Malt Extract Agar Research Articles

Assessment of Fungi Infection on Clarias anguillaris (Linnaeus, 1758) and Oreochromis niloticus (Linnaeus, 1758), Two Fish Species Farmed in Burkina Faso

Worlwide, fungi are by far the most common pathogen in fish farming. They are responsible of important economic losses in the fishery sector. However, in Burkina Faso knowledge of fungi infecting farmed fish are scarce. As a consequence, the prevalence as well as the effect of these pathogens are not known. A study was carried out on fungal infection of farmed fish. It aimed to evaluate the diversity of fungi associated with Oreochromis niloticus (Linnaeus, 1758) and Clarias anguillaris (Linnaeus, 1758) farmed in Burkina Faso. In total, 89 individuals of fish consisted of 47 specimens of Oreochromis niloticus and 42 specimens of Clarias anguillaris were collected from eleven fish farms. Swabs were taken on fish bodies and inoculated in Malt Extract Agar (MEA). The chloramphenicol was added to avoid bacterial contamination. Seventy-seven (77) fish were infected by fungi (85.51%). Four genera including Aspergillus (four species), Rhizopus (one species), Penicillium (one species) and Mucor (one species) were isolated. Small and big fish were all infected. This study shows fungi as a potential factor that impacts fish farming and suggests a need for more research on their effect on fish. Knowledge of fish parasites like fungi will allow to set effective means of fish pathology control, which once implemented will lead to an increase in fish farming productivity.

Developing Sustainable Wood Preservatives: The Antifungal Efficiency of Afzelia quanzensis Welv. and Androstachys johnsonii Prain Sawdust Extracts from Mozambique

This study aimed to both develop and assess the antifungal efficacy of extractives derived from different sets of sawdust originating from two hardwood species, namely chanfuta (Afzelia quanzensis Welv.) and mecrusse (Androstachys johnsonnii Prain). These hardwood species possess inherent characteristics of high natural durability. The primary objective was to use these extractives to impregnate perishable wood species, enhancing their durability and augmenting their commercial value. Collected wood sawdust was initially sieved to remove residues and unwanted materials and conditioned until 12% moisture content. Subsequently, the sawdust was Soxhlet-extracted using a mixture of organic solvents, including acetone, ethanol, and toluene. After evaporating the solvents, the resulting extractives were used to prepare a preservative solution with ethanol and acetone. The extractive solutions from each wood species were mixed with malt extract agar and then diluted to various concentrations: 0.125 mg/mL, 0.25 mg/mL, 0.5 mg/mL, 1.25 mg/mL, 2.0 mg/mL, and 2.5 mg/mL. For each concentration, fungal plugs from the periphery of actively growing cultures were moved to the centre of Petri dishes and placed in controlled laboratory conditions for incubation. The antifungal efficacy was assessed against specific wood-decaying fungi, including brown rot fungi (Coniophora puteana, Postia placenta, Lentinus lapideus) and white rot (Trametes versicolor). The evaluation involved daily monitoring of the linear expansion along two perpendicular radii for each fungus expressed as a percentage of the empty Petri dish area. The results indicated that the chanfuta extractives inhibited the growth of brown rot fungi at a concentration of 0.25 mg/mL and white rot fungi at 2.0 mg/mL. Similarly, the mecrusse extractives inhibit brown rot at 0.5 mg/mL and white rot at 2.0 mg/mL. The fatty acids Oleic (C18:1) present in the chanfuta extractives solution and linoleic (C18:2) in mecrusse extractives contributed to restraining the fungal growth. These results suggest that sawdust extractives from both wood species exhibit promising potential for creating environmentally friendly wood preservatives, which, with effective treatments, could extend the lifespan of perishable wood species

Unveiling the Substrate-Dependent Dynamics of Mycotoxin Production in Fusarium verticillioides Using an OSMAC-Metabolomics Approach.

Fusarium verticillioides is a prevalent plant pathogenic fungus known to produce harmful mycotoxins, including fumonisins and emerging toxins. This study aimed to investigate the influence of substrate on the temporal patterns of mycotoxin biosynthesis by F. verticillioides, employing a combined OSMAC (One Strain-Many Compounds) strategy and metabolomics approach. The fungus was cultured under various media conditions, and samples were collected over time. LC-MS/MS analyses and a dereplicative workflow were used to profile the secondary metabolite production, focusing on mycotoxins. The results demonstrated that modifying the culture conditions led to significant variations in fungal growth and the nature and relative concentrations of mycotoxins produced. Corn meal agar (CMA) medium was favorable for fumonisins A1 and B1, while malt extract agar (MEA) favored fumonisins A2 and B2. The study also identified the production of other mycotoxins related compounds as fusarins, bikaverin derivatives and fumonisins analogs, under different growth conditions. This study highlights the potential of combining OSMAC and metabolomics to unravel the substrate-dependent and time-dependent variations in mycotoxin biosynthesis by F. verticillioides. The insights gained provide a better understanding of the ecophysiology of this fungus and the occurrence of its mycotoxins, which can inform targeted mitigation strategies to ensure food and feed safety.

Isolation, Antibacterial Activity and Molecular Identification of Avocado Rhizosphere Actinobacteria as Potential Biocontrol Agents of Xanthomonas sp.

Actinobacteria, especially the genus Streptomyces, have been shown to be potential biocontrol agents for phytopathogenic bacteria. Bacteria spot disease caused by Xanthomonas spp. may severely affect chili pepper (Capsicum annuum) crops with a subsequent decrease in productivity. Therefore, the objective of the study was to isolate rhizospheric actinobacteria from soil samples treated by physical methods and evaluate the inhibitory activity of the isolates over Xanthomonas. Initially, soil samples collected from avocado tree orchards were treated by dry heat air and microwave irradiation; thereafter, isolation was implemented. Then, antibacterial activity (AA) of isolates was evaluated by the double-layer agar method. Furthermore, the positive/negative effect on AA for selected isolates was evaluated on three culture media (potato-dextrose agar, PDA; yeast malt extract agar, YME; and oat agar, OA). Isolates were identified by 16S rRNA sequence analysis. A total of 198 isolates were obtained; 76 (series BVEZ) correspond to samples treated by dry heat and 122 strains (series BVEZMW) were isolated from samples irradiated with microwaves. A total of 19 dry heat and 25 microwave-irradiated isolates showed AA with inhibition zones (IZ, diameter in mm) ranging from 12.7 to 82.3 mm and from 11.4 to 55.4 mm, respectively. An increment for the AA was registered for isolates cultured on PDA and YME, with an IZ from 21.1 to 80.2 mm and 14.1 to 69.6 mm, respectively. A lower AA was detected when isolates were cultured on OA media (15.0 to 38.1 mm). Based on the 16S rRNA gene sequencing analysis, the actinobacteria belong to the Streptomyces (6) and Amycolatopsis (2) genera. Therefore, the study showed that microwave irradiation is a suitable method to increase the isolation of soil bacteria with AA against Xanthomonas sp. In addition, Streptomyces sp. BVEZ 50 was the isolate with the highest IZ (80.2 mm).

Comparative Analysis of Some Morpho-cultural Characters of Venturia inaequalis (Apple Scab Pathogen) under Kashmir Conditions

Apple (Malus × domestica Borkh.) represents one of the most widely cultivated and economically important temperate fruit crops in the world. However, its cultivation faces significant challenges due to various fungal pathogens, particularly apple scab inflicted by Venturia inaequalis, which has a profound impact on the yield and quality of apple, resulting in substantial economic loss. The pervasive nature of V. inaequalis and its ability to damage crops poses a serious threat to sustainable apple production. In this study, the morpho-cultural characteristics of V. inaequalis were systematically analyzed and compared between the Shopian and Baramullah districts of the Kashmir Valley. Ten isolates from each district were grown on Malt Extract Agar (MEA) and Potato Dextrose Agar (PDA) for comparative analysis. The colonies were characterized by a compact hue ranging from greyish-green to blackish and exhibited a densely velvety texture. Mycelial growth was predominantly aerial, with some isolates displaying partial irregularity in colony margins, while others exhibited greater uniformity. The mean colony radii for potato dextrose agar and malt extract agar media was measured as 23.01 mm and 28.50 mm for the Shopian district, and 28.09 mm and 33.33 mm for the Baramullah district, respectively. The mean conidial spore density was recorded at 27.87 spores/cm² for the Baramullah district and 34.67 spores/cm² for the district Shopian, respectively. This variation could be attributed to several factors, including genetic diversity within the pathogen populations, differences in altitude, climate, and other environmental factors, the selection pressure exerted by fungicide applications, the emergence of novel pathogen races, and phenotypic plasticity driven by the differing agricultural practices and microclimatic conditions in the respective regions.

Xerophilic Aspergillaceae Dominate the Communities of Culturable Fungi in the Mound Nests of the Western Thatching Ant (Formica obscuripes)

The nests of mound-building ants are unexplored reservoirs of fungal diversity. A previous assessment of this diversity in the nests of Formica ulkei suggested that water availability may be a determinant of the composition of this mycota. To investigate this question, we recovered 3594 isolates of filamentous Ascomycota from the nests of Formica obscuripes and adjacent, non-nest sites, employing Dichloran Rose Bengal agar (DRBA), Dichloran Rose Bengal agar containing glycerol (DRBAG), and malt extract agar containing sucrose (MEA20S). Higher numbers of fungi were isolated from the tops of mounds than from within mounds and non-mound sites. Mound nest soils were dominated by members of the family Aspergillaceae, and up to 50% of the colonies isolated on DRBAG belonged to the genus Aspergillus. Pseudogymnoascus pannorum and species of Talaromyces were also present in higher numbers in mound soils. Species of Penicillium were more abundant in non-nest soils, where they accounted for over 66% of isolates on DRBA. All Aspergillaceae assessed for xerotolerance on a medium augmented with glycerol or sucrose were xerophilic. These results, and our observation that the nests of F. obscuripes are low-water environments, indicate that water availability influences the structure of the fungal communities in these animal-modified habitats.

Three new species of Talaromyces sect. Talaromyces discovered in China.

Talaromyces species play an important role in the nutrient cycle in natural ecosystems, degradation of vegetal biomass in industries and the implications in medicine. However, the species diversity of this genus is still far from fully understood. The polyphasic taxonomic approach integrating morphological comparisons and molecular phylogenetic analyses based on BenA, CaM, Rpb2 and ITS sequences was used to propose three new Talaromyces species. Three new species of sect. Talaromyces isolated from soil are proposed, namely, T. disparis (ex-type AS3.26221), T. funiformis (ex-type AS3.26220) and T. jianfengicus (ex-type AS3.26253). T. disparis is unique in low growth rate, velvety texture, limited to moderate sporulation, biverticillate, monoverticillate and irregular penicilli bearing a portion of abnormally large globose conidia, it has no close relatives in phylogeny. Being a member of T. pinophilus complex, T. funiformis produces mycelial funicles on Czapek yeast autolysate agar (CYA), 5% malt extract agar (MEA) and yeast extract (YES), sparse sporulation on Czapek agar (Cz), CYA, MEA and YES while abundant on oatmeal agar (OA), bearing appressed biverticillate penicilli and globose to pyriform conida with smooth to finely rough walls. T. jianfengicus belongs to T. verruculosus complex, is characterized by velvety colony texture with moderate to abundant elm-green conidia en masse, producing biverticillate penicilli, globose conidia with verrucose walls. It is now a common practice in establishing new species of Aspergillus, Penicillium and Talaromyces based on morphological characters and phylogenetic analyses of BenA, CaM, Rpb2 and ITS sequences. The proposal of the three novelties of Talaromyces in this article is not only supported by their morphological distinctiveness, but also confirmed by the phylogenetic analyses of the concatenated BenA-CaM-Rpb2 and BenA-CaM-ITS, as well as the individual BenA, CaM, Rpb2 and ITS sequence matrices.

Primary Screening of Fungi with Aflatoxin-Production Potential in Rotten Tomato sold at Shasha Market Akure

The present study aimed to isolate, characterise, and evaluate aflatoxin-producing fungus from rotting tomatoes sold in Shasha market, Akure. Rotten tomato fruits from the Shasha market in Akure were cultured on potato dextrose and malt extract agar that was made selective for fungi by adding chloramphenicol to inhibit bacteria. Results showed that fungal isolates have 1.40 to 3.30 x 103 sfu/g of total fungus. Penicillium spp., Rhizopus stolonifer, Mucor mucedo, and Phytophthora spp. had the lowest proportion of occurrence (4.76%), followed by Aspergillus flavus (33.33%) and Aspergillus niger (23.81%). Hepatoma, or liver cancer, and severe hepatitis are caused by aflatoxin, especially in underdeveloped nations like Nigeria. This study informs people that eating rotten tomatoes is harmful. To avoid aflatoxins-producing fungus contamination of tomato fruits, farmers and marketers must implement pre- and post-harvest procedures.

Competitive antagonistic action of laccase between Trichoderma species and the newly identified wood pathogenic Ganoderma camelum.

Ganoderma, a well-known genus in the Ganodermataceae family, has caused the extinction of several tree species due to its pathogenicity. This study explored the pathogenic effect of a newly identified Ganoderma species on trees and its competitive efficiency against Trichoderma species. Ganoderma camelum sp. nov. is characterized by small sessile basidiomata and a velvety, soft, camel-brown pileus. Phylogenetic analysis and ITS rDNA sequences indicated that the species were Trichoderma and Ganoderma camelum. Both fungal species competed antagonistically by secreting laccase. The laccase activity of G. camelum, with a value of 8.3 ± 4.0 U/mL, demonstrated the highest competitive activity against Trichoderma species. The laccase produced by T. atroviride (2.62 U/mL) was most effective in countering the pathogenic action of the novel G. camelum. The molecular weights of laccase were determined using SDS-PAGE (62.0 kDa for G. camelum and 57.0 kDa for T. atroviride). Due to the white rot induced by this Ganoderma species in the host tree, G. camelum showed the highest percentage inhibition of radial growth (76.3%) compared to T. atroviride (28.7%). This study aimed to evaluate the competitive antagonistic activity of Ganoderma and Trichoderma on malt extract agar media in the context of white rot disease in the host tree. This study concluded that the laccase from G. camelum caused weight loss in rubber wood blocks through laccase action, indicating tissue injury in the host species. Therefore, it was also concluded that G. camelum was more effective in pathogenic action of the host and resisted the biological action of T. atroviride. In principal components analysis (PCA), all the species associated with laccase exhibited a very strong influence on the variability of the system. The PIRG rate (percentage inhibition of radial growth) was strongly and positively correlated with laccase activity.

A simple culture medium for phenotypic characterization and long-term storage of medically relevant fusarioid fungi

Fusarioid fungi, particularly Neocosmospora solani and Fusarium oxysporum, are emerging as significant human pathogens, causing infections ranging from localized mycoses to life-threatening systemic diseases. Accurate identification and preservation of these fungi in clinical laboratories remain challenging because of their diverse morphologies and specific growth requirements. This study evaluated a novel milk-honey and malt agar (MHM) against conventional media for cultivating and preserving 60 clinical fusarioid isolates, including Neocosmospora spp. (n = 47), Bisifusarium spp. (n = 5), and Fusarium spp. (n = 8). Compared with Sabouraud dextrose 2 % agar (SDA) and malt extract agar (ME2), MHM significantly increased conidia production (p < 0.0001, mean = 3.4 × 103, standard deviation (SD) = ±1.3 × 103), with results similar to those of carnation leaf agar (CLA). MHM facilitated superior preservation of fusarioid viability for up to one year at room temperature on slant cultures and over two years on swabs in Amies gel with charcoal, outperforming current methods such as Castellani (water) or cryopreservation. Morphological characterization of fusarioid fungi grown on MHM revealed distinct growth patterns and conidial structures for Neocosmospora, Bisifusarium, and Fusarium species, aiding in identifying these genera. The superior performance of MHM in stimulating conidiation, maintaining viability, and preserving morphology underscore its potential as a reference medium for medically relevant fusarioid fungi, with broad implications for clinical mycology laboratories and resource-limited settings.

Effect of Media on the Mycelial Growth of Honey Bee Fungal Pathogen &lt;i&gt;Ascosphaera apis&lt;/i&gt; Mating Types

The fungal pathogen Ascosphaera apis significantly impacts the honey bee Apis mellifera by causing larval mortality and reducing colony productivity. Understanding the growth dynamics of A. apis under different media conditions is crucial for advancing research on its biology and pathogenicity. This study evaluates the effect of eight artificial media namely Potato Dextrose Agar (PDA), Carrot Dextrose Agar (CDA), Beetroot Dextrose Agar (BDA), Tender Coconut Water (TCW) media, Sabouraud Dextrose Agar (SDA), Sabouraud Dextrose Agar Yeast (SDAY), Sabouraud Maltose Agar Yeast (SMAY), and Malt Extract Agar (MEA) on the mycelial growth and reproductive structure formation of A. apis's two mating types. Results indicated significant differences in mycelial growth across media. SDA (75.40 mm dia) and SDAY (74.83 mm dia) supported maximum growth for mating type 1 (MAT1) and, SDA (72.72 mm dia) and BDA (68.17 mm dia) yielded the maximum growth for mating type 2 (MAT2). The TCW resulted in the least growth for MAT1 (44.19 mm dia) and MAT2 (41.25 mm dia). The growth patterns showed that media supplemented with sugars generally enhanced A. apis growth, whereas non-sugar media did not. Furthermore, reproductive structures formed faster on PDA and CDA than on other media. The study confirms that media composition, particularly sugar content, critically influences the growth and development of A. apis, providing insights that could help to develop better management strategies for controlling chalkbrood disease in honey bee colonies.

First Report of Phyllosticta capitalensis Causing Postharvest Brown Spot Disease on Guava Fruit in Thailand.

Guava (Psidium guajava L.) is a popular fruit crop that is widely cultivated in Thailand. In November 2023, brown spot disease on guava was observed during postharvest storage at 22 to 31°C and 70 to 75% relative humidity over a period of 3 to 7 days in Fang District, Chiang Mai Province, Thailand. The disease incidence was ~20% of 100 fruits per pallet box. The disease severity on each fruit ranged from 40 to 70% of the surface area affected by lesions. The symptoms appeared as circular to irregular brown to dark brown spots, ranging from 5 to 30 mm in diameter. Fungi were isolated from lesions using a single conidial isolation method (Choi et al. 1999). Two fungal isolates (SDBR-CMU497 and SDBR-CMU498) with similar morphology were obtained. Colonies on potato dextrose agar (PDA) and malt extract agar (MEA) were 65 to 67 and 29 to 38 mm in diameter, respectively after incubation for 1 week at 25°C. Colonies on PDA and MEA were flat, slightly undulate, greenish gray in the center, greyish green at the margin; reverse black. Both isolates produced asexual structures. Pycnidia were black, granular, and grouped. Conidiogenous cells were hyaline, subcylindrical to cylindrical, 8.5 to 17.5 × 3 to 5.5 µm. Conidia were single-celled, hyaline, obovoid to ellipsoid, 5.2 to 9.4 × 3.6 to 7.5 µm (n = 50), smooth-walled, with a single apical appendage. Morphologically, both isolates resembled Phyllosticta capitalensis (Wikee et al. 2013). The internal transcribed spacer (ITS) region, large subunit (nrLSU), translation elongation factor 1-alpha (tef1-α), actin (act), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were amplified using primer pairs ITS5/ITS4, LROR/LRO5, EF1-728F/EF2, ACT-512F/ACT-783R, and GPD1-LM/GPD2-LM, respectively (White et al. 1990; Zhang et al. 2022). Sequences were deposited in GenBank (ITS: PP946770, PP946771; nrLSU: PP948677, PP948678; tef1-α: PP948012, PP948013; act: PP948014, PP948015; GAPDH: PP948016, PP948017). Maximum likelihood phylogenetic analyses of the concatenated five genes identified both isolates as P. capitalensis. Thus, both morphology and molecular data confirmed the fungus as P. capitalensis. To confirm pathogenicity, healthy commercial guava fruits cultivar Kim Ju were surface disinfected by 0.1% NaClO for 3 min, rinsed three times with sterile distilled water, and wounded (Cruz-Lagunas et al. 2023). Conidia were collected from 2-week-old cultures on PDA and suspended in sterile distilled water. Fifteen microliters of a 1 × 106 conidia/ml suspension were dropped onto the wounded fruits. Mock inoculations were used as a control with sterile distilled water. Ten replications were conducted for each treatment and repeated twice. The inoculated fruits were stored in individual sterile plastic boxes at 25°C with 80 to 90% relative humidity. After 7 days, all inoculated fruits exhibited brown to dark brown lesions, while control fruits were asymptomatic. Phyllosticta capitalensis was consistently reisolated from the inoculated tissues on PDA to complete Koch's postulates. Prior to this study, P. capitalensis was known to cause brown or black spot disease on guava fruits cultivated in fields in China (Liao et al. 2020), Egypt (Arafat 2018), and Mexico (Cruz-Lagunas et al. 2023). To our knowledge, this is the first report of P. capitalensis causing postharvest brown spot disease on guava fruit in Thailand. The results will inform epidemiological investigations and future approaches to managing this disease.

QUANTITATIVE ANALYSIS OF CHITOSAN CONCENTRATION-DEPENDENT MODULATION OF PHYTOPATHOGENIC FUNGAL GROWTH

The study investigated the impact of varying concentrations of chitosan on fungal growth, measured by mycelial diameter, in a solid medium containing 2% malt extract agar (MEA). Concentrations of chitosan (0.05%, 0.10%, 0.15%, and 0.25%) were compared against a control group. The results demonstrated a notable decrease in fungal growth as chitosan concentration increased, indicating a linear relationship between fungal growth and chitosan concentration. The fungal mycelium covered the chitosan-amended medium within 7 days at lower (0.05%), while a prolonged duration (18-22 days) was required for growth at medium (0.10 and 0.15%) and higher concentrations (0.15 and 0.25%), compared to the control. Minimum inhibitory concentration (MIC) values for chitosan were determined at 0.25% for A. alternata, A. flavus, and S. rolfsii, while concentration &gt; 0.25% was required to achieve complete inhibition in the growth of M. phaseolina. Principal component analysis (PCA) was conducted to elucidate fungal growth inhibition at different chitosan concentrations signifying fungal sensitivity to chitosan concentrations. A. alternata exhibited a more sensitivity, followed by S. rolfsii and A. flavus, to chitosan concentrations. The findings of this study will contribute valuable insights into the potential utility of chitosan nanoparticles as an antimycotic agent against these pathogenic fungi

Mycobiota contaminating some market cake samples with reference to their toxin and enzyme

Fungi can spoil the majority of baked products. Spoilage of cake during storage is commonly associated with fungi. Therefore, this study aimed to assess the quality of different types of cakes sold in the market. The most predominant fungal genera in the tested cake samples (14 samples) were Aspergillus spp., and Penicillium spp. On Potato Dextrose Agar (PDA), the medium fungal total count was 43.3 colonies /g. Aspergillus was the most dominant genus and was isolated from six samples of cake. Aspergillus was represented by 3 species namely, A. flavus, A. niger, and A. nidulans, represented by 13.32, 19.99, and 3.33 colonies /g respectively. On Malt Extract Agar (MEA) Medium, the fungal total count was 123.24 colonies / g. Aspergillus was the most dominant isolated genus from 11 samples of cake and was represented by 5 species, namely, A. flavus, A. niger, A. ochraceous, A. terreus, and A. versicolor (26. 65, 63.29, 3.33, 6.66, and 3.33 colonies / g , respectively). Twenty-four isolates (88.88 %) of the total tested twenty-seven filamentous fungi showed positive results for amylase production. Ten isolates (37.03%) of the total tested filamentous fungi showed positive results for lipase production, and finally eleven isolates (40.74 %) of the total fungal isolates showed positive results for protease production. Aflatoxins B1, B2, G1, G2, and ochratoxin A were not detected in fourteen collected samples of cake. In this study, clove oil was the best choice overpeppermint oil and olive oil for preventing mold development when natural agents were compared. It might be due to the presence of a varietyof bioactive chemical compounds in clove oil, whose major bioactive component is eugenol, which acts as an antifungal reagent. Therefore, freshly baked cake should be consumed within afew days to avoid individuals experiencing foodborne illnesses.

A new Paecilomyces from wooden utility poles in South Africa.

During a survey of fungi on electricity utility poles in South Africa, a diverse range of fungi were discovered. Paecilomyces was frequently isolated, with five species identified using ITS and β-tubulin (BenA) sequences. These were P. brunneolus, P. dactylethromorphus, P. lecythidis, P. paravariotii and a potential new species. The genomes of 30 of these strains were subsequently sequenced and used in a phylogenomic analysis with 45 previously published genomes of the genus. Phylogenetic analyses were also conducted using ITS, BenA, calmodulin (CaM), RNA polymerase II second largest subunit (RPB2), RNA polymerase II largest subunit (RPB1), the genes coding for the theta subunit of the TCP-1 chaperonin complex (Cct8), and for a putative ribosome biogenesis protein (Tsr1). Both phylogenomic and phylogenetic analyses supported the 15 Paecilomyces species currently accepted and confirmed the novelty of the new species, which we describe as P. lignorum. The latter is the sister species of P. brunneolus and belongs to a clade also containing P. variotii and P. paravariotii. Morphologically, the new species produces longer ellipsoidal conidia and grows more restricted on malt extract agar at 30 °C compared to its closest relatives. Citation: Visagie CM, Cruywagen EM, Duong TA (2024). A new Paecilomyces from wooden utility poles in South Africa. Fungal Systematics and Evolution 13: 163-181. doi: 10.3114/fuse.2024.13.10.

Evaluation of antioxidant potential of crude extract of metabolites from endophytic fungi isolated from &lt;i&gt;Annona senegalensis&lt;/i&gt; Pers

Degenerative diseases resulting from free radicals can be prevented through the use of natural antioxidants. This study aimed to assess the free radical scavenging potential of the underexplored endophytic fungal metabolites from Annona senegalensis Pers (wild custard apple). Freshly collected root, midrib, and leaf tissues were planted on malt extract agar following surface sterilization with 70% ethanol for 3 minutes, washed twice with distilled water, immersed in a sodium hypochlorite solution (4%) for 5 minutes, and subsequently rinsed with sterile water. Seven endophytic fungi were isolated, and the antioxidant activity of their metabolites was evaluated using the 2,2- diphenyl-1-picrylhydrazyl free radical scavenging method, with ascorbic acid serving as a reference antioxidant. The crude extract from the seven endophytic fungal isolates demonstrated concentration- dependent antioxidant activities. LB2 exhibited a strong antioxidant activity with an IC50 value of 38.15 μg/ml. Extracts from RT1 and LB1 showed antioxidant activities, with the highest inhibition of 60% and 65%, respectively, observed at a concentration of 1000 μg/ml. This was compared favorably to ascorbic acid, which exhibited 94% inhibition. This indicates that the crude extract from endophytic fungi isolated from A. senegalensis possesses free radical scavenging properties. Further purification and elucidation of the crude extract will reveal the bioactive compounds responsible for the antioxidant activities.

First Report of Green Mould on Leaf of Phaseolus vulgaris Caused by Cladosporium tenuissimum in Liaoning, China.

Phaseolus vulgaris Linn. is a widely cultivated vegetable throughout the world. From spring 2019 to 2022, green mould symptoms were observed on leaves of P. vulgaris in the greenhouse in Liaoning, China, with disease incidence of 8-75% (plants) and 6-23% (leaves). Symptoms appeared as chlorotic lesions covered with dark green mould. The infections started at the apex or margin of the leaves and then spread inward with a characteristic "V" shape. Lesions exhibited curly morphology. 15 leaf samples with typical symptoms were collected from 5 different greenhouses. A total of 75 (5 replicates of each sample) leaf tissues (0.5 cm × 0.5 cm) were selected from the boundary between diseased and healthy parts. These samples were surface sterilized in 0.5% NaClO formin, rinsed 3 times in sterile distilled water and subsequently incubated at 28℃ on potato dextrose agar (PDA) supplemented with streptomycin (50 μg/ml). Numerous morphologically uniform colonies had been purified, with no other fungi observed. Afterwards, the strains were subcultured on malt extract agar (MEA). Colonies on MEA reached 70 to 80 mm diam after 14 days, smoke-grey to pale olivaceous-grey, woolly, sometimes radially wrinkled. The mycelia were pale olivaceous-grey, with hyphae measuring 1-5 μm wide (n = 20). The conidiophores were solitary or in groups of 2 to 5, and measured 50-280(-350) × 2.5-4 μm (n = 20), with 2-7 septa. The conidiogenous cells exhibited a cylindrical-oblong morphology and measured 10-44 × 5 μm (n = 20), with 0-2 septa, and the loci frequently thickened. The conidia were catenate in densely branched chains, ellipsoid to obovoid, smooth, and measured 2.5-5 × 2-3 μm (n = 50), with 0-4 septa. The morphological characteristics were similar to Cladosporium tenuissimum (Zhang 2003). The representative isolate KZ-19 was selected for molecular identification. The rDNA-ITS, translation elongation factor 1-α and actin genes were amplified, sequenced, and the resulting sequence data were submitted to GenBank (ITS: OQ931048; EF-1α: OQ954495; ACT: OQ954496). The BLAST results exhibited a 99 to 100% similarity with the sequences of C. tenuissimum type strain CBS 125995(ITS: HM148197; EF-1α: HM148442; ACT: HM148687). Furthermore, a multi-locus phylogenetic tree was constructed using the PhyloSuite (v 1. 2. 2) software, which revealed that the strains were most closely related to C. tenuissimum (Zhang et al. 2020). Based on both morphological and molecular characteristics, KZ-19 was finally identified as C. tenuissimum (Bensch 2012). Pathogenicity testing was performed on healthy 1-month-old P. vulgaris plants by inoculating the spore suspension (1×106 conidia/ml) of KZ-19 onto leaf surfaces, while control plants were simulated inoculated with sterile water, and five pots were used for each treatment. The test was performed under field conditions of 16-28°C (temperature) and 24-56% (relative humidity). Chlorotic lesions became evident within 2 days of inoculation, followed by the appearance of green mold on leaves after 7 days. No symptoms were observed in the control group. To fulfill Koch's postulates, the pathogen was re-isolated from three inoculated leaves. The morphological identification of re-isolated pathogens was similar to that of originally isolated pathogens. No infection was observed in non-inoculated control. To the best of our knowledge, this is the first report of C. tenuissimum causing green mould on P. vulgaris. As a ubiquitous saprobic hyphomycete, C. tenuissimum has been implicated in leaf mold in Punica granatum and Trifolium repens, larch bud blight, and strawberry blossom blight in previous years (He et al. 1987; Zhang et al. 2003; Zheng et al. 2010; Nam et al. 2015), presenting a potential threat to numerous crops. Therefore, an investigation of its distribution and pathogenic potential is essential in addition to the development of effective disease management strategies.

Phenotypic Characteristics, Pathogenicity, and Molecular Identification of Hypomyces perniciosus Causing Wet Bubble Disease of Edible Mushrooms

Abstract The research aimed to determine the phenotypic characteristic, pathogenicity and molecular characterization of Hypomyces perniciosus isolates responsible for wet bubble disease of the white button mushroom Agaricus bisporus. Phenotypic characteristics such as colony appearance, mycelium texture, and pigmentation were studied on four different agar media, i.e., potato dextrose agar (PDA), malt extract agar (MEA), Czapek-Dox yeast agar (CYA), and Sabouraud dextrose agar (SDA), after eight days of incubation. Additionally, the growth rate of the tested isolates was studied depending on the pH of the medium. Fungal isolates showed the highest mycelial growth on MEA and SDA at pH 6.0. However, on CYA at pH 7.0, the mycelium exhibited the worst growth. Isolate identification and genetic relationship analysis were carried out using internal transcribed spacer region sequencing and the random amplified polymorphic DNA method. The research confirmed that all Polish isolates belong to the species H. perniciosus, and the genetic diversity is relatively low. Phylogenetic analyses revealed three subgroups of H. perniciosus isolates. The first group included three genetically distinct isolates with a similarity coefficient in the range of 0.76–0.85 to isolates CBS 815.73 and CBS 322.52. The second group was divided into two subgroups and included 16 isolates with a genetic similarity range of 0.91 to 1.0 to CBS 815.73 and CBS 322.52 isolates. Furthermore, the eight genetically similar isolates exhibited the greatest pathogenicity towards A. bisporus.

First report of Cryptostroma corticale causing sooty bark disease in California and first worldwide report of silver maple as a host.

In November 2022 and February 2023, CAL FIRE tree health experts examined four maples (Acer spp.) planted decades earlier in a residential setting in Elk Grove, Sacramento Co., California (USA). Three of the trees were silver maples (Acer saccharinum ) and one was a Norway maple (A. platanoides); both species are exotic to California. The trees were in an irreversible state of decline, with the canopy substantially thinned and browning. Extensive bark cankers elongating longitudinally along the stem were visible on all trees (Fig. S1). Cankers were filled by fungal stromata protruding through the bark and producing masses of elliptical dark brown conidia (Fig. S2), approximately 5.5 x 3.7 um in size, giving the cankers a sooty appearance. The cankered bark could be peeled off easily, revealing dark and discrete lesions in the phloem and xylem. Samples from the three trees were shipped to the U.C. Berkeley Forest Pathology and Mycology Laboratory and to the CDFA PPDC in Sacramento, CA. In the laboratories, small wood chips were taken from the margins of the lesions, surface sterilized by dipping them for 30 seconds in 70% Ethanol, rinsed for 30 seconds in sterile water and plated onto 2.5% Malt Extract Agar amended with 0.3g/L Streptomycin or onto one-half strength acidified potato dextrose agar (APDA). Two morphologically identical cultures were obtained, one (T2) from a silver maple and one (T6) from the Norway maple. Cultures were then grown in liquid 2.5% malt extract broth and, after one week, DNA was extracted using the Qiagen Plant DNeasy DNA extraction kit. The ITS sequences are diagnostic for this fungus (Li et al. 2021) and those of the two cultures (GB OR064033 and OR933565) were 100% homologous to GenBank sequences of Cryptostroma corticale ( e.g. GB OP474010-11). The RPB2 sequence of T2 ( GB OR992132) was 100% homologous to that of C. corticale (GB HG934116.1). The isolate obtained from silver maple was inoculated in four potted silver maples by removing a bark disk 50 mm in diameter with a cork borer in three spots staggered at different heights and sides on the stem, placing a colonized agar plug of C. corticale in contact with the phloem, replacing the bark disk and wrapping with parafilm. Two control trees were mock inoculated using sterile agar plugs. Trees were in 57 L pots, had an average stem caliper of 2.7 cm, an average height of 3.5 m and were kept in a lath house at average high temperatures of 18-24 degrees C. After ten weeks, average lesion length was 15.4 cm (SE= 4.6) and 4.3 cm (SE=2.3) in the fungus-inoculated and control trees, respectively. An ANOVA test, nesting lesions sizes within tree, determined lesions lengths were different between inoculated and mock trees (P= 0.04). The fungus was reisolated from all points in all inoculated trees but never from control trees. C. corticale was first described in the UK from sycamore maple (Acer pseudoplatanus) (Gregory et al. 1949) and is an emerging problem in Europe (Muller et al. 2023). In North America, it has been reported from A. negundo, A. campestre, A. macrophyllum and Cornus nuttallii (Worral 2020), and it appears to be present in the Pacific Northwest (Brooks et al. 2023, Goree 1969). Norway maple is included in the European Plant Protection Organization list of hosts for C. corticale (EPPO 2023), however our finding of C. corticale on silver maple is a first report of this host worldwide and of this pathogen in California. This report is noteworthy, given that C. corticale is also a human pathogen infecting the respiratory system (Braun et al. 2021).

Survey of Phyllosticta citricarpa mating type in the São Paulo citrus belt and optimization of in vitro ascospore production

AbstractPhyllosticta citricarpa, the citrus black spot causal agent, requires both mating types, designated as MAT1‐1 and MAT1‐2, to produce ascospores. Mating‐type ratio in some citrus‐growing areas has been characterized but remains little known in the São Paulo (SP) citrus belt, the largest sweet orange producer worldwide. A protocol for in vitro ascospore production was developed recently; however, there are few studies regarding the optimal conditions for their production. Thus, this study aimed to determine the mating‐type ratio in SP and quantify ascospores produced under different conditions in vitro. The mating types were identified by duplex PCR, and ascospore production was assessed in five culture media: potato dextrose agar (PDA), ½ PDA, malt extract agar (MEA), oatmeal agar (OMA) and citrus agar (CA), and at temperatures from 10 to 30°C. The ratio of MAT1‐1 and MAT1‐2 was similar to 1:1. Ascospore production reached peaks of 8.0, 7.0 and 3.0 × 103 ascospores/mL in MEA, PDA and ½ PDA, respectively. There were no ascospores observed in OMA and CA. P. citricarpa ascospores were observed only at 15, 20 and 25°C in PDA, with peaks of up to 2.0 × 103 ascospores/mL at 42, 35 and 21 days, respectively. There were no ascospores observed at 10 and 30°C. Both mating types are similarly distributed in the SP citrus belt, and in vitro ascospore production may be optimized by using MEA at 25°C. These data provide a better understanding of P. citricarpa sexual reproduction and a background for further studies with ascospores.