Adding-value to Ganoderma lingzhi by producing enzymes and antioxidant compounds under submerged fermentation using different culture media.

Ganoderma lingzhi is widely reported for its medicinal properties, presenting several bioactive substances with potential pharmaceutical and industrial application. This study aimed to evaluate the production of mycelial biomass, extracellular enzymes and antioxidant compounds by G. lingzhi under submerged fermentation. G. lingzhi was cultured in Polysaccharide (POL) and Melin-Norkrans (MNM) media for 7 days. The cellulases, xylanases, pectinases, laccases, and proteases activities were quantified in the culture broth, while the antioxidant potential was evaluated for the mycelial biomass. G. lingzhi showed higher biomass production in MNM. However, it exhibited similar microstructural characteristics in both culture media. In the POL there was greater activity of CMCase (0.229 U/mL), xylanase (0.780 U/mL), pectinase (0.447 U/mL) and proteases (16.13 U/mL). FPase did not differ (0.01 U/mL), and laccase was detected only in MNM (0.122 U/mL). The biomass water extract from MNM showed high levels of phenolic compounds (951.97 mg AGE/100 g). DPPH• inhibition (90.55%) and reducing power (0.456) were higher in MNM medium, while ABTS•+ inhibition (99.95%) and chelating ability (54.86%) were higher in POL. Thus, the MNM medium was more favorable to the production of mycelial biomass and phenolic compounds, while the POL medium favored the synthesis and excretion of hydrolytic enzymes.

Antifungal activity of 2-chloro-5-trifluoromethoxybenzeneboronic acid and inhibitory mechanisms on Geotrichum candidum from sour rot Xiaozhou mustard root tuber.

Xiaozhou mustard (Brassica napiformis) root tuber, a traditional fermented vegetable, has a long history in Rongan County, Guangxi Province. However, the frequent occurrence of root tuber sour rot by Geotrichum candidum (G. candidum) has seriously reduced Xiaozhou mustard production and quality in recent years. The objective of the present study is to investigate the antifungal efficacy of 2-chloro-5-trifluoromethoxybenzeneboronic acid (Cl-F-BBA) against G. candidum and its possible mechanisms. The results revealed that a concentration of 0.25 mg/mL Cl-F-BBA completely halted mycelial growth and spore germination. Furthermore, a slightly lower concentration of 0.20 mg/mL was sufficient to compromise the integrity of the plasma membrane in mycelia and mitochondria, leading to a reduction in respiratory rate, activities of malate dehydrogenase (MDH), and succinate dehydrogenase (SDH), ATP content, and energy charge. This concentration also significantly disordered antioxidant metabolism, resulting in the accumulation of reactive oxygen species (ROS) and malondialdehyde (MDA), and caused intracellular leakage in mycelia. In vivo experiments further demonstrated that Xiaozhou mustard root tubers treated with Cl-F-BBA exhibited markedly lower decay rates and lesion diameters compared to the control group. In summary, Cl-F-BBA presents a promising solution for controlling root tuber sour rot in Xiaozhou mustard caused by G. candidum.

Morphological responses of filamentous fungi to stressful environmental conditions.

The filamentous growth mode of fungi, with its modular design, facilitates fungal adaptation to stresses they encounter in diverse terrestrial and anthropogenic environments. Surface growth conditions elicit diverse morphological responses in filamentous fungi, particularly demonstrating the remarkable adaptability of mycelial systems to metal- and mineral-rich environments. These responses are coupled with fungal biogeochemical activity and can ameliorate hostile conditions. A tessellated agar tile system, mimicking natural environmental heterogeneity, revealed negative chemotropism to toxic metals, distinct extreme growth strategies, such as phalanx and guerrilla movements and transitions between them, and the formation of aggregated re-allocation structures (strands, cords, synnemata). Other systems showed intrahyphal growth, intense biomineralization, and extracellular hair-like structures. Studies on submerged mycelial growth, using the thermophilic fungus Thielavia terrestris as an example, provided mechanistic insights into the morphogenesis of two extreme forms of fungal submerged culture-pelleted and dispersed growth. It was found that the development of fungal pellets was related to fungal adaptation to unfavorable stressful conditions. The two key elements affecting morphogenesis leading to the formation of either pelleted or dispersed growth were found to be (1) a lag phase (or conidia swelling stage) as a specific period of fungal morphogenesis when a certain growth form is programmed in response to morphogenic stressors, and (2) cAMP as a secondary messenger of cell signaling, defining the implementation of the particular growth strategy. These findings can contribute to knowledge of fungal-based biotechnologies, providing a means for controllable industrial processes at both morphological and physiological levels.

How Metarhizium robertsii's mycelial consciousness gets its conidia Zen-ready for stress.

This memoir takes a whimsical ride through my professional adventures, spotlighting my fungal stress research on the insect-pathogenic fungus Metarhizium robertsii, which transformed many of my wildest dreams into reality. Imagine the magic of fungi meeting science and me, a happy researcher, arriving at Utah State University ready to dive deep into studies with the legendary insect pathologist, my advisor Donald W. Roberts, and my co-advisor Anne J. Anderson. From my very first "Aha!" moment in the lab, I plunged into a vortex of discovery, turning out research like a mycelium on a mission. Who knew 18 h/day, seven days a week, could be so exhilarating? I was fueled by an insatiable curiosity, boundless creativity, and a perhaps slightly alarming level of motivation. Years later, I managed to bring my grandest vision to life: the International Symposium on Fungal Stress-ISFUS. This groundbreaking event has attracted 162 esteemed speakers from 29 countries to Brazil, proving that fungi can be both fun and globally fascinating. ISFUS is celebrating its fifth edition in 2024, a decade after its 2014 debut.

Effects of Humidity on Mycelium-Based Leather.

Leather is a product that has been used for millennia. While it is a natural material, its production raises serious environmental and ethical concerns. To mitigate those, the engineering of sustainable biobased leather substitutes has become a trend over the past few years. Among the biobased materials, mycelium, the fungal "root" of a mushroom, is one of the promising alternatives to animal leather, as a material with tunable physicomechanical properties. Understanding the effect of humidity on mycelium-based leather material properties is essential to the production of durable, competitive, and sustainable leather products. To this end, we measured the water sorption isotherms on several samples of mycelium-based leather materials and investigated the effects of water sorption on their elastic properties. The ultrasonic pulse transmission method was used to measure the wave speed through the materials while measuring their sorption isotherms at different humidity levels. Additionally, the material's properties were mechanically tested by performing uniaxial tensile tests under ambient and immersed conditions. An overall reduction in elastic moduli was observed during both absorption and immersion. The changes in the measured longitudinal modulus during water sorption reveal changes in the elasticity of the test materials. The observed irreversible variation of the longitudinal modulus during the initial water sorption can be related to the material production process and the presence of various additives that affect the mechanical properties of the leather materials. Our results presented here should be of interest to material science experts developing a new generation of sustainable leather products.

Cultivation of a Wild Strain of Wood Ear Auricularia cornea from Brazil.

Auricularia cornea has become one of the most important cultivated mushrooms worldwide. Although not remarkably flavorful, Auricularia species are very versatile and rehydrate easily after drying, adding a unique and pleasing texture to the dishes. In this study, we collected, identified, and domesticated a wild strain of A. cornea from the Brazilian Atlantic Rainforest. The wild strain was evaluated for mycelial growth at different temperatures and substrates, biological efficiency, and nutritional composition. The temperature that best favored the A. cornea mycelium growth was 30 °C, and the substrate was sterile Eucalyptus sawdust. The highest biological efficiency value obtained was 106.90 ± 13.28%. Nutritional analysis showed that the produced wood ears contained 71.02% carbohydrates, 19.63% crude fiber, 11.59% crude protein, 10.19% crude fat, and 4.24% ash on dry matter basis. For the mineral content profile, the elements K and P were the most abundant. This is the first report on cultivation of a wild strain of A. cornea from Brazil.

Hepatoprotective Effect of Antrodia camphorata Mycelium Powder on Alcohol-Induced Liver Damage.

BACKGROUND/OBJECTIVES: Antrodia camphorata, also known as "Niuchangchih" in Taiwan, is a unique medicinal mushroom native to Taiwan. It is used in traditional medicine to treat various health conditions. In this study, we investigated the efficacy of A. camphorata mycelia on alcohol-induced liver damage, both in vitro and in vivo, in a Good Laboratory Practice (GLP) facility. METHODS: The experimental groups consisted of a normal control group (G1), a negative control group (G2), an A. camphorata mycelium powder 50 mg/kg/day administration group (G3), a 100 mg/kg/day administration group (G4), a 200 mg/kg/day administration group (G5), and a positive control silymarin 200 mg/kg/day administration group (G6), with 10 Sprague Dawley rats assigned to each treatment group. RESULTS: We found that treatment with A. camphorata mycelium powder significantly reduced alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, cholesterol, adiponectin, triglyceride, and malondialdehyde concentrations. Histopathological analysis also revealed that the inflammation score significantly decreased in the A. camphorata-treated groups. CONCLUSION: Based on these results, we conclude that repeated oral administration of A. camphorata mycelium powder is effective in improving alcoholic liver disease.

The Effects of swnN Gene Function of Endophytic Fungus Alternaria oxytropis OW 7.8 on Its Swainsonine Biosynthesis.

The swnN gene in the endophytic fungus Alternaria oxytropis OW 7.8 isolated from Oxytropis glabra was identified, and the gene knockout mutant ΔswnN was first constructed in this study. Compared with A. oxytropis OW 7.8, the ΔswnN mutant exhibited altered colony and mycelia morphology, slower growth rate, and no swainsonine (SW) in mycelia. SW was detected in the gene function complementation strain ΔswnN/swnN, indicating that the function of the swnN gene promoted SW biosynthesis. Six differentially expressed genes (DEGs) closely associated with SW synthesis were identified by transcriptomic analysis of A. oxytropis OW 7.8 and ΔswnN, with P5CR, swnR, swnK, swnH2, and swnH1 down-regulating, and sac up-regulating. The expression levels of the six genes were consistent with the transcriptomic analysis results. Five differential metabolites (DEMs) closely associated with SW synthesis were identified by metabolomic analysis, with L-glutamate, α-ketoglutaric acid, and L-proline up-regulating, and phosphatidic acid (PA) and 2-aminoadipic acid down-regulating. The SW biosynthetic pathways in A. oxytropis OW 7.8 were predicted and refined. The results lay the foundation for in-depth elucidation of molecular mechanisms and the SW synthesis pathway in fungi. They are also of importance for the prevention of locoism in livestock, the control and utilization of locoweeds, and the protection and sustainable development of grassland ecosystems.

Micro PIXE mapping proves a differential distribution and concentration of trace elements in fungal structures of Rhizophagus intraradices.

Arbuscular mycorrhizal (AM) fungi can sequester different potentially toxic elements, such as trace elements (TEs), within their structures to alleviate the toxicity for its host plant and themselves. To elucidate the role of AM fungi in TEs immobilization in the rhizosphere of host plants, it is important to know the TEs distribution in AM fungal structures. In the present study, we investigated the distribution and concentration of TEs within extraradical spores and mycelium of the AM fungus Rhizophagus intraradices, collected from the rhizosphere of Senecio bonariensis plants grown in a soil polluted with multiple TEs, by using Particle-Induced X-ray Emission with a micro-focused beam (micro PIXE). This technique enabled the simultaneous micrometric mapping of elements in a sample. The calculated values were compared with those in the polluted substrate, measured by the Wavelength Dispersive X-ray Fluorescence technique. The highest concentrations of Fe, P, Ti, Mn, Cr, Cu and Zn were found in AM fungal spores, where they were accumulated, while extraradical mycelium was enriched in Cu. Finally, we demonstrated that AM fungi can simultaneously accumulate high amounts of different TEs in their structures, thus reducing the toxicity of these elements to its host plant.

Cadmium and calcium ions' effects on the growth of Pleurotus ostreatus mycelia are related to phosphatidylethanolamine content.

Heavy metal Cd2+ can easily be accumulated by fungi, causing significant stress, with the fungal cell membrane being one of the primary targets. However, the understanding of the mechanisms behind this stress remains limited. This study investigated the changes in membrane lipid molecules of Pleurotus ostreatus mycelia under Cd2+ stress and the antagonistic effect of Ca2+ on this stress. Cd2+ in the growth media significantly inhibited mycelial growth, with increasing intensity at higher concentrations. The addition of Ca2+ mitigated this Cd2+-induced growth inhibition. Lipidomic analysis showed that Cd2+ reduced membrane lipid content and altered lipid composition, while Ca2+ counteracted these changes. The effects of both Cd2+ and Ca2+ on lipids are dose dependent and phosphatidylethanolamine appeared most affected. Cd2+ also caused a phosphatidylcholine/phosphatidylethanolamine ratio increase at high concentrations, but Ca2+ helped maintain normal levels. The acyl chain length and unsaturation of lipids remained unaffected, suggesting Cd2+ doesn't alter acyl chain structure of lipids. These findings suggest that Cd2+ may affect the growth of mycelia by inhibiting the synthesis of membrane lipids, particular the synthesis of phosphatidylethanolamine, providing novel insights into the mechanisms of Cd2+ stress in fungi and the role of Ca2+ in mitigating the stress.

Transcriptomic Communication between Nucleus and Mitochondria during the Browning Process of Lentinula edodes.

To explore the reason for cytoplasmic replacement's significant effect on browning, transcriptomic data of nuclear (N) and mitochondrial (M) mRNAs and long noncoding RNAs (lncRNAs) in L808 and two cytoplasmic hybrids (cybrids) (L808-A2 and L808-B) of Lentinula edodes at three different culturing times (80, 100, and 120 days) were obtained. The results showed that the expression of N and M genes and lncRNAs changed with the culture time and cytoplasmic source. Cytoplasmic replacement significantly affected some M and N genes related to the internal mechanism and external morphological characteristics of L. edodes browning. The internal browning mechanism should be the nicotinamide adenine dinucleotide phosphate (NADPH)-mediated antioxidant machinery to protect mycelia against oxidative stress induced by the generation of reactive oxygen species under light irradiation. External morphological characteristics were the changing features of brown films by melanin (an antioxidant) aggregation on the surface of the mycelia of the bag or log. Especially, some genes were related to the remodeling of the plasma membrane, extracellular enzymes of celluloses and hemicellulases, small molecules, and NADPH metabolic processes. Additionally, communication between the nucleus and mitochondria mediated by M-rps3 was reported for the first time, and it is mainly appreciated in M structural assembly, functional implementation, and cooperation with other organelles.

Antifungal Potential and Mechanism of Bacillus velezensis HeN-7 Isolated from Tobacco Leaves on Bipolaris sorokiniana.

Wheat leaf blight caused by Bipolaris sorokiniana is a widespread fungal disease that poses a serious risk to wheat. Biological control without causing environmental pollution is one of the safest and most effective method to control plant diseases. The antagonistic bacterial strain HeN-7 (identified as Bacillus velezensis) was isolated from tobacco leaves cultivated in Henan province, China. The results of different concentrations of cell-free supernatant (CFS) from HeN-7 culture against B. sorokiniana mycelia showed that 20% HeN-7 CFS (v/v) reached the maximum inhibition rate of 96%. In the potted plants control assay, B. velezensis HeN-7 CFS exhibited remarkable biocontrol activity on the wheat infected with B. sorokiniana, the best pot control efficacy was 65% at 20% CFS. The research on the mechanism of action demonstrated that HeN-7 CFS induced the membrane lipid peroxidation in B. sorokiniana, leading to the disruption of cell membrane integrity and resulting in the leakage of cell contents; in addition, the intracellular mitochondrial membrane potential in mycelium dissipated and reactive oxygen species accumulated, thereby inhibiting the growth of B. sorokiniana. These results indicate that B. velezensis HeN-7 is a promising candidate as a biological control agent against Bipolaris sorokiniana infection.

Extraction and characterization of microfibrillated cellulose (MFC) from Rhododendron ponticum isolated using cryocrush pre-treatment and its potential for mycelium cultivation.

Rhododendron ponticum (R. ponticum), a rapidly spreading invasive species in Ireland, was investigated for its potential use in creating sustainable bioproducts. This study explored the utilization of R. ponticum biomass as a source of microfibrillated cellulose (MFC) for fungal cultivation. The production of MFC was evaluated employing a novel cryocrushing treatment combined with a twin-screw extruder (TSE). The results demonstrated a significant increase in film strength, up to 332.3 MPa, with increasing TSE steps compared to 72.5 MPa in untreated samples. X-ray diffraction (XRD) analysis revealed a decrease in crystallinity from 68.93 % to 59.2 %, following cryocrushing and TSE treatment. Additionally, MFC subjected to the highest TSE treatment (12 steps) was successfully used as a substrate for cultivating Agaricus blazei mushrooms using 0.2 wt%, 0.5 wt%, and 1 wt% MFC over a period of 7 days. Fourier-transform infrared spectroscopy (FTIR) confirmed the presence of chitin/chitin glucan within the fungal fibers. This research highlights the potential for transforming the invasive R. ponticum into valuable biocomposite materials. These MFC-fungus composites hold promise for various applications, including sustainable packaging, biodegradable plastics, and eco-friendly textiles.

Sulfated polysaccharide from Antrodia cinnamomea mycelium cultured with zinc sulfate stimulates M1 polarization of macrophages through AKT/mTOR pathways.

Antrodia cinnamomea-derived sulfated polysaccharides (Ac-SPSs) have health benefits, but their yield is low. This study explores a strategy to increase Ac-SPS yield and elucidates the biofunctions of Ac-SPS. For this, A. cinnamomea mycelia were treated with zinc sulfate (ZnSO4) administered at 1, 10, and 100 µM. Firstly, functional assay indicated that ZnSO4 increases the Ac-SPS yield by 20 %-30 % compared with the control treatment. ZnSO4 engenders a population of middle-molecular-weight (~200 kDa) Ac-SPSs. Ac-SPS (ASZ-10) from A. cinnamomea treated with 10 µM ZnSO4 exhibits the best anti-proliferation ability against lung cancer A549 cells. Co-treatment of ASZ-10 does not inhibit lipopolysaccharide-induced inflammation but does induce M1-related markers of macrophage RAW264.7 cells. Secondly, immunomodulatory properties showed that ASZ-10 increases the expression of CD80+ and CD86+ in M-CSF-stimulated bone-marrow-derived macrophages. ASZ-10 induces M1 polarization through up-regulation of the AKT/mTOR pathway as confirmed by AKT and mTOR inhibitors eliminating ASZ-10-induced M1-like markers of macrophages. Through systemic chemical and functional analysis, this study shows that trace amounts (10 µM) of ZnSO4 increase Ac-SPS yield and it reveals that ASZ-10 exhibits anti-cancer activity and acts as a stimulator for M1 macrophages by stimulation of AKT and mTOR.

Transcriptome Analysis Reveals the Effect of Oyster Mushroom Spherical Virus Infection in Pleurotus ostreatus.

Oyster mushroom spherical virus (OMSV) is a mycovirus that inhibits mycelial growth, induces malformation symptoms, and decreases the yield of fruiting bodies in Pleurotus ostreatus. However, the pathogenic mechanism of OMSV infection in P. ostreatus is poorly understood. In this study, RNA sequencing (RNA-seq) was conducted, identifying 354 differentially expressed genes (DEGs) in the mycelium of P. ostreatus during OMSV infection. Verifying the RNA-seq data through quantitative real-time polymerase chain reaction on 15 DEGs confirmed the consistency of gene expression trends. Both Gene Ontology and Kyoto Encyclopedia of Genes and Genomes analyses highlighted the pivotal role of primary metabolic pathways in OMSV infection. Additionally, significant changes were noted in the gene expression levels of carbohydrate-active enzymes (CAZymes), which are crucial for providing the carbohydrates needed for fungal growth, development, and reproduction by degrading renewable lignocellulose. The activities of carboxymethyl cellulase, laccase, and amylase decreased, whereas chitinase activity increased, suggesting a potential mechanism by which OMSV influenced mycelial growth through modulating CAZyme activities. Therefore, this study provided insights into the pathogenic mechanisms triggered by OMSV in P. ostreatus.

[Oscillation-static cycle cultivation enhances the synthesis of triterpenes and mycelium activity in Ganoderma lucidum].

Ganoderma lucidum is a precious fungus with both edible and medicinal values and has a long history of medical use. Triterpenes as the main active components endow G. lucidum with anti-tumor, antioxidant, and other pharmacological activities. The present study endeavors to establish a proficient liquid-state fermentation technology for the enhanced production of triterpenes. In view of the limitations inherent in conventional submerged fermentation and oscillation-static two-stage cultivation, this study established an oscillation-static cycle cultivation process and optimized the cultivation conditions by building an artificial neural network model based on genetic algorithms. The cultivation conditions for the high-yield production of triterpenes were optimized as follows: 2.8 days of oscillation, 7.3 days of static cultivation, 0.2 day of oscillation, and 0.3 day of static cultivation. Under these conditions, the content of triterpenes reached 20.82 mg/g. The yield of triterpenes reached 129.09 mg/L, showing a remarkable increase of 324.78% compared with that of the Z10J0 method. Moreover, the established method shortened the cultivation cycle by 10.6 days. The mycelia cultivated under this regimen exhibited commendable anti-tumor and antioxidant activities. This study not only presents an economical liquid-state fermentation approach but also streamlines the fermentation flow, reduces fermentation duration, and effectively ameliorates drawbacks associated with conventional cultivation methods. In addition, this study gives valuable insights into the scaled application of liquid-state fermentation in the high-yield production of triterpenes, which showcases broad prospects.

Plant-derived citronellol can significantly disrupt cell wall integrity maintenance of Colletotrichum camelliae.

Anthracnose, a fungal disease, commonly infects tea plants and severely impacts the yield and quality of tea. One method for controlling anthracnose is the application of citronellol, a plant extract that exhibits broad-spectrum antimicrobial activity. Herein, the physiological and biochemical mechanism by which citronellol controls anthracnose caused by Colletotrichum camelliae was investigated. Citronellol exhibited excellent antifungal activity based on direct and indirect mycelial growth inhibition assays, with EC50 values of 76.88 mg/L and 29.79 µL/L air, respectively. Citronellol also exhibited good control effects on C. camelliae in semi-isolated leaf experiments. Optical and scanning electron microscopy revealed that citronellol caused C. camelliae mycelia to thin, fracture, fold and deform. Transmission electron microscopy revealed that the mycelial cell walls collapsed inward and separated, and the organelles became blurred after treatment with citronellol. The sensitivity of C. camelliae to calcofluor white staining was significantly enhanced by citronellol, while PI staining showed minimal fluorescence, and the relative conductivity of mycelia were not significantly different. Under citronellol treatment, the expression levels of ß-1,3-glucanase, chitin synthase, and chitin deacetylase-related genes were significantly decreased, while the expression levels of chitinase genes were increased, leading to lower chitinase activity and increased ß-1,3-glucanase activity. Therefore, citronellol disrupted the cell wall integrity of C. camelliae and inhibited normal mycelial growth.

The antagonistic activity of Streptomyces spiroverticillatus (No. HS1) against of poplar canker pathogen Botryosphaeria dothidea.

BACKGROUND: Poplar canker caused by Botryosphaeria dothidea is one of the most severe plant disease of poplars worldwide. In our study, we aimed to investigate the modes of antagonism by fermentation broth supernatant (FBS) of Streptomyces spiroverticillatus HS1 against B. dothidea. RESULTS: In vitro, the strain and FBS of S. spiroverticillatus HS1 significantly inhibited mycelial growth and biomass accumulation, and also disrupted the mycelium morphology of B. dothidea. On the 3rd day after treatment, the inhibition rates of colony growth and dry weight were 80.72% and 52.53%, respectively. In addition, FBS treatment damaged the plasma membrane of B. dothidea based on increased electrical conductivity in the culture medium, and malondialdehyde content of B. dothidea mycelia. Notably, the analysis of key enzymes in glycolysis pathway showed that the activity of hexokinase (HK), phosphofructokinase (PFK), and pyruvate kinase (PK), Ca2+Mg2+-ATPase were significantly increased after FBS treatment. But the glucose contents were significantly reduced, and pyruvate contents were significantly increased in B. dothidea after treatment with FBS. CONCLUSIONS: The inhibitory mechanism of S. spiroverticillatus HS1 against B. dothidea was a complex process, which was associated with multiple levels of mycelial growth, cell membrane structure, material and energy metabolism. The FBS of S. spiroverticillatus HS1 could provide an alternative approach to biological control strategies against B. dothidea.

Continuous production of chitooligosaccharides in a column reactor by the PUF-immobilized whole cell enzymes of Mucor circinelloides IBT-83.

BACKGROUND: Chitosan oligosaccharides (COS) have great potential for applications in several fields, including agriculture, food industry or medicine. Nevertheless, the large-scale use of COS requires the development of cost-effective technologies for their production. The main objective of our investigation was to develop an effective method of enzymatic degradation of chitosan in a column reactor using Mucor circinelloides IBT-83 cells, immobilized in a polyurethane foam (PUF). These cells serve as a source of chitosanolytic enzymes. RESULTS: The study revealed that the process of freeze-drying of immobilized mycelium increases the stability of the associated enzymes during chitosan hydrolysis. The use of stabilized preparations as an active reactor bed enables the production of COS at a constant level for 16 reactor cycles (384 h in total), i.e. 216 h longer compared to non-stabilized mycelium. In the hydrolysate, oligomers ranging in structure from dimer to hexamer as well as D-glucosamine were detected. The potential application of the obtained product in agriculture has been verified. The results of phytotests have demonstrated that the introduction of COS into the soil at a concentration of 0.01 or 0.05% w/w resulted in an increase in the growth of Lepidium sativum stem and root, respectively (extensions by 38 and 44% compared to the control sample). CONCLUSIONS: The research has verified that the PUF-immobilized M. circinelloides IBT-83 mycelium, which has been stabilized through freeze-drying, is a promising biocatalyst for the environmentally friendly and efficient generation of COS. This biocatalyst has the potential to be used in fertilizers.

Effect of temperature on in vitro germination and growth of Colletotrichum fioriniae, a new emerging pathogen of olive fruits.

Olive anthracnose induced by different Colletotrichum species causes dramatic losses of fruit yield and oil quality. The increasing incidence of Colletotrichum fioriniae (Colletotrichum acutatum species complex) as causal agent of olive anthracnose in Italy, is endorsing new studies on its biology, ecology, and environmental factors such as temperature. Five isolates from different sampling sites in Lazio region (Central Italy) were studied under controlled laboratory conditions aiming to better understand the differences of thermal development among the isolates and to lay the foundations of a future mathematical model able to describe the key aspects of the pathogen's life cycle. The mycelial growth rate and the conidial germination rate were assessed at seven different constant temperatures (5, 10, 15, 20, 25, 30, and 35°C) and fixed relative humidity (100% RH). The obtained dataset was analysed to estimate the parameters of mathematical functions that connect the mycelial growth rate and the spore germination with the environmental temperature. The parameters set provided as the result of this study constitute a key step forward in the biological knowledge of the species and the basis for future formulations of mathematical models that might be the core of decision support systems in an integrated pest management framework.