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Frontiers in Microbiology 2024The thermophilic fungus is a saprobe that is commonly isolated from soil. Here, we identified a Gram-positive bacteria-selective antimicrobial secondary metabolite from...
The thermophilic fungus is a saprobe that is commonly isolated from soil. Here, we identified a Gram-positive bacteria-selective antimicrobial secondary metabolite from this fungal species, harzianic acid (HA). Using strain 168 combined with dynamic bacterial morphology imaging, we found that HA targeted the cell membrane. To further study the antimicrobial activity of HA, we isolated an HA-resistant strain, strain M9015, and discovered that the mutant had more translucent colonies than the wild type strain, showed cross resistance to rifampin, and harbored five mutations in the coding region of four distinct genes. Further analysis of these genes indicated that the mutation in might be responsible for the translucency of the colonies, and mutation in for resistance to both HA and rifampin. We conclude that HA is an antimicrobial agent against Gram-positive bacteria that targets the cell membrane.
PubMed: 38348189
DOI: 10.3389/fmicb.2024.1332774 -
The Science of the Total Environment Mar 2024Anthropogenic nitrogen (N) deposition and fertilization in boreal forests frequently reduces decomposition and soil respiration and enhances C storage in the topsoil....
Anthropogenic nitrogen (N) deposition and fertilization in boreal forests frequently reduces decomposition and soil respiration and enhances C storage in the topsoil. This enhancement of the C sink can be as strong as the aboveground biomass response to N additions and has implications for the global C cycle, but the mechanisms remain elusive. We hypothesized that this effect would be associated with a shift in the microbial community and its activity, and particularly by fungal taxa reported to be capable of lignin degradation and organic N acquisition. We sampled the organic layer below the intact litter of a Norway spruce (Picea abies (L.) Karst) forest in northern Sweden after 20 years of annual N additions at low (12.5 kg N ha yr) and high (50 kg N ha yr) rates. We measured microbial biomass using phospholipid fatty-acid analysis (PLFA) and ergosterol measurements and used ITS metagenomics to profile the fungal community of soil and fine-roots. We probed the metabolic activity of the soil community by measuring the activity of extracellular enzymes and evaluated its relationships with the most N responsive soil fungal species. Nitrogen addition decreased the abundance of fungal PLFA markers and changed the fungal community in humus and fine-roots. Specifically, the humus community changed in part due to a shift from Oidiodendron pilicola, Cenococcum geophilum, and Cortinarius caperatus to Tylospora fibrillosa and Russula griseascens. These microbial community changes were associated with decreased activity of Mn-peroxidase and peptidase, and an increase in the activity of C acquiring enzymes. Our results show that the rapid accumulation of C in the humus layer frequently observed in areas with high N deposition is consistent with a shift in microbial metabolism, where decomposition associated with organic N acquisition is downregulated when inorganic N forms are readily available.
Topics: Nitrogen; Soil; Carbon; Forests; Microbiota; Soil Microbiology
PubMed: 38325494
DOI: 10.1016/j.scitotenv.2024.170741 -
Data in Brief Feb 2024Mining activities in the Zambian Copperbelt Province have led to the release of heavy metal-containing waste, causing contamination in nearby areas. Despite this...
Mining activities in the Zambian Copperbelt Province have led to the release of heavy metal-containing waste, causing contamination in nearby areas. Despite this environmental challenge, limited knowledge exists regarding the mycobiota in copper mine sites. This study investigates fungal community structure in copper(Cu) and cobalt (Co) contaminated soils around decommisioned dams in Kitwe. Metagenomic analysis of the ITSF1 gene amplicons was used for the purpose. The composition of soil fungal communities was characterized, and the findings revealed significant insights. At the phylum level, dominated the fungal profiles in the tailings (64.59%), followed by (21.30%), (4.53%), and (0.0275%). Several fungal genera, including , P, and , were more abundant in contaminated tailings soils, suggesting their potential in leaching, absorbing, and transforming heavy metals. In contrast, the reference soil at Mwekera National Forest exhibited different dominance patterns with four fungal phyla identified, with and dominating most samples. , known for forming arbuscular mycorrhizae with plants, were found in contaminated soils, while , which can serve ecological roles in various ecosystems, were also present. Notable fungal species such as , and demonstrated resilience to Cu and Co, the primary contaminants in the Copperbelt.
PubMed: 38186741
DOI: 10.1016/j.dib.2023.109951 -
World Journal of Microbiology &... Oct 2023The continuous cropping obstacle is the main factor in leading to difficulty in American ginseng replanting. The dormant microbiota in the soil may be the cause of...
The continuous cropping obstacle is the main factor in leading to difficulty in American ginseng replanting. The dormant microbiota in the soil may be the cause of American ginseng disease and eventually caused continuous cropping obstacles, but there are few studies on the dynamic changes of soil microenvironment after American ginseng planting. In this study, we tracked short-term variation in physicochemical properties, enzyme activities, and fungal communities over time-series in soils with continuous cropping obstacle under crop rotation and probiotic Bacillus treatments. Furthermore, we examined the relationships between the important fungal compositions and the soil properties. The results showed that sucrase, cellulase, urease and acid phosphatase activities were significantly increased, while catalase and dehydrogenase were decreased with treatments time. Rotation treatment significantly affected the diversity, dissimilarity degree and species distribution of soil fungal community with continuous cropping obstacle over a short-term. Moreover, beneficial fungal biomarkers such as Cladorrhinum, Oidiodendron, and Mariannaea were accumulated at 48 h under rotation treatments. Almost all fungal biomarkers were negatively correlated with hydrolases and positively correlated with oxidoreductases and acid phosphatase under crop rotation treatments. This study suggested that compared to probiotic Bacillus, crop rotation can significantly affect soil fungal community structure, especially the enrichment of specific potentially beneficial fungal species. Our findings provide a scientific basis for understanding the dynamic changes of fungal communities and soil properties with continuous cropping obstacle of American ginseng in initial stage of soil improvement.
Topics: Soil; Mycobiome; Bacillus; Panax; Acid Phosphatase; Biomarkers; Soil Microbiology
PubMed: 37874395
DOI: 10.1007/s11274-023-03807-w -
Journal of Fungi (Basel, Switzerland) Jul 2023G.L. Barron is a recognized fungal species capable of forming ericoid mycorrhiza with various positive effects on host plants; therefore, newly found and previously...
G.L. Barron is a recognized fungal species capable of forming ericoid mycorrhiza with various positive effects on host plants; therefore, newly found and previously uncharacterized strains may be valuable for heather plants' controlled mycorrhization. Characteristics of the F3860 strain were studied, i.e., mycelium growth on various nutrient media and the ability to secrete auxins and enzymes. F3860 grew rapidly on malt extract agar and potato dextrose agar. It was also able to grow on nutrient media suitable for heather plant cultivation. The presence of the flavonoids rutin and quercetin increased the mycelium growth rate compared to the control, starting from the 8th to the 13th days of cultivation. The ability to secrete auxins was confirmed with bioassay and thin-layer chromatography, and their content, as well as phytase activity, was estimated spectrophotometrically. Both in nutrient media with tryptophan and without it, F3860 secreted about 6 μg IAA/mL growth medium. F3860 possessed extracellular phytase, protease, and phenol oxidase activities. The investigation indicates F3860's promise for heather seedling inoculation as an approach to increase their fitness.
PubMed: 37504716
DOI: 10.3390/jof9070728 -
Frontiers in Microbiology 2023Corm rot is the most important disease of saffron, for which fungi from several genus such as spp. spp. and spp., have been previously reported to be the pathogens....
Corm rot is the most important disease of saffron, for which fungi from several genus such as spp. spp. and spp., have been previously reported to be the pathogens. In this research, we used a combination of amplicon sequencing and traditional isolation methods to identify the causal agents, main infection source. The diversity of microbial communities in diseased saffron corms and soil decreased significantly compared with healthy corms and soil. The contents of and in healthy and diseased corms were similarly high, indicating that them were not directly related to the occurrence of corm rot. But the relative abundance of , and were significantly higher in the diseased corms than healthy ones. The abundance of increased, while the abundance of , and the endophytic beneficial bacteria decreased, which may relate to the occurrence of the disease. The co-occurrence network diagram showed that the correlation between fungal and bacterial communities was mainly positive. Plant pathogens were relatively abundant in the diseased soil, according to functional gene prediction. At the same time, we also collected 100 diseased corms from the fields in Jiande, where is known as the "hometown of saffron." All isolated pathogenic strains were identified as through morphological observation and phylogenetic tree analysis of ITS, and . To better clarify the biological characteristics of . , we cultured the isolates at different temperatures and pH values. The optimum temperature for mycelial growth and sporulation was 25°C, pH 6,carbon sources sorbitol and nitrogen sources, peptone. In short, our results suggests that was the pathogen causing corm rot in Jiande and corms other than soils are the main primary infection source. These new understanding of saffron corm rot will provide the theoretical basis for its better and efficiently management.
PubMed: 37362925
DOI: 10.3389/fmicb.2023.1188376 -
Frontiers in Microbiology 2023Mycorrhizal helper bacteria (MHB) can promote mycorrhizal fungal colonization and form mycorrhizal symbiosis structures. To investigate the effect of interactions...
Mycorrhizal helper bacteria (MHB) can promote mycorrhizal fungal colonization and form mycorrhizal symbiosis structures. To investigate the effect of interactions between mycorrhizal beneficial microorganisms on the growth of blueberry, 45 strains of bacteria isolated from the rhizosphere soil of were screened for potential MHB strains using the dry-plate confrontation assay and the bacterial extracellular metabolite promotion method. The results showed that the growth rate of mycelium of 143, an ericoid mycorrhizal fungal strain, was increased by 33.33 and 77.77% for bacterial strains L6 and LM3, respectively, compared with the control in the dry-plate confrontation assay. In addition, the extracellular metabolites of L6 and LM3 significantly promoted the growth of 143 mycelium with an average growth rate of 40.9 and 57.1%, respectively, the cell wall-degrading enzyme activities and genes of 143 was significantly increased. Therefore, L6 and LM3 were preliminarily identified as potential MHB strains. In addition, the co-inoculated treatments significantly increased blueberry growth; increased the nitrate reductase, glutamate dehydrogenase, glutamine synthetase, and glutamate synthase activities in the leaves; and promoted nutrient uptake in blueberry. Based on the physiological, and 16S rDNA gene molecular analyses, we initially identified strain L6 as and LM3 as . Metabolomic analysis revealed that mycelial exudates contain large amounts of sugars, organic acids and amino acids, which can be used as substrates to stimulate the growth of MHB. In conclusion, L6 and LM3 and 143 promote each other's growth, while co-inoculation of L6 and LM3 with 143 can promote the growth of blueberry seedlings, providing a theoretical basis for further studies on the mechanism of ericoid mycorrhizal fungi-MHB-blueberry interactions. It laid the technical foundation for the exploitation of biocontrol strain resources and the development of biological fertilizer.
PubMed: 37143547
DOI: 10.3389/fmicb.2023.1180319 -
Plants (Basel, Switzerland) Feb 2023Blueberry roots are inefficient in taking up water and nutrients, a fact partially related to their scarcity of root hairs, but they improve nutrient uptake by...
Blueberry roots are inefficient in taking up water and nutrients, a fact partially related to their scarcity of root hairs, but they improve nutrient uptake by associating with ericoid mycorrhizal and endophytic fungi. However, the benefits of this association are both cultivar- and fungus-dependent. Our objective was to assess the effect of inoculation with three native fungal strains ( A, BP, and BC) on plantlet growth, plantlet survival, and nitrogen (N) absorption of the southern highbush blueberry (SHB) cultivars Biloxi and Misty. The fungal strains were inoculated into the peat-based substrate for growing blueberry cultivars, and plantlets produced by micropropagation were transplanted and grown for four months. The three inoculated strains positively affected the survival percentage in at least one of the cultivars tested, whereas BP positively affected plant biomass, N derived from fertilizer absorption, N content, and plant N recovery (%) in both Biloxi and Misty. Our results show that the BP strain may prove useful as a bio-inoculant to improve blueberry production during the nursery stage.
PubMed: 36840140
DOI: 10.3390/plants12040792 -
Mycorrhiza Mar 2023Most of our knowledge on the ericoid mycorrhizal (ErM) symbiosis comes from temperate heathlands characterized by acidic peaty soils and many experiments with a few...
Most of our knowledge on the ericoid mycorrhizal (ErM) symbiosis comes from temperate heathlands characterized by acidic peaty soils and many experiments with a few ascomycetous fungi. However, ericaceous plants thrive in many other ecosystems and in temperate coniferous forests, their seedlings often prosper on decomposing wood. While wood is typically exploited by basidiomycetous ectomycorrhizal (EcM) and saprobic fungi, the role of ErM fungi (ErMF) is much less clear. We explored the cultivable mycobiota of surface sterilized hair roots of Vaccinium spp. growing on decomposing wood in two coniferous forests in Mid-Norway (Scandinavia) and Northern Bohemia (Central Europe). Obtained isolates were identified using molecular tools and their symbiotic potential was tested in vitro. While the detected community lacked the archetypal ErMF Hyaloscypha hepaticicola and the incidence of dark septate endophytes and EcM fungi was negligible, it comprised other frequent asexual ascomycetous ErMF, namely H. variabilis and Oidiodendron maius, together with several isolates displaying affinities to sexual saprobic H. daedaleae and H. fuckelii. Ascomycete-suppressing media revealed representatives of the saprobic basidiomycetous genera Coprinellus, Gymnopilus, Mycena (Agaricales), and Hypochnicium (Polyporales). In the resyntheses, the tested basidiomycetes occasionally penetrated the rhizodermal cells of their hosts but never formed ericoid mycorrhizae and in many cases overgrew and killed the inoculated seedlings. In contrast, a representative of the H. daedaleae/H. fuckelii-related isolates repeatedly formed what morphologically appears as the ErM symbiosis and supported host's growth. In conclusion, while basidiomycetous saprobic fungi have a potential to colonize healthy-looking ericaceous hair roots, the mode(-s) of their functioning remain obscure. For the first time, a lineage in Hyaloscypha s. str. (corresponding to the former Hymenoscyphus ericae aggregate) where sexual saprobes are intermingled with root symbionts has been revealed, shedding new light on the ecology and evolution of these prominent ascomycetous ErMF.
Topics: Symbiosis; Mycorrhizae; Ericaceae; Vaccinium; Plant Roots; Wood; Ecosystem; Basidiomycota; Agaricales
PubMed: 36700963
DOI: 10.1007/s00572-023-01101-z -
Frontiers in Plant Science 2022Several microorganisms in the plant root system, especially in the rhizosphere, have their own compositions and functions. Corm rot is the most severe disease of ,...
INTRODUCTION
Several microorganisms in the plant root system, especially in the rhizosphere, have their own compositions and functions. Corm rot is the most severe disease of , leading to more than 50% mortality in field production.
METHODS
In this study, metagenomic sequencing was used to analyze microbial composition and function in the rhizosphere of for possible microbial antagonists against pathogenic .
RESULTS
The microbial diversity and composition were different in the rhizosphere from different habitats. The diversity index (Simpson index) was significantly lower in the rhizospheric soil from Chongming (Rs_CM) and degenerative rhizospheric soil from Chongming (RsD_CM) than in others. Linear discriminant analysis effect size results showed that differences among habitats were mainly at the order (Burkholderiales, Micrococcales, and Hypocreales) and genus ( and ) levels. Correlation analysis of the relative lesion area of corm rot showed that was the most negatively correlated bacterial genus (ρ = -0.7934, < 0.001), whereas was the most negatively correlated fungal genus (ρ = -0.7047, < 0.001). The relative lesion area result showed that from Qiaocheng had the highest resistance, followed by Xiuzhou and Jiande. groups with high disease resistance had abundant pathogen resistance genes, such as chitinase and β-1,3-glucanase genes, from rhizosphere microorganisms. Further, 13 bacteria and 19 fungi were isolated from rhizosphere soils, and antagonistic activity against pathogenic . was observed on potato dextrose agar medium. corm experiments confirmed that SR38, sp. SR55, SR379, and sp. SR343 displayed biocontrol activity against corm rot disease, with biocontrol efficiency of 20.26%, 31.37%, 39.22%, and 14.38%, respectively.
DISCUSSION
This study uncovers the differences in the microbial community of rhizosphere soil of with different corm rot disease resistance and reveals the role of four rhizospheric microorganisms in providing the host with resistance against corm rot. The obtained biocontrol microorganisms can also be used for application research and field management.
PubMed: 36483959
DOI: 10.3389/fpls.2022.1045147