Phylogeny, identification and nomenclature of the genus Aspergillus

Differentiation and quantification of the ochratoxin A producers Aspergillus ochraceus and Aspergillus westerdijkiae using PCR-DGGE

Ochratoxin A (OTA) is a nephrotoxic, teratogenic, immunotoxic, and carcinogenic mycotoxin which is produced in tropical zones mainly by Aspergillus carbonarius, A. niger, A. ochraceus, and A. westerdijkiae. A. ochraceus and A. westerdijkiae species are phenotypically and genomically very close but A. westerdijkiae produce OTA at a very higher level than A. ochraceus. These species have been differentiated recently. The DNA primer pairs which were drawn so far are not specific and a genomic region of the same size is amplified for both species or they are too specific, and in this case, the DNA of a single species is amplified. To help preventing OTA contamination of foodstuffs, the PCR-DGGE (Denaturing Gradient Gel Electrophoresis) method was used to discriminate between A. ochraceus and A. westerdijkiae DNA fragments of the same size but with different sequences and thus faster access to a diagnosis of the toxigenic potential of the fungal microflora. The proposed methodology was able to differentiate A. westerdijkiae from A. ochraceus with only one primer pairs in a single run. A calibration based on initial DNA content was obtained from image analysis of the DGGE gels and a method of quantification of the two strains was proposed.

Surveillance for Azole-Resistant Aspergillus fumigatus in a Centralized Diagnostic Mycology Service, London, United Kingdom, 1998-2017

Background/Objectives: Aspergillus fumigatus is the leading cause of invasive aspergillosis. Treatment is hindered by the emergence of resistance to triazole antimycotic agents. Here, we present the prevalence of triazole resistance among clinical isolates at a major centralized medical mycology laboratory in London, United Kingdom, in the period 1998-2017. Methods: A large number (n = 1469) of clinical A. fumigatus isolates from unselected clinical specimens were identified and their susceptibility against three triazoles, amphotericin B and three echinocandin agents was carried out. All isolates were identified phenotypically and antifungal susceptibility testing was carried out by using a standard broth microdilution method. Results: Retrospective surveillance (1998-2011) shows 5/1151 (0.43%) isolates were resistant to at least one of the clinically used triazole antifungal agents. Prospective surveillance (2015-2017) shows 7/356 (2.2%) isolates were resistant to at least one triazole antifungals demonstrating an increase in incidence of triazole-resistant A. fumigatus in our laboratory. Among five isolates collected from 2015 to 2017 and available for molecular testing, three harbored TR34/L98H alteration in the cyp51A gene that are associated with the acquisition of resistance in the non-patient environment. Conclusion: These data show that historically low prevalence of azole resistance may be increasing, warranting further surveillance of susceptible patients.

Comparative genotyping and phenotyping of Aspergillus fumigatus isolates from humans, dogs and the environment

Background

Aspergillus fumigatus is a ubiquitous saprotrophic fungus and an opportunistic pathogen of humans and animals. Humans and animals can inhale hundreds of A. fumigatus spores daily. Normally this is harmless for humans, but in case of immunodeficiency, invasive pulmonary aspergillosis (IPA) can develop with a high mortality rate. A. fumigatus also causes non-invasive mycoses like sino-nasal aspergillosis (SNA) in dogs.

Results

In this study we compared A. fumigatus isolates from humans with suspected IPA, dogs with SNA, and a set of environmental isolates. Phylogenetic inference based on calmodulin (CaM) and beta-tubulin (benA) sequences did not reveal A. fumigatus sub-groups linked to the origin of the isolates. Genotyping and microsatellite analysis showed that each dog was infected by one A. fumigatus genotype, whereas human patients had mixed infections. Azole resistance was determined by antifungal susceptibility testing and sequencing of the cyp51A gene. A total of 12 out of 29 human isolates and 1 out of 27 environmental isolates were azole resistant. Of the azole resistant strains, 11 human isolates showed TR₃₄/L98H (n = 6) or TR46/Y121F/T289A (n = 5). Phenotypically, isolates from dogs were more variable in growth speed and morphology when compared to those isolated from human and the environment.

Conclusions

A. fumigatus from dogs with SNA are phenotypically very diverse in contrast to their environmental and human counterparts.

Phenotypic variability can be induced during the chronic infection process in the sinus of the dogs. The basis of this heterogeneity might be due to genomic differences and/or epigenetic variations.

Differences in dogs is a could be a result of within-host adaption and might be triggered by environmental factors in the sinus, however this hypothesis still needs to be tested.

Electronic supplementary material

The online version of this article (10.1186/s12866-018-1244-2) contains supplementary material, which is available to authorized users.

Genomic and transcriptomic comparison of Aspergillus oryzae strains: a case study in soy sauce koji fermentation

The filamentous fungus Aspergillus oryzae is used in soy sauce koji making due to its high productivity of hydrolytic enzymes. In this study, we compared the genomes and transcriptomes of an industrial strain RD2 and a strain with decreased fermentation performance TS2, aiming to explain their phenotypic differences at the molecular level. Under the regulation of conidiation and fermentation conditions, the enhanced hydrolytic enzyme production and flavor precursor formation in RD2 described a complete expression profile necessary to maintain desirable fermentation performance. By contrast, central carbon metabolism was up-regulated in TS2 for fast growth, suggesting a conflicting relationship between mycelium growth and fermentation performance. Accumulation of mutations also lowered the fermentation performance of TS2. Our study has deepened the understanding of the metabolism and related regulatory mechanisms in desirable koji fermentation. A list of potential molecular markers identified here could facilitate targeted strain maintenance and improvement for better koji fermentation.

A unique fungal strain collection from Vietnam characterized for high performance degraders of bioecological important biopolymers and lipids

Fungal strains are abundantly used throughout all areas of biotechnology and many of them are adapted to degrade complex biopolymers like chitin or lignocellulose. We therefore assembled a collection of 295 fungi from nine different habitats in Vietnam, known for its rich biodiversity, and investigated their cellulase, chitinase, xylanase and lipase activity. The collection consists of 70 isolates from wood, 55 from soil, 44 from rice straw, 3 found on fruits, 24 from oil environments (butchery), 12 from hot springs, 47 from insects as well as 27 from shrimp shells and 13 strains from crab shells. These strains were cultivated and selected by growth differences to enrich phenotypes, resulting in 211 visually different fungi. DNA isolation of 183 isolates and phylogenetic analysis was performed and 164 species were identified. All were subjected to enzyme activity assays, yielding high activities for every investigated enzyme set. In general, enzyme activity corresponded with the environment of which the strain was isolated from. Therefore, highest cellulase activity strains were isolated from wood substrates, rice straw and soil and similar substrate effects were observed for chitinase and lipase activity. Xylanase activity was similarly distributed as cellulase activity, but substantial activity was also found from fungi isolated from insects and shrimp shells. Seven strains displayed significant activities against three of the four tested substrates, while three degraded all four investigated carbon sources. The collection will be an important source for further studies. Therefore representative strains were made available to the scientific community and deposited in the public collection of the Leibniz-Institute DSMZ-German Collection of Microorganisms and Cell Cultures, Braunschweig.

Experimental and molecular approximation to microbial niche: trophic interactions between oribatid mites and microfungi in an oligotrophic freshwater system

Mite-fungal interactions play a key role in structuring core ecosystem processes such as nutrient dynamics. Despite their ecological relevance, these cross-kingdom interactions remain poorly understood particularly in extreme environments. Herein, we investigated feeding preferences of a novel genetic lineage of aquatic oribatids obtained from an oligotrophic freshwater system in the Cuatro Ciénegas Basin (CCB) within the Chihuahuan Desert, Mexico. During in vitro diet preference bioassays, transient aquatic microfungi (Aspergillus niger, Talaromyces sp., and Pleosporales sp.) recovered from the same mesocosm samples were offered individually and simultaneously to mites. Gut content was analyzed using classic plating and culture-independent direct PCR (focusing on the fungal barcoding region) methods. Our results indicated that oribatids fed on all tested fungal isolates, yet the profusely developing A. niger was preferentially consumed with all fungal components being digested. This feeding habit is particularly interesting since A. niger has been reported as an unsuitable dietary element for population growth, being consistently avoided by mites in previous laboratory experiments. It is possible that our mites from the CCB have adapted to exploit available resources within this oligotrophic site. This work confirms the trophic relationship between microfungi and mites, two rarely investigated major components of the microbial community, shedding light on the niche dynamics under low-nutrient conditions.

Biochemical Components Associated With Microbial Community Shift During the Pile-Fermentation of Primary Dark Tea

Primary dark tea is used as raw material for compressed dark tea, such as Fu brick tea, Hei brick tea, Hua brick tea, and Qianliang tea. Pile-fermentation is the key process for the formation of the characteristic properties of primary dark tea, during which the microorganism plays an important role. In this study, the changes of major chemical compounds, enzyme activities, microbial diversity, and their correlations were explored during the pile-fermentation process. Our chemical and enzymatic analysis showed that the contents of the major compounds were decreased, while the activities of polyphenol oxidase, cellulase, and pectinase were increased during this process, except peroxidase activity that could not be generated from microbial communities in primary dark tea. The genera Cyberlindnera, Aspergillus, Uwebraunia, and Unclassified Pleosporales of fungus and Klebsiella, Lactobacillus of bacteria were predominant in the early stage of the process, but only Cyberlindnera and Klebsiella were still dominated in the late stage and maintained a relatively constant until the end of the process. The amino acid was identified as the important abiotic factor in shaping the microbial community structure of primary dark tea ecosystem. Network analysis revealed that the microbial taxa were grouped into five modules and seven keystone taxa were identified. Most of the dominant genera were mainly distributed into module III, which indicated that this module was important for the pile-fermentation process of primary dark tea. In addition, bidirectional orthogonal partial least squares (O2PLS) analysis revealed that the fungi made more contributions to the formation of the characteristic properties of primary dark tea than bacteria during the pile-fermentation process. Furthermore, 10 microbial genera including Cyberlindnera, Aspergillus, Eurotium, Uwebraunia, Debaryomyces, Lophiostoma, Peltaster, Klebsiella, Aurantimonas, and Methylobacterium were identified as core functional genera for the pile-fermentation of primary dark tea. This study provides useful information for improving our understanding on the formation mechanism of the characteristic properties of primary dark tea during the pile-fermentation process.

Sterigmatocystin in foodstuffs and feed: aspects to consider

Sterigmatocystin (STC) is a possible human carcinogen (2B) according to International Agency for Research on Cancer classification and has been associated with immunotoxic and immunomodulatory activity, together with mutagenic effects. It might be found in numerous substrates, from foods and feeds to chronically damp building materials and indoor dust. Although European Food Safety Authority concluded that the exposure to STC to be of low concern for public health, reinforces the need of data concerning exposure of European citizens. Climate change can represent an increased risk of exposure to STC since it is a crucial factor for agro-ecosystem powering fungal colonisation and mycotoxin production This aspect can represent an increased risk for European countries with temperate climates and it was already reported by the scientific community.

Big Sound and Extreme Fungi-Xerophilic, Halotolerant Aspergilli and Penicillia with Low Optimal Temperature as Invaders of Historic Pipe Organs

Recent investigations have shown that xerophilic fungi may pose a biodeterioration risk by threatening objects of cultural heritage including many types of materials, including wood, paint layers, organic glues or leather and even metal. Historic—and also new built—pipe organs combine all those materials. In this study, halotolerant aspergilli and penicillia with low optimal temperatures were shown to be the most frequent invaders of pipe organs. The fungi form white mycelia on the organic components of the organs with a clear preference for the bolus paint of the wooden pipes, the leather-made hinges of the stop actions and all parts fixed by organic glue. Physiological tests showed that the strains isolated from the instruments all show a halotolerant behavior, although none was halophilic. The optimum growth temperature is below 20 °C, thus the fungi are perfectly adapted to the cool and relatively dry conditions in the churches and organs respectively. The de-novo genome sequences analyses of the strains are currently ongoing and will reveal the genomic basis for the halotolerant behavior of the fungi.

Putting the Mess in Order: Aspergillus welwitschiae (and Not A. niger) Is the Etiological Agent of Sisal Bole Rot Disease in Brazil

Approximately 75% of the worldwide production of hard natural fibers originates from sisal, an industrial crop from arid and semiarid tropical regions. Brazil is the world's largest producer of sisal fiber, accounting for more than 40% of the worldwide production, and sisal bole rot disease has been the main phytosanitary problem of this crop. All previous studies reporting Aspergillus niger as the causal agent of the disease were based on the morphological features of fungal isolates from infected plant tissues in pure cultures. Black aspergilli are one of the most complex and difficult groups to classify and identify. Therefore, we performed an integrative analysis of this disease based on the isolation of black aspergilli from the endospheres and soils in the root zones of symptomatic adult plants, in vivo pathogenicity tests, histopathology of symptomatic plants, and molecular phylogeny and worldwide genetic variability of the causal agent. All sisal isolates were pathogenic and unequivocally produced symptoms of bole rot disease in healthy plants. In all tree-based phylogenetic methods used, a monophyletic group formed by A. welwitschiae along with all sisal isolates was retrieved. Ten A. welwitschiae haplotypes have been identified in the world, and three occur in the largest sisal-producing area. Most of the isolates are from a unique haplotype, present in only the sisal-producing region. A. welwitschiae destroyed parenchymatic and vascular cylinder cells and induced the necrosis of internal stem tissues. Therefore, sisal bole disease is probably the consequence of a saprotrophic fungus that opportunistically invades sisal plants and behaves as a typical necrotrophic pathogen.

Penicillium gravinicasei, a new species isolated from cave cheese in Apulia, Italy

Several species of the genus Penicillium were isolated during a survey of the mycobiota of Apulian cave cheeses ripened in a cave in Gravina di Puglia, Italy. A novel species, Penicillium gravinicasei, is described in Penicillium section Cinnamopurpurea. Its taxonomic novelty was determined using a polyphasic approach, combining phenotypic, molecular (β-tubulin, calmodulin, ITS and DNA dependent RNA polymerase) DNA sequences and mycotoxin production data. Phylogenetic analyses of the RPB2 data showed that isolates of the novel species form a clade most closely related to Penicillium cinnamopurpureum and P. parvulum with high bootstrap support. The fungus did not produce ochratoxin A, citrinin, patulin, sterigmatocystin or aflatoxin B₁ on standard agar media. The novel species had a high growth rate on agar media supplemented with 5% NaCl, and could be distinguished from other Penicillium section Cinnamopurpurea species by phenotypic and molecular characteristics.

Purification and characterization of a novel extracellular serine-protease with collagenolytic activity from Aspergillus tamarii URM4634

An extracellular serine-protease from Aspergillus tamarii URM4634 was purified and characterized. The possibility of using Aspergillus tamarii URM4634 protease in detergent formulations and collagenolytic activity was investigated. The protease demonstrated excellent stability at pH range 7.0-11.0, the optimum being at pH 9.0. The enzyme was stable at 40 °C for 180 min, enhanced by Mg⁺⁺ and Ca⁺⁺, but inhibited by Zn⁺⁺, and strongly inhibited by phenylmethylsulfonyl fluoride (PMSF), suggested as serine-protease. The azocasein substrate result showed Km = 0.434 mg/mL and V_max = 7.739 mg/mL/min. SDS-PAGE and azocasein zymography showed that the purified alkaline protease (2983.8 U/mg) had a molecular mass of 49.3 kDa. The enzyme was purified by column chromatography using Sephadex A50 resin. The proteolytic activity was activated by SDS (sodium dodecyl sulfate), Tween-80, Tween 20 and Triton-100. This study demonstrated that A. tamarii URM4634 protease has potent, stable and compatible collagenolytic activity to the desired level in local laundry detergent brands compared with similar enzymes produced by solid-state fermentation. This protease can thus be chosen as an option in both the food industry to tenderization meat and the detergent industry to washing process.

Competing sexual and asexual generic names in Pucciniomycotina and Ustilaginomycotina (Basidiomycota) and recommendations for use

With the change to one scientific name for pleomorphic fungi, generic names typified by sexual and asexual morphs have been evaluated to recommend which name to use when two names represent the same genus and thus compete for use. In this paper, generic names in Pucciniomycotina and Ustilaginomycotina are evaluated based on their type species to determine which names are synonyms. Twenty-one sets of sexually and asexually typified names in Pucciniomycotina and eight sets in Ustilaginomycotina were determined to be congeneric and compete for use. Recommendations are made as to which generic name to use. In most cases the principle of priority is followed. However, eight generic names in the Pucciniomycotina, and none in Ustilaginomycotina, are recommended for protection: Classicula over Naiadella, Gymnosporangium over Roestelia, Helicobasidium over Thanatophytum and Tuberculina, Melampsorella over Peridermium, Milesina over Milesia, Phragmidium over Aregma, Sporobolomyces over Blastoderma and Rhodomyces, and Uromyces over Uredo. In addition, eight new combinations are made: Blastospora juruensis, B. subneurophyla, Cronartium bethelii, C. kurilense, C. sahoanum, C. yamabense, Milesina polypodii, and Prospodium crusculum combs. nov.

Sequence-based nomenclature: a reply to Thines et al. and Zamora et al. and provisions for an amended proposal "from the floor" to allow DNA sequences as types of names

We reply to two recently published, multi-authored opinion papers by opponents of sequence-based nomenclature, namely Zamora et al. (IMA Fungus9: 167-175,2018) and Thines et al. (IMA Fungus9: 177-183, 2018). While we agree with some of the principal arguments brought forward by these authors, we address misconceptions and demonstrate that some of the presumed evidence presented in these papers has been wrongly interpreted. We disagree that allowing sequences as types would fundamentally alter the nature of types, since a similar nature of abstracted features as type is already allowed in the Code (Art. 40.5), namely an illustration. We also disagree that there is a high risk of introducing artifactual taxa, as this risk can be quantified at well below 5 %, considering the various types of high-throughput sequencing errors. Contrary to apparently widespread misconceptions, sequence-based nomenclature cannot be based on similarity-derived OTUs and their consensus sequences, but must be derived from rigorous, multiple alignment-based phylogenetic methods and quantitative, single-marker species recognition algorithms, using original sequence reads; it is therefore identical in its approach to single-marker studies based on physical types, an approach allowed by the Code. We recognize the limitations of the ITS as a single fungal barcoding marker, but point out that these result in a conservative approach, with "false negatives" surpassing "false positives"; a desirable feature of sequence-based nomenclature. Sequence-based nomenclature does not aim at accurately resolving species, but at naming sequences that represent unknown fungal lineages so that these can serve as a means of communication, so ending the untenable situation of an exponentially growing number of unlabeled fungal sequences that fill online repositories. The risks are outweighed by the gains obtained by a reference library of named sequences spanning the full array of fungal diversity. Finally, we elaborate provisions in addition to our original proposal to amend the Code that would take care of the issues brought forward by opponents to this approach. In particular, taking up the idea of the Candidatus status of invalid, provisional names in prokaryote nomenclature, we propose a compromise that would allow valid publication of voucherless, sequence-based names in a consistent manner, but with the obligate designation as "nom. seq." (nomen sequentiae). Such names would not have priority over specimen- or culture-based names unless either epitypified with a physical type or adopted for protection on the recommendation of a committee of the International Commission on the Taxonomy of Fungi following evaluation based on strict quality control of the underlying studies based on established rules or recommendations.

Taxonomy and evolution of Aspergillus, Penicillium and Talaromyces in the omics era - Past, present and future

Aspergillus, Penicillium and Talaromyces are diverse, phenotypically polythetic genera encompassing species important to the environment, economy, biotechnology and medicine, causing significant social impacts. Taxonomic studies on these fungi are essential since they could provide invaluable information on their evolutionary relationships and define criteria for species recognition. With the advancement of various biological, biochemical and computational technologies, different approaches have been adopted for the taxonomy of Aspergillus, Penicillium and Talaromyces; for example, from traditional morphotyping, phenotyping to chemotyping (e.g. lipotyping, proteotypingand metabolotyping) and then mitogenotyping and/or phylotyping. Since different taxonomic approaches focus on different sets of characters of the organisms, various classification and identification schemes would result. In view of this, the consolidated species concept, which takes into account different types of characters, is recently accepted for taxonomic purposes and, together with the lately implemented 'One Fungus - One Name' policy, is expected to bring a more stable taxonomy for Aspergillus, Penicillium and Talaromyces, which could facilitate their evolutionary studies. The most significant taxonomic change for the three genera was the transfer of Penicillium subgenus Biverticillium to Talaromyces (e.g. the medically important thermally dimorphic 'P. marneffei' endemic in Southeast Asia is now named T. marneffei), leaving both Penicillium and Talaromyces as monophyletic genera. Several distantly related Aspergillus-like fungi were also segregated from Aspergillus, making this genus, containing members of both sexual and asexual morphs, monophyletic as well. In the current omics era, application of various state-of-the-art omics technologies is likely to provide comprehensive information on the evolution of Aspergillus, Penicillium and Talaromyces and a stable taxonomy will hopefully be achieved.

Occurrence of Toxigenic Fungi and Mycotoxins on Root Herbs from Chinese Markets

Herbs derived from roots, leaves, flowers, or fruits of plants are unavoidably contaminated with fungi and mycotoxins during growth, harvest, and storage, thereby posing a health threat to humans. Especially, root herbs (RHs) are more easily contaminated with fungi and mycotoxins because the roots are in direct contact with the soil. Here, we investigated the occurrence of fungi, aflatoxins (AFs), and ochratoxin A (OTA) in eight RHs that are used as medicines, beverages, dietary supplements, and functional foods in China and other countries. Morphological observation and MultiGeneBlast (β-tubulin and calmodulin) were used to identify the potentially toxigenic fungi. Of the 48 samples tested, all were contaminated by fungi, and 1,844 isolates belonging to 25 genera were detected. The genera Aspergillus and Penicillium, which contain potentially toxigenic fungal species, represented a frequency of 10 and 25%, respectively. Thirty-three isolates of Aspergillus flavus, Aspergillus parasiticus, Aspergillus niger, and Penicillium polonicum were arbitrarily selected for analysis of their toxigenic potential. Five of 13 isolates of A. flavus and 1 isolate of A. parasiticus produced AFs, whereas OTA production was not detected for any of the isolates of A. niger and P. polonicum. The occurrence of AFs and OTA in the 48 samples of eight RHs was tested by ultraperformance liquid chromatography-tandem mass spectrometry; 37.50% of samples from six RHs were contaminated with AFs and 16.67% of samples from four RHs were contaminated with OTA. Seven (14.58%) and four (8.33%) samples of ginseng, polygala, and liquorice exceeded the permissible limits of aflatoxin B₁ and AFs, respectively. Because ginseng, polygala, and liquorice are widely used as herbs, dietary supplements, and functional foods, the high frequency of AF contamination of these herbs indicated by our current study warrant attention to raise public awareness.

Species Identification and In Vitro Antifungal Susceptibility of Aspergillus terreus Species Complex Clinical Isolates from a French Multicenter Study

Aspergillus section Terrei is a species complex currently comprised of 14 cryptic species whose prevalence in clinical samples as well as antifungal susceptibility are poorly known. The aims of this study were to investigate A. Terrei clinical isolates at the species level and to perform antifungal susceptibility analyses by reference and commercial methods. Eighty-two clinical A. Terrei isolates were collected from 8 French university hospitals. Molecular identification was performed by sequencing parts of beta-tubulin and calmodulin genes. MICs or minimum effective concentrations (MECs) were determined for 8 antifungal drugs using both EUCAST broth microdilution (BMD) methods and concentration gradient strips (CGS). Among the 79 A. Terrei isolates, A. terreus stricto sensu (n = 61), A. citrinoterreus (n = 13), A. hortai (n = 3), and A. alabamensis (n = 2) were identified. All strains had MICs of ≥1 mg/liter for amphotericin B, except for two isolates (both A. hortai) that had MICs of 0.25 mg/liter. Four A. terreus isolates were resistant to at least one azole drug, including one with pan-azole resistance, yet no mutation in the CYP51A gene was found. All strains had low MECs for the three echinocandins. The essential agreements (EAs) between BMD and CGS were >90%, except for those of amphotericin B (79.7%) and itraconazole (73.4%). Isolates belonging to the A section Terrei identified in clinical samples show wider species diversity beyond the known A. terreus sensu stricto Azole resistance inside the section Terrei is uncommon and is not related to CYP51A mutations here. Finally, CGS is an interesting alternative for routine antifungal susceptibility testing.

Bis-Indolyl Benzenoids, Hydroxypyrrolidine Derivatives and Other Constituents from Cultures of the Marine Sponge-Associated Fungus Aspergillus candidus KUFA0062

A previously unreported bis-indolyl benzenoid, candidusin D (2e) and a new hydroxypyrrolidine alkaloid, preussin C (5b) were isolated together with fourteen previously described compounds: palmitic acid, clionasterol, ergosterol 5,8-endoperoxides, chrysophanic acid (1a), emodin (1b), six bis-indolyl benzenoids including asterriquinol D dimethyl ether (2a), petromurin C (2b), kumbicin B (2c), kumbicin A (2d), 2″-oxoasterriquinol D methyl ether (3), kumbicin D (4), the hydroxypyrrolidine alkaloid preussin (5a), (3S, 6S)-3,6-dibenzylpiperazine-2,5-dione (6) and 4-(acetylamino) benzoic acid (7), from the cultures of the marine sponge-associated fungus Aspergillus candidus KUFA 0062. Compounds 1a, 2a-e, 3, 4, 5a-b, and 6 were tested for their antibacterial activity against Gram-positive and Gram-negative reference and multidrug-resistant strains isolated from the environment. Only 5a exhibited an inhibitory effect against S. aureus ATCC 29213 and E. faecalis ATCC29212 as well as both methicillin-resistant S. aureus (MRSA) and vancomycin-resistant enterococci (VRE) strains. Both 1a and 5a also reduced significant biofilm formation in E. coli ATCC 25922. Moreover, 2b and 5a revealed a synergistic effect with oxacillin against MRSA S. aureus 66/1 while 5a exhibited a strong synergistic effect with the antibiotic colistin against E. coli 1410/1. Compound 1a, 2a-e, 3, 4, 5a-b, and 6 were also tested, together with the crude extract, for cytotoxic effect against eight cancer cell lines: HepG2, HT29, HCT116, A549, A 375, MCF-7, U-251, and T98G. Except for 1a, 2a, 2d, 4, and 6, all the compounds showed cytotoxicity against all the cancer cell lines tested.

[Isolation of Aspergillus tritici from internal environment (Chile): Ecological and clinical scope]

Indoor environments provide important protective habitats for humans, who live or work in them most of the time. Many of these environments lack ventilation, which affects the composition of microbial communities, especially that of the fungal community. The aim of this study is to report the isolation of Aspergillus section Candidi from indoor environments of the School of Medicine at Universidad de Valparaiso, Chile, and identification through morpho-physiological and molecular approaches. Their ecological and clinical features were highlighted. An environmental non-volumetric sampling was performed on PDA medium; 2 petri dishes were exposed in 10 different places to select the Aspergillus samples. Subcultures were performed on agar Czapek with yeast extract (CYA), malt extract agar (MEA) and creatin sacarose agar (CREA) media only for the morpho-physiological and later the molecular identification of white spore species. Of the 20 samples analyzed, one Aspergillus belonging to Candidi section was isolated. Based on its morphology and molecular features, it was classified as Aspergillustritici Mehrotra & Basu. Its ecology and medical relevance are reviewed and discussed.

Mould spoilage of foods and beverages: Using the right methodology

Fungal spoilage of products manufactured by the food and beverage industry imposes significant annual global revenue losses. Mould spoilage can also be a food safety issue due to the production of mycotoxins by these moulds. To prevent mould spoilage, it is essential that the associated mycobiota be adequately isolated and accurately identified. The main fungal groups associated with spoilage are the xerophilic, heat-resistant, preservative-resistant, anaerobic and psychrophilic fungi. To assess mould spoilage, the appropriate methodology and media must be used. While classic mycological detection methods can detect a broad range of fungi using well validated protocols, they are time consuming and results can take days or even weeks. New molecular detection methods are faster but require good DNA isolation techniques, expensive equipment and may detect viable and non-viable fungi that probably will not spoil a specific product. Although there is no complete and easy method for the detection of fungi in food it is important to be aware of the limitation of the methodology. More research is needed on the development of methods of detection and identification that are both faster and highly sensitive.

Aspergillus-specific antibodies - Targets and applications

Aspergillus is a fungal genus comprising several hundred species, many of which can damage the health of plants, animals and humans by direct infection and/or due to the production of toxic secondary metabolites known as mycotoxins. Aspergillus-specific antibodies have been generated against polypeptides, polysaccharides and secondary metabolites found in the cell wall or secretions, and these can be used to detect and monitor infections or to quantify mycotoxin contamination in food and feed. However, most Aspergillus-specific antibodies are generated against heterogeneous antigen preparations and the specific target remains unknown. Target identification is important because this can help to characterize fungal morphology, confirm host penetration by opportunistic pathogens, detect specific disease-related biomarkers, identify new candidate targets for antifungal drug design, and qualify antibodies for diagnostic and therapeutic applications. In this review, we discuss how antibodies are raised against heterogeneous Aspergillus antigen preparations and how they can be characterized, focusing on strategies to identify their specific antigens and epitopes. We also discuss the therapeutic, diagnostic and biotechnological applications of Aspergillus-specific antibodies.

Azole-Resistance in Aspergillus terreus and Related Species: An Emerging Problem or a Rare Phenomenon?

Objectives: Invasive mold infections associated with Aspergillus species are a significant cause of mortality in immunocompromised patients. The most frequently occurring aetiological pathogens are members of the Aspergillus section Fumigati followed by members of the section Terrei. The frequency of Aspergillus terreus and related (cryptic) species in clinical specimens, as well as the percentage of azole-resistant strains remains to be studied.

Methods: A global set (n = 498) of A. terreus and phenotypically related isolates was molecularly identified (beta-tubulin), tested for antifungal susceptibility against posaconazole, voriconazole, and itraconazole, and resistant phenotypes were correlated with point mutations in the cyp51A gene.

Results: The majority of isolates was identified as A. terreus (86.8%), followed by A. citrinoterreus (8.4%), A. hortai (2.6%), A. alabamensis (1.6%), A. neoafricanus (0.2%), and A. floccosus (0.2%). One isolate failed to match a known Aspergillus sp., but was found most closely related to A. alabamensis. According to EUCAST clinical breakpoints azole resistance was detected in 5.4% of all tested isolates, 6.2% of A. terreus sensu stricto (s.s.) were posaconazole-resistant. Posaconazole resistance differed geographically and ranged from 0% in the Czech Republic, Greece, and Turkey to 13.7% in Germany. In contrast, azole resistance among cryptic species was rare 2 out of 66 isolates and was observed only in one A. citrinoterreus and one A. alabamensis isolate. The most affected amino acid position of the Cyp51A gene correlating with the posaconazole resistant phenotype was M217, which was found in the variation M217T and M217V.

Conclusions:Aspergillus terreus was most prevalent, followed by A. citrinoterreus. Posaconazole was the most potent drug against A. terreus, but 5.4% of A. terreus sensu stricto showed resistance against this azole. In Austria, Germany, and the United Kingdom posaconazole-resistance in all A. terreus isolates was higher than 10%, resistance against voriconazole was rare and absent for itraconazole.

Real-time PCR-based method for rapid detection of Aspergillus niger and Aspergillus welwitschiae isolated from coffee

Some species from Aspergillus section Nigri are morphologically very similar and altogether have been called A. niger aggregate. Although the species included in this group are morphologically very similar, they differ in their ability to produce mycotoxins and other metabolites and their taxonomical status has evolved continuously. Among them, A. niger and A. welwitschiae are ochratoxin A and fumonisin B₂ producers and their detection and/or identification is of crucial importance for food safety. The aim of this study was the development of a real-time PCR-based method for simultaneous discrimination of A. niger and A. welwitschiae from other species of the A. niger aggregate isolated from coffee beans. One primer pair and a hybridization probe specific for detection of A. niger and A. welwitschiae strains were designed based on the BenA gene sequences, and used in a Real-time PCR assay for the rapid discrimination between both these species from all others of the A. niger aggregate. The Real-time PCR assay was shown to be 100% efficient in discriminating the 73 isolates of A. niger/A. welwitschiae from the other A. niger aggregate species analyzed as a negative control. This result testifies to the use of this technique as a good tool in the rapid detection of these important toxigenic species.

Whole-genome sequencing of Aspergillus tubingensis G131 and overview of its secondary metabolism potential

Background

Black Aspergilli represent one of the most important fungal resources of primary and secondary metabolites for biotechnological industry. Having several black Aspergilli sequenced genomes should allow targeting the production of certain metabolites with bioactive properties.

Results

In this study, we report the draft genome of a black Aspergilli, A. tubingensis G131, isolated from a French Mediterranean vineyard. This 35 Mb genome includes 10,994 predicted genes. A genomic-based discovery identifies 80 secondary metabolites biosynthetic gene clusters. Genomic sequences of these clusters were blasted on 3 chosen black Aspergilli genomes: A. tubingensis CBS 134.48, A. niger CBS 513.88 and A. kawachii IFO 4308. This comparison highlights different levels of clusters conservation between the four strains. It also allows identifying seven unique clusters in A. tubingensis G131. Moreover, the putative secondary metabolites clusters for asperazine and naphtho-gamma-pyrones production were proposed based on this genomic analysis. Key biosynthetic genes required for the production of 2 mycotoxins, ochratoxin A and fumonisin, are absent from this draft genome. Even if intergenic sequences of these mycotoxins biosynthetic pathways are present, this could not lead to the production of those mycotoxins by A. tubingensis G131.

Conclusions

Functional and bioinformatics analyses of A. tubingensis G131 genome highlight its potential for metabolites production in particular for TAN-1612, asperazine and naphtho-gamma-pyrones presenting antioxidant, anticancer or antibiotic properties.

Electronic supplementary material

The online version of this article (10.1186/s12864-018-4574-4) contains supplementary material, which is available to authorized users.

Species identification and in vitro antifungal susceptibility testing of Aspergillus section Nigri strains isolated from otomycosis patients

INTRODUCTION

Aspergillus niger is the most commonly reported etiology of otomycosis based on morphological characteristics. This fungus is a member of Aspergillus section Nigri, a set of morphologically indistinguishable species that can harbor various antifungal susceptibility patterns. The aim of this study was to accurately identify and determine the susceptibility pattern of a set of black aspergilli isolated from otomycosis patients.

METHODS

Forty-three black Aspergillus isolates from otomycosis patients were identified by using the PCR-sequencing of the β-tubulin gene. Furthermore, the susceptibility of isolates to three antifungal drugs, including fluconazole (FLU), clotrimazole (CLT) and nystatin (NS), were tested according to CLSI M38-A2. The data were analyzed using the SPSS software (version 15).

RESULTS

The majority of isolates were identified as A. tubingensis (32/43, 74.42%) followed by A. niger (11/43, 25.58%). The lowest minimum inhibitory concentration (MIC) values were observed for NS with geometric means (GM) of 4.65μg/mL and 4.83μg/mL against A. tubingensis and A. niger isolates, respectively. CLT showed wide MIC ranges and a statistically significant inter-species difference was observed between A. tubingensis and A. niger isolates (P<0.05). FLU was inactive against both species with GMs>64μg/mL.

CONCLUSION

Species other than A. niger can be more frequent as observed in our study. In addition, considering the low and variable activity of tested antifungal drugs, empirical treatment can result in treatment failure. Accurate identification and antifungal susceptibility testing of isolates is, however, recommended.

A critical review of producers of small lactone mycotoxins: patulin, penicillic acid and moniliformin

A very large number of filamentous fungi has been reported to produce the small lactone mycotoxins patulin, penicillic acid and moniliformin. Among the 167 reported fungal producers of patulin, only production by 29 species could be confirmed. Patulin is produced by 3 Aspergillus species, 3 Paecilomyces species, 22 Penicillium species from 7 sections of Penicillium, and one Xylaria species. Among 101 reported producers of penicillic acid, 48 species could produce this mycotoxin. Penicillic acid is produced by 23 species in section Aspergillus subgenus Circumdati section Circumdati, by Malbranchea aurantiaca and by 24 Penicillium species from 9 sections in Penicillium and one species that does not actually belong to Penicillium (P. megasporum). Among 40 reported producers of moniliformin, five species have been regarded as doubtful producers of this mycotoxin or are now regarded as taxonomic synonyms. Moniliformin is produced by 34 Fusarium species and one Penicillium species. All the accepted producers of patulin, penicillic acid and moniliformin were revised according to the new one fungus – one name nomenclatural system, and the most recently accepted taxonomy of the species.

Polyphasic data support the splitting of Aspergillus candidus into two species; proposal of Aspergillus dobrogensis sp. nov

Aspergillus candidus is a species frequently isolated from stored grain, food, indoor environments, soil and occasionally also from clinical material. Recent bioprospecting studies highlighted the potential of using A. candidus and its relatives in various industrial sectors as a result of their significant production of enzymes and bioactive compounds. A high genetic variability was observed among A. candidus isolates originating from various European countries and the USA, that were mostly isolated from indoor environments, caves and clinical material. The A. candidus sensu lato isolates were characterized by DNA sequencing of four genetic loci, and agreement between molecular species delimitation results, morphological characters and exometabolite spectra were studied. Classical phylogenetic methods (maximum likelihood, Bayesian inference) and species delimitation methods based on the multispecies coalescent model supported recognition of up to three species in A. candidus sensu lato. After evaluation of phenotypic data, a broader species concept was adopted, and only one new species, Aspergillus dobrogensis, was proposed. This species is represented by 22 strains originating from seven countries (ex-type strain CCF 4651^T=NRRL 62821^T=IBT 32697^T=CBS 143370^T) and its differentiation from A. candidus is relevant for bioprospecting studies because these species have different exometabolite profiles. Evaluation of the antifungal susceptibility of section Candidi members to six antifungals using the reference EUCAST method showed that all species have low minimum inhibitory concentrations for all tested antifungals. These results suggest applicability of a wide spectrum of antifungal agents for treatment of infections caused by species from section Candidi.

Identification of Immunoglobulin E-Binding Proteins of the Xerophilic Fungus Aspergillus penicillioides Crude Mycelial Mat Extract and Serological Reactivity Assessment in Subjects with Different Allergen Reactivity Profiles

BACKGROUND

Aspergillus penicillioides is a very common indoor xerophilic fungus and potential causative agent of respiratory conditions. Although people are constantly exposed to A. penicillioides, no proteins with allergenic potential have been described. Therefore, we aim to confirm allergic sensitization to A. penicillioides through reactivity in serological assays and detect immunoglobulin E (IgE)-binding proteins.

METHODS

In an indirect ELISA, we compared the serological reactivity to A. penicillioides between subjects with specific IgE (sIgE) (group 1, n = 54) and no sIgE reactivity (group 2, n = 15) against commercial allergens. Correlations and principal component analysis were performed to identify associations between reactivity to commercial allergens and A. penicillioides. IgE-binding proteins in A. penicillioides were visualized using Western blotting (WB) in group 1. The IgE-binding proteins with the highest reactivity were analyzed by mass spectrometry and confirmed by transcript matching.

RESULTS

There was no statistical significance (p = 0.1656) between the study groups in serological reactivity. Correlations between reactivity to A. penicillioides, dog epithelia, Aspergillus fumigatus, and Penicillium chrysogenum were observed. WB experiments showed 6 IgE-binding proteins with molecular weights ranging from 45 to 145 kDa. Proteins of 108, 83, and 56 kDa showed higher reactivity. Mass spectrometry analysis of these 3 proteins led to the putative identification of NADP-specific glutamate dehydrogenase and catalase B. This was confirmed with transcriptome analysis.

CONCLUSIONS

These results provide evidence of the presence of potential allergenic components in A. penicillioides. Further analysis of the putatively identified proteins should reveal their allergenic potential.

Aspergillus terreus Inhibits Growth and Induces Morphological Abnormalities in Pythium aphanidermatum and Suppresses Pythium-Induced Damping-Off of Cucumber

The study investigated the efficacy of two isolates of Aspergillus terreus (65P and 9F) on the growth, morphology and pathogenicity of Pythium aphanidermatum on cucumber. In vitro tests showed that the two isolates inhibited the growth of P. aphanidermatum in culture. Investigating P. aphanidermatum hyphae close to the inhibition zone showed that the hyphae showed abnormal growth and loss of internal content. Treating P. aphanidermatum with the culture filtrate (CF) of A. terreus resulted in significant rise in cellular leakage of P. aphanidermatum mycelium. Testing glucanase enzyme activity by both A. terreus isolates showed a significant increase in glucanase activity. This suggests that the cell walls of Pythium, which consist of glucan, are affected by the glucanase enzyme produced by A. terreus. In addition, Aspergillus isolates produced siderephore, which is suggested to be involved in inhibition of Pythium growth. Also, the CFs of 65P and 9F isolates significantly reduced spore production by P. aphanidermatum compared to the control (P < 0.05). In bioassay tests, the two isolates of A. terreus increased the survival rate of cucumber seedlings from 10 to 20% in the control seedlings treated with P. aphanidermatum to 38-39% when the biocontrol agents were used. No disease symptoms were observed on cucumber seedlings only treated with the isolates 65P and 9F of A. terreus. In addition, the A. terreus isolates did not have any negative effects on the growth of cucumber seedlings. This study shows that isolates of A. terreus can help suppress Pythium-induced damping-off of cucumber, which is suggested to be through the effect of A. terreus and its glucanase enzyme on P. aphanidermatum mycelium.

Targeting Conserved Genes in Aspergillus Species

The genus Aspergillus is among the economically most important fungal genera, which contains about 350 species. They occur worldwide, and have both beneficial and harmful effects on humans, animals, and plants. Several molecular sequence-based approaches have been tested to identify Aspergillus isolates at the species level. In this chapter, we give an overview of the methods which proved to be most suitable in our experience.

Linking secondary metabolites to gene clusters through genome sequencing of six diverse Aspergillus species

The fungal genus of Aspergillus is highly interesting, containing everything from industrial cell factories, model organisms, and human pathogens. In particular, this group has a prolific production of bioactive secondary metabolites (SMs). In this work, four diverse Aspergillus species (A. campestris, A. novofumigatus, A. ochraceoroseus, and A. steynii) have been whole-genome PacBio sequenced to provide genetic references in three Aspergillus sections. A. taichungensis and A. candidus also were sequenced for SM elucidation. Thirteen Aspergillus genomes were analyzed with comparative genomics to determine phylogeny and genetic diversity, showing that each presented genome contains 15-27% genes not found in other sequenced Aspergilli. In particular, A. novofumigatus was compared with the pathogenic species A. fumigatus This suggests that A. novofumigatus can produce most of the same allergens, virulence, and pathogenicity factors as A. fumigatus, suggesting that A. novofumigatus could be as pathogenic as A. fumigatus Furthermore, SMs were linked to gene clusters based on biological and chemical knowledge and analysis, genome sequences, and predictive algorithms. We thus identify putative SM clusters for aflatoxin, chlorflavonin, and ochrindol in A. ochraceoroseus, A. campestris, and A. steynii, respectively, and novofumigatonin, ent-cycloechinulin, and epi-aszonalenins in A. novofumigatus Our study delivers six fungal genomes, showing the large diversity found in the Aspergillus genus; highlights the potential for discovery of beneficial or harmful SMs; and supports reports of A. novofumigatus pathogenicity. It also shows how biological, biochemical, and genomic information can be combined to identify genes involved in the biosynthesis of specific SMs.

Main Groups of Microorganisms of Relevance for Food Safety and Stability

Microbiology is important to food safety, production, processing, preservation, and storage. Microbes such as bacteria, molds, and yeasts are employed for the foods production and food ingredients such as production of wine, beer, bakery, and dairy products. On the other hand, the growth and contamination of spoilage and pathogenic microorganisms is considered as one of the main causes to loss of foodstuff nowadays. Although technology, hygienic strategies, and traceability are important factors to prevent and delay microbial growth and contamination, food remains susceptible to spoilage and activity of pathogen microorganisms. Food loss by either spoilage or contaminated food affects food industry and consumers leading to economic losses and increased hospitalization costs. This chapter focuses on general aspects, characteristics, and importance of main microorganisms (bacteria, yeasts, molds, virus, and parasites) involved in food spoilage or contamination: known and recently discovered species; defects and alterations in foodstuff; most common food associated with each foodborne disease; resistance to thermal processing; occurrence in different countries; outbreaks; and associated symptoms.

Fungal Planet description sheets: 625-715

Novel species of fungi described in this study include those from various countries as follows: Antarctica: Cadophora antarctica from soil. Australia: Alfaria dandenongensis on Cyperaceae, Amphosoma persooniae on Persoonia sp., Anungitea nullicana on Eucalyptus sp., Bagadiella eucalypti on Eucalyptus globulus, Castanediella eucalyptigena on Eucalyptus sp., Cercospora dianellicola on Dianella sp., Cladoriella kinglakensis on Eucalyptus regnans, Cladoriella xanthorrhoeae (incl. Cladoriellaceae fam. nov. and Cladoriellales ord. nov.) on Xanthorrhoea sp., Cochlearomyces eucalypti (incl. Cochlearomyces gen. nov. and Cochlearomycetaceae fam. nov.) on Eucalyptus obliqua, Codinaea lambertiae on Lambertia formosa, Diaporthe obtusifoliae on Acacia obtusifolia, Didymella acaciae on Acacia melanoxylon, Dothidea eucalypti on Eucalyptus dalrympleana, Fitzroyomyces cyperi (incl. Fitzroyomyces gen. nov.) on Cyperaceae, Murramarangomyces corymbiae (incl. Murramarangomyces gen. nov., Murramarangomycetaceae fam. nov. and Murramarangomycetales ord. nov.) on Corymbia maculata, Neoanungitea eucalypti (incl. Neoanungitea gen. nov.) on Eucalyptus obliqua, Neoconiothyrium persooniae (incl. Neoconiothyrium gen. nov.) on Persoonia laurina subsp. laurina, Neocrinula lambertiae (incl. Neocrinulaceae fam. nov.) on Lambertia sp., Ochroconis podocarpi on Podocarpus grayae, Paraphysalospora eucalypti (incl. Paraphysalospora gen. nov.) on Eucalyptus sieberi, Pararamichloridium livistonae (incl. Pararamichloridium gen. nov., Pararamichloridiaceae fam. nov. and Pararamichloridiales ord. nov.) on Livistona sp., Pestalotiopsis dianellae on Dianella sp., Phaeosphaeria gahniae on Gahnia aspera, Phlogicylindrium tereticornis on Eucalyptus tereticornis, Pleopassalora acaciae on Acacia obliquinervia, Pseudodactylaria xanthorrhoeae (incl. Pseudodactylaria gen. nov., Pseudodactylariaceae fam. nov. and Pseudodactylariales ord. nov.) on Xanthorrhoea sp., Pseudosporidesmium lambertiae (incl. Pseudosporidesmiaceae fam. nov.) on Lambertia formosa, Saccharata acaciae on Acacia sp., Saccharata epacridis on Epacris sp., Saccharata hakeigena on Hakea sericea, Seiridium persooniae on Persoonia sp., Semifissispora tooloomensis on Eucalyptus dunnii, Stagonospora lomandrae on Lomandra longifolia, Stagonospora victoriana on Poaceae, Subramaniomyces podocarpi on Podocarpus elatus, Sympoventuria melaleucae on Melaleuca sp., Sympoventuria regnans on Eucalyptus regnans, Trichomerium eucalypti on Eucalyptus tereticornis, Vermiculariopsiella eucalypticola on Eucalyptus dalrympleana, Verrucoconiothyrium acaciae on Acacia falciformis, Xenopassalora petrophiles (incl. Xenopassalora gen. nov.) on Petrophile sp., Zasmidium dasypogonis on Dasypogon sp., Zasmidium gahniicola on Gahnia sieberiana.Brazil: Achaetomium lippiae on Lippia gracilis, Cyathus isometricus on decaying wood, Geastrum caririense on soil, Lycoperdon demoulinii (incl. Lycoperdon subg. Arenicola) on soil, Megatomentella cristata (incl. Megatomentella gen. nov.) on unidentified plant, Mutinus verrucosus on soil, Paraopeba schefflerae (incl. Paraopeba gen. nov.) on Schefflera morototoni, Phyllosticta catimbauensis on Mandevilla catimbauensis, Pseudocercospora angularis on Prunus persica, Pseudophialophora sorghi on Sorghum bicolor, Spumula piptadeniae on Piptadenia paniculata.Bulgaria: Yarrowia parophonii from gut of Parophonus hirsutulus. Croatia: Pyrenopeziza velebitica on Lonicera borbasiana.Cyprus: Peziza halophila on coastal dunes. Czech Republic: Aspergillus contaminans from human fingernail. Ecuador: Cuphophyllus yacurensis on forest soil, Ganoderma podocarpense on fallen tree trunk. England: Pilidium anglicum (incl. Chaetomellales ord. nov.) on Eucalyptus sp. France: Planamyces parisiensis (incl. Planamyces gen. nov.) on wood inside a house. French Guiana: Lactifluus ceraceus on soil. Germany: Talaromyces musae on Musa sp. India: Hyalocladosporiella cannae on Canna indica, Nothophoma raii from soil. Italy: Setophaeosphaeria citri on Citrus reticulata, Yuccamyces citri on Citrus limon.Japan: Glutinomyces brunneus (incl. Glutinomyces gen. nov.) from roots of Quercus sp. Netherlands (all from soil): Collariella hilkhuijsenii, Fusarium petersiae, Gamsia kooimaniorum, Paracremonium binnewijzendii, Phaeoisaria annesophieae, Plectosphaerella niemeijerarum, Striaticonidium deklijnearum, Talaromyces annesophieae, Umbelopsis wiegerinckiae, Vandijckella johannae (incl. Vandijckella gen. nov. and Vandijckellaceae fam. nov.), Verhulstia trisororum (incl. Verhulstia gen. nov.). New Zealand: Lasiosphaeria similisorbina on decorticated wood. Papua New Guinea: Pseudosubramaniomyces gen. nov. (based on Pseudosubramaniomyces fusisaprophyticus comb. nov.). Slovakia: Hemileucoglossum pusillum on soil. South Africa: Tygervalleyomyces podocarpi (incl. Tygervalleyomyces gen. nov.) on Podocarpus falcatus.Spain: Coniella heterospora from herbivorous dung, Hymenochaete macrochloae on Macrochloa tenacissima, Ramaria cistophila on shrubland of Cistus ladanifer.Thailand: Polycephalomyces phaothaiensis on Coleoptera larvae, buried in soil. Uruguay: Penicillium uruguayense from soil. Vietnam: Entoloma nigrovelutinum on forest soil, Volvariella morozovae on wood of unknown tree. Morphological and culture characteristics along with DNA barcodes are provided.

Effect of water activity and temperature on the growth of Eurotium species isolated from animal feeds

BACKGROUND

Xerophilic fungi represent a serious problem due to their ability to grow at low water activities causing the spoiling of low and intermediate moisture foods, stored goods and animal feeds, with the consequent economic losses.

AIMS

The combined effect of water activity and temperature of four Eurotium species isolated from animal feeds was investigated.

METHODS

Eurotium amstelodami, Eurotium chevalieri, Eurotium repens and Eurotium rubrum were grown at 5, 15, 25, 37 and 45°C on malt extract agar adjusted with glycerol in the range 0.710-0.993 of water activities.

RESULTS

The cardinal model proposed by Rosso and Robinson (2001) was applied to fit growth data, with the variable water activity at fixed temperatures, obtaining three cardinal water activities (a_wmin, a_wmax, a_wopt) and the specific growth rate at the optimum a_w (μ_opt). A probabilistic model was also applied to define the interface between growth and no-growth. The cardinal model provided an adequate estimation of the optimal a_w to grow and the maximum growth rate. The probabilistic model showed a good performance to fit growth/no-growth cases in the predicted range.

CONCLUSIONS

The results presented here could be applied to predict Eurotium species growth in animal feeds.