The development and nutritional quality of Lyophyllum decastes affected by monochromatic or mixed light provided by light-emitting diode.

Edible fungi has certain photo-sensitivity during the mushroom emergence stage, but there has been few relevant studies on the responses of Lyophyllum decastes to different light quality. L. decastes were planted in growth chambers with different light qualities that were, respectively, white light (CK), monochromatic red light (R), monochromatic blue light (B), mixed red and blue light (RB), and the mixture of far-red and blue light (FrB). The photo-sensitivity of L. decastes was investigated by analyzing the growth characteristics, nutritional quality, extracellular enzymes as well as the light photoreceptor genes in mushroom exposed to different light treatments. The results showed that R led to mycelium degeneration, fungal skin inactivation and failure of primordial formation in L. decastes. The stipe length, stipe diameter, pileus diameter and the weight of fruiting bodies exposed to RB significantly increased by 8.0, 28.7, 18.3, and 58.2% respectively, compared to the control (p < 0.05). B significantly decreased the stipe length and the weight of fruiting body, with a decrease of 8.5 and 20.2% respectively, compared to the control (p < 0.05). Increased color indicators and deepened simulated color were detected in L. decastes pileus treated with B and FrB in relative to the control. Meanwhile, the expression levels of blue photoreceptor genes such as WC-1, WC-2 and Cry-DASH were significantly up-regulated in mushroom exposed to B and FrB (p < 0.05). Additionally, the contents of crude protein and crude polysaccharide in pileus treated with RB were, respectively, increased by 26.5 and 9.4% compared to the control, while those in stipes increased by 5.3 and 58.8%, respectively. Meanwhile, the activities of extracellular enzyme such as cellulase, hemicellulase, laccase, manganese peroxidase, lignin peroxidase and amylase were significant up-regulated in mushroom subjected to RB (p < 0.05), which may promote the degradation of the culture materials. On the whole, the largest volume and weight as well as the highest contents of nutrients were all detected in L. decastes treated with RB. The study provided a theoretical basis for the regulation of light environment in the industrial production of high quality L. decastes.

Eco-hydrological processes regulate lake riparian soil organic matter under dryness stress.

As transitional zone between terrestrial and aquatic ecosystems, the soil properties of riparian zones are deeply influenced by the eco-hydrological conditions of lakes. However, with the increasing frequent drought events caused by climate change, the response of riparian soil organic matter (SOM) dynamics to the eco-hydrological process of lakes under dryness stress is unclear. In this study, we utilized the field research, indoor experiments, ecoenzymatic stoichiometry model and data analysis to identify whether riparian SOM and enzyme activity were affected by dryness stress and determine the feedback relationship between soil biochemical properties and lake eco-hydrological processes. The results showed that lake dryness stress reduced the non-vegetated riparian soil quality (the mean Carbon Pool Management Index decreased by 18 % and 6 % for water-land interface (WL) and bare land (BL), respectively), and the humification degree and molecular weight of the riparian soil dissolved organic matter (DOM) (with E2/E3 and E3/E4 value of WL 6.1 and 1.9 times higher than main lake sediment), which was not conducive to soil carbon storage. In addition, lake dryness stress reduced the C-hydrolytic enzyme activity and soil enzyme stoichiometry. The vector and Vector-TER analysis suggested the riparian soil was C and N limitation of the microbial community (vector length of 2.05 ± 0.57 and vector angle of 30.10° ± 7.70°), and dryness had reduced the limitations to some extent. Most notably, we combined structural equation model (SEM) analysis and found that lake dryness stress affects riparian soil organic carbon (SOC) dynamics by significantly affecting microbial biomass carbon (MBC) and soil pH. Finally, the response of riparian zone to eco-hydrological condition under climate change should receive further attention, which can effectively deepen our understanding of the carbon water cycle mechanism in riparian soil under changing environments.

Purpureocillium lilacinum SBF054: Endophytic in Phaseolus vulgaris, Glycine max, and Helianthus annuus; Antagonistic to Rhizoctonia solani; and Virulent to Euschistus heros.

Microorganisms with multiple ecological functions can be a useful biotechnological resource in integrated pest- and disease-management programs. This work aimed to investigate the potential endophytic and virulent effects of a strain of Purpureocillium lilacinum on organic cultivation in Brazil. Specifically, the strain's ability to establish itself as an endophyte in common bean, soybean, and sunflower plants when inoculated via seed was evaluated. Furthermore, its antifungal activity against phytopathogens and its pathogenicity and virulence against insects of the order Lepidoptera, Coleoptera, and Hemiptera were evaluated. Furthermore, the strain was evaluated for its biochemical and physiological characteristics. For virulence bioassays, the experiments were conducted under a factorial scheme (2 × 3), with the following factors: (a) fungal inoculation and control without inoculum and (b) types of inocula (blastospores, aerial conidia, and metabolites). The treatments were sprayed on insect species at different stages of development. In summary, it was found that the SBF054 strain endophytically colonized the common bean, with partial recovery from the root tissues of soybean and sunflower plants, 30 days after inoculation; suppressed 86% of Rhizoctonia solani mycelial growth in an in vitro assay; and controlled eggs, nymphs, and Euschistus heros adults. These multifunctional abilities are mainly attributed to the strain's mechanisms of producing metabolites, such as organic acids, soluble nutrients, and hydrolytic enzymes.

Phytoplankton-derived polysaccharides and microbial peptidoglycans are key nutrients for deep-sea microbes in the Mariana Trench.

BACKGROUND: The deep sea represents the largest marine ecosystem, driving global-scale biogeochemical cycles. Microorganisms are the most abundant biological entities and play a vital role in the cycling of organic matter in such ecosystems. The primary food source for abyssal biota is the sedimentation of particulate organic polymers. However, our knowledge of the specific biopolymers available to deep-sea microbes remains largely incomplete. One crucial rate-limiting step in organic matter cycling is the depolymerization of particulate organic polymers facilitated by extracellular enzymes (EEs). Therefore, the investigation of active EEs and the microbes responsible for their production is a top priority to better understand the key nutrient sources for deep-sea microbes. RESULTS: In this study, we conducted analyses of extracellular enzymatic activities (EEAs), metagenomics, and metatranscriptomics from seawater samples of 50-9305 m from the Mariana Trench. While a diverse array of microbial groups was identified throughout the water column, only a few exhibited high levels of transcriptional activities. Notably, microbial populations actively transcribing EE genes involved in biopolymer processing in the abyssopelagic (4700 m) and hadopelagic zones (9305 m) were primarily associated with the class Actinobacteria. These microbes actively transcribed genes coding for enzymes such as cutinase, laccase, and xyloglucanase which are capable of degrading phytoplankton polysaccharides as well as GH23 peptidoglycan lyases and M23 peptidases which have the capacity to break down peptidoglycan. Consequently, corresponding enzyme activities including glycosidases, esterase, and peptidases can be detected in the deep ocean. Furthermore, cell-specific EEAs increased at 9305 m compared to 4700 m, indicating extracellular enzymes play a more significant role in nutrient cycling in the deeper regions of the Mariana Trench. CONCLUSIONS: Transcriptomic analyses have shed light on the predominant microbial population actively participating in organic matter cycling in the deep-sea environment of the Mariana Trench. The categories of active EEs suggest that the complex phytoplankton polysaccharides (e.g., cutin, lignin, and hemicellulose) and microbial peptidoglycans serve as the primary nutrient sources available to deep-sea microbes. The high cell-specific EEA observed in the hadal zone underscores the robust polymer-degrading capacities of hadal microbes even in the face of the challenging conditions they encounter in this extreme environment. These findings provide valuable new insights into the sources of nutrition, the key microbes, and the EEs crucial for biopolymer degradation in the deep seawater of the Mariana Trench. Video Abstract.

[Plant Diversity Changes and Its Driving Factors of Abandoned Land at Different Restoration Stages in the Middle of the Qinling Mountains].

The process of vegetation restoration is often accompanied by significant changes in aboveground plant diversity. To explore the driving mechanism of litter nutrient-soil nutrient-enzyme activity stoichiometry on aboveground vegetation change is of great importance for maintaining regional biodiversity conservation and ecological stability. Taking typical abandoned farmland of different restoration years （1， 8， 16， 31， and 50 a） in the Qinling Mountains as the research object， the variation characteristics of plant community diversity during vegetation restoration were analyzed through field investigation. Litter nutrients， soil nutrients， and the activities of five extracellular enzymes， including ß-1，4-glucosidase （BG）， cellobiohydrolase （CBH）， ß-1，4-N-acetylglucosaminidase （NAG）， leucine aminopeptidase （LAP）， and acid phosphatase （AP）， were determined. The characteristics of litter nutrients， soil nutrients， and enzyme stoichiometric ratios during vegetation restoration and the driving mechanism of plant diversity changes were discussed. The results showed that the plant community diversity index firstly decreased and then increased with the increase in vegetation restoration years， and the minimum was reached at 16 years after restoration. The results of principal component analysis showed that there were significant differences between total plant community diversity index and litter-soil-enzyme stoichiometric characteristics in different years of vegetation restoration. The plant community diversity index had a strong positive correlation with litter C∶P ratio and litter N∶P ratio but had a negative correlation with soil enzyme C∶P ratio （EEA C∶P）. The results of redundancy analysis showed that soil EEA C∶P had the highest explanation rate of plant diversity changes during vegetation restoration （25.93%）， followed by soil TP （5.94%）， which was the key factor regulating plant diversity changes. In conclusion， plant species and quantity increased significantly in abandoned farmland in the middle part of the Qinling Mountains at the late stage of vegetation restoration. Changes in the soil environment affected microbial metabolic activities and thus changed enzyme activities. Litter-soil-soil extracellular enzymes affected the community environment and plant diversity through feedback and regulation. EEA C∶P and TP were the main driving factors of aboveground plant diversity change during vegetation restoration.

Decreased snow depth inhibits litter decomposition via changes in litter microbial biomass and enzyme activity.

Decreased snow depth resulting from global warming has the potential to significantly impact biogeochemical cycles in cold forests. However, the specific mechanisms of how snow reduction affects litter decomposition and the underlying microbial processes remain unclear, this knowledge gap limits our ability to precisely predict ecological processes within cold forest ecosystems under climate change. Hence, a field experiment was conducted in a subalpine forest in southwestern China, involving a gradient of snow reduction levels (control, 50 %, 100 %) to investigate the effects of decreased snow on litter decomposition, as well as microbial biomass and activity, specifically focused on two common species: red birch (Betula albosinensis) and masters larch (Larix mastersiana). After one year of incubation, the decomposition rate (k-value) of the two types of litter ranged from 0.12 to 0.24 across three snow treatments. A significant lower litter mass loss, microbial biomass and enzyme activity were observed under decreased snow depth in winter. Furthermore, a hysteresis inhibitory effect of snow reduction on hydrolase activity was observed in the following growing season. Additionally, the high initial quality (lower C/N ratio) of red birch litter facilitated the colonization by a greater quantity of microorganisms, making it more susceptible to snow reduction compared to the low-quality masters larch litter. Structural equation models indicated that decreased snow depth hindered litter decomposition by altering the biological characterization of litter (e.g., microbial biomass and enzyme activity) and environmental variables (e.g., mean temperature and moisture content). The findings suggest that the potential decline in snow depth could inhibit litter decomposition by reducing microbial biomass and activity, implying that the future climate change may alter the material cycling processes in subalpine forest ecosystems.

Shifts in microbial community composition and metabolism correspond with rapid soil carbon accumulation in response to 20 years of simulated nitrogen deposition.

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-1 yr-1) and high (50 kg N ha-1 yr-1) 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.

Biotechnological insights into extracellular enzyme production by thermotolerant fungi from hot springs and caves: Morphology, pellets formation, and protease production.

This study investigates the thermotolerant fungal biodiversity in caves and hot springs, focusing on their potential for extracellular enzyme production, specifically proteases. Samples were collected from the Cardonal region in Hidalgo, Mexico, using three different isolation methods. The study characterizes the morphological diversity of the isolated fungi and identifies various genera, including Aspergillus, Penicillium, Trichoderma, Cladosporium, and Fusarium, based on morphology. The isolated fungi were screened for their ability to produce extracellular enzymes on solid media, with a particular emphasis on proteases due to their industrial significance. Among the 35 isolated fungi, 20 exhibited proteolytic activity, and 12 strains were identified as good protease producers based on enzymatic index values. The study also evaluated the formation of fungal pellets by proteolytic fungi and found certain strains to display significant pellet formation. Additionally, protease production was examined by fungal pellets in submerged cultures, with isolate 6 demonstrating the highest protease activity. The findings highlight the diverse thermotolerant fungal biodiversity in extreme environments, and emphasize their potential for enzymatic production. This research contributes to our understanding of fungal ecology and provides insights into the biotechnological applications of these enzymes. The study recommends further molecular investigations to enhance biodiversity studies in such extreme environments.

Characteristic volatiles of Fu brick tea formed primarily by extracellular enzymes during Aspergillus cristatus fermentation.

Fu brick tea (FBT) has unique "fungal flower" aroma traits, but its source of crucial aroma compounds is still controversial. Aspergillus cristatus is the dominant fungus that participated in the fermentation of FBT. In this study, volatiles of Aspergillus cristatus and corresponding fermented FBT were examined using GC × GC-Q-TOFMS. A total of 59 volatiles were shared by three strains of Aspergillus cristatus isolated from representative FBT. Among them, 1-octen-3-ol and 3-octanone were the most abundant. A total of 133 volatiles were screened as typical FBT volatiles from three FBTs fermented by the corresponding fungi. Aspergillus cristatus and FBT had only 29 coexisting volatiles, indicating that the volatiles of Aspergillus cristatus could not directly contribute to the aroma of FBT. The results of no significant correlation between volatile content in FBT and volatile content in Aspergillus cristatus suggested that intracellular metabolism of Aspergillus cristatus was not a direct driver of FBT aroma formation. Metabolic pathway analysis and proteomic analysis showed that the aroma in FBT was mainly formed by the enzymatic reaction of extracellular enzymes from Aspergillus cristatus. This study enriched our understanding of Aspergillus cristatus in the aroma formation process of FBT.

Hydrolysis of Antimicrobial Peptides by Extracellular Peptidases in Wastewater.

Several antimicrobial peptides (AMPs) are emerging as promising novel antibiotics. When released into wastewater streams after use, AMPs might be hydrolyzed and inactivated by wastewater peptidases─resulting in a reduced release of active antimicrobials into wastewater-receiving environments. A key step towards a better understanding of the fate of AMPs in wastewater systems is to investigate the activity and specificity of wastewater peptidases. Here, we quantified peptidase activity in extracellular extracts from different stages throughout the wastewater treatment process. For all four tested municipal wastewater treatment plants, we detected highest activity in raw wastewater. Complementarily, we assessed the potential of enzymes in raw wastewater extracts to biotransform 10 selected AMPs. We found large variations in the susceptibility of AMPs to enzymatic transformation, indicating substantial substrate specificity of extracted enzymes. To obtain insights into peptidase specificities, we searched for hydrolysis products of rapidly biotransformed AMPs and quantified selected products using synthetic standards. We found that hydrolysis occurred at specific sites and that these sites were remarkably conserved across the four tested wastewaters. Together, these findings provide insights into the fate of AMPs in wastewater systems and can inform the selection and design of peptide-based antibiotics that are hydrolyzable by wastewater peptidases.

Analysis of the virulence, infection process, and extracellular enzyme activities of Aspergillus nomius against the Asian corn borer, Ostrinia furnacalis guenée (Lepidoptera: Crambidae).

The control of Ostrinia furnacalis, a major pest of maize in Xinjiang, is challenging owing to the occurrence of resistant individuals. Entomopathogenic fungi (EPF) are natural insect regulators used as substitutes for synthetic chemical insecticides. The fungus Aspergillus nomius is highly pathogenic to O. furnacalis; however, its virulence characteristics have not been identified. This study aimed to analyse the lethal efficacy, mode of infection on the cuticle, and extracellular enzyme activity of A. nomius against O. furnacalis. We found that the mortality and mycosis of O. furnacalis were dose-dependent when exposed to A. nomius and varied at different life stages. The egg-hatching and adult emergence rates decreased with an increase in conidial suspension. The highest mortality (83.33%, 7 d post-infection [DPI]) and mycosis (74.33%, 7 DPI) and the lowest mortality response (8.52 × 103 conidia mL-1) and median lethal time (4.91 d) occurred in the 3rd instar larvae of O. furnacalis. Scanning electron microscopy indicated that numerous conidia germination and infection structure formation may have contributed to the high pathogenicity of A. nomius against O. furnacalis. There were significant correlations between O. furnacalis mortality and the activities of extracellular protease, lipase, and chitinase of A. nomius. This study revealed the infection process of the highly pathogenic A. nomius against O. furnacalis, providing a theoretical basis and reference for strain improvement and field application of EPF.

The completed genome sequence of Pestalotiopsis versicolor, a pathogenic ascomycete fungus with implications for bayberry production.

The pathogenic fungus Pestalotiopsis versicolor is a major etiological agent of fungal twig blight disease affecting bayberry trees. However, the lack of complete genome sequence information for this crucial pathogenic fungus hinders the molecular and genetic investigation of its pathogenic mechanism. To address this knowledge gap, we have generated the complete genome sequence of P. versicolor strain XJ27, employing a combination of Illumina, PacBio, and Hi-C sequencing technologies. This comprehensive genome sequence, comprising 7 chromosomes with an N50 contig size of 7,275,017 bp, a GC content ratio of 50.16%, and a total size of 50.80 Mb, encompasses 13,971 predicted coding genes. By performing comparative genomic analysis between P. versicolor and the genomes of eleven plant-pathogenic fungi, as well as three closely related fungi within the same group, we have gained initial insights into its evolutionary trajectory, particularly through gene family analysis. These findings shed light on the distinctive characteristics and evolutionary history of P. versicolor. Importantly, the availability of this high-quality genetic resource will serve as a foundational tool for investigating the biology, molecular pathogenesis, and virulence of P. versicolor. Furthermore, it will facilitate the development of more potent antifungal medications by uncovering potential vulnerabilities in its genetic makeup.

Localization of C Cycle Enzymes in Arable and Forest Phaeozems within Levels of Soil Microstructure.

Soil microbial and enzyme activities are closely related to the spatial variability of soil environmental conditions at the microscale (µm-mm). The origin and localization of the enzymes are somewhat neglected when the measured activity is used to evaluate specific soil functions. The activity of four hydrolytic enzymes (ß-glucosidase, Cellobiohydrolase, Chitinase, Xylanase) and microbial diversity based on community-level physiological profiling were determined in samples of arable and native Phaeozems with increasing physical impact to soil solids. The level of impact on the soil solids had a significant effect on enzyme activity and depended on both the enzyme type and soil land use. The highest proportion of the activity of Xylanase and Cellobiohydrolase of arable Phaeozem was determined at the dispersion energy in the range of 450-650 J·mL-1 and was associated with the primary soil particles' hierarchy level. The highest proportions of ß-glucosidase and Chitinase activities were determined for forest Phaeozem after applying energies lower than 150 J·mL-1 and characterizing the level of soil microaggregates. The increased activity of Xylanase and Cellobiohydrolase in primary soil particles of arable soil compared to those in forest soil might be a reflection of the substrates being unavailable to decomposition, leading to enzyme accumulation on the solid surface. For the Phaeozems, the lower the level of soil microstructure organization, the greater the differences observed between soils of different land use type, i.e., microbial communities, associated with lower microstructure levels, were more specific to land use type.

The Signal Peptidase FoSpc2 Is Required for Normal Growth, Conidiation, Virulence, Stress Response, and Regulation of Light Sensitivity in Fusarium odoratissimum.

Signal peptidase (SPase) is responsible for cleavage of N-terminal signal peptides in most secretory precursor proteins and many membrane proteins during maturation. In this study, we identified four components of the SPase complex (FoSec11, FoSpc1, FoSpc2, and FoSpc3) in the banana wilt fungal pathogen Fusarium odoratissimum. We proved that interactions exist among the four SPase subunits by bimolecular fluorescence complementation (BiFC) and affinity purification and mass spectrometry (AP-MS) assays. Among the four SPase genes, FoSPC2 was successfully deleted. FoSPC2 deletion caused defects in vegetative growth, conidiation, and virulence. Loss of FoSPC2 also affected the secretion of some pathogenicity-related extracellular enzymes, suggesting that SPase without FoSpc2 may have a lower efficiency in managing the maturation of the extracellular enzymes in F. odoratissimum. In addition, we found that the ΔFoSPC2 mutant had increased sensitivity to light, and the colonies of the mutant grew faster under all-dark conditions than under all-light conditions. We further observed that deletion of FoSPC2 affected expression of the blue light photoreceptor gene FoWC2, leading to cytoplasmic accumulation of FoWc2 under all-light conditions. Since FoWc2 has signal peptides, FoSpc2 may regulate the expression and subcellular localization of FoWc2 indirectly. Contrary to its response to light, the ΔFoSPC2 mutant displayed a significant decreased sensitivity to osmotic stress, and culturing the mutant under osmotic stress conditions restored both the localization of FoWc2 and light sensitivity of the ΔFoSPC2, suggesting that a cross talk between osmotic stress and light response pathways in F. odoratissimum and FoSpc2 takes part in these processes. IMPORTANCE In this study, we identified four components of SPase in the banana wilt pathogen Fusarium odoratissimum and characterized the SPase FoSpc2. Loss of FoSPC2 affected the secretion of extracellular enzymes, suggesting that SPase without FoSpc2 may have a lower efficiency in managing the maturation of the extracellular enzymes in F. odoratissimum. In addition, this is the first time that we have found a relationship between the SPase and fungal light response. Deletion of FoSPC2 resulted in decreased sensitivity to the osmotic stresses but with increased sensitivity to light. Continuous light inhibited the growth rate of the ΔFoSPC2 mutant and affected the cellular localization of the blue light photoreceptor FoWc2 in this mutant, but culturing the mutant under osmotic stress both restored the localization of FoWc2 and eliminated the light sensitivity of the ΔFoSPC2 mutant, suggesting that loss of FoSPC2 may affect a cross talk between the osmotic stress and light response pathways in F. odoratissimum.

Characterization of membrane vesicles in Alteromonas macleodii indicates potential roles in their copiotrophic lifestyle.

Bacterial membrane vesicles (MVs) are abundant in the oceans, but their potential functional roles remain unclear. In this study we characterized MV production and protein content of six strains of Alteromonas macleodii, a cosmopolitan marine bacterium. Alteromonas macleodii strains varied in their MV production rates, with some releasing up to 30 MVs per cell per generation. Microscopy imaging revealed heterogenous MV morphologies, including some MVs aggregated within larger membrane structures. Proteomic characterization revealed that A. macleodii MVs are rich in membrane proteins related to iron and phosphate uptake, as well as proteins with potential functions in biofilm formation. Furthermore, MVs harbored ectoenzymes, such as aminopeptidases and alkaline phosphatases, which comprised up to 20% of the total extracellular enzymatic activity. Our results suggest that A. macleodii MVs may support its growth through generation of extracellular 'hotspots' that facilitate access to essential substrates. This study provides an important basis to decipher the ecological relevance of MVs in heterotrophic marine bacteria.

Highlighting the potential for crude oil bioremediation of locally isolated Cunninghamella echinulata and Mucor circinelloides.

The current investigation was carried out to assess the potential of fungi isolated from polluted soil samples in Al Jubail, Saudi Arabia, to degrade crude oil. In a minimal salt medium with 1% crude oil as the carbon source, the growth potential of various fungal isolates was examined. Among twelve fungal isolates, YS-6 and YS-10, identified as Cunninghamella echinulata and Mucor circinelloides based on multiple sequence comparisons and phylogenetic analyses, were selected as having superior crude oil degrading abilities. To the best of our knowledge, the isolated species have never been detected in polluted soil samples in the eastern province of Saudi Arabia. YS-6 and YS-10 have shown their capacity to metabolize crude oil by removing 59.7 and 78.1% of crude oil, respectively. Interestingly, they succeeded in reducing the surface tension to 41.2 and 35.9 mN/m, respectively. Moreover, the emulsification activity and hydrophobicity were determined to be 36.7, 44.9, 35.9, and 53.4%, respectively. The recovery assays included zinc sulfate, ammonium sulfate, acid precipitation, and solvent extraction techniques. All these approaches showed that the amount of biosurfactants correlates to the tested hydrocarbons. Furthermore, the enzyme activity of these two isolates generated significantly more laccase (Lac) than manganese peroxidase (MnP) and lignin peroxidase (LiP), as compared to the control. In conclusion, our study highlights new perspectives on the fungal resources found in persistently polluted terrestrial ecosystems. This knowledge will be useful for bioremediation, safe disposal of petroleum-oil contamination, and other industrial uses.

Therapeutic compounds from medicinal plant endophytes: molecular and metabolic adaptations.

During the last few decades, endophytes have attracted increased attention due to their ability to produce a plethora of bioactive secondary metabolites. These compounds not only help the endophytes to outcompete other plant-associated microbes or pathogens through quorum sensing, but also enable them to surmount the plant immune system. However, only a very few studies have described the interlink between various biochemical and molecular factors of host-microbe interactions involved in the production of these pharmacological metabolites. The peculiar mechanisms by which endophytes modulate plant physiology and metabolism through elicitors, as well as how they use transitional compounds of primary and secondary metabolism as nutrients and precursors for the synthesis of new compounds or enhancing existing metabolites, are still less understood. This study thus attempts to address the aspects of synthesis of such metabolites used in therapeutics by the endophytes in the light of their ecological significance, adaptation, and intercommunity interactions. Our study explores how endophytes adapt to the specific host environment, especially in medicinal plants that produce metabolites with pharmacological potential and simultaneously modulate host gene expression for the biosynthesis of these metabolites. We also discuss the differential interactions of fungal and bacterial endophytes with their hosts.

Simultaneous Heavy Metal-Polycyclic Aromatic Hydrocarbon Removal by Native Tunisian Fungal Species.

Multi-contamination by organic pollutants and toxic metals is common in anthropogenic and industrial environments. In this study, the five fungal strains Chaetomium jodhpurense (MH667651.1), Chaetomium maderasense (MH665977.1), Paraconiothyrium variabile (MH667653.1), Emmia lacerata, and Phoma betae (MH667655.1), previously isolated in Tunisia, were investigated for the simultaneous removal and detoxification of phenanthrene (PHE) and benzo[a]anthracene (BAA), as well as heavy metals (HMs) (Cu, Zn, Pb and Ag) in Kirk's media. The removal was analysed using HPLC, ultra-high performance liquid chromatography (UHPLC) coupled to a QToF mass spectrometer, transmission electron microscopy, and toxicology was assessed using phytotoxicity (Lepidium sativum seeds) and Microtox® (Allivibrio fisherii) assays. The PHE and BAA degradation rates, in free HMs cultures, reached 78.8% and 70.7%, respectively. However, the addition of HMs considerably affected the BAA degradation rate. The highest degradation rates were associated with the significant production of manganese-peroxidase, lignin peroxidase, and unspecific peroxygenase. The Zn and Cu removal efficacy was considerably higher with live cells than dead cells. Transmission electron microscopy confirmed the involvement of both bioaccumulation and biosorption processes in fungal HM removal. The environmental toxicological assays proved that simultaneous PAH and HM removal was accompanied by detoxification. The metabolites produced during co-treatment were not toxic for plant tissues, and the acute toxicity was reduced. The obtained results indicate that the tested fungi can be applied in the remediation of sites simultaneously contaminated with PAHs and HMs.

New insight into the mechanisms of autochthonous fungal bioaugmentation of phenanthrene in petroleum contaminated soil by stable isotope probing.

Autochthonous fungal bioaugmentation (AFB) is considered a reliable bioremediation approach for polycyclic aromatic hydrocarbon (PAH) contamination, but little is known about its mechanisms in contaminated soils. Here, a microcosm experiment was performed to explore the AFB mechanisms associated with two highly efficient phenanthrene degrading agents of fungi (with laccase-producing Scedosporium aurantiacum GIG-3 and non-laccase-producing Aspergillus fumigatus LJD-29), using stable-isotope-probing (SIP) and high-throughput sequencing. The results showed that each fungus markedly improved phenanthrene removal, and microcosms with both fungi exhibited the best phenanthrene removal performance among all microcosms. Additionally, AFB markedly shifted the composition of the microbial community, particularly the phenanthrene-degrading bacterial taxa. Interestingly, based on SIP results, strains GIG-3 and LJD-29 did not assimilate phenanthrene directly during AFB, but instead played key roles in the preliminary decomposition of phenanthrene though secretion of different extracellular enzymes to oxidize the benzene ring (GIG-3 bioaugmentation with laccase, and LJD-29 bioaugmentation with manganese and lignin peroxidases). In addition, all functional degraders directly involved in phenanthrene assimilation were indigenous bacteria, while native fungi rarely participated in the direct phenanthrene mineralization. Our findings provide a new mechanism of AFB with multiple fungi, and support AFB as a promising strategy for the in situ bioremediation of PAH-contaminated soil.

Roles of various enzymes in the biotransformation of 6:2 fluorotelomer alcohol (6:2 FTOH) by a white-rot fungus.

Six-carbon-chained polyfluoroalkyl substances, such as 6:2 fluorotelomer alcohol (6:2 FTOH), are being used to replace longer chained compounds in the manufacture of various commercial products. This study examined the effects of growth substrates and nutrients on specific intracellular and extracellular enzymes mediating 6:2 FTOH aerobic biotransformation by the white-rot fungus, Phanerochaete chrysosporium. Cellulolytic conditions with limited glucose were a suitable composition, resulting in high 5:3 FTCA yield (37 mol%), which is a key intermediate in 6:2 FTOH degradation without forming significant amounts of terminal perfluorocarboxylic acids (PFCAs). Sulfate and ethylenediaminetetraacetic acid (EDTA) were also essential for 5:3 FTCA production, but, at lower levels, resulted in the buildup of 5:2 sFTOH (52 mol%) and 6:2 FTUCA (20 mol%), respectively. In non-ligninolytic nutrient-rich medium, 45 mol% 6:2 FTOH was transformed but produced only 12.7 mol% 5:3 FTCA. Enzyme activity studies imply that cellulolytic conditions induce the intracellular cytochrome P450 system. In contrast, extracellular peroxidase synthesis is independent of 6:2 FTOH exposure. Gene expression studies further verified that peroxidases were relevant in catalyzing the downstream transformations from 5:3 FTCA. Collectively, the identification of nutrients and enzymatic systems will help elucidate underlying mechanisms and biogeochemical conditions favorable for fungal transformation of PFCA precursors in the environment.