Saprotrophic Fungi Research Articles

High ectomycorrhizal relative abundance during winter at the treeline

Abstract The rhizosphere is the soil region around plant roots hosting a diverse microbial community, influencing nutrient availability and how plants react to extreme conditions. However, our understanding of the fungi biodiversity and the impact of environmental variations on this biodiversity is still in its infancy. Our study investigates fungal communities’ diversity and functional traits in the rhizosphere of Nothofagus pumilio, one of the few winters deciduous treeline species in the world, forming the treeline in southern South America. At four distinct locations covering 10° latitude, we collected soil samples at treeline and 200 meters below over four seasons during a single year. We employed ITS metabarcoding to elucidate fungal community structures. Our results reveal that fungal diversity was mainly determined by latitudinal variation, with higher levels during warmer seasons and lower altitudes. Interestingly, we found a marked dominance of ectomycorrhizal (EcM) fungi at the treeline, particularly during the winter. In contrast, saprotrophic fungi were more abundant at lower altitudes, particularly during the warmer spring and summer seasons. These findings highlight the temporal and spatial dynamics of rhizospheric fungal communities and their potential roles in ecological processes, emphasizing the value of these communities as indicators of environmental change in high-elevation forests.

Effect of Multiyear Biodegradable Plastic Mulch on Soil Microbial Community, Assembly, and Functioning

The increasing use of biodegradable plastic mulch like polybutylene adipate terephthalate (PBAT) has raised concerns about its long-term environmental impact. In this study, we investigated the effects of multiyear PBAT mulch application on bacterial and fungal communities, assembly mechanisms, and key ecological functions. The microbial community diversity and composition were significantly altered after multiyear biodegradable plastic mulching. We observed that PBAT treatment enriched specific bacterial genera, such as Pantoea, potentially involved in plastic degradation, and fungal genera like Cephaliophora and Stephanosporaceae, which may play a role in organic matter decomposition. A null model analysis revealed that bacterial community assembly was largely shaped by deterministic processes, with stronger environmental selection pressures in PBAT-treated soils, while fungal communities were more influenced by stochastic processes. In addition, multiyear PBAT mulch application also impacted the functionality of the soil microbial communities. PBAT exposure enhanced biofilm formation in aerobic bacteria, promoting aerobic degradation processes while also reducing the abundance of stress-tolerant bacteria. Additionally, PBAT altered key microbial functions related to carbon, nitrogen, and sulfur cycling. Notably, the fungal communities exhibited functional shifts, with an increase in saprotrophic fungi being beneficial for nutrient cycling, alongside a potential rise in plant pathogenic fungi. These findings underscore the multiyear ecological impacts of biodegradable plastics, suggesting microbial adaptation to plastic degradation and changes in key ecological functions, with implications for agricultural sustainability and bioremediation strategies.

Growth Characteristics and Freezing Tolerance of Ectomycorrhizal and Saprotrophic Fungi: Responses to Normal and Freezing Temperatures

Growth Characteristics and Freezing Tolerance of Ectomycorrhizal and Saprotrophic Fungi: Responses to Normal and Freezing Temperatures

The Impact of Nanoparticles and Molecular Forms of TiO2 on the Rhizosphere of Plants in the Example of Common Wheat (Triticum aestivum L.)-Shifts in Microbiome Structure and Predicted Microbial Metabolic Functions.

This study investigated the effects of various titanium nanoparticles (TiO2NPs) on the structure, function, and trophic levels of the wheat rhizobiome. In contrast to the typically toxic effects of small nanoparticles (~10 nm), this research focused on molecular TiO2 and larger nanoparticles, as follows: medium-sized (68 nm, NPs1) and large (>100 nm, NPs2). The results demonstrated significant yet diverse impacts of different TiO2 forms on the rhizosphere microbiota. Large TiO2NPs2 and molecular TiO2 adversely affected the bacteriobiome and mycobiome, leading to an increase in autotrophic microbial groups. In contrast, medium-sized TiO2NPs1 shifted the microbiome toward chemoheterotrophy, promoting plant growth-associated bacteria, fungal saprotrophs, and potential phytopathogens, suggesting a beneficial r-strategy within the rhizosphere. Other treatments induced oligotrophic conditions, resulting in a less flexible rhizobiome with diminished root associations but an increased abundance of Trichoderma spp. Structural modelling revealed that even minor changes in operational taxonomic units (OTUs) could significantly alter the microbiota's metabolic potential. These findings highlight the importance of further research to optimize nanoparticle applications for sustainable agriculture.

Moss Cover Modulates Soil Fungal Functional Communities and Nutrient Cycling in Alpine Forests

Moss–cyanobacteria associations serve as significant nitrogen fixers and represent the primary nitrogen sink in boreal forests. Fungi, which are essential for soil biogeochemical cycling, have community structures intrinsically linked to forest ecosystem health and productivity. Using high-throughput sequencing, we investigated differences between moss-covered and non-moss soils in two alpine forests (both plantation and natural forests) by examining soil nitrogen contents, fungal community structure, composition, and functional guilds. Results demonstrated that moss cover enhanced soil nutrient contents, including total carbon, total nitrogen, and inorganic nitrogen. It also altered fungal community characteristics, resulting in higher Chao1 and Shannon diversity indices, as well as a more complex fungal network. Notable changes in functional guilds included an increase in saprotrophic fungi abundance and a decrease in ectomycorrhizal fungi. Our findings support the concept that moss cover creates distinct soil environments: moss-covered soils attract decomposers and nutrient-mobilizing fungi (particularly saprotrophs and ectomycorrhiza), while non-moss soils favor ectomycorrhizal fungi that relieve nutrient limitation through extensional mycelial networks. These findings highlight the critical role of moss cover in sustaining forest soil health and resilience, positioning it as a cornerstone of carbon and nutrient cycling within forest ecosystems.

Bacterial wilt disease alters the structure and function of fungal communities around plant roots

BackgroundFungal communities around plant roots play crucial roles in maintaining plant health. Nonetheless, the responses of fungal communities to bacterial wilt disease remain poorly understood. Here, the structure and function of fungal communities across four consecutive compartments (bulk soil, rhizosphere, rhizoplane and root endosphere) were investigated under the influence of bacterial wilt disease.ResultsThe results showed that bacterial wilt disease caused different assembly patterns of fungal communities in the bulk soil, rhizosphere, rhizoplane and endosphere. Under the influence of bacterial wilt disease, a decreased fungal diversity was observed in the rhizoplane and endosphere, and completely different kinds of fungal genera were enriched in the four compartments. The complexity and stability of fungal networks were less affected, but the number of key fungal members in networks were significantly reduced in diseased samples. Functional predictions based on FUNGuild suggested that with the pathogen infection, saprotrophic fungi were increased in the bulk soil, but pathotrophic fungi (potential plant and animal pathogens) were increased in the rhizosphere, rhizoplane and endosphere.ConclusionThis work provides a deep insight into the effects of bacterial wilt disease on fungal communities along the soil-root continuum, and is helpful to identify plant-associated beneficial fungi to resist plant disease.Clinical trial numberNot applicable.

Urbanized lands degrade surrounding grasslands by deteriorating the interactions between plants and soil microbiome.

To mitigate overgrazing on grasslands, towns were constructed in some pastoral regions of China to relocate pastoralists. Nevertheless, whether and how the urbanized lands impact the surrounding grassland ecosystem remains unclear. We assessed the impacts of urbanized lands on the plant and soil interactions within the surrounding grasslands in order to ensure an eco-sustainable pastoralist relocation. The town with 1 km radius was selected as urbanization sample and a grassland with 1 km radius was selected as nature grassland sample. Plants and soil were investigated in nature grassland (NG), and areas 1 km (T-1 km), 2 km (T-2 km), and 3 km (T-3 km) from the center of the town. In T-1 km and T-2 km, compared to the NG, plant diversity, the abundance of dominant plant species, the abundance of soil wood saprotroph fungi, soil water content (SWC), and total organic carbon (TOC) decreased, while soil plant pathogen fungi, soil pH, and total phosphatase (TP) increased. Conversely, no such changes were observed in T-3 km. The results of Mantel test and Partial least squares path model suggest that the decrease in soil TOC and SWC, along with the increase in pH and TP in T-1 km and T-2 km, lead to a decline in wood saprotroph fungi and an increase in plant pathogen fungi, ultimately resulting in reductions in plant diversity and the abundance of dominant plant species. These results indicate that towns in pastoral areas can lead to surrounding grassland degradation by deteriorating the plant-soil interactions.

<i>Phaeocalicium populneum</i>, a saprotrophic fungus rediscovered in Poland

The saprotrophic fungus <i>Phaeocalicium populneum</i> was noted from Poland only from one confirmed locality at the end of the 19th century, from the vicinity of Żagań (SW Poland). A new locality of this species is presented, which was found in 2017 on the bark of <i>Populus nigra</i>, within the Puszcza Darżlubska Forest in northern Poland. The species is common in Europe, and we consider that <i>Ph. populneum</i> is not rare in the country,

Effects of Ectomycorrhizae and Hyphae on Soil Fungal Community Characteristics Across Forest Gap Positions

The interactive effects of environmental heterogeneity caused by forest gaps and ectomycorrhizae on fungal community characteristics remain insufficiently explored. To address this knowledge gap, we established a three-year field manipulation experiment in a Picea asperata (Picea asperata Mast.) plantation located in the subalpine region of western Sichuan, China. Growth bags with three mesh sizes—1000 μm (allowing ectomycorrhizae and hyphae), 48 μm (excluding ectomycorrhizae), and 1 μm (excluding both)—were placed across forest gaps (closed canopy, gap edge, and gap center) to investigate how gap disturbances influence soil fungal communities via changes in ectomycorrhizal and hyphal turnover alongside soil physicochemical properties. Soil fungal α-diversity was significantly lower under closed-canopy conditions than at forest gap centers and remained unaffected by ectomycorrhizal and hyphal treatments. Particularly, species diversity increased by 9%, and phylogenetic diversity increased by 10% in forest gap centers compared to the closed canopy. In contrast, soil fungal β-diversity responded to both ectomycorrhizal/hyphal treatments (R2 = 0.061; p = 0.001) and forest gap positions (R2 = 0.033; p = 0.003). Pairwise comparative analyses revealed significant distinctions between treatments, concurrently excluding ectomycorrhizal and hyphal treatments versus other experimental treatments, as well as between closed-canopy conditions and forest gap centers. The fungal community was dominated by four major phyla: Ascomycota (25.6%–71.0%), Basidiomycota (17.7%–43.7%), Mortierellomycota (1.4%–24.5%), and Rozellomycota (0.4%–2.9%), the relative abundances of which were unaffected by either ectomycorrhizal/hyphal treatments or forest gap positions. The biomass of ectomycorrhizal and saprotrophic fungi showed no significant response to ectomycorrhizal/hyphal treatments. Notably, the exclusion of ectomycorrhizae and hyphae enhanced the significant correlations between fungal community characteristics and soil physicochemical properties. Hierarchical partitioning analysis revealed that the soil water content (SWC) and dissolved organic carbon content were the key determinants of soil fungal community characteristics beneath closed-canopy conditions. In contrast, at forest gap edges and centers, the fungal communities were predominantly shaped by the SWC and dissolved carbon and nitrogen contents. This study highlights the impacts of forest gap disturbances and ectomycorrhizal treatments on soil fungal communities, offering valuable insights for the sustainable management and biodiversity conservation of subalpine forest ecosystems.

Evaluation of DNA Extraction Methods for Microbial Community Profiling in Deadwood Decomposition.

As technologies advance alongside metabarcoding and metagenomic resources, particularly for larger fungal genomes, DNA extraction methods must be optimized to meet higher thresholds, especially from complex environmental substrates. This study focused on extracting fungal genomic compounds from woody substrates, a challenge due to the embedment of endophytic and saprotrophic fungi within wood cells, the physical recalcitrance of wood, the adsorption of nucleic acids to wood polymers, and the release of downstream inhibitors. Hypothesizing that cetyltrimethylammonium bromide would be the best option, we compared prominent methods by extracting and sequencing microbial DNA from sound and decayed birch (Betula papyrifera) and pine (Pinus resinosa). DNA quantities varied significantly depending on extraction methods and decay stage. The quality of DNA, in terms of purity and integrity, significantly impacted whether the samples could be amplified and sequenced. However, amplicon sequencing of bacterial and fungal communities revealed no significant extraction bias. This, along with the sequencing effectiveness and cost/time efficiency, indicates that Qiagen is the gold standard for woody substrates. This study increases confidence in published amplicon data sets regardless of the extraction methods, provides a cost-benefit table for making protocol decisions, and offers guidance on fungal DNA extractions from complex organic substrates (sound and decayed wood) that would best suit future metagenomic efforts.

Soil properties and microbial evolution during cropping system conversion: Insights from a 105-year study in southern China

Understanding the mechanisms by which soil environments and microbial communities evolve in response to long-term changes in cropping systems is essential for the development of effective ecological conservation and restoration strategies. In this study, variations of soil characteristics and the succession of microbial community assemblages and functions were investigated in southern Chinese deciduous forests and adjacent converted tea plantations at different ages (20, 40, 60, and 105 years). The results revealed significant alterations in soil properties and the emergence of distinct diversity patterns and assembly mechanisms for bacterial and fungal communities over the century-long succession period. Bacterial α-diversity exhibited a declining trend throughout succession, while fungal α-diversity experienced a rebound in the later stages. Null model analysis indicated that stochastic processes primarily drove the assembly of the bacterial community in both forests and tea plantations, whereas fungal community assembly gradually shifted from stochastic dominance to deterministic dominance. The strength of interactions between bacterial taxa in tea plantations decreased over time, but the topological properties of fungal networks were restored in tea plantations aged 60 and 105 years. The functional groups of bacteria associated with carbon cycling and saprotrophic fungi significantly increased after tea cultivation, which was closely linked to the proliferation of r-strategists stimulated by sufficient nutrients in tea plantations. It is noteworthy that in addition to typical environmental variables such as nutrients and pH, soil polyphenols in tea plantations also have a profound effect on the composition and assembly processes of bacterial and fungal communities. These findings advance the current understanding of how long-term cropping system changes affect soil microbial community assembly and functionality, and highlight the distinct strategies by which bacteria and fungi respond to cropping system change.

Nearly 30a shrub introduction in desert steppes has led to an increase in saprotrophic fungi, accelerating the degradation of carbon compounds and nitrate reduction

Clarifying how soil microbial communities respond to shrub introduction after overgrazing in desert steppe and their potential functions is crucial for understanding the biogeochemical processes involved in vegetation transformation and sustainability of desert grasslands. However, the dynamics of microbial communities remain poorly understood. We selected enclosed grasslands (20a), overgrazed grasslands, and shrublands (6a, 15a, and 25a) to explore how shrubs introduced influence soil microbial structure and functional groups over the long term after desert grassland degradation. The results showed that overgrazing and shrub introduction (Caragana korshinskii) had more significant impacts on microbial β diversity than on α diversity. Fungal communities were more sensitive to grassland degradation. In contrast, introducing shrubs affected both fungal and bacterial communities, and an increase in shrub age drove the synergistic effects of fungal species. Soil nitrate and microbial biomass nitrogen were the key factors affecting bacterial and fungal communities. Compared with enclosed grasslands, overgrazing and introducing shrubs significantly increased soil nitrate reduction, ectomycorrhizals, and endophytes. The introduction of shrubs after overgrazing in desert steppe further enhanced the decomposition of carbon compounds and reduced processes such as denitrification. During shrub introduction, total phosphorus, nitrate–nitrogen, and N-acetylglucosaminidase were key factors affecting carbon, nitrogen, and fungal functional groups. Variations in microbial diversity and functional groups, through their influence on extracellular enzymes activity and the availability of microbial biomass nutrients, ultimately explained 85%, 42%, and 34% the observed variations in soil carbon, nitrogen, and phosphorus content, respectively. This study aimed to investigate the long-term effects of anthropogenic shrub expansion on the structure and function of soil microbial communities in degraded desert steppes, provide a scientific basis for steppe restoration and management, and further understand their significance for ecosystem sustainability.

Stochasticity-dominated rare fungal endophytes contribute to coexistence stability and saponin accumulation in Panax species

Fungal communities inhabiting plant tissues are complex systems of inter-species interactions, consisting of both the “abundant biosphere” and “rare biosphere”. However, the composition, assembly, and stability of these subcommunities, as well as their contributions to productivity remain unclear. In this study, the taxonomic and functional composition, co-occurrence, and ecological assembly of abundant and rare fungal subcommunities in different tissues of three Panax species were investigated. Abundant subcommunities were dominated by potential plant pathogens belonging to Microbotryomycetes, while saprotrophic fungi like Agaricomycetes and Mortierellomycetes were more prevalent in rare subcommunities. The rare taxa played a central role in upholding the stability of the fungal networks as driven by Dothideomycetes and Sordariomycetes. Homogeneous selection played a larger role in the assembly of abundant fungal subcommunities compared to the rare counterparts, which was more dominated by stochastically ecological drift in all plant species. Rare biospheres played a larger role in the accumulation of saponin compared to their abundant counterparts, especially in the leaf endosphere, which was mainly affected by environmental factors (Mg, pH, OC, and etc.). Furthermore, we found that rare species belonging to unidentified saprotrophs were associated with saponin formation. This study provides hypotheses for future experiments to understand mechanisms accounting for the variations in the composition and function of rare fungal subcommunities across different Panax species.

Organic Farming Enhances Diversity and Recruits Beneficial Soil Fungal Groups in Traditional Banana Plantations.

This study investigates the impact of organic (OF) and conventional farming (CF) on soil fungal communities in banana monoculture plantations on Madeira Island. We hypothesized that OF promotes beneficial fungal groups over harmful ones, sustaining soil health. Soil samples were collected from six plantations (three OF and three CF) for ITS amplicon sequencing to assess fungal diversity. Results showed that OF significantly enhanced fungal alpha-diversity (Shannon-Wiener index) and Evenness. The phylum Ascomycota dominated OF systems, while Basidiomycota prevailed in CF. Mortierella, a beneficial genus, was abundant in OF and is observed in CF but was less evident, being the genus Trechispora the most well represented in CF agrosystems. Additionally, OF was associated with higher soil pH and Mg levels, which correlated positively with beneficial fungal groups. Functional analysis revealed that OF promoted saprotrophic fungi, crucial for the decomposition of organic matter and nutrient cycling. However, both systems exhibited low levels of arbuscular mycorrhizal fungi, likely due to high phosphorus levels. These findings suggest that organic practices can enhance soil fungal diversity and health, although attention to nutrient management is critical to further improving soil-plant-fungi interactions.

Impact of stockpiling on soil fungal communities and their functions

Fungal communities are important components of soil biology and play crucial roles in multiple ecosystem functions and services; therefore, they can be used as effective indicators of soil function in stockpiled reclamation soils. We profiled the fungal communities of seven stockpiles of different ages (0.5, 1.5, 2, 5, 7, 11, and 28 years old) at various soil depths (0–300 cm) in two oil sand extraction locations in northern Alberta. Fungal communities of the stockpiles differed from the communities in the nearby undisturbed reference soils. The differences with the reference soils were more pronounced for the oldest and some of the younger stockpiled soils. Similar to previous studies, there was a decrease in fungal richness and overall diversity with increasing stockpile depth. Furthermore, soil stockpiling generated a shift in the functional composition based on inferred fungal guilds and trophic modes. Ectomycorrhizal fungi decreased and saprotrophic fungi increased in the stockpiles relative to the reference soils. Such a shift may have important implications for ecosystem functions and services associated with fungal communities, such as litter decomposition and plant growth promotion, when these stockpiles are used to reclaim ecosystems. Our results align with previous research identifying the negative effects of stockpiling on soil microbial communities, shed light on the soil functions that may be affected by this disturbance and their consequences for ecosystem functioning, and reflect the high sensitivity of fungal communities to soil disturbances like stockpiling.

Soil inoculation changed soil microbial communities, but did not accelerate the decomposition of European Beachgrass (Ammophila arenaria) in Point Reyes National Seashore

Legacy effects after the removal of invasive plants present significant challenges to restoration. The pivotal role of soil microbial communities in shaping these legacy effects is increasingly recognized, yet there is a lack of effective methods to mitigate altered microbial communities. In Point Reyes National Seashore (California), although the invaded European beachgrass (Ammophila arenaria [L.] Link) was successfully controlled by herbicide treatment, beachgrass litter remained undecomposed for over 5 years, leaving pronounced legacy effects on soil organic matter and microbial community composition. We hypothesized that soil inoculation from uninvaded dune scrub can accelerate the decomposition of beachgrass litter in herbicide‐treated sites by restoring the soil microbial communities and the abundance of microbial decomposers. Three litterbags containing European beachgrass litter or litter from two common shrubs at dune scrub were deployed into each plot to assess the impact of soil inoculation on litter decomposition rates. Our results revealed that soil inoculation, regardless of the inoculation level, did not accelerate the decomposition of European beachgrass. Only the decomposition of bush lupine litter, which had the highest litter quality among three types of litter, was accelerated at the highest inoculation level (approximately 11,880 g/m2). Additionally, soil inoculation increased the richness and compositional homogeneity of soil microbial communities, along with the relative abundances of wood saprotrophic fungi, soil saprotrophic fungi, and lichenized fungi. Although these findings demonstrate the potential of soil inoculation, the cost‐effectiveness of soil inoculation limits its feasibility in accelerating the delayed decomposition of European beachgrass litter in Point Reyes.

Evaluation of the persistence of Epichloë endophyte and its possible effect on fungal assemblages in dead leaf sheaths

The systemic fungal endophytes of the genus Epichloë inhabit the aerial part of host grasses. Recent studies have reported that Epichloë affects the non-systemic endophytic assemblages in live leaves, but few studies that have demonstrated the occurrence of Epichloë and its effect on fungal assemblages in dead leaves. We proposed a hypothesis that Epichloë decreases from live to dead leaves but affects the non-systemic endophytic assemblages also in dead leaves. To test this hypothesis, we sampled leaf sheaths from four leaf types (live, senescent, attached dead and fallen dead) of two native grass species Elymus racemifer and Elymus tsukushiensis var. transiens in Japan and assessed for fungi by DNA metabarcoding. The occurrence of Epichloë OTU was significantly greater in E. tsukushiensis var. transiens than in E. racemifer and varied significantly between the four-leaf types, with decreased and no detections in attached dead and fallen dead leaves, respectively. The composition of non-systemic endophytic assemblages was also significantly affected by the presence/absence of Epichloë OTU, leaf type, host grass species and their interactions. These results supported our hypothesis and suggested that Epichloë can indirectly lead to the changes in belowground processes such as litter decomposition by affecting saprotrophic fungi in dead leaves.

Karst Ecosystem: Moso Bamboo Intercropping Enhances Soil Fertility and Microbial Diversity in the Rhizosphere of Giant Lily (Cardiocrinum giganteum)

Intercropping affects soil microbial community structure significantly; however, the effects on understory medicinal plants in karst areas remain unclear. We investigated the effects of four intercropping systems (Moso bamboo, Chinese fir, bamboo-fir mixed forest, and forest gap) on the rhizosphere microbial communities of giant lily (Cardiocrinum giganteum), an economically important medicinal plant in China. We assessed the intercropping impact on rhizosphere microbial diversity, composition, and co-occurrence networks and identified key soil properties driving the changes. Bacterial and fungal diversity were assessed by 16S rRNA and ITS gene sequencing, respectively; soil physicochemical properties and enzyme activities were measured. Moso bamboo system had the highest fungal diversity, with relatively high bacterial diversity. It promoted a distinct microbial community structure with significant Actinobacteria and saprotrophic fungi enrichment. Soil organic carbon, total nitrogen, and available potassium were the most influential drivers of microbial community structure. Co-occurrence network analysis revealed that the microbial network in the Moso bamboo system was the most complex and highly interconnected, with a higher proportion of positive interactions and a greater number of keystone taxa. Thus, integrating Moso bamboo into intercropping systems can enhance soil fertility, microbial diversity, and ecological interactions in the giant lily rhizosphere in karst forests.

Field Reduction of Ectomycorrhizal Fungi Has Cascading Effects on Soil Microbial Communities and Reduces the Abundance of Ectomycorrhizal Symbiotic Bacteria.

Specific interactions between bacteria and ectomycorrhizal fungi (EcMF) can benefit plant health, and saprotrophic soil fungi represent a potentially antagonistic guild to these mutualisms. Yet there is little field-derived experimental evidence showing how the relationship among these three organismal groups manifests across time. To bridge this knowledge gap, we experimentally reduced EcMF in forest soils and monitored both bacterial and fungal soil communities over the course of a year. Our analyses demonstrate that soil trenching shifts the community composition of fungal communities towards a greater abundance of taxa with saprotrophic traits, and this shift is linked to a decrease in both EcMF and a common ectomycorrhizal helper bacterial genus, Burkholderia, in a time-dependent manner. These results not only reveal the temporal nature of a widespread tripartite symbiosis between bacteria, EcMF and a shared host tree, but they also refine our understanding of the commonly referenced 'Gadgil effect' by illustrating the cascading effects of EcMF suppression and implicating soil saprotrophic fungi as potential antagonists on bacterial-EcMF interactions.

Influence of environmental conditions on the growth of Pleurotus ostreatus in sand

Pleurotus ostreatus, a saprotrophic fungus, has been proposed for the remediation of organic contaminants in soils and more recently for modifying the hydraulic and mechanical behaviour of granular soils. The in situ performance of fungal-based biotechnologies will be controlled by the fungal growth and associated biochemical activity that can be achieved in soil. In this study, the influence of environmental conditions (temperature, degree of saturation), substrate type (lignocellulose and spent coffee grounds) and concentration on the mycelium growth of P. ostreatus in sand are investigated. Furthermore, the evolution of growth/survival indicators (respiration, ergosterol concentration) and enzymatic activity (laccase, manganese peroxidase) are investigated. Temperature was shown to have a strong influence on the growth of P.ostreatus in sand: growth was observed to be delayed at low temperatures (e.g. 5 °C), whereas growth was prevented at high temperatures (e.g. 35 °C). No growth was observed at very low degrees of saturation (Sr=0% and 1.2%), indicating there is a critical water content required to support P.ostreatus growth. Within the mid-range of water contents tested radially, growth of P.ostreatus was similar. However, growth under saturated soil conditions was restricted to the air-water atmosphere due to the requirement for oxygen availability. Low substrate concentrations (1%–5%) resulted in high radial growth of P.ostreatus, whereas increasing substrate content further acted to reduce radial growth, but visual observations indicated that fungal biomass density increased. These results are important for understanding the feasibility of P.ostreatus growth under specific site conditions and for the design of successful treatment strategies.