Diversity and Soil Physicochemical Properties of Different Vegetations in Tundra of Changbai Mountain

By studying the diversity and community structure of rhizosphere soil fungi of different plants in the tundra on the northern slope of Changbai Mountain, it provides theoretical support for the restoration of environmental degradation and in-depth study of fungal diversity in the tundra of Changbai Mountain. High-throughput sequencing technology was used to determine the ITS1 region of fungal amplicons, so as to analyze the diversity of fungal communities in the rhizosphere soil of six plants in the tundra of Changbai Mountain, and to analyze the correlation between the environment and the diversity and richness of fungal communities in combination with relevant soil physical and chemical factors. The diversity and richness of fungal community in the rhizosphere soil of six plants in Changbai Mountain tundra were different. The Simpson and Shannon indexes of Saxifraga stolonifera Curt were the highest, and the richness of fungal community in Dryas octopetala was the highest. The analysis of fungal community composition showed that the fungal colonies in plant rhizosphere soil samples mainly belonged to Ascomycota and Basidiomycota, which were the main dominant phyla. Mortierella, Fusarium and Sordariomycetes are common fungal genera in the rhizosphere soil of six plants, but their abundances are different among different plants. Water content was negatively correlated with fungal diversity, and TP was positively correlated with fungal community diversity. There were some differences in the composition and diversity of rhizosphere soil fungal communities of six plants in Changbai Mountain tundra. Ascomycota and Basidiomycota were the main soil fungal phyla in the rhizosphere of six plants in Changbai Mountain tundra. The results could provide theoretical guidance for ecological protection of Changbai Mountain tundra.

Comunidades bacterianas e fúngicas da rizosfera de pimentão sadio e murcho(Capsicum annuum L.) em sistema de cultivo orgânico

ABSTRACT: Rhizosphere microorganisms play an important role in the growth and health of plants. Around the world, diverse soil-borne pathogens attack Capsicum annuum causing significant damage and economic losses. This study determined whether the diversity and composition of microbial communities in the rhizosphere soil of C. annuum plants is significantly changed by wilt disease. We used the 16S rRNA gene for bacteria and the internal transcribed spacer region for fungi to characterize the rhizosphere microbiomes of healthy and wilted plants. The most abundant bacterial phyla were Proteobacteria and Gemmatimonadetes, while the most abundant fungal phyla were Ascomycota and Mucoromycota. The bacterial α-diversity did not show significant differences in richness and diversity, but did show a significant difference in evenness and dominance of species. Rare taxa were present in both healthy and wilted conditions with relative abundances &lt; 1%. In the fungi, all evaluated estimators showed a significant reduction in the wilted condition. The β-diversity showed significant differences in the structure of bacterial and fungal communities, which were segregated according to plant health conditions. The same occurred when comparing the alpha and beta diversity of this study based on organic agriculture with that of other studies based on conventional agriculture. We observed a significant difference with estimators analyzed by segregating rhizosphere communities depending on the farming method used. Finally, the differential abundance analysis did not show significant results in the bacterial communities; however, in the fungal communities, Fusarium, Thanatephorus, Rhizopus, Curvularia, Cladosporium, and Alternaria were more abundant in the rhizosphere of wilted than healthy plants. Species from these genera have been previously reported as phytopathogens of several plants, including C. annuum.

Characterization of root microbial communities associated with Astragalus membranaceus and their correlation with soil environmental factors

The study aims to explore the structure of rhizosphere and root endophyte microbial communities of Astragalus membranaceus and the correlation among various soil environmental factors. The root-related microbial communities of A. membranaceus at four sampling sites in Dingxi City (i.e. Longxi, Minxian, Weiyuan and Zhangxian), Gansu Province, were studied by high-throughput sequencing technology. 1676 bacterial OTUs and 1718 fungal OTUs were obtained from rhizospheric soil samples, respectively. On the other hand, 1769 bacterial OTUs and 214 fungal OTUs were calculated from root endophyte samples, respectively. The predominant species inside the root of A. membranaceus were confirmed to be Proteobacteria, Bacteroidete and Acidobacteria at bacterial phylum level, and Ascomycota and Mortierellomycota at fungal phylum level, respectively. PCoA and NMDS analyses demonstrated that the microbial community composition of rhizosphere was significantly different from that of endophyte, especially the rhizospheric bacteria and endophytic fungi of A. membranaceus in Longxi region, which were distinguished from other regions. The results of co-occurrence network analysis showed that the network structure of rhizosphere microorganisms was more complex than that of root endophyte, and the network interaction among distinct bacteria was closer than that of fungi. Moreover, RDA analysis illustrated that Proteobacteria possessed strongly positive associations with TN and AN, and Ascomycota was strongly positively associated with pH and PRO. Mortierellomycota was in high abundance within A. membranaceus endophyte in Longxi region and was negatively correlated with SOM. AN inflicted the greatest effect on the root microbial community. Taken together, we provide powerful evidence that A. membranaceus has abundant microbial community, whose composition and diversity are influenced by various soil environmental factors.

Soybean continuous cropping affects yield by changing soil chemical properties and microbial community richness.

In agroecosystems, different cropping patterns cause changes in soil physicochemical properties and thus in microbial communities, which in turn affect crop yields. In this study, the yields of soybean continuous cropping for 5 years (C5), 10 years (C10), and 20 years (C20) and of soybean-corn rotational cropping (R) treatments were determined, and samples of the tillage layer soil were collected. High-throughput sequencing technology was used to analyze the diversity and composition of the soil bacterial and fungal communities. The factors influencing microbial communities, along with the effects of these communities and those of soil chemical indexes on yield, were further evaluated. The results showed that the community richness index of bacteria was higher in C20 than in R and that of fungi was highest in C5. The differences in the bacterial and fungal communities diversity indexes were not significant among the different continuous cropping treatments, respectively. The soil microbial community composition of all continuous cropping treatments differed significantly from R. The dominant bacterial phylum was Actinobacteriota and the dominant fungal phylum was Ascomycota. The relative abundance of Fusarium did not differ significantly among the continuous cropping treatments, while that of the plant pathogen fungi Lectera sp., Plectosphaerella sp., and Volutella sp. increased with continuous cropping years. Soil pH, SOM, N, and TP had significant effects on both bacterial and fungal communities, and TK and C/N had highly significant effects on fungal communities. The yield of C5 was significantly lower than that of R, and the differences in yield between C10, C20, and R were not significant. TN, TP, and pH had significant effects on yield, and fungal community abundance had a greater negative effect on yield than bacterial community abundance.

Dynamic changes in the yak rumen eukaryotic community and metabolome characteristics in response to feed type.

With diversification of yak breeding, it is important to understand the effects of feed type on the rumen, especially microbiota and metabolites. Due to the unique characteristics of yak, research on rumen microbes and metabolites is limited. In this study, the effects of two diet types on rumen eukaryotic microflora and metabolites were evaluated using the Illumina MiSeq platform and liquid chromatography-mass spectrometry (LC-MS). All identified protozoa belonged to Trichostomatia. At the genus level, the relative abundance of Metadinium and Eudiplodinium were significantly (p < 0.05) higher in the roughage group than that of concentrate group, while the concentrate group harbored more Isotricha. Ascomycota, Basidiomycota, and Neocallimastigomycota were the main fungal phyla, and the Wallemia, Chordomyces, Chrysosporium, Cladosporium, Scopulariopsis, and Acremonium genera were significantly (p < 0.05) more abundant in the roughage group than the concentrate group, while the concentrate group harbored more Aspergillus, Neocallimastix, Thermoascus, and Cystofilobasidium (p < 0.05). Metabolomics analysis showed that feed type significantly affected the metabolites of rumen protein digestion and absorption (L-proline, L-phenylalanine, L-tryosine, L-leucine, L-tryptophan, and β-alanine), purine metabolism (hypoxanthine, xanthine, guanine, guanosine, adenosine, and adenine), and other metabolic pathway. Correlation analysis revealed extensive associations between differential microorganisms and important metabolites. The results provide a basis for comprehensively understanding the effects of feed types on rumen microorganisms and metabolites of yaks. The findings also provide a reference and new directions for future research.

Morphology, phylogeny, mitogenomics and metagenomics reveal a new entomopathogenic fungus Ophiocordycepsnujiangensis (Hypocreales, Ophiocordycipitaceae) from Southwestern China.

Ophiocordyceps contains the largest number of Cordyceps sensu lato, various species of which are of great medicinal value. In this study, a new entomopathogenic fungus, Ophiocordycepsnujiangensis, from Yunnan in southwestern China, was described using morphological, phylogenetic, and mitogenomic evidence, and its fungal community composition was identified. It was morphologically characterized by a solitary, woody, and dark brown stromata, smooth-walled and septate hyphae, solitary and gradually tapering conidiogenous cells with plenty of warty protrusions, and oval or fusiform conidia (6.4-11.2 × 3.7-6.4 µm) with mucinous sheath. The phylogenetic location of O.nujiangensis was determined based on the Bayesian inference (BI) and the maximum likelihood (ML) analyses by concatenating nrSSU, nrLSU, tef-1a, rpb1, and rpb2 datasets, and ten mitochondrial protein-coding genes (PCGs) datasets (atp6, atp9, cob, cox2, nad1, nad2, nad3, nad4, nad4L, and nad5). Phylogenetic analyses revealed that O.nujiangensis belonged to the Hirsutellasinensis subclade within the Hirsutella clade of Ophiocordyceps. And O.nujiangensis was phylogenetically clustered with O.karstii, O.liangshanensis, and O.sinensis. Simultaneously, five fungal phyla and 151 fungal genera were recognized in the analysis of the fungal community of O.nujiangensis. The fungal community composition differed from that of O.sinensis, and differences in the microbial community composition of closely related species might be appropriate as further evidence for taxonomy.

Divergent taxonomic responses of below-ground microbial communities to silicate fertilizer and biofertilizer amendments in two rice ecotypes

Using silicate fertilizer and bacterial inoculum as biofertilizer is significant for increasing soil silicon (Si) availability and rice agronomic performance. To use microbial technology for sustainable agriculture, it is crucial to have a deeper knowledge of how microbial populations shift among the plant hosts and related compartments, as well as how they respond to various fertilization models. In this study, the effects of silicate fertilizer, a single bacterial strain Bacillus mucilagniosis as biofertilizer, and their integrated application on soil physiochemical properties and soil microbiota structure, composition, and diversity in two eco-geographically diverse races (Indica and Japonica rice) were evaluated. Plant compartment, cultivar type, and fertilizer treatments contributed to microbiome variation. Indica and Japonica harbor different root microbiota; notably, taxa enriched in the rhizosphere soil were more diverse than in the root. Bacterial genera Leptonema, Azospira, Aquabacterium, Fluviicola, Aquabacterium, Leptonema, and fungal genera Metarhizium, Malassezia, and Cladosporium all were found in the rice core microbiome. Both silicate and biofertilizer applications increase the relative abundance of Betaproteobacteria, Deltaproteobacteria, and Actinobacteria, while suppressing fungal pathogens Alternaria and Fusarium. Silicate and bacterial inoculum applications increased the soil pH, available silicon content (ASi), available phosphorous (AP), available potassium (AK), and organic carbon (OC), while reduced the total nitrogen (N). These changes were also associated with major bacterial phyla Spirochaetes, Bacteroidetes, Actinobacteria, and Proteobacteria, except for Acidobacteria, and fungal phyla Ascomycota, Mortierellomycota and unassigned fungi. Several treatment-specific biomarkers were revealed through Linear discriminant analysis effect size (LEfSe) analysis. In conclusion, the change in the structure of root-associated communities driven by plant compartment and genetics suggests dynamic interactions in the host plant microbiome. Short-term silicate and biofertilizer amendments improved soil physiochemical status and altered bacterial and saprotrophic fungal communities, which have important implications for sustainable rice production.

Molecular characterization of two novel totiviruses coinfecting the basal fungus Conidiobolus adiaeretus.

A number of viruses have recently been discovered in all major fungal phyla using high-throughput sequencing. However, basal fungi remain among the least-explored organisms with respect to the presence of mycoviruses. In this study, we characterized two mycoviruses coinfecting the basal fungus Conidiobolus adiaeretus, which we have named "Conidiobolus adiaeretus totivirus 1" (CaTV1) and "Conidiobolus adiaeretus totivirus 2" (CaTV2). Due to their similar sizes, the genomic RNAs of these two viruses comigrated as a single band in 1.5% agarose gel electrophoresis but could be distinguished and characterized by next-generation sequencing and RT-PCR. Like those of other totiviruses, the genomes of both CaTV1 and CaTV2 have two discontinuous open reading frames: ORF1 and ORF2, encoding a putative capsid protein and a putative RNA-dependent RNA polymerase (RdRp), respectively. The RdRps of CaTV1 and CaTV2 have 62.73% and 63.76% amino acid sequence identity, respectively, to Wuhan insect virus 26 and have 62.15% amino acid sequence identity to each other. A maximum-likelihood phylogenetic tree based on RdRp amino acid sequences showed that both CaTV1 and CaTV2 clustered in a clade with members of the genus Totivirus. Therefore, we propose that CaTV1 and CaTV2 are two new members of the genus Totivirus in the family Totiviridae.

Assessing the impact of seasonal freezing and thawing on the soil microbial quality in arid northwest China

In drylands, soil microorganisms play a vital role in restoring degraded soils, and soil microbiota is significantly affected by human activities and climate events, such as seasonal freezing and thawing. However, the response of soil microbes to freezing and thawing, as well as their properties in drylands agroecosystems, remains unknown. This study investigated the effects of seasonal freezing and thawing on soil fungal and bacterial communities, multifunctionality, and soil microbial quality in a dryland agroecosystem. It has been observed that seasonal freezing and thawing promoted nutrient releases such as total carbon and available phosphorus. After thawing, soil catalase and cellulase activities increased while acid phosphatase and urease activities and total nitrogen content at topsoil decreased. Soil microbial biomass carbon content at 0–40 cm depth was significantly reduced by 94.77 %. Importantly, freezing and thawing considerably shifted the composition of fungal groups, while the soil bacterial community exhibited more stress tolerance to freezing-thawing. Compared to pre-freezing, the relative abundance of dominant fungal phyla such as Basidiomycota and Mortierellomycota decreased. At the same time, Ascomycota increased after thawing, and the relative abundance of pathogenic fungus also increased. For dominant bacteria phylum, freezing and thawing increased the relative abundance of Proteobacteria and Gemmatimonadetes while Micrococcaceae declined. Freezing and thawing significantly increased bacterial diversity and evenness by 4.94 % and 4.19 %, respectively, but decreased fungal richness and diversity by 23.49 % and 14.91 %, respectively. The minimum and total data sets were used to evaluate soil quality and we found that freezing and thawing significantly negatively impacted soil multifunctionality and microbial quality. In summary, this study demonstrates that the seasonal freezing-thawing has a significant negative impact on soil microbial quality and multifunctionality, and accelerates soil degeneration in dryland agroecosystem.

Evaluating the Effect on Cultivation of Replacing Soil with Typical Soilless Growing Media: A Microbial Perspective

Bacteria and fungi are good indicators for soil health as well as soilless growing media (SGM) health. However, there is very limited information about the fungal and bacterial communities for SGM. In the present study, coir substrate and peat-based substrate were used as typical SGM under drip irrigation and tidal irrigation to understand the situation of fungal and bacterial communities by high-throughput sequencing technology. In this study, both environmental factors and microbial communities were significantly affected by SGM type and irrigation pattern, in which SGM type played a major role and irrigation pattern played a minor role. The bacterial phyla Actinobacteriota and Proteobacteria and the fungal phyla Ascomycota were more closely related to environmental factors including EC, pH, NO3−, NH4+ and ω as well as urease and phosphatase. The bacterial and fungal communities in the two SGM had some similarities with those in soil. In addition, the functions of the soil, including key soil organisms, carbon mineralization, wood decomposition, nitrification, denitrification, carbon fixation, nitrogen fixation and methanotrophy, could be basically performed by the two SGM. In general, the SGM should possess common soil capabilities according to bacterial and fungal analyses, but there are numerous fungi of unknown function that need be addressed in the future. Meanwhile, these results improve our understanding of the correlation between the environmental factors and the microbiome, and provide basic guidance for management and research on SGM in the future.

Effects of Wheat Tempering with Slightly Acidic Electrolyzed Water on the Microbiota and Flour Characteristics.

Slightly acidic electrolyzed water (SAEW) was prepared and used as wheat tempering water. This study explored the impacts of tempering with SAEW on microbial load and diversity and quality properties of wheat flour. As SAEW volume ratio increased, the residual level of total plate counts (TPC) and mould/yeast counts (MYC) decreased dramatically (p &lt; 0.05). Based on genomics analysis, bacterial 16S rRNA gene and fungal ITS1 gene region were performed to characterize the changes in microbial communities' composition and diversity in response to SAEW treatment. SAEW optimal volume ratio (6.5:10, v/v) of SAEW with distilled water influenced wheat microbiome composition, with a higher microbial diversity and abundance discovered on the control grains. Bacteroidetes of predominant bacterial phylum and Ascomycota of the most abundant fungal phylum were reduced after SAEW optimal volume ratio tempering. The flour yield is higher and ash content is lower than the control samples. Falling number and "b*" in terms of colour markedly increased. DSC (Differential Scanning Calorimetry) test showed that To (onset temperature), Tp (peak temperature), and Tc (conclusion temperature) were significantly decreased in thermal characteristics of flour. Gluten content, protein content, ΔH and pasting properties tests showed no significant change. It can be concluded that SAEW should be applied on wheat tempering for producing clean wheat flour. ANOVA and Tukey's honestly significant difference (HSD) test were used for the analysis of variance and differences between the experimental and control groups, with p &lt; 0.05.

Effects of Exogenous Bacterial Agents on Material Transformation and Microbial Community Composition during Composting of Tomato Stalks

Tomato stems can pollute the environment and also cause resource costs. In this study, five combinations of microbial agents were added to tomato stems for aerobic composting to find effective microbial formulations to improve composting performance and product quality through comparative analysis. Six treatments were set up: T1 (Microbial agents A), T2 (0.5% Microbial agents B), T3 (0.5% Microbial agents C), T4 (0.5% Microbial agents D), T5 (0.5% Microbial agents E) and T6 (no addition). The physicochemical parameters of the composting system were measured, and the dynamics of the microbial community during the composting process were studied using high-throughput sequencing technology. The results showed that the T1 treatment had a longer high-temperature period than T6 and the highest cellulose degradation rate (62.0%). The contents of total phosphorus (TP), total potassium (TK) and effective potassium (AK) were 8.11 g·kg−1, 53.98 g·kg−1 and 45.62 g·kg−1, respectively, at the end of composting, representing increases of 270.3%, 56.6% and 25.40% compared to the initial values, significantly higher than the control (p &lt; 0.05). The Chao1 and Shannon indexes of T1 treatment were 73.5% and 41.7% higher in the compost decay stage for bacteria, and 50.2% and 18.1% for fungi, significantly higher than in T6 (p &lt; 0.05) compared to the initial values. During the high-temperature phase, the abundance of Aspergillus increased (4.13% to 44.24%) the abundance of Staphylococcus decreased (58.31% to 8.90%). In terms of numbers and species diversity, bacterial communities were more abundant than fungal communities. Proteobacteria, Firmicutes, Actinomycetes and Bacteroides were the four main bacterial phyla, while Ascomycetes was the absolutely dominant fungal phylum. In conclusion, the addition of microbial agent A can effectively improve the nutrient content of tomato stem compost, promote the maturation of compost, and regulate the microbial community structure and can realize the resource utilization of tomato stems.

Effects of residual mulching films with different mulching years on the diversity of soil microbial communities in typical regions

Polyethylene mulching film plays a critical role in agricultural production. To clarify the impact of residual film and microplastics on soil microorganisms, this study examined four cotton fields with different film coverage years in typical areas of Xinjiang and analyzed the changes in soil bacterial and fungal community structure and diversity under residual film and microplastics using high-throughput sequencing technology. The results showed that the residual film in the 0–150 mm soil layers and 150–300 mm soil layers at the same sampling point had spatial distribution characteristics of 60–70% and 30–40%, respectively. The short period of the 0–10 years film mulching treatment increased the soil microbial diversity of the cotton field, whereas continuous film mulching for 25 years significantly decreased the soil microbial diversity, in which Proteobacteria was the dominant bacterial phylum and Ascomycetes was the dominant fungal phylum. The microbial diversity of the film-covered soil was lower than that of the control group. The spatial distribution of the residual film and microplastic changed the distribution of the microbial communities. The diversity of the microbial community structure of the 0–150 mm soil layers was higher than that of the 150–300 mm soil layers. The increase in residual film and microplastics had no significant effect on the diversity of the fungal community but decreased the diversity of the soil bacterial community and decreased the relative abundance of Proteobacteria and Campylobacter. In conclusion, long-term film mulching reduced the soil microbial diversity in cotton fields. This study provides a theoretical basis for understanding the impact of film residues on microorganisms and the ecological environment in typical areas.

Preparation of phosphorus-modified biochar for the immobilization of heavy metals in typical lead-zinc contaminated mining soil: Performance, mechanism and microbial community

The use of modified biochar for the remediation of heavy metal (HM) has received much attention. However, the immobilization mechanism of biochar to multiple HMs and the interaction of different forms of HMs with microorganisms are still unclear. K2HPO4-modified biochar (PBC) was produced and used in a 90-days immobilization experiment with soil collected from a typic lead-zinc (Pb–Zn) mining soil. Incubation experiments showed that PBC enhanced the transformation of Cd, Pb, Zn and Cu from exchangeable (Ex-) and/or carbonate-bound forms (Car-) to organic matter-bound (Or-) and/or residual forms (Re-). After scanning electron microscopy-energy dispersive X-ray spectrometer (SEM-EDS), X-ray diffractometry (XRD), fourier transform infrared (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS) analysis, the mechanisms of HM immobilization by PBC were proposed as precipitation (PO43-, HPO42-, OH- and CO32-), electrostatic attraction, complexation (–COOH, –OH and R–O–H) and the indirect roles of soil parameter variations (pH, moisture and microbial community). Microbial community analysis through high-throughput sequencing showed that PBC reduced bacterial and fungal abundance. However, addition of PBC increased the relative proportions of Proteobacteria by 15.04%–42.99%, Actinobacteria by 4.74%–22.04%, Firmicutes by 0.76%–23.35%, Bacteroidota by 0.16%–12.34%, Mortierellomycota by 4.00%–9.66% and Chytridiomycota by 0.10%–13.7%. Ex-Cd/Pb/Zn, Car-Cd/Zn and Re–Cd/Pb/As were significantly positively (0.001<P≤0.05) correlated with bacterial phyla of Crenarchaeota and Methylomirabilota, and Re–Cu and Ex-/Car-/Fe–Mn oxide-bound (Fe–Mn-)/Or-As were significantly positively correlated (0.001<P≤0.05) with the bacterial phyla of Proteobacteria and Bacteroidota. While Car-Cd/Zn and Re–Pb/As were positively correlated (0.01<P≤0.05) with fungal phyla of Ascomycota, Glomeromycota, Kickxellomycota, Basidiomycota and Mucoromycota. The bacterial network contained more complex interactions than the fungal network, suggesting that bacteria play a larger role in HMs transformation processes. The results indicate that PBC is an effective agent for the remediation of HMs polluted soil in Pb–Zn mining areas.