Penicillium species endophytic in coffee plants and ochratoxin A production

Fungi associated with the potato taste defect in coffee beans from Rwanda

BACKGROUND

Potato taste defect (PTD) of coffee is characterized by a raw potato like smell that leads to a lower quality taste in the brewed coffee, and harms the commercial value of some East African coffees. Although several causes for PTD have been proposed, none of them have been confirmed. Recently, high throughput sequencing techniques and bioinformatic analysis have shown great potential for identifying putative causal agents of plant diseases. Toward the goal of determining the cause of PTD, we examined raw coffee beans from Rwanda exhibiting varying PTD scores using an Illumina-based sequence analysis of the fungal rRNA ITS region.

RESULTS

Six fungal amplicon sequence variants (ASVs) with high relative abundances correlated with coffee taste scores. Four of these ASVs exhibited negative correlations - Aspergillus versicolor, Penicillium cinnamopurpureum, Talaromyces radicus, and Thermomyces lanuginosus - indicating that they might be causing PTD. Two of these fungi exhibited positive correlations - Kazachstania humilis and Clavispora lusitaniae - indicating that they might be inhibiting organisms that cause PTD.

CONCLUSIONS

This study addressed PTD causality from a new angle by examining fungi with high throughput sequencing. To our knowledge, this is the first study characterizing fungi associated with PTD, providing candidates for both causality and biocontrol.

Coffee Microbiota and Its Potential Use in Sustainable Crop Management. A Review

Intensive coffee production is accompanied by several environmental issues, including soil degradation, biodiversity loss, and pollution due to the wide use of agrochemical inputs and wastes generated by processing. In addition, climate change is expected to decrease the suitability of cultivated areas while potentially increasing the distribution and impact of pests and diseases. In this context, the coffee microbiota has been increasingly studied over the past decades in order to improve the sustainability of the coffee production. Therefore, coffee associated microorganisms have been isolated and characterized in order to highlight their useful characteristics and study their potential use as sustainable alternatives to agrochemical inputs. Indeed, several microorganisms (including bacteria and fungi) are able to display plant growth-promoting capacities and/or biocontrol abilities toward coffee pests and diseases. Despite that numerous studies emphasized the potential of coffee-associated microorganisms under controlled environments, the present review highlights the lack of confirmation of such beneficial effects under field conditions. Nowadays, next-generation sequencing technologies allow to study coffee associated microorganisms with a metabarcoding/metagenomic approach. This strategy, which does not require cultivating microorganisms, now provides a deeper insight in the coffee-associated microbial communities and their implication not only in the coffee plant fitness but also in the quality of the final product. The present review aims at (i) providing an extensive description of coffee microbiota diversity both at the farming and processing levels, (ii) identifying the “coffee core microbiota,” (iii) making an overview of microbiota ability to promote coffee plant growth and to control its pests and diseases, and (iv) highlighting the microbiota potential to improve coffee quality and waste management sustainability.

Cork Oak Endophytic Fungi as Potential Biocontrol Agents against Biscogniauxia mediterranea and Diplodia corticola

An increase in cork oak diseases caused by Biscogniauxia mediterranea and Diplodia corticola has been reported in the last decade. Due to the high socio-economic and ecologic importance of this plant species in the Mediterranean Basin, the search for preventive or treatment measures to control these diseases is an urgent need. Fungal endophytes were recovered from cork oak trees with different disease severity levels, using culture-dependent methods. The results showed a higher number of potential pathogens than beneficial fungi such as cork oak endophytes, even in healthy plants. The antagonist potential of a selection of eight cork oak fungal endophytes was tested against B. mediterranea and D. corticola by dual-plate assays. The tested endophytes were more efficient in inhibiting D. corticola than B. mediterranea growth, but Simplicillium aogashimaense, Fimetariella rabenhorstii, Chaetomium sp. and Alternaria alternata revealed a high potential to inhibit the growth of both. Simplicillium aogashimaense caused macroscopic and microscopic mycelial/hyphal deformations and presented promising results in controlling both phytopathogens' growth in vitro. The evaluation of the antagonistic potential of non-volatile and volatile compounds also revealed that A. alternata compounds could be further explored for inhibiting both pathogens. These findings provide valuable knowledge that can be further explored in in vivo assays to find a suitable biocontrol agent for these cork oak diseases.

Natural Products from Endophytic Fungi Associated with Rubiaceae Species

This review presents the chemical diversity and pharmacological properties of secondary metabolites produced by endophytic fungi associated with various genera of Rubiaceae. Several classes of natural products are described for these endophytes, although, this study highlights the importance of some metabolites, which are involved in antifungal, antibacterial, anti-protozoal activities; neurodegenerative diseases; cytotoxic activity; anti-inflammatory and antioxidant activity; and hyperglycemic control.

Penicillium setosum, a new species from Withania somnifera (L.) Dunal

Medicinal plants are considered as sources of novel and unexplored groups of endophytic microorganisms. A study on endophytic fungal species from the medicinal plant Withania somnifera (L.) Dunal resulted in the isolation of a Penicillium isolate (WSR 62) with antibiotic activity. Phylogenetic analysis showed that the isolate belongs to section Lanata-divaricata, and it is most closely related to P. javanicum. Subsequent detailed phylogenetic analyses using partial β-tubulin (BenA), calmodulin (CaM) and DNA-dependent RNA polymerase II (RPB2) gene sequences of a larger number of related strains revealed the distinctiveness of the isolate in the P. javanicum-clade. The isolate grows fast on Czapek yeast autolysate agar (CYA) and malt extract agar (MEA) incubated at 25°C, 30°C and 37°C. The obverse colony colour is dominated by the conspicuous production of cleistothecia and is greyish yellow on CYA and yellowish brown on MEA. Production of cleistothecia containing prominent spinose ascospores was present on all tested agar media. Based on the phylogenetic analysis and the phenotypic characterisation, strain WSR 62 from Withania is described here as a novel species named Penicillium setosum.

Molecular Identification of Endophytic Fungi from Banana Leaves (Musa spp.)

Endophytic fungi are part of microbial community found in various types of plant tissues including the leave, and display a range of symbiotic interactions with the plant host. In this study, endophytic fungi isolated from banana leaves were identified using ITS (Internal Transcribed Spacer region) sequences of which 10 genera comprising 17 species were molecularly identified. Endophytic fungal species identified were Nigrospora oryzae, Nigrospora sphaerica, Colletotrichum gloeosporioides, Colletotrichum siamense, Fusarium equiseti, Fusarium chlamydosporum, Phoma sorghina, Pestalotiopsis oxyanthi, Pestalotiopsis theae, Pestalotiopsis eugeniae, Penicillium steckii, Penicillium purpurogenum, Bipolaris papendorfii, Bipolaris sp., Lasidiodiplodia theobromae, Cochliobolus intermedius dan Aspergillus niger. The present study showed that several endophytic fungal genera/species are common plant pathogen and there is a possibility that these endophytes can become pathogenic. Some of the fungal endophyte might be mutualist or saprophyte.

Highly diverse endophytes in roots of Cycas bifida (Cycadaceae), an ancient but endangered gymnosperm

As an ancient seed plant, cycads are one of the few gymnosperms that develop a root symbiosis with cyanobacteria, which has allowed cycads to cope with harsh geologic and climatic conditions during the evolutionary process. However, the endophytic microbes in cycad roots remain poorly identified. In this study, using next-generation sequencing techniques, we investigated the microbial diversity and composition of both the coralloid and regular roots of Cycas bifida (Dyer) K.D. Hill. Highly diverse endophytic communities were observed in both the coralloid and regular roots. Of the associated bacteria, the top five families were the Nostocaceae, Sinobacteraceae, Bradyrhizobiaceae, Bacillaceae, and Hyphomicrobiaceae. The Nectriaceae, Trichocomaceae, and Incertae sedis were the predominant fungal families in all root samples. A significant difference in the endophytic bacterial community was detected between coralloid roots and regular roots, but no difference was observed between the fungal communities in the two root types. Cyanobacteria were more dominant in coralloid roots than in regular roots. The divergence of cycad root structures and the modified physiological processes may have contributed to the abundance of cyanobionts in coralloid roots. Consequently, the colonization of cyanobacteria inhibits the assemblage of other endophytes. Our results contribute to an understanding of the species diversity and composition of the cycad-endophyte microbiome and provide an abbreviated list of potential ecological roles of the core microbes present.

T Cell Activation in South African HIV-Exposed Infants Correlates with Ochratoxin A Exposure

The introduction of non-breastmilk foods to HIV-infected infants is associated with increased levels of immune activation, which can impact the rate of HIV disease progression. This is particularly relevant in countries where mother-to-child transmission of HIV still occurs at unacceptable levels. The goal of this study was to evaluate the levels of the toxic food contaminant ochratoxin A (OTA) in HIV-exposed South African infants that are either breastfed or consuming non-breast milk foods. OTA is a common mycotoxin, found in grains and soil, which is toxic at high doses but has immunomodulatory properties at lower doses. Samples from HIV-exposed and HIV-unexposed infants enrolled in prospective observational cohort studies were collected and analyzed at birth through 14 weeks of age. We observed that infants consuming non-breast milk foods had significantly higher plasma levels of OTA at 6 weeks of age compared to breastfed infants, increasing until 8 weeks of age. The blood levels of OTA detected were comparable to levels observed in OTA-endemic communities. OTA plasma levels correlated with HIV target cell activation (CCR5 and HLADR expression on CD4+ T cells) and plasma levels of the inflammatory cytokine CXCL10. These findings provide evidence that elevated OTA levels in South African infants are associated with the consumption of non-breastmilk foods and activation of the immune system. Reducing infant OTA exposure has the potential to reduce immune activation and provide health benefits, particularly in those infants who are HIV-exposed or HIV-infected.

Fruit fracture biomechanics and the release of Lepidium didymum pericarp-imposed mechanical dormancy by fungi

The biomechanical and ecophysiological properties of plant seed/fruit structures are fundamental to survival in distinct environments. Dispersal of fruits with hard pericarps (fruit coats) encasing seeds has evolved many times independently within taxa that have seed dispersal as their default strategy. The mechanisms by which the constraint of a hard pericarp determines germination timing in response to the environment are currently unknown. Here, we show that the hard pericarp of Lepidium didymum controls germination solely by a biomechanical mechanism. Mechanical dormancy is conferred by preventing full phase-II water uptake of the encased non-dormant seed. The lignified endocarp has biomechanically and morphologically distinct regions that serve as predetermined breaking zones. This pericarp-imposed mechanical dormancy is released by the activity of common fungi, which weaken these zones by degrading non-lignified pericarp cells. We propose that the hard pericarp with this biomechanical mechanism contributed to the global distribution of this species in distinct environments.

Plant growth-promoting activities for bacterial and fungal endophytes isolated from medicinal plant of Teucrium polium L

Bacterial and fungal endophytes are widespread inhabitants inside plant tissues and have been shown to assist plant growth and health. However, little is known about plant growth-promoting endophytes (PGPE) of medicinal plants. Therefore, the aims of this study were to identify bacterial and fungal endophytes of Teucrium polium and to characterize plant growth-promoting (PGP) properties of these endophytes. Seven bacterial endophytes were isolated and identified as Bacillus cereus and Bacillus subtilis, where five endophytic fungi were obtained and assigned to Penicillium chrysogenum and Penicillium crustosum. The isolated endophytes differentially produced indole acetic acid (IAA) and ammonia, and in addition to their enzymatic and antimicrobial activities, they exhibited variable capacity for phosphate solubilization. In order to investigate the effect of endophytes on plant growth, four representative endophytes and their consortiums were selected concerning to their potential ability to promote plant growth. The results indicated that microbial endophytes isolated from medicinal plants possessing a vital role to improve plant growth and could be used as inoculants to establish a sustainable crop production system.

Phylogeny and morphological analyses of Penicillium section Sclerotiora (Fungi) lead to the discovery of five new species

Phylogeny of Penicillium section Sclerotiora is still limitedly investigated. In this study, five new species of Penicillium are identified from the samples collected from different places of China, and named P. austrosinicum, P. choerospondiatis, P. exsudans, P. sanshaense and P. verrucisporum. The conidiophores of P. austrosinicum and P. exsudans are monoverticillate like most members of the section, while the rest species are biverticillate similar to the only two species P. herquei and P. malachiteum previously reported in the section Sclerotiora. The phylogenetic positions of the new taxa are determined based on the sequence data of ITS, BenA, CaM and RPB2 regions, which reveals that all the species with biverticillate condiophores form a well-supported subclade in the section. The new Penicillium species clearly differ from the existing species of the genus in culture characteristics on four standard growth media, microscopic features, and sequence data. Morphological discrepancies are discussed between the new species and their allies.

Fungal Root Microbiome from Healthy and Brittle Leaf Diseased Date Palm Trees (Phoenix dactylifera L.) Reveals a Hidden Untapped Arsenal of Antibacterial and Broad Spectrum Antifungal Secondary Metabolites

In this study, we aimed to explore and compare the composition, metabolic diversity and antimicrobial potential of endophytic fungi colonizing internal tissues of healthy and brittle leaf diseased (BLD) date palm trees (Phoenix dactylifera L.) widely cultivated in arid zones of Tunisia. A total of 52 endophytic fungi were isolated from healthy and BLD roots of date palm trees, identified based on internal transcribed spacer-rDNA sequence analysis and shown to represent 13 species belonging to five genera. About 36.8% of isolates were shared between healthy and diseased root fungal microbiomes, whereas 18.4 and 44.7% of isolates were specific to healthy and BLD root fungal microbiomes, respectively. All isolates were able to produce at least two of the screened enzymes including amylase, cellulase, chitinase, pectinase, protease, laccase and lipase. A preliminary screening of the isolates using disk diffusion method for antibacterial activity against four Gram-positive and three Gram-negative bacteria and antifungal activities against three phytopathogenic fungi indicated that healthy and BLD root fungal microbiomes displayed interesting bioactivities against examined bacteria and broad spectrum bioactivity against fungal pathogens. Some of these endophytic fungi (17 isolates) were fermented and their extracts were evaluated for antimicrobial potential against bacterial and fungal isolates. Results revealed that fungal extracts exhibited antibacterial activities and were responsible for approximately half of antifungal activities against living fungi. These results suggest a strong link between fungal bioactivities and their secondary metabolite arsenal. EtOAc extracts of Geotrichum candidum and Thielaviopsis punctulata originating from BLD microbiome gave best results against Micrococcus luteus and Bacillus subtilis with minimum inhibitory concentration (MIC, 0.78 mg/mL) and minimum bactericidal concentration (6.25 mg/mL). G. candidum gave the best result against Rhizoctonia solani with MIC 0.78 mg/mL and minimum fungicidal concentration (MFC, 6.25 mg/mL). In conclusion, using plant microbiomes subjected to biotic stresses offers new endophytes with different bioactivities than those of healthy plants. Therefore, date palm endophytic fungi represent a hidden untapped arsenal of antibacterial and broad spectrum antifungal secondary metabolites and could be considered promising source of bioactive compounds with industrial and pharmaceutical applications.

Comments on "Screening and Identification of Novel Ochratoxin A-Producing Fungi from Grapes. Toxins 2016, 8, 333"-In Reporting Ochratoxin A Production from Strains of Aspergillus, Penicillium and Talaromyces

Recently a species in the genus Talaromyces, a uniseriate species of Aspergillus section Nigri and an isolate each of two widespread species, Penicillium rubens and P. commune, were reported to produce ochratoxin A. This claim was based on insufficient biological and chemical data. We propose a list of criteria that need to be met before an unexpected mycotoxin producer is reported. There have only been convincing data on ochratoxin A production for Penicillium verrucosum, P. nordicum, P. thymicola, all from Penicillium series Verrucosa, and from species in three sections of Aspergillus: section Circumdati, section Nigri and section Flavi.

Penicillium Species and Their Associated Mycotoxins

Penicillium are very diverse and cosmopolite fungi, about 350 species are recognized within this genus. It is subdivided in four subgenera Aspergilloides, Penicillium, Furcatum, and Biverticillium; recently the first three has been included in Penicillium genus, and Biverticillium under Talaromyces. They occur worldwide and play important roles as decomposers of organic materials, cause destructive rots in the food industry where produces a wide range of mycotoxins; they are considered enzyme factories, and common indoor air irritants. In terms of human health are rarely associated as human pathogen because they hardly growth at 37°, while the main risk is related to ingestion of food contaminated by mycotoxins produced by several species of Penicillium. Various mycotoxins can occur in foods and feeds contaminated by Penicillium species, the most important are ochratoxin A and patulin; for which regulation are imposed in a number of countries, and at a less extent cyclopiazonic acid. In this chapter we summarize the main aspect of the morphology, ecology and toxigenicity of Penicillium foodborne mycotoxigenic species which belong mainly in subgenus Penicillium sections Brevicompacta, Chrysogena, Fasciculata, Penicillium, and Roquefortorum.

Metagenomic analysis of medicinal Cannabis samples; pathogenic bacteria, toxigenic fungi, and beneficial microbes grow in culture-based yeast and mold tests

Background: The presence of bacteria and fungi in medicinal or recreational Cannabis poses a potential threat to consumers if those microbes include pathogenic or toxigenic species. This study evaluated two widely used culture-based platforms for total yeast and mold (TYM) testing marketed by 3M Corporation and Biomérieux, in comparison with a quantitative PCR (qPCR) approach marketed by Medicinal Genomics Corporation.

Methods: A set of 15 medicinal Cannabis samples were analyzed using 3M and Biomérieux culture-based platforms and by qPCR to quantify microbial DNA. All samples were then subjected to next-generation sequencing and metagenomics analysis to enumerate the bacteria and fungi present before and after growth on culture-based media.

Results: Several pathogenic or toxigenic bacterial and fungal species were identified in proportions of >5% of classified reads on the samples, including Acinetobacter baumannii, Escherichia coli, Pseudomonas aeruginosa, Ralstonia pickettii, Salmonella enterica, Stenotrophomonas maltophilia, Aspergillus ostianus, Aspergillus sydowii, Penicillium citrinum and Penicillium steckii. Samples subjected to culture showed substantial shifts in the number and diversity of species present, including the failure of Aspergillus species to grow well on either platform. Substantial growth of Clostridium botulinum and other bacteria were frequently observed on one or both of the culture-based TYM platforms. The presence of plant growth promoting (beneficial) fungal species further influenced the differential growth of species in the microbiome of each sample.

Conclusions: These findings have important implications for the Cannabis and food safety testing industries.

Comments on "Mycobiota and Mycotoxins in Traditional Medicinal Seeds from China. Toxins 2015, 7, 3858-3875"- in Attributing Ochratoxin A Biosynthesis Within the Genus Penicillium Occurring on Natural Agricultural Produce

The unusual attribution of trace amounts of ochratoxin A in some Chinese food commodities to Penicillium polonicum is questioned by European experience in searches for ochratoxinogenic food-spoilage Penicillia, where mistaken attribution is now known to have been due to cryptic Penicillium verrucosum contamination. Consequently, selection of single-spore isolates is recommended as pre-requisite for attributing mycotoxin biosynthetic potential to fungi.

Ochratoxin A Producing Fungi, Biosynthetic Pathway and Regulatory Mechanisms

Ochratoxin A (OTA), mainly produced by Aspergillus and Penicillum species, is one of the most important mycotoxin contaminants in agricultural products. It is detrimental to human health because of its nephrotoxicity, hepatotoxicity, carcinogenicity, teratogenicity, and immunosuppression. OTA structurally consists of adihydrocoumarin moiety linked with l-phenylalanine via an amide bond. OTA biosynthesis has been putatively hypothesized, although several contradictions exist on some processes of the biosynthetic pathway. We discuss recent information on molecular studies of OTA biosynthesis despite insufficient genetic background in detail. Accordingly, genetic regulation has also been explored with regard to the interaction between the regulators and the environmental factors. In this review, we focus on three aspects of OTA: OTA-producing strains, OTA biosynthetic pathway and the regulation mechanisms of OTA production. This can pave the way to assist in protecting food and feed from OTA contamination by understanding OTA biosynthetic pathway and regulatory mechanisms.

What's Inside That Seed We Brew? A New Approach To Mining the Coffee Microbiome

Coffee is a critically important agricultural commodity for many tropical states and is a beverage enjoyed by millions of people worldwide. Recent concerns over the sustainability of coffee production have prompted investigations of the coffee microbiome as a tool to improve crop health and bean quality. This review synthesizes literature informing our knowledge of the coffee microbiome, with an emphasis on applications of fruit- and seed-associated microbes in coffee production and processing. A comprehensive inventory of microbial species cited in association with coffee fruits and seeds is presented as reference tool for researchers investigating coffee-microbe associations. It concludes with a discussion of the approaches and techniques that provide a path forward to improve our understanding of the coffee microbiome and its utility, as a whole and as individual components, to help ensure the future sustainability of coffee production.

Unexpected diversity of basidiomycetous endophytes in sapwood and leaves of Hevea

Research on fungal endophytes has expanded dramatically in recent years, but little is known about the diversity and ecological roles of endophytic basidiomycetes. Here we report the analysis of 310 basidiomycetous endophytes isolated from wild and planted populations of the rubber tree genus, Hevea. Species accumulation curves were nonasymptotic, as in the majority of endophyte surveys, indicating that more sampling is needed to recover the true diversity of the community. One hundred eighteen OTUs were delimited, representing nine orders of Basidiomycota (Agaricales, Atheliales, Auriculariales, Cantharellales, Hymenochaetales, Polyporales, Russulales, Septobasidiales, Tremellales). The diversity of basidiomycetous endophytes found inhabiting wild populations of Hevea was comparable to that present in plantations. However, when samples were segregated by tissue type, sapwood of wild populations was found to contain a higher number of species than sapwood of planted trees. Seventy-five percent of isolates were members of the Polyporales, the majority in the phlebioid clade. Most of the species belong to clades known to cause a white-rot type of wood decay. Two species in the insect-associated genus Septobasidium were isolated. The most frequently isolated genera included Bjerkandera, Ceriporia, Phanerochaete, Phlebia, Rigidoporus, Tinctoporellus, Trametes (Polyporales), Peniophora, Stereum (Russulales) and Coprinellus (Agaricales), all of which have been reported as endophytes from a variety of hosts, across wide geographic locations. Literature records on the geographic distribution and host association of these genera revealed that their distribution and substrate affinity could be extended if the endophytic niche was investigated as part of fungal biodiversity surveys.

Endophytes in the plant Huperzia serrata: fungal diversity and discovery of a new pentapeptide

Endophytic fungi are an underexploited resource of natural products and have a capacity to produce diverse classes of plant-derived secondary metabolites. Here, we investigated the diversity of endophytic fungi from Huperzia serrata and the potential for discovering novel fungal natural products. One hundred and fifty-five endophytic fungi isolates obtained from H. serrata, belonging to four classes Dothideomycetes (47.3 %), Sordariomycetes (36.8 %), Eurotiomycetes (10.6 %) and an undefined class (5.3 %, Mucoraceae), were grouped into nine genera based on morphological and molecular identification. Colletotrichum, Cladosporium, Sordariomycetes and Guignardia were the dominant genera, whereas the remaining genera were infrequent groups. To our knowledge, the fungal genera Mucor and Neurospora were first reported in Huperzia plant. Among these endophytic fungi isolates, strain B14, belonging to Penicillium oxalicum, gave a gray precipitate with Dragendorff's reagent. A new pentapeptide was isolated from the culture of strain B14, and its chemical structure was elucidated on the basis of spectroscopic data from (1)H NMR, (13)C NMR and ESI-MS/MS. Taken together, H. serrata has a significant diversity of endophytic fungi that could be a rich resource for the discovery of new natural products.

A new ochratoxin A biodegradation strategy using Cupriavidus basilensis Őr16 strain

Ochratoxin-A (OTA) is a mycotoxin with possibly carcinogenic and nephrotoxic effects in humans and animals. OTA is often found as a contaminant in agricultural commodities. The aim of the present work was to evaluate OTA-degrading and detoxifying potential of Cupriavidus basilensis ŐR16 strain. In vivo administration of OTA in CD1 male mice (1 or 10 mg/kg body weight for 72 hours or 0.5 mg/kg body weight for 21 days) resulted in significant elevation of OTA levels in the blood, histopathological alterations- and transcriptional changes in OTA-dependent genes (annexinA2, clusterin, sulphotransferase and gadd45 and gadd153) in the renal cortex. These OTA-induced changes were not seen in animals that have been treated with culture supernatants in which OTA was incubated with Cupriavidus basilensis ŐR16 strain for 5 days. HPLC and ELISA methods identified ochratoxin α as the major metabolite of OTA in Cupriavidus basilensis ŐR16 cultures, which is not toxic in vivo. This study has demonstrated that Cupriavidus basilensis ŐR16 efficiently degrade OTA without producing toxic adventitious metabolites.

DNA Based Identification and Phylogenetic Characterisation of Endophytic and Saprobic Fungi from Antidesma madagascariense, a Medicinal Plant in Mauritius

Endophytes are fungi associated with plants without causing symptoms, and they are quite diverse and have enormous potential for production of important secondary metabolites for the pharmaceutical industry. In this study, we report for the first time fungi (both endophytes and saprobes) from Antidesma madagascariense, a medicinal plant in Mauritius, in view of identifying potential candidates for screening of fungi for pharmaceutical importance. In addition the phylogenetic placement of fungi recovered from leaves samples was investigated based on rDNA sequence analysis. Most commonly isolated fungi were related to Aspergillus, Guignardia, Fusarium, Penicillium, Pestalotiopsis, and Trichoderma. Phylogenetic analyses revealed that fungi recovered belong to 5 different fungal lineages (Hypocreaceae, Trichocomaceae, Nectriaceae, Xylariaceae, and Botryosphaeriaceae). DNA data from the ITS regions were reliable in classification of all recovered isolates up to genus level, but identification to an exact species name was not possible at this stage. Despite criticisms pertaining to the use of ITS sequence data in molecular systematics, our approach here provides an opportunity to justify the reliability of ITS sequence data for possible identification and discovering of evolutionary scenarios among isolates that do not sporulate under cultural conditions.

Toxigenic potential of Aspergillus species occurring on maize kernels from two agro-ecological zones in Kenya

Two agro-ecological zones in Kenya were selected to compare the distribution in maize of Aspergillus spp. and their toxigenicity. These were Nandi County, which is the main maize growing region in the country but where no human aflatoxicoses have been reported, and Makueni County where most of the aflatoxicosis cases have occurred. Two hundred and fifty-five households were sampled in Nandi and 258 in Makueni, and Aspergillus was isolated from maize. Aspergillus flavus and A. parasiticus isolates were tested for the presence of aflD and aflQ genes. Positive strains were induced to produce aflatoxins on yeast extract sucrose and quantified using liquid chromatography-tandem mass spectrometry (LCMSMS). Aspergillus flavus was the most common contaminant, and the incidence of occurrence in Nandi and Makueni was not significantly different (82.33% and 73.26%, respectively). Toxigenic strains were more prevalent than non-toxigenic strains. All the toxigenic strains from Makueni were of the S-type while those from Nandi belonged to the l-type. Quantitative differences in aflatoxin production in vitro between isolates and between strains were detected with S strains producing relatively larger amounts of total aflatoxins, B toxins and lower values for G toxins. This was in accord with the frequent aflatoxicosis outbreaks in Makueni. However some L strains produced considerable amounts of B toxins. Given the widespread distribution of toxigenic strains in both regions, the risk of aflatoxin poisoning is high when favorable conditions for toxin production occur.

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.

A taxonomic and phylogenetic revision of the Penicillium sclerotiorum complex

The morphological concept of Penicillium sclerotiorum (subgenus Aspergilloides) includes strains with monoverticillate, vesiculate conidiophores, and vivid orange to red colony colours, with colourful sclerotia sometimes produced. Multigene phylogenetic analyses with the nuclear ribosomal internal transcribed spacer (ITS) region, cytochrome c oxidase subunit 1 (cox1), β-tubulin (benA), translation elongation factor 1-α (tef1-α), and calmodulin (cmd), reveal that the P. sclerotiorum morphospecies is a complex of seven phylogenetically distinct species, three of which were recently described, namely P. guanacastense, P. mallochii, and P. viticola. Three previously unidentified species are described here as P. cainii, P. jacksonii, and P. johnkrugii. The phylogenetic species are morphologically similar, but differ in combinations of colony characters, sclerotium production, conidiophore stipe roughening and branching, and conidial shape. Ecological characters and differences in geographical distribution further characterise some of the species, but increased sampling is necessary to confirm these differences. The fungal DNA barcode, the ITS, and the animal DNA barcode, cox1, have lower species resolving ability in our phylogenetic analyses, but still allow identification of all the species. Tef1-α and cmd were superior in providing fully resolved, statistically well-supported phylogenetic trees for this species complex, whereas benA resolved all species but had some issues with paraphyly. Penicilliumadametzioides and P. multicolor, considered synonyms of P. sclerotiorum by some previous authors, do not belong to the P. sclerotiorum complex.

TAXONOMIC NOVELTIES

New species:Penicillium cainii K.G. Rivera, Malloch & Seifert, P. jacksonii K.G. Rivera, Houbraken & Seifert, P. johnkrugii K.G. Rivera, Houbraken & Seifert.

Immunological status of the progeny of breeder hens kept on ochratoxin A (OTA)-contaminated feed

This study aimed to evaluate the immunological status of the progeny of breeder hens kept on ochratoxin A (OTA)-contaminated feed. For this purpose, 84 White Leghorn (WL) layer breeder hens (40-weeks-of-age) were divided into seven groups (A-G). Hens in the Group A were fed a commercial layer ration while those in Groups B-G were kept on a diet amended with 0.1, 0.5, 1.0, 3.0, 5.0, or 10.0 mg OTA/kg, respectively, for 3 weeks. Fertile eggs were set for hatching on the weekly basis to get the progeny of each week separately. Hatched chicks (n = 10 from each group) were euthanized at Day 14 of age, and their immunological organs weighed and fixed in neutral buffered formalin. An indirect immunoperoxidase method was applied to study the frequency of immunoglobulin(s)-bearing cells in the spleen and bursa of Fabricius from these progeny. From other chicks within each set, at Day 16 of age, lymphoblastogenic responses against an intradermal administration of phytohemagglutinin (PHA-P) were determined. Relative weights of the bursa of Fabricius and of the thymus were significantly lower in the progeny of hens fed OTA-contaminated diet for 14 and 21 days. The frequencies of IgA-, IgG-, and IgM-bearing cells were also significantly (P ≤ 0.05) lower in the bursa of Fabricius and spleen of the progeny chicks obtained from dams fed the OTA-mixed diet. Progeny chicks obtained from the breeder hens fed higher doses of OTA showed significantly lower responses to PHA-P than did counterpart chicks from control hens. The findings of this study suggested that there were immunosuppressive effects from OTA in the progeny obtained from breeder hens kept on OTA-contaminated diets.

Characterization of cultivated fungi isolated from grape marc wastes through the use of amplified rDNA restriction analysis and sequencing

Microbial assessment of grape marc wastes, the residual solid by-product of the wine-industry, was performed by identifying phylogenetically the fungal culturable diversity in order to evaluate environmental and disposal safety issues and to discuss ecological considerations of applications on agricultural land. Fungal spores in grape marc were estimated to 4.7 x 10(6) per g dry weight. Fifty six fungal isolates were classified into eight operational taxonomic units (OTUs) following amplified ribosomal DNA restriction analysis (ARDRA) and colony morphology. Based on 18S rRNA gene and 5.8S rRNA gene-ITS sequencing, the isolates representing OTUs #1, #2, #3, and #4, which comprised 44.6%, 26.8%, 12.5%, and 5.3%, respectively, of the number of the total isolates, were identified as Aspergillus fumigatus, Bionectria ochroleuca, Haematonectria haematococca, and Trichosporon mycotoxinivorans. The isolates of OTU#5 demonstrated high phylogenetic affinity with Penicillium spp., while members of OTUs #6 and #7 were closer linked with Geotrichum candidum var. citri-aurantii and Mycocladus corymbifer, respectively (95.4 and 97.9% similarities in respect to their 5.8S rRNA gene-ITS sequences). The OTU#8 with a single isolate was related with Aspergillus strains. It appears that most of the fungal isolates are associated with the initial raw material. Despite the fact that some of the species identified may potentially act as pathogens, measures such as the avoidance of maintaining large and unprocessed quantities of grape marc wastes in premises without adequate aeration, together with its suitable biological treatment (e.g., composting) prior to any agriculture-related application, could eliminate any pertinent health risks.

Biodegradation of ochratoxin a for food and feed decontamination

Ochratoxin A (OTA) is one of the most important mycotoxins that is found in food and feed products. It has proven toxic properties, being primarily known for its nephrotoxicity and carcinogenicity to certain animal species. OTA is produced by several species of Aspergillus and Penicillium that can be found in a wide variety of agricultural products, which makes the presence of OTA in these products common. Many countries have statutory limits for OTA, and concentrations need to be reduced to as low as technologically possible in food and feed. The most important measures to be taken to control OTA are preventive in order to avoid fungal growth and OTA production. However, these measures are difficult to implement in all cases with the consequence of OTA remaining in agricultural commodities. Remediation processes are often used to eliminate, reduce or avoid the toxic effects of OTA. Biological methods have been considered increasingly as an alternative to physical and chemical treatments. However, examples of practical applications are infrequent. This review will focus on the (i) known microorganisms and enzymes that are able to biodegrade OTA; (ii) mode of action of biodegradation and (iii) current applications. A critical discussion about the technical applicability of these strategies is presented.

Incidence and distribution of filamentous fungi during fermentation, drying and storage of coffee (Coffea arabica L.) beans

The objective of this work was to isolate and characterize filamentous fungi present in different stages of harvest, fermentation, drying and storage of coffee beans processed by natural method. The cherries were hand-picked and then placed on a cement drying platform where they remained until reached 11% of humidity. Microbial counts were found in all samples during fermentation and drying of the coffee beans. Counts of fungi in the coffee cherries collected from the tree (time 0) were around 1.5 x 10(3) CFU/g. This number increased slowly during the fermentation and drying reaching values of 2 x 10(5) CFU/g within 22 days of processing. Two hundred and sixty three isolates of filamentous fungi were identified. The distribution of species during fermentation and drying was very varied while there was a predominance of Aspergillus species during storage period. The genera found were Pestalotia (4), Paecelomyces (4), Cladosporium (26), Fusarium (34), Penicillium (81) and Aspergillus (112) and comprised 38 different species.

Multilocus sequence identification of Penicillium species in cork bark during plank preparation for the manufacture of stoppers

Despite several studies reporting Penicillium as one of the most frequent fungal genera in cork planks, the isolates were rarely identified to species level. We conducted a detailed study to identify Penicillium species from the field to the factory environment prior to and after boiling the cork planks. A total of 84 samples were analyzed. Of the 486 Penicillium isolates phenotypically identified, 32 representative or unusual strains were selected for identification by multilocus DNA sequence type. Cork proved to be a rich source of Penicillium biodiversity. A total of 30 taxa were recognized from cork including rarely seen species and 6 phylogenetically unique groups. Spores of some species lodged deep in cork can survive the boiling process. P. glabrum, P. glandicola and P. toxicarium, species with high CFU numbers in the field, are still frequently present in cork after boiling. Other species are killed by the boiling treatment and replaced by Penicillium species originating from the factory environment. Species known to contribute to cork taint were isolated at all stages. Good manufacturing practices are necessary at all stages in the preparation of cork planks to minimize the load of Penicillium species that produce cork taint.