Penicillium parvulum and Penicillium georgiense, sp. nov., isolated from the conidial heads of Aspergillus species

First Report of Penicillium oxalicum Causing Leaf Blight on Maize in China

In August 2022, two-month-old maize plants (Zea mays cv. 'Zihei'; "Chinese purple corn") exhibited irregular lesions on leaves and leaf blight symptoms (Figure 1). Although the lesions were yellow at the early infection stages, they turned brown during the pathogen advancement and culminated in leaf blight. Nearly 60% of plants from a non-commercial maize field (0.2 ha) in south-eastern Jiangsu (Nantong municipality, China; 120.54º E, 31.58º N) exhibited brown lesions, and about 4% of the diseased plants showed advanced leaf blight symptoms. The disease resulted in approximately a 9% yield loss compared to previous years when no disease symptoms were observed. Thirty small leaf pieces, approximately 0.3 cm2 in size and showing disease symptoms, were surface sterilized in 1.5% NaOCl for 1 min and washed twice with sterile ddH2O. The pathogen was cultured on PDA medium in the dark at 25 ºC, with grayish colonies observed after 5 days. Morphological analysis showed the presence of round/oval conidia (8.81 ± 0.50 μm diameter; n = 86) and branched conidiophores, which was consistent with the morphology of Penicillium spp. (Visagie et al. 2014). Nine representative isolates were obtained from different leaf pieces via single spore isolation, and the internal transcribed spacer (ITS), β-tubulin (TUB2) and calmodulin (CMD) genes were amplified using ITS1/ITS4, BT2a/BT2b and CMD5/CMD6 primers, respectively. The obtained ITS (OP954496-OP954497 and OP942428-OP942434), TUB2 (OP966781-OP966784 and OQ025045-OQ025049) and CMD (OQ078664-OQ078672) sequences were submitted in GenBank. Two isolates belonged to the P. citrinum species, while seven of the isolates belonged to the P. oxalicum species. A blast search revealed that the obtained P. citrinum ITS and CMD sequences had 99.39% and 100% homology to the ex-type strain P. citrinum NRRL 1841; GenBank numbers: AF033422 and GU944638 (Peterson & Horn 2009). Additionally, the obtained P. oxalicum ITS and CMD sequences had 99.82-100% and 94.64-95.49% homology to the ex-type strain P. oxalicum NRRL 787; GenBank numbers: AF033438 and KF296367 (Visagie et al. 2015). A molecular phylogenetic tree was constructed using MEGA7 to confirm the identity of the pathogen (Figure 2). To confirm pathogenicity, 3-week-old healthy 'Zihei' plants were used. The leaves were sprayed with aqueous solutions (sterilized ddH2O) that contained 1 × 106 spores/mL of each isolate. For the control experiment, sterilized ddH2O was used. After 5 days in a growth chamber at 25 ºC and 70% relative humidity, yellow lesions were observed. The number of lesions was higher when inoculating with P. oxalicum than when inoculating with P. citrinum. This result, together with the higher occurrence of P. oxalicum isolates, suggests that P. oxalicum is the main species causing the disease symptoms. The pathogen was recovered from the infected plants, and its identity was confirmed by ITS sequencing and morphological analysis. As far as we know, this is the first report of P. citrinum and P. oxalicum causing maize leaf blight worldwide. These species have previously been associated with maize kernels, as a source of mycotoxins posing relevant hazards to human health (Keller et al. 2013; Yang et al. 2020). P. citrinum was recently identified as the causal agent of green mold on Dictyophora rubrovalvata in China (Qin et al. 2022), while P. oxalicum was reported to cause citrus rot, pineapple leaf spot, and blue mold on Gastrodia elata, Astralagus membranaceus and muskmelon (Tang et al. 2020; Wu et al. 2022; Zheng et al. 2022). China is one of the world's largest producers of maize, harvesting more than 171 million tons in 2021. This report will help to better understand the pathogens that affect China's maize production.

Critical control point-based assessment and intervention of ochratoxin A risk in Angelicae Gigantis Radix production

Improperly practiced postharvest procedures can pose mycotoxin-related risks during medicinal herb production. As a health food material with pharmacological activities, Angelicae Gigantis Radix (AGR) has been extensively used in oriental medicine or functional foods. Compared with the official protocol, conventional practices were investigated for provisional critical control points (CCPs) in terms of ochratoxin A (OTA) contamination. Conventional practices include field-drying, which was associated with increased fungal exposure. Compared with conventional methods, the washing process in the official protocol was not advantageous for reducing OTA contamination in final products. Instead, drying was examined to assess the fungal growth risk during AGR production. To reduce the energy cost, product overload and shortened drying time could lead to failure in controlling fungal overgrowth and subsequent OTA production. In particular, inner parts of the load contained a higher OTA content than outer parts close to the heat outlet of the dryer. Improper thermal drying of loads allowed the growth of ochratoxigenic species during AGR production. Collectively, non-field-drying and optimally loaded thermal drying are easy preventive actions in key CCPs that need to be well maintained to attenuate any further microbial risk. These assessments provide insights into good practice-based mycotoxin risk management in producing herbal medicinal crops and new cost-efficient appropriate interventions for small-scale farms.

Classification of Aspergillus, Penicillium, Talaromyces and related genera (Eurotiales): An overview of families, genera, subgenera, sections, series and species

The Eurotiales is a relatively large order of Ascomycetes with members frequently having positive and negative impact on human activities. Species within this order gain attention from various research fields such as food, indoor and medical mycology and biotechnology. In this article we give an overview of families and genera present in the Eurotiales and introduce an updated subgeneric, sectional and series classification for Aspergillus and Penicillium. Finally, a comprehensive list of accepted species in the Eurotiales is given. The classification of the Eurotiales at family and genus level is traditionally based on phenotypic characters, and this classification has since been challenged using sequence-based approaches. Here, we re-evaluated the relationships between families and genera of the Eurotiales using a nine-gene sequence dataset. Based on this analysis, the new family Penicillaginaceae is introduced and four known families are accepted: Aspergillaceae, Elaphomycetaceae, Thermoascaceae and Trichocomaceae. The Eurotiales includes 28 genera: 15 genera are accommodated in the Aspergillaceae (Aspergillago, Aspergillus, Evansstolkia, Hamigera, Leiothecium, Monascus, Penicilliopsis, Penicillium, Phialomyces, Pseudohamigera, Pseudopenicillium, Sclerocleista, Warcupiella, Xerochrysium and Xeromyces), eight in the Trichocomaceae (Acidotalaromyces, Ascospirella, Dendrosphaera, Rasamsonia, Sagenomella, Talaromyces, Thermomyces, Trichocoma), two in the Thermoascaceae (Paecilomyces, Thermoascus) and one in the Penicillaginaceae (Penicillago). The classification of the Elaphomycetaceae was not part of this study, but according to literature two genera are present in this family (Elaphomyces and Pseudotulostoma). The use of an infrageneric classification system has a long tradition in Aspergillus and Penicillium. Most recent taxonomic studies focused on the sectional level, resulting in a well-established sectional classification in these genera. In contrast, a series classification in Aspergillus and Penicillium is often outdated or lacking, but is still relevant, e.g., the allocation of a species to a series can be highly predictive in what functional characters the species might have and might be useful when using a phenotype-based identification. The majority of the series in Aspergillus and Penicillium are invalidly described and here we introduce a new series classification. Using a phylogenetic approach, often supported by phenotypic, physiologic and/or extrolite data, Aspergillus is subdivided in six subgenera, 27 sections (five new) and 75 series (73 new, one new combination), and Penicillium in two subgenera, 32 sections (seven new) and 89 series (57 new, six new combinations). Correct identification of species belonging to the Eurotiales is difficult, but crucial, as the species name is the linking pin to information. Lists of accepted species are a helpful aid for researchers to obtain a correct identification using the current taxonomic schemes. In the most recent list from 2014, 339 Aspergillus, 354 Penicillium and 88 Talaromyces species were accepted. These numbers increased significantly, and the current list includes 446 Aspergillus (32 % increase), 483 Penicillium (36 % increase) and 171 Talaromyces (94 % increase) species, showing the large diversity and high interest in these genera. We expanded this list with all genera and species belonging to the Eurotiales (except those belonging to Elaphomycetaceae). The list includes 1 187 species, distributed over 27 genera, and contains MycoBank numbers, collection numbers of type and ex-type cultures, subgenus, section and series classification data, information on the mode of reproduction, and GenBank accession numbers of ITS, beta-tubulin (BenA), calmodulin (CaM) and RNA polymerase II second largest subunit (RPB2) gene sequences.

Biocontrol of Aspergillus flavus in Ensiled Sorghum by Water Kefir Microorganisms

The capacity of microorganisms from water kefir (WK) to control Aspergillus flavus growth during the aerobic phase of ensiled sorghum grains was determined. Sorghum inoculated with A. flavus was treated with filter-sterilized and non-sterilized water kefir, ensiled, and incubated 7 days at 25 °C. A. flavus growth was quantified by qPCR after incubation. Mold growth was inhibited in the presence of water kefir while no inhibition was observed when filter-sterilized water kefir was applied, demonstrating the relevant role of the microorganisms in the kefir water in the biocontrol process. Fungal and bacterial diversity in treated sorghum mini-silos was analyzed by high-throughput sequencing. Firmicutes was the predominant bacterial phyla and Lactobacillus represented the most abundant genus, while Ascomycota was the predominant fungal phyla with Saccharomyces and Pichia as the major genera. Bacterial and yeast counts before and after incubation indicated that the microbial community obtained from WK was able to grow in the sorghum mini-silos in the presence of A. flavus. Results of the present work indicate that the use of a mixed inoculum of microorganisms present in WK may represent an alternative management practice to avoid the growth of A. flavus in ensiled sorghum grains and the concomitant contamination with aflatoxins.

Thermotolerant hemicellulolytic and cellulolytic enzymes from Eupenicillium parvum 4-14 display high efficiency upon release of ferulic acid from wheat bran

AIMS

To characterize the hemicellulolytic and cellulolytic enzymes from novel fungi, and evaluate the potential of novel enzyme system in releasing ferulic acid (FA) from biomass resource.

METHODS AND RESULTS

A hemicellulolytic and cellulolytic enzyme-producing fungus 4-14 was isolated from soil by Congo red staining method, and identified as Eupenicillium parvum based on the morphologic and molecular phylogenetic analysis. The optimum temperature of fungal growth was 37°C. Hemicellulolytic and cellulolytic enzymes were produced by this fungus in solid-state fermentation (SSF), and their maximum activities were 554, 385, 218, 2·62 and 5·25 U g(-1) for CMCase, xylanase, β-glucosidase, FPase and FAE respectively. These enzymes displayed the best catalytic ability at low pH values (pH 4·5-5·0). The optimum temperatures were 70°C, 70°C, 75°C and 55°C for CMCase, β-glucosidase, xylanase and FAE respectively. CMCase, xylanase and FAE were stable at different pHs or high temperature (60°C). Enzymatic hydrolysis experiment indicated that the maximum (76·8 ± 4)% of total alkali-extractable FA was released from de-starched wheat bran by the fungal enzyme system.

CONCLUSIONS

High activities of thermotolerant CMCase, β-glucosidase, xylanase and FAE were produced by the newly isolated fungus E. parvum 4-14 in SSF. The fungal enzyme system displayed high efficiency at releasing FA from wheat bran.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides a new fungal strain for researches of novel hemicellulolytic and cellulolytic enzymes and will improve the bioconversion and utilization of agricultural by-products.

The Impact of Ozone Treatment in Dynamic Bed Parameters on Changes in Biologically Active Substances of Juniper Berries

The development of the parameters of ozone decontamination method assuring the least possible losses of biologically active substances (essential oils and polyphenols) and their activity in common juniper (Juniperus communis (L.)) berries was studied. Ozone treatment in dynamic bed was conducted 9 times. The process was conducted under different ozone concentrations (100.0; 130.0; 160.0 g O₃/m³) and times (30, 60, 90 min). After each decontamination, the microbiological profile of the juniper berries was studied, and the contaminating microflora was identified. Next to the microbiological profile, the phenolic profile, as well as antioxidant activity of extracts and essential oils were determined. The total polyphenol content (TPC), composition of essential oils, free radical-scavenging capacity, total antioxidant capacity, ferric-reducing antioxidant power (FRAP), beta-carotene bleaching test (BCB) and LC-MS polyphenol analysis were carried out. The study reveals that during short ozone contact times, higher amounts of TPC, 15.47 and 12.91 mg CE/g of extract, for samples 100/30 and 130/30, respectively, were demonstrated. Whereas samples 100/60, 130/60, 100/90, and 160/90 exhibited the lowest amount of phenolics. The highest antioxidant activity was found in the methanol extract obtained from ozonated berries which exhibited the lowest IC₅₀ in all the antioxidant assays, such as DPPH, FRAP, and BCB assays. Ozone treatment showed noteworthy potential and its usage in food manufacturing and as an alternative decontamination method should be considered.

Expanding the species and chemical diversity of Penicillium section Cinnamopurpurea

A set of isolates very similar to or potentially conspecific with an unidentified Penicillium isolate NRRL 735, was assembled using a BLAST search of ITS similarity among described (GenBank) and undescribed Penicillium isolates in our laboratories. DNA was amplified from six loci of the assembled isolates and sequenced. Two species in section Cinnamopurpurea are self-compatible sexual species, but the asexual species had polymorphic loci suggestive of sexual reproduction and variation in conidium size suggestive of ploidy level differences typical of heterothallism. Accordingly we use genealogical concordance analysis, a technique valid only in heterothallic organisms, for putatively asexual species. Seven new species were revealed in the analysis and are described here. Extrolite analysis showed that two of the new species, P. colei and P. monsserratidens produce the mycotoxin citreoviridin that has demonstrated pharmacological activity against human lung tumors. These isolates could provide leads in pharmaceutical research.

Diversity of Penicillium section Citrina within the fynbos biome of South Africa, including a new species from a Protea repens infructescence

During a survey of the fynbos biome in the Western Cape of South Africa, 61 Penicillium species were isolated and nine belong to Penicillium section Citrina. Based on morphology and multigene phylogenies, section Citrina species were identified as P. cairnsense, P. citrinum, P. pancosmium, P. pasqualense, P. sanguifluum, P. sizovae, P. sumatrense and P. ubiquetum. One of the species displayed unique phenotypic characters and DNA sequences and is described here as P. sucrivorum. Multigene phylogenies consistently resolved the new species in a clade with P. aurantiacobrunneum, P. cairnsense, P. miczynksii, P. neomiczynskii and P. quebecense. However, ITS, β-tubulin and calmodulin gene sequences are unique for P. sucrivorum and growth rates on various media, the ability to grow at 30 C, a positive Ehrlich reaction and the absence of sclerotia on all media examined, distinguish P. sucrivorum from all of its close relatives.

Molecular identification of isolated fungi from stored apples in Riyadh, Saudi Arabia

Fungi causes most plant disease. When fruits are stored at suboptimal conditions, fungi grows, and some produce mycotoxin which can be dangerous for human consumption. Studies have shown that the Penicillium and Monilinia species commonly cause spoilage of fruits, especially apples. Several other genera and species were reported to grow to spoil fruits. This study was conducted to isolate and identify fruit spoilage by fungi on apples collected in Riyadh, Saudi Arabia and conduct a molecular identification of the fungal isolates. Thus, we collected 30 samples of red delicious and Granny Smith apples with obvious spoilage from different supermarkets between February and March of 2012 in Riyadh, Saudi Arabia. Each apple was placed in a sterile plastic bag in room temperature (25-30 °C) for six days or until fungal growth was evident all over the sample. Growth of fungal colonies on PDA was counted and sent for molecular confirmation by PCR. Six fruit spoilage fungi were isolated, including Penicillium chrysogenum, Penicillium adametzii, Penicillium chrysogenum, Penicillium steckii, Penicillium chrysogenum, and Aspergillus oryzae. P. chrysogenum was the most frequent isolate which was seen in 14 of a total of 34 isolates (41.2%), followed by P. adametzii and A. oryzae with seven isolates each (20.6%) and the least was P. steckii with six isolates (17.6%). Penicillium species comprised 27 of the total 34 (79.4%) isolates. Sequence analysis of the ITS regions of the nuclear encoded rDNA showed significant alignments for P. chrysogenum, P. adametzii and A. oryzae. Most of these fungal isolates are useful and are rarely pathogenic; however they can still produce severe illness in immune-compromised individuals, and sometimes otherwise healthy people may also become infected. It is therefore necessary to evaluate the possible production of mycotoxins by these fungi to determine a potential danger and to establish its epidemiology in order to develop adequate methods of control.

Five new Penicillium species in section Sclerotiora: a tribute to the Dutch Royal family

Current literature accepts 17 species in Penicillium section Sclerotiora. Several produce colonies in bright yellow to orange colours and have monoverticillate conidiophores, apart from P. herquei, P. malachiteum and P. nodositatum, which are biverticillate. The focus of this paper is to refine the concepts of the species currently accepted in the section and introduce five new species, named after the Dutch Royal family as P. vanoranjei, P. maximae, P. amaliae, P. alexiae and P. arianeae. Penicillium vanoranjei produces orange (Dutch = oranje) colonies in culture, and is named after Willem-Alexander Claus George Ferdinand, ‘Zijne Koninklijke Hoogheid de Prins van Oranje’ (translated from Dutch as: ‘His Royal Highness the Prince of Orange’) and his family, to coincide with his coronation. We review the current taxonomic positions of P. lilacinoechinulatum and P. nodositatum, both currently considered to be synonyms of P. bilaiae. Sequence data generated in this study show that both species are phylogenetically distinct. Penicillium lilacinoechinulatum is closely related to P. amaliae sp. nov., whereas P. nodositatum does not belong to Penicillium sensu stricto. All species were compared morphologically and phylogenetically, based on β-tubulin and calmodulin DNA data. A table summarising the morphological characters of all species is included, together with photomicrographs and recommended DNA markers for identification.

Taxonomy of Penicillium section Citrina

Species of Penicillium section Citrina have a worldwide distribution and occur commonly in soils. The section is here delimited using a combination of phenotypic characters and sequences of the nuclear ribosomal RNA gene operon, including the internal transcribed spacer regions ITS1 and ITS2, the 5.8S nrDNA (ITS) and partial RPB2 sequences. Species assigned to section Citrina share the production of symmetrically biverticillate conidiophores, flask shaped phialides (7.0–9.0 μm long) and relatively small conidia (2.0–3.0 μm diam). Some species can produce greyish-brown coloured cleistothecia containing flanged ascospores. In the present study, more than 250 isolates presumably belonging to section Citrina were examined using a combined analysis of phenotypic and physiological characters, extrolite profiles and ITS, β-tubulin and/or calmodulin sequences. Section Citrina includes 39 species, and 17 of those are described here as new. The most important phenotypic characters for distinguishing species are growth rates and colony reverse colours on the agar media CYA, MEA and YES; shape, size and ornamentation of conidia and the production of sclerotia or cleistothecia. Temperature-growth profiles were made for all examined species and are a valuable character characters for species identification. Species centered around P. citrinum generally have a higher maximum growth temperature (33–36 °C) than species related to P. westlingii (27–33 °C). Extrolite patterns and partial calmodulin and β-tubulin sequences can be used for sequence based identification and resolved all species. In contrast, ITS sequences were less variable and only 55 % of the species could be unambiguously identified with this locus.

Phylogeny of Penicillium and the segregation of Trichocomaceae into three families

Species of Trichocomaceae occur commonly and are important to both industry and medicine. They are associated with food spoilage and mycotoxin production and can occur in the indoor environment, causing health hazards by the formation of β-glucans, mycotoxins and surface proteins. Some species are opportunistic pathogens, while others are exploited in biotechnology for the production of enzymes, antibiotics and other products. Penicillium belongs phylogenetically to Trichocomaceae and more than 250 species are currently accepted in this genus. In this study, we investigated the relationship of Penicillium to other genera of Trichocomaceae and studied in detail the phylogeny of the genus itself. In order to study these relationships, partial RPB1, RPB2 (RNA polymerase II genes), Tsr1 (putative ribosome biogenesis protein) and Cct8 (putative chaperonin complex component TCP-1) gene sequences were obtained. The Trichocomaceae are divided in three separate families: Aspergillaceae, Thermoascaceae and Trichocomaceae. The Aspergillaceae are characterised by the formation flask-shaped or cylindrical phialides, asci produced inside cleistothecia or surrounded by Hülle cells and mainly ascospores with a furrow or slit, while the Trichocomaceae are defined by the formation of lanceolate phialides, asci borne within a tuft or layer of loose hyphae and ascospores lacking a slit. Thermoascus and Paecilomyces, both members of Thermoascaceae, also form ascospores lacking a furrow or slit, but are differentiated from Trichocomaceae by the production of asci from croziers and their thermotolerant or thermophilic nature. Phylogenetic analysis shows that Penicillium is polyphyletic. The genus is re-defined and a monophyletic genus for both anamorphs and teleomorphs is created (Penicillium sensu stricto). The genera Thysanophora, Eupenicillium, Chromocleista, Hemicarpenteles and Torulomyces belong in Penicilliums. str. and new combinations for the species belonging to these genera are proposed. Analysis of Penicillium below genus rank revealed the presence of 25 clades. A new classification system including both anamorph and teleomorph species is proposed and these 25 clades are treated here as sections. An overview of species belonging to each section is presented.

Aspergillus and Penicillium identification using DNA sequences: barcode or MLST?

Current methods in DNA technology can detect single nucleotide polymorphisms with measurable accuracy using several different approaches appropriate for different uses. If there are even single nucleotide differences that are invariant markers of the species, we can accomplish identification through rapid DNA-based tests. The question of whether we can reliably detect and identify species of Aspergillus and Penicillium turns mainly upon the completeness of our alpha taxonomy, our species concepts, and how well the available DNA data coincide with the taxonomic diversity in the family Trichocomaceae. No single gene is yet known that is invariant within species and variable between species as would be optimal for the barcode approach. Data are published that would make an MLST approach to isolate identification possible in the most well-studied clades of Aspergillus and Penicillium.

Penicillium simile sp. nov. revealed by morphological and phylogenetic analysis

The morphology of three phenetically identical Penicillium isolates, collected from the bioaerosol in a restoration laboratory in Italy, displayed macro- and microscopic characteristics that were similar though not completely ascribable to Penicillium raistrickii. For this reason, a phylogenetic approach based on DNA sequencing analysis was performed to establish both the taxonomic status and the evolutionary relationships of these three peculiar isolates in relation to previously described species of the genus Penicillium. We used four nuclear loci (both rRNA and protein coding genes) that have previously proved useful for the molecular investigation of taxa belonging to the genus Penicillium at various evolutionary levels. The internal transcribed spacer region (ITS1–5.8S–ITS2), domains D1 and D2 of the 28S rDNA, a region of the tubulin beta chain gene (benA) and part of the calmodulin gene (cmd) were amplified by PCR and sequenced. Analysis of the rRNA genes and of the benA and cmd sequence data indicates the presence of three isogenic isolates belonging to a genetically distinct species of the genus Penicillium, here described and named Penicillium simile sp. nov. (ATCC MYA-4591T  = CBS 129191T). This novel species is phylogenetically different from P. raistrickii and other related species of the genus Penicillium (e.g. Penicillium scabrosum), from which it can be distinguished on the basis of morphological trait analysis.

Penicillium menonorum, a new species related to P. pimiteouiense

Penicillium menonorum is described as a new monoverticillate, non-vesiculate species that resembles P. restrictum and P. pimiteouiense. On the basis of phylogenetic analysis of DNA sequences from four loci, P. menonorum occurs in a clade with P. pimiteouiense, P. vinaceum, P. guttulosum, P. rubidurum, and P. parvum. Genealogical concordance analysis was applied to P. pimiteouiense and P. parvum, substantiating the phenotypically defined species. The species P. rubidurum, P. guttulosum, and P. menonorum were on distinct branches statistically excluded from inclusion in other species and have distinct phenotypes.