Mycelial Content Research Articles

Scaling-up fungal pretreatment of lignocellulose biomass: Impact on nutritional value, ruminal degradability, methane production, and performance of lactating dairy cows

Scaling-up fungal pretreatment of lignocellulose biomass (LCB) for ruminant nutrition has become a major research challenge in recent years. This study systematically investigated the effectiveness of fungal (Pleurotus ostreatus) pretreatment (for 30 days under solid state fermentation (SSF)) of large quantities (8400 kg) of lime-pasteurized wheat straw, in terms of improvement in nutritional value, in vitro ruminal fermentation characteristics and methane (CH4) production potential. We further investigated the effects of stepwise replacement of untreated wheat straw (UTWS) with the lime pasteurized P. ostreatus treated wheat straw (PTWS) on dry matter intake (DMI), apparent total tract digestibility, production performance, CH4 emission and feed efficiency of lactating dairy cows. The results revealed that PTWS had lower lignin (P< 0.001), hemicellulose (P< 0.001) and cellulose (P< 0.05) contents and higher crude protein (CP; P< 0.001) content and cellulose to lignin ratio (P< 0.01), as compared to UTWS. The PTWS had higher in vitro DM digestibility (IVDMD; P< 0.001), total gas production (IVGP; P< 0.01), total volatile fatty acids (VFAs, P< 0.01) and propionate (P< 0.05) concentration, and lower (P< 0.05) pH and CH4 gas production during 72 h in vitro fermentation. Notably, the fungus degraded 33.3 % lignin at the expense of 6.56 % cellulose, and markedly increased CP content (46.3 %), IVDMD (20.2 %), IVGP (16.8 %) and VFAs (10.0 %) production, and decreased CH4 production (10.3 %). The aflatoxin B1 concentration of PTWS was <5.0 µg/kg, and mycelium concentration was 181.9 mg/kg DM, reflecting safe and effective tretment of the straw. Replacement of 32 % UTWS in total mixed ration with the PTWS, increased DMI (0.84 kg/day; P = 0.01), apparent total tract DM digestibility (5.5 g/100 g; P< 0.05) and milk yield (1.17 liter/day; P= 0.032), and decreased CH4 emission (1.45 g/kg DMI; P< 0.05). In conclusion, hydrated lime can replace traditional high-tech pasteurization methods for the fungal pretreatment of LCB, and present prospects for scaling up the process for ruminant nutrition.

Artificial intelligence unveils key interactions between soil properties and climate factors on Boletus edulis and B. reticulatus mycelium in chestnut orchards of different ages

The main objective of this study was to determine the possible interaction of two important abiotic factors (soil and climate) on the mycelial concentration and frequency of the ectomycorrhizal fungi Boletus edulis and B. reticulatus, using traditional statistics and artificial neural network tools. The frequency and concentration of Boletus mycelium were determined over three months (September, October, and November), and two years (2018 and 2020), in three hybrid chestnuts (Castanea × coudercii) orchards of 40-, 10-, and 3- years-old, using real-time qPCR. Statistical analysis revealed a significant effect of the year on B. edulis mycelium concentration and of the sampling plot (different tree ages) on B. reticulatus frequency. The combination of artificial intelligence networks (ANN) with fuzzy logic, named neurofuzzy logic (NF), allowed the construction of two robust models. In the first, using year, month, and sampling plot as inputs, NF identified hidden interactions between year and month on B. edulis mycelium concentration and between sampling plot and sampling month on B. reticulatus mycelium frequency, thus improving the information obtained from the statistical analysis. In the second model, those three factors were disaggregated into 44 inputs, including 20 soil properties and 24 climatic factors, being NF able to select only 8 as critical factors to explain the variability found in both ectomycorrhizal Boletus species regarding mycelial frequency and concentration. Specifically, NF selected two chemical soil properties (cation exchange capacity and total carbon) and three physical properties (macroaggregates, total porosity, and soil moisture at field capacity), as well as their interactions with three climatic elements (cumulative difference between precipitation and potential evapotranspiration (P-PET-1-2) and water deficit (WD-1-2) in the previous two months and excess water (WE-1) in the month prior to sampling. These results provide a much deeper understanding and new insights into the ecology and the role of abiotic factors which explain the different mycelial development patterns of ectomycorrhizal fungi such as B. edulis and B. reticulatus in chestnut agroecosystems.

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.

Media optimization of antimicrobial activity production and beta-glucan content of endophytic fungi Xylaria sp. BCC 1067

Fungi is a notable asset for drug discovery and production of pharmaceuticals; however, slow growth and poor product yields have hindered industrial utilization. Here, the mycelial biomass of Xylaria sp. BCC 1067 was examined in parallel with the assessment of antimicrobial properties by using media-type selection. To enhance both mycelial content and antifungal activity, the media replacement approach was successfully applied to stimulate fungal growth and successively switched to poorer malt-peptone extract media for metabolite production. This simple optimization reduced fungal cultivation time by 7 days and yielded 4-fold increased mycelial mass (32.59 g/L), with approximately 3-fold increased antifungal activity against the model yeast Saccharomyces cerevisiae strain. A high level of β-glucan (115.84 mg/g of cell dry weight) and additive antibacterial effect against Propionibacterium acnes were also reported. This simple strategy of culture media optimization allows for investigation of novel and rich source of health-promoting substances for effective microbial utilization.

Effect of Crude Oil on Biomass Production, Polysaccharide, and Polyphenol Content of Leucocoprinus cretaceus(Bull.) Locq. a white rot fungus

There is need to establish the best lignocellulosic wastes with bio-stimulatory effects on mushrooms been investigated for myco-remediation purposes. Solid state fermentation of four substrates (sawdust of Anthostema aubryanum Baill, Mansonia altissima (A. Chev.) A. Chev., Nauclea diderrichii (De Eild &amp; T. Durand) Merr and Malt Extract Agar) contaminated with various levels of crude oil contamination by Leucocoprinus cretaceus (Bull.) Locq., was studied. The effect of crude oil on mycelial biomass production, polysaccharide, and polyphenol contents of L. cretaceus during solid state fermentation of lignocellulosic wastes was determined. The polysaccharide and polyphenol content of the mycelia was determined with the Phenol-Sulphuric acid and Folin-Ciocalteu methods, respectively. Solid state fermentation of crude contaminated substrates improved biomass and polysaccharide content of L. cretaceus. The fungus is a good bioremediation agent degrading crude oil with increasing levels of crude oil contamination (28.00% in 1.00% crude oil contamination to 81% in 10.00% crude oil contamination). Radial mycelial extension increased with increasing levels of crude oil contamination. Crude oil did not cause increased polyphenol concentration and therefore not a stress factor. There was increase in polysaccharide content indicating metabolization of crude oil for metabolic build up. Supplementing crude oil contaminated substrates with the sawdust of M. altissima resulted in the highest level of crude oil degradation by the test fungus. L. cretaceus is a potential strong myco-remediation agent. This study records the first time the fungus is used for degradation of crude oil contaminated substrates. The mushroom has the potential to completely mineralize petroleum hydrocarbons.

Development of Monascus purpureus monacolin K-hyperproducing mutant strains by synchrotron light irradiation and their comparative genome analysis

Monascus purpureus have been used for making koji and other fermented foods and supplements. M.purpureus characteristically produces monacolin K (MK), a secondary metabolite that competitively inhibits cholesterol synthesis. Synchrotron light irradiation was applied to induce mutation in the strain KUPM5 to improve the MK-producing ability of M.purpureus strain KUPM5. Screening by a bioassay utilizing sensitivities to yeast Saccharomyces cerevisiae from 936 colonies allows isolating three mutant strains: SC01, SC02, and SC03. These mutant strains and the parental strain KUPM5 were subjected to make koji using rice, and their metabolites were compared. All strains SC01, SC02, and SC03 in koji showed higher production of MK than the strain KUPM5. Particularly, the SC02 strain produced MK threefold higher than KUPM5 and maintained the production capabilities of other metabolites, including red, yellow, and orange pigments, mycelial contents, and α-amylase activity comparable to those of the strain KUPM5. Comparative genome analysis among strain KUPM5 and the mutants revealed that synchrotron light irradiation introduced mutations in approximately 90% of the total genes, including SNV, MNV, and indel mutations. The frequencies of SNV substitution in the whole genome occupied 68.96% of all mutations, of which 92.38% were transversions and 7.62% were transitions. This study, therefore, proved the synchrotron light irradiation was highly efficient for the strain improvement of a filamentous fungus, M.purpureus, and provided insights into the properties of mutation in the fungus by this mutagen.

Proximate Composition, Essential Heavy Metal Concentrations and Nutrient Density of the Mycelium and Fruiting Bodies of Organically Cultivated Pleurotus ostreatus

Proximate composition, essential heavy metal concentration of fruiting bodies (POFB) and mycelium (POMY) of Pleurotus ostreatus were conducted using standard methods. Moisture content was higher (9.79%) in POFB than in POMY (8.76%) on dry weight basis. Ash was higher in POFB(6.25%) than in POMY(3.25%).POFB presented higher crude protein value (24.66%) than POMY (21.17%). Crude fat values were low in both samples(POFB:0.28%; POMY:0.46) respectively. Fiber was higher in the mycelium (14.72%) than in the fruiting bodies (12.90%). The carbohydrate content of the mycelium was 51.93% while the value of carbohydrate in the fruiting bodies was 46.10%. POFB indicated energy value of 285.60Kcal/100g and the value in POMY was 296.57Kcal/100g. Iron, copper, manganese and chromium presented higher values in POFB than in POMY but zinc indicated higher level in POMY than in POFB. The %DV highlighted in the study showed that the fruiting bodies and mycelium of organically cultivated P. ostreatus are rich in protein, fiber, carbohydrate, copper and iron. The nutrient density (ND) results revealed that POFB and POMY samples are nutritionally dense in fiber, copper and iron based on the World Health Food Rating System. The results showed that POFB and POMY obtained by organic cultivation possess high nutritional profile, suggesting that people may use them in food and medicinal formulations.

Effect of pH and Temperature on the Growth and Laccases Production in the Cultivation of Pleurotus sajor-caju PS-2001 in Stirred-tank Bioreactor

Background: Laccases are multi-copper enzymes that oxidize phenolic/aromatic compounds and represent a promising alternative to environmental decontamination processes and biotechnological applications. Objective: The effects of pH and temperature on the growth and the production of laccases during the cultivation of Pleurotus sajor-caju PS-2001 in stirred-tank bioreactor were assessed. Methods: Assays were performed at fixed pH values from 4.5 to 7.5 (28°C) and at temperatures from 24 to 36°C (pH 6.5). Results: In pH testing, larger biomass concentration (4.5 g L-1) was reached at pH 5.5, whereas concentrations of 3.7, 3.1 and 1.7 g L-1 were measured at pH 4.5, 6.5 and 7.5, respectively. With ABTS as substrate, peaks of laccases activity of 50, 30 and 24 U mL-1, at pH 6.5, 5.5 and 7.5, respectively, were detected. Under different temperatures, higher mycelial concentrations (3.0 g L-1) were quantified at 66 hours at 28°C, while concentrations below 2.0 g L-1 were observed at 24, 32, and 36°C. Maximum laccases activities of 50, 42, 6 and 5 U mL-1 were obtained at 28, 32, 24, and 36°C, respectively. In all tests, the presence of other phenol oxidases – total peroxidase, manganese peroxidase, lignin peroxidase and veratryl alcohol oxidase – was observed. Conclusion: The results indicate that variations in pH and temperature during fungal cultivation strongly affect the enzymatic activity and growth kinetics of P. sajor-caju PS-2001 in a stirredtank bioreactor.

Tissue specific colonization of Phytophthora capsici in Capsicum spp.: molecular insights over plant-pathogen interaction

Root and crown rot (RCR) caused by Phytophthora capsici is present in all crop production areas of pepper and chili worldwide. This pathogen was recently reported at the Pacific coast of Ecuador (province of Manabi), as an etiological agent of wilt and root and crown rot in commercial fields of bell pepper (Capsicum annuum). This study aimed to evaluate the resistance of ten Capsicum spp. genotypes artificially infected with P. capsici and to compare the tissue-specific colonization of P. capsici under greenhouse conditions. Disease intensity, mycelial growth incidence and pathogen DNA content in root and hypocotyl tissues of P. capsici infected Capsicum germplasm was evaluated at 17 days after infection (dai). Results indicated that genotypes Nathalie, ECU-12831, ECU-9129, Codigo 5, and ECU-1296 were found to be resistant, and ECU-11995, ECU-2254 B, California Wonder, Quetzal and Marcato showed susceptibility to the disease. The amount of pathogen DNA in roots was the only variable that did not correlate with the resistance or susceptibility of the genotypes. In fact, in resistant genotypes the pattern of pathogen DNA content was higher in roots than hypocotyls (but also in the susceptible ECU-11995), while in the susceptible genotypes (e.g. ECU-2254 B, C. Wonder, Quetzal and Marcato) showed the opposite pattern. The present work provides new insights of host-pathogen interaction, which might be used in breeding programs aiming to develop Capsicum cultivars with resistance to RCR.

Effects of nanobubble water supplementation on biomass accumulation during mycelium cultivation of Cordyceps militaris and the antioxidant activities of extracted polysaccharides

Cordyceps militaris (C. militaris) has traditionally been used as medicine and daily supplement for hundreds of years. Nanobubble water (NBW) can promote mass transfer, chemical reactions and metabolism. In this study, the NBW-liquid fermentation system was first established to evaluate the effects of NBW on mycelia of C. militaris. The highest mycelium concentration (3.90 mg/mL) and crude polysaccharides extraction yield (12.76%) were obtained in 25%-NBW (v/v) group. The antioxidant activities of mycelia were significantly promoted after supplementation with NBW. The polysaccharides from 25%-NBW, 75%-NBW, and 50%-NBW groups exhibited the strongest DPPH radical, ABTS radical scavenging activities, and reducing power, respectively, achieving the highest radical scavenging rate (nearly 100% at 1.2 mg/mL), the lowest IC50 value (1.09 mg/mL) and the highest OD value (2.13 at 2.0 mg/mL). Results from this study suggest that NBW supplementation can be utilized as a new approach for bioactive compounds production from C. militaris.

Effect of monoterpene ester from Blumea axillaris (Lam.) DC and its acetyl derivative against plant pathogenic fungi and their in silico molecular docking

The present study was aimed to isolate active constituents from Blumea axillaris (Lam.) DC (Asteraceae) against phytopathogenic fungi. Bioactivity guided fractionation of the successive n-hexane, chloroform and methanol extract led to the isolation of the monoterpene ester (4 R,5S)-4-hydroxy-7-tigloyloxycarvotanacetone (1). The compound 1 was converted into acetyl derivative (2). The acetyl derivative (2) and the parent compound 1 were tested again phytopathogenic fungi by using mycelial inhibition and minimal inhibitory concentration values were found out by the broth microdilution method. The acetyl derivative (2) showed the highest antifungal activity against Rhizoctonia solani and Aspergillus niger. Based upon in vitro results, compound 1 was tested against Fusarium oxyporum (wilting disease) and compound 2 was tested against R. solani (leaf blight disease) in vivo using the foliar spray method. Both compounds had no phytotoxicity and also in silico docking study showed that both compounds were binding similarly as commercial fungicide carbendazim.

Ontogenetic and trans-generational dynamics of a vertically transmitted fungal symbiont in an annual host plant in ozone-polluted settings.

Tropospheric ozone is an abiotic stress of increasing importance in the context of global climate change. This greenhouse gas is a potent phytotoxic molecule with demonstrated negative effects on crop yield and natural ecosystems. Recently, oxidative stress has been proposed as a mechanism that could regulate the interaction between cool-season grasses and Epichloë endophytes. We hypothesized that exposure of Lolium multiflorum plants, hosting endophytes to an ozone-polluted environment at different ontogenetic phases, would impact the trans-generational dynamics of the vertically transmitted fungal symbiont. Here, we found that the ozone-induced stress on the mother plants did not affect the endophyte vertical transmission but it impaired the persistence of the fungus in the seed exposed to artificial ageing. Endophyte longevity in seed was reduced by exposure of the mother plant to ozone. Although ozone exposure did not influence either the endophyte mycelial concentration or their compound defences (loline alkaloids), a positive correlation was observed between host fitness and the concentration of endophyte-derived defence compounds. This suggests that fungal defences in grass seeds were not all produced in situ but remobilized from the vegetative tissues. Our study reveals ozone trans-generational effects on the persistence of a beneficial symbiont in a host grass.

Effects of the &amp;lt;i&amp;gt;Castanea mollissima Blume&amp;lt;/i&amp;gt; Shell Cultivation Substrate on the Yield and Nutritional Composition of &amp;lt;i&amp;gt;Pleurotus geesteranus&amp;lt;/i&amp;gt;

Cottonseed hull substrates blended with different ratios of Castanea mollissima Blume shell were prepared and used for the cultivation of Pleurotus geesteranus. The effects of the chestnut shell content on the mycelial growth rate, yield, nutritional composition and contents of heavy metals of the cultivated Pleurotus geesteranus were investigated. The results suggest that the Castanea mollissima Blume shell in substrate can increase the mycelial growth rate, yield, biological efficiency and the contents of protein, crude fiber, amino acids and essential amino acids of Pleurotus geesteranus. Further investigation suggests that the tannin and saponin in Castanea mollissima Blume shell and the C/N ratio of substrate significantly influence the mycelial growth rate. The crude fat content of Pleurotus geesteranus decreased, while the contents of heavy metals including mercury (Hg), arsenic (As), cadmium (Cd) and lead (Pb) increased with the increase of the Castanea mollissima Blume shell content in substrate. Based on these results, the content of Castanea mollissima Blume shell was optimized to be less than 30% for the cultivation of Pleurotus geesteranus.

Effect of &amp;lt;i&amp;gt;Carya cathayensis Sarg&amp;lt;/i&amp;gt; Shell Substrate on Yield and Nutrient Amount of &amp;lt;i&amp;gt;Pleurotus geesteranus&amp;lt;/i&amp;gt;

Using cottonseed hull as the control substrate, different proportions of the untreated and treated Carya cathayensis Sarg shells were added to cultivation of Pleurotus geesteranus. The mycelial growth rate, yield, nutritional composition and contents of heavy metals of the Pleurotus geesteranus cultivated on these substrates were determined. The results suggest that added to treated Carya cathayensis Sarg shell promoted the mycelial growth and increased the yield, biological efficiency and the contents of crude fiber, ash, amino acids and essential amino acids of Pleurotus geesteranus. In addition, the fat content and soluble sugar contents of Pleurotus geesteranus were decreased with the increase of the Carya cathayensis Sarg shell content in substrate, but their contents of heavy metals including mercury (Hg), arsenic (As), cadmium (Cd) and lead (Pb) were higher than that obtained on control substrate.

Distribution of Mycelia of Morchella esculenta in Wild Field.

It was well-known that Morchella esculenta has a life cycle including vegetative hyphae, sclerotia, primordia, and fruiting bodies, but there is no report yet about the influence of mycelial mass on fruiting process. Since 2014, we have developed an ELISA method to detect the content of Morchella esculenta. In this study, we utilized this method to measure the mycelia content, and find the correlation between mycelial content and fruiting in the wild. The study demonstrated the changes of mycelial concentration at different location around fruiting spot.

Enhancing cordycepin production in liquid static cultivation of Cordyceps militaris by adding vegetable oils as the secondary carbon source

This study evaluated different vegetable oils as the second carbon source in liquid static culture of Cordyceps militaris in terms of mycelial growth and cordycepin production. The maximum mycelial concentration and cordycepin production were observed under cottonseed oil and peanut oil induction, respectively. In the condition of adding 20 g/L of peanut oil at Day 0, the final concentration of cordycepin reached to the highest, about 5.29 g/L, which was about 3.17 times higher than that of the control. The qRT-PCR and enzyme activity analysis confirmed that addition of peanut oil up-regulated the expression of the genes encoding glucose-6-phosphate dehydrogenase and isocitrate lyase, as well as the genes in the cordycepin biosynthesis pathway, cns1 and cns2, during the cultivation in C. militaris.

Inhibitory effect of chlorine dioxide (ClO2) fumigation on growth and patulin production and its mechanism in Penicillum expansum

The effect of chlorine dioxide (ClO2) on Penicillium expansum growth and patulin production in vitro and on its disease severity in apples was investigated. ClO2 treatment significantly reduced the lesion diameter in apples infected with P. expansum and inhibited mycelial growth and spore germination. After ClO2 treatment, P. expansum mycelial morphology was strongly affected, and a reduced spore plasma membrane integrity with an increased malondialdehyde (MDA) mycelial content was observed. Moreover, patulin production by P. expansum was reduced by ClO2 treatment, both in apples and in PDB meidium. These data showed new and precise clues to the inhibitory effect of ClO2 on P. expansum growth, and provided an effective method to ensure safety of apple products caused by P. expansum.

STEREO AND SCANNING ELECTRON MICROSCOPY CHARACTERISTICS OF POULTRY BREEDING BEETLE (Alphitobius diaperinus) – A FILAMENTOUS TOXIGENIC FUNGI CARRIER

This study isolated Alphitobius diaperinus (live and dead) insects from shed’s aviary bed to investigate their fungi spores distribution (that affects chicken health and meat production) and their accumulation sites (dorsal &amp; ventral) characteristics by different microscopies (stereo and scanning electron). Despite live beetles being the main fungi spore carriers, the dead ones had far more spores attached on their body exoskeleton thereby being a focus of infection. That was due to the anatomical sites favoring spores trapping effect, together with beetles’ different moisture content. Regarding the spores distribution and so the hyphae presence &amp; mycelia concentration on dead A. diaperinus, they were mainly detected at the (a) elytra, elytral suture and pronotum (on the dorsal side). Despite that, the highest spores/mycelia concentration was at the mouthparts, prosternum and legs (femur &amp; tarsus) (on the ventral side). Indeed the beetle’s ventral anatomical microscopic structures (mouthparts &amp; legs) sheltered the highest fungi spores concentration and colonies proliferation. Thus dead beetle colonies growth lead to spore multiplication, their dissemination throughout the aviary bed environment and so their contact to chicken feet and body, leading to discomfort and diseases development / mycotoxicosis. The filamentous fungi were most detected from the Aspergillus and Penicillium genera. Therefore dead beetles should be removed from aviary (at each 45 breeding cycle) to reduce contamination. They represent rich substrates for fungi development with possibility of toxin formation, apart from the chicken diseases exposure due to their insects eating habits.

Mycelium-bound lipase from Aspergillus oryzae as efficient biocatalyst for cis-3-hexen-1-yl acetate synthesis in organic solvent

Abstract Aspergillus oryzae , isolated from traditional Japanese food “Miso”, has efficiently catalyzed the direct esterification between acetic acid and cis -3-hexen-1-ol in organic solvent. The esterification between acids and alcohols having different chain lengths was initially investigated, observing a conversion decrement parallel to the increase of the linear chain length of alcohol. Esterification between acetic acid and cis -3-hexen-1-ol was optimized using an experimental design (Doehlert matrix design). In the range of the studied parameters, esterification, was increased with temperature and dry mycelium concentration. Higher acetic acid concentration decreased the conversion. The optimum conditions found to achieve the highest esterification yield (98%) were: 70 °C, 60 mM of acid and 30 g/L of dry mycelium. In these conditions, A. oryzae dry mycelium could be recycled five times. Thus, this biocatalyst could be an attractive alternative to commercial immobilized lipase in the synthesis of cis -3-hexen-1-yl acetate, because of its low-cost preparation and high enzymatic activity.

Fractionation and assimilation of Mg isotopes by fungi is species dependent.

Symbiotic ectomycorrhizal fungi mobilize nutrients from both organic and inorganic substrates and supply them to their host plants. Their role in mobilizing base cations and phosphorus from mineral substrates through weathering has received increasing attention in recent years but the processes involved remain to be elucidated. We grew selected ectomycorrhizal and nonmycorrhizal fungi in axenic systems containing mineral and organic substrates and examined their capacity to fractionate and assimilate stable isotopes of magnesium. The mycorrhizal fungi were significantly depleted in heavy isotopes with the lowest Δ26 Mg values (the difference between δ26 Mg in fungal tissue and δ26 Mg in the substrate) compared with nonmycorrhizal fungi, when grown on mineral substrates containing granite particles. The ectomycorrhizal fungi accumulated significantly higher concentrations of Mg, K and P than the nonmycorrhizal fungi. There was a highly significant statistical relationship between δ26 Mg tissue signature and mycelial concentration of Mg, with a clear separation between most ectomycorrhizal fungi and the nonmycorrhizal fungi. These results are consistent with the idea that ectomycorrhizal fungi have evolved efficient mechanisms to mobilize, transport and store Mg within their mycelia.