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Introduction: Moesziomyces spp. are connected with poaceous plants (Grass family), and Moesziomyces bullatus is commonly associated with smut in pearl millet. Currently, the scientific knowledge of this pathogen is limited to only a few taxonomic studies and there are no clinical reports that describe the isolation of M. bullatus from humans. Case presentation: A female neonate born prematurely at 32 weeks of gestation was referred to the University Teaching Hospital in Jos, Nigeria, with a provisional diagnosis of preterm low birth weight at risk for sepsis. The birth weight of the newborn was 2000 g and her body temperature on admission was 34.3 °C. Blood cultures revealed the presence of a fungal isolate that was identified as M. bullatus by molecular methods. This fungus showed high MIC values for anidulafungin, caspofungin and micafungin, as well as fluconazole and 5‐flucytosine, and exhibited varying degrees of susceptibility to itraconazole, amphotericin B, posaconazole and voriconazole. To the best of our knowledge, this is the first case of a human M. bullatus bloodstream infection. Conclusion: Here, we report the first case of an unusual human infection caused by the fungal plant pathogen M. bullatus and highlight a high level of resistance to classical and modern antifungal drugs.

Fusarium species have started appearing increasingly as the main cause of infections, particularly in immunocompromised patients. In this study, we aimed to present the first epidemiological data from Turkey, analyze fusariosis cases that have been monitored in a university hospital during the past 20 years, identify the responsible Fusarium species, and determine antifungal susceptibilities. A total of 47 cases of fusariosis was included in the study. Fusarium isolates were identified by multilocus sequence typing (MLST). Antifungal susceptibility was tested by the broth microdilution method according to the Clinical and Laboratory Standards Institute (CLSI) methodology. Of the Fusarium infections, 23.4 % were superficial, 44.7 % were locally invasive, and 31.9 % were disseminated. A significant increase was observed over the years. The Fusarium fujikuroi species complex (FFSC) proved to be the most frequent agent group (17 cases; 51.5 %), followed by the Fusarium solani species complex (FSSC) (14 cases; 42.4 %), the Fusarium dimerum species complex (FDSC), and the Fusarium oxysporum species complexes (FOSC) (one case each). Amphotericin B had the highest in vitro activity against all species. Voriconazole and posaconazole showed interspecies variability across and within Fusarium species complexes. In conclusion, our data support the fact that regional differences exist in the distribution of the Fusarium species and that species-specific differences are observed in antifungal susceptibility patterns. The monitoring of local epidemiological data by determining fungal identity and susceptibility are of importance in guiding the clinical follow-up of patients.

Proximal subungual onychomycosis (PSO) is a fungal infection on the inner layer of the nail plate which starts from the eponychium and nail matrix.(1) Onychomycosis can be caused by a variety of dermatophytes, yeasts and non-dermatophyte molds (NDMs) including species of Aspergillus, Acremonium, Scopulariopsis, Chaetomium, and Fusarium.(2) Fusarium and Acremonium species require special attention, because of their intrinsically low susceptibility to most common antifungal agents and their ability to disseminate in severely compromised hosts, using the nail as a potential source of infection.(3,4) This article is protected by copyright. All rights reserved.

Background Fusarium species are among the most common fungi present in the environment and some species have emerged as major opportunistic fungal infection in human. However, in immunocompromised hosts they can be virulent pathogens and can cause death. The pathogenesis of this infection relies on three factors: colonization, tissue damage, and immunosuppression. A novel Fusarium species is reported for the first time from keratitis in an agriculture worker who acquired the infection from plant material of maize. Maize plants are the natural host of this fungus where it causes stalk rot and seeding malformation under temperate and humid climatic conditions. The clinical manifestation, microbiological morphology, physiological features and molecular data are described.MethodsDiagnosis was established by using polymerase chain reaction of fungal DNA followed by sequencing portions of translation elongation factor 1 alpha (TEF1 ¿) and beta-tubulin (BT2) genes. Susceptibility profiles of this fungus were evaluated using CLSI broth microdilution method.ResultsThe analyses of these two genes sequences support a novel opportunist with the designation Fusarium temperatum. Phylogenetic analyses showed that the reported clinical isolate was nested within the Fusarium fujikuroi species complex. Antifungal susceptibility testing demonstrated that the fungus had low MICs of micafungin (0.031 ¿g/ml), posaconazole (0.25 ¿g/ml) and amphotericin B (0.5 ¿g/ml).ConclusionThe present case extends the significance of the genus Fusarium as agents of keratitis and underscores the utility of molecular verification of these emerging fungi in the human host.

OBJECTIVES: The aim of the present study was to evaluate and assess the in vitro activity of eight drugs, including the new azole isavuconazole, against 81 strains representing 13 species of the Fusarium fujikuroi species complex.METHODS: A total of 81 Fusarium spp. isolates, within the F. fujikuroi species complex, were identified by molecular methods and tested according to CLSI M38-A2. Eight antifungal compounds, including the new azole isavuconazole, were tested. Isolates were selected to represent the widest variety of geographical regions and to include clinical as well as environmental strains.RESULTS: Susceptibility profiles differed between and within species, with Fusarium verticillioides showing the lowest MICs and Fusarium nygamai the highest MICs. Amphotericin B was the most active drug, followed by voriconazole, posaconazole, isavuconazole and natamycin. The remaining antifungals (fluconazole, itraconazole and micafungin) showed poor activity with MIC/minimum effective concentration values of ≥32, ≥16 and >8 mg/L, respectively.CONCLUSIONS: Resistance patterns in the F. fujikuroi species complex are species specific and therefore identification down to species level is important for the choice of antifungal treatment.

Sporotrichosis is a subcutaneous mycosis caused by dimorphic fungi in the genus Sporothrix. The lymphocutaneous form is the classic type of the disease(1) . Agents in Sporothrix are present in plant debris and in soil throughout the world, particularly in the Americas, East Asia, and South Africa, but are uncommon in Europe, and it is uncertain if European cases are autochthonous or imported (Zhang et al. 2014, unpublished data). This article is protected by copyright. All rights reserved.

Autophagy is a well-conserved catabolic process, involving the degradation of a cell's own components through the lysosomal/vacuolar machinery. Autophagy is typically induced by nutrient starvation and has a role in nutrient recycling, cellular differentiation, degradation and programmed cell death. Another common response in eukaryotes is the extension of lifespan through dietary restriction (DR). We studied a link between DR and autophagy in the filamentous fungus Podospora anserina, a multicellular model organism for ageing studies and mitochondrial deterioration. While both carbon and nitrogen restriction extends lifespan in P. anserina, the size of the effect varied with the amount and type of restricted nutrient. Natural genetic variation for the DR response exists. Whereas a switch to carbon restriction up to halfway through the lifetime resulted in extreme lifespan extension for wild-type P. anserina, all autophagy-deficient strains had a shorter time window in which ageing could be delayed by DR. Under nitrogen limitation, only PaAtg1 and PaAtg8 mediate the effect of lifespan extension; the other autophagy-deficient mutants PaPspA and PaUth1 had a similar response as wild-type. Our results thus show that the ageing process impinges on the DR response and that this at least in part involves the genetic regulation of autophagy.

Abstract The structure of the Fusarium gerlachii mitogenome is similar to that of closely related Fusarium graminearum; it has a total length of 93,428 bp, the base composition of the genome is: A (35.3%), T (32.8%), C (14.7%) and G (17.2%). The mitogenome contains 13 protein-coding genes, 2 ribosomal RNA (rRNA) and 28 transfer RNA (tRNA) genes. The tRNA genes range in size from 62 bp to 88 bp. The gene order is identical to that of the other Fusarium mitogenomes.

Sporotrichosis is one of the most frequent subcutaneous fungal infections to human and animals caused by members of the plant-associated, dimorphic genus Sporothrix. Three of the four medically important Sporothrix species found in Brazil have been considered asexual, as no sexual stage has ever been reported in S. schenckii, S. brasiliensis or S. globosa. We have identified the mating-type (MAT) loci in the S. schenckii (strain 1099-18/ATCC MYA-4821) and S. brasiliensis (strain 5110/ATCC MYA-4823) genomes by using comparative genomic approaches and to determine the mating type ratio in these pathogens populations. Our analysis revealed the presence of a MAT1-1 locus in S. schenckii while a MAT1-2 locus was found in the S. brasiliensis presenting genomic synteny to other Sordariomycetes. Furthermore, the components of the MAPK-pheromone pathway, pheromone processing enzymes as well as meiotic regulators have also been identified in the two pathogens, suggesting the potential for sexual reproduction. The MAT1-1:MAT1-2 ratio was not significantly different from 1:1 all three Sporothrix species, but the population of S. brasiliensis in the outbreaks was originated from a single mating type. We also explored the population genetic structure of these pathogen populations using sequence data of two loci to improve our knowledge on the pattern of geographic distribution, genetic variation and virulence phenotypes. Population genetics data showed significant population differentiation and clonality with low level of haplotype diversity in S. brasiliensis from different regions of sporotrichosis outbreaks in Brazil. In contrast, S. schenckii demonstrated a high degree of genetic variability without significant geographic differentiation, indicating the presence of recombination. This study demonstrated that two species causing the same disease have contrasting reproductive strategies and genetic variability patterns.

Disseminated infections caused by members of the Fusarium fujikuroi species complex (FFSC) occur regularly in immunocompromised patients. Here, we present the first human case caused by FFSC-member Fusarium andiyazi. Fever, respiratory symptoms and abnormal computerised tomography findings developed in a 65-year-old man with acute myelogenous leukaemia who was under posaconazole prophylaxis during his remission-induction chemotherapy. During the course of infection, two consecutive blood galactomannan values were found to be positive, and two blood cultures yielded strains resembling Fusarium species, according to morphological appearance. The aetiological agent proved to be F. andiyazi based on multilocus sequence typing. The sequencing of the internal transcribed spacer region did not resolve the closely related members of the FFSC, but additional data on partial sequence of transcription elongation factor 1 alpha subunit did. A detailed morphological study confirmed the identification of F. andiyazi, which had previously only been reported as a plant pathogen affecting various food crops.

Members of the Fusarium solani species complex (FSSC) are causing the majority of the fusariosis in humans. Disseminated fusariosis has a high mortality and is predominantly observed in patients with leukemia. Here, we present the case of a fatal infection by a Fusarium strain with a degenerated phenotype, in a patient with acute lymphatic leukemia. Multiple nasal and skin biopsies as well as blood cultures yielded fungal growth, while in direct and histopathological examination of biopsy material septate hyphae were visible. Initial colonies were white with slimy masses with microconidia reminiscent of Fusarium/Acremonium, but with conidiospore production directly on the hyphae. Multi-locus sequence typing discerned a pionnotal-morphologically degenerated-colony of the recently recognized F. petroliphilum as etiological agent. The culture returned to a typical F. solani species complex morphology only after several weeks of growth in culture. Antifungal susceptibility tests indicate amphotericin B as best drug for this FSSC member rather than any of the azoles or echinocandins.

Aspergillus fumigatus is a fungus that causes opportunistic infections in immunocompromised patients, with high morbidity and mortality. In its turn, A. fumigatus can become infected with mycoviruses. Most mycoviruses have a dsRNA genome and can cause fungal hypovirulence. For that reason, mycoviruses could theoretically be used as therapeutic tools to combat fungal infections. We determined if a certain genetic make-up of A. fumigatus was associated with the presence of mycoviruses in 86 clinical A. fumigatus isolates. Mycovirus screening was performed by isolating dsRNA from mycelial cultures using a Trizol/Chloroform method. The genetic relatedness of dsRNA infected A. fumigatus was determined by cell surface protein (CSP) typing and determination of the mating type. Sixteen (18.6%) of the 86 clinical A. fumigatus isolates contained dsRNA. The A. fumigatus collection could be divided into 11 different CSP types. DsRNA infected A. fumigatus isolates had similar CSP types as non-infected isolates. In both cases, the CSP types t01, t02, t03 and t04 were the most prevalent and the distribution comparable to the CSP types observed in other Dutch collections. Mating types MAT1-1 and MAT1-2 were evenly distributed among all A. fumigatus strains, regardless of CSP type. No difference was observed in mycovirus infections between MAT1-1 and MAT1-2 isolates. DsRNA mycovirus infections in A. fumigatus are not related to either CSP or mating type and therefore represent an interesting future therapeutic tool to combat fungal infections.

A new species of nonsporulating fungus, isolated in a case of black-grain mycetoma in Sudan, is described as Madurella fahalii. The species is characterized by phenotypic and molecular criteria. Multigene phylogenies based on the ribosomal DNA (rDNA) internal transcribed spacer (ITS), the partial beta-tubulin gene (BT2), and the RNA polymerase II subunit 2 gene (RPB2) indicate that M. fahalii is closely related to Madurella mycetomatis and M. pseudomycetomatis; the latter name is validated according to the rules of botanical nomenclature. Madurella ikedae was found to be synonymous with M. mycetomatis. An isolate from Indonesia was found to be different from all known species based on multilocus analysis and is described as Madurella tropicana. Madurella is nested within the order Sordariales, with Chaetomium as its nearest neighbor. Madurella fahalii has a relatively low optimum growth temperature (30 degrees C) and is less susceptible to the azoles than other Madurella species, with voriconazole and posaconazole MICs of 1 mu g/ml, a ketoconazole MIC of 2 mu g/ml, and an itraconazole MIC of > 16 mu g/ml. Since eumycetoma is still treated only with azoles, correct species identification is important for the optimal choice of antifungal therapy., A new species of nonsporulating fungus, isolated in a case of black-grain mycetoma in Sudan, is described as Madurella fahalii. The species is characterized by phenotypic and molecular criteria. Multigene phylogenies based on the ribosomal DNA (rDNA) internal transcribed spacer (ITS), the partial beta-tubulin gene (BT2), and the RNA polymerase II subunit 2 gene (RPB2) indicate that M. fahalii is closely related to Madurella mycetomatis and M. pseudomycetomatis; the latter name is validated according to the rules of botanical nomenclature. Madurella ikedae was found to be synonymous with M. mycetomatis. An isolate from Indonesia was found to be different from all known species based on multilocus analysis and is described as Madurella tropicana. Madurella is nested within the order Sordariales, with Chaetomium as its nearest neighbor. Madurella fahalii has a relatively low optimum growth temperature (30 degrees C) and is less susceptible to the azoles than other Madurella species, with voriconazole and posaconazole MICs of 1 mu g/ml, a ketoconazole MIC of 2 mu g/ml, and an itraconazole MIC of > 16 mu g/ml. Since eumycetoma is still treated only with azoles, correct species identification is important for the optimal choice of antifungal therapy.

Evolutionary theory predicts that senescence – a decline in reproduction and survival with increasing age - can evolve as a trade-off between the investment in reproduction on one side and in somatic maintenance and repair on the other side. The ecology of a species is crucial here, since it provides the external causes of death that determine the statistical limit to a species’ lifespan. Filamentous fungi are generally believed to be non-senescent, and there are indeed spectacular examples of very old fungal individuals in nature. Yet, for some fungi the growth conditions are ephemeral and therefore senescence is expected to have evolved, like in the coprophilic Podospora anserina, the only well-studied filamentous fungus with intrinsic senescence. Here we hypothesize that rapid senescence is more common in fungi than generally believed and that the phylogenetic distribution of senescence correlates with its ecology. We examined a set of Sordariomycetes for their lifespan and constructed phylogenies based on several nuclear sequences. Part of the strains were from the CBS culture collection, originally isolated from various substrates, some of which ephemeral. In addition we isolated new strains from short-lived substrates. Senescence was observed throughout the phylogeny. Correlation tests support the hypothesis that in the Sordariomycetes senescence is a trait that has arisen as an evolved adaptation to ephemeral substrates, and that it has evolved repeatedly and independently along the phylogeny.,Alignment ITS sequencesFasta (txt) file with all the aligned ITS sequences of all strains from our culture collection and isolated from dung, used in the analysis to detect correlated evolution between substrate and (rapid) senescence.Alignment non-redundant ITS sequencesFasta (txt) file with the aligned non-redundant ITS sequences, used in the analysis to detect correlated evolution between substrate and (rapid) senescence.Character matrix-non-redundant scenarioBinomic

Calorie restriction (CR) is a regimen of reduced food intake that, although the underlying mechanism is unknown, in many organisms leads to life span extension. Podospora anserina is one of the few known ageing filamentous fungi and the ageing process and concomitant degeneration of mitochondria have been well-studied. CR in P. anserina increases not only life span but also forestalls the ageing-related decline in fertility. Here we review what is known about CR in P. anserina and about possibly involved mechanisms like enhanced mitochondrial stability, reduced production of reactive oxygen species and changes in the OXPHOS machinery. Additionally, we present new microscopic data on mitochondrial dynamics under rich nutritional and CR conditions at different points in life. Lines that have grown under severe CR for more than 50x the normal life span, show no accumulation of age-related damage, though fecundity is reduced in some of these lines. Finally, we discuss the possible role of CR in P. anserina in nature and the effect of CR at different points in life.

With uniparental inheritance of mitochondria, there seems little reason for homologous recombination in mitochondria, but the machinery for mitochondrial recombination is quite well-conserved in many eukaryote species. In fungi and yeasts heteroplasmons may be formed when strains fuse and transfer of organelles takes place, making it possible to study mitochondrial recombination when introduced mitochondria contain different markers. A survey of wild-type isolates from a local population of the filamentous fungus Podospora anserina for the presence of seven optional mitochondrial introns indicated that mitochondrial recombination does take place in nature. Moreover the recombination frequency appeared to be correlated with age: the more rapidly ageing fraction of the population had a significantly lower linkage disequilibrium indicating more recombination. Direct confrontation experiments with heterokaryon incompatible strains with different mitochondrial markers at different (relative) age confirmed that mitochondrial recombination increases with age. We propose that with increasing mitochondrial damage over time, mitochondrial recombination - even within a homoplasmic population of mitochondria - is a mechanism that may restore mitochondrial function.

Although most fungi appear to be immortal, some show systemic senescence within a distinct time frame. Podospora anserina for example shows an irreversible growth arrest within weeks of culturing associated with a destabilization of the mitochondrial genome. Here, we show that calorie restriction (CR), a regimen of under-nutrition without malnutrition, increases not only life span but also forestalls the aging-related decline in fertility. Similar to respiratory chain deficiencies the life span extension is associated with lower levels of intracellular H(2)O(2) measurements and a stabilization of the mitochondrial genome. Unlike respiratory chain deficiencies, CR cultures have a wild-type-like OXPHOS machinery similar to that of well-fed cultures as shown by native electrophoresis of mitochondrial protein complexes. Together, these data indicate that life span extension via CR is fundamentally different from that via respiratory chain mutations: Whereas the latter can be seen as a pathology, the former promotes healthy life span extension and may be an adaptive response.

Potato brown rot disease (Ralstonia solanacearum) is a serious economic problem in Egypt, partly due to an European Union requirement that potatoes for export to the EU should be grown in so-called pest free area's (PFA's), where fields are tested and infested fields are put under quarantine measures. To investigate pathogen survival and to determine the time required to keep infested fields in quarantine, the survival of R. solanacearum race 3 biovar 2 was tested in soils differing in origin (Dutch versus Egyptian soils), soil type (sand versus clay), and management type (organic versus conventional). All eight soils were tested at moderate (15 ??C) and elevated temperatures (28 ??C). Also the effects of artificial fertilizer and organic (compost and cow manure) amendments on survival of R. solanacearum were tested. In all soils, with and without amendments, the pathogen dropped below the detection limit (102 CFU g-1 d.w. soil) within 5 months. At both temperatures, all Egyptian soils showed a significantly faster decline in pathogen density than the Dutch soils. The decline in colony forming units of R. solanacearum per gram of soil was faster in sandy soils than in clay soils from both countries. Management effects on decline of R. solanacearum were smaller and less consistent: for some soils, organic management resulted in a significantly shorter 50%-reduction-time and/or greater decline rate than conventional management, for other soils the differences were not significant. Survival periods at 15 ??C were longer than at 28 ??C in Dutch soils, but not in Egyptian soils, where survival was slightly shorter at the lower temperature. Amendments with NPK fertilizer to the conventional soils and with cow manure to the organic soils enhanced the decline rate of R. solanacearum in these soils. The decline rate of the pathogen was negatively correlated with total soluble organic matter and positively with bacterial diversity. In conclusion, the overriding factors determ

Heterokaryon incompatibility among Aspergillus niger strains is a widespread phenomenon that is observed as the inability to form stable heterokaryons. The genetic basis of heterokaryon incompatibility reactions is well established in some sexual filamentous fungi but largely unknown in presumed asexual species, such as A. niger. To test whether the genes that determine heterokaryon incompatibility in Neurospora crassa, such as het-c, vib-1 and pin-c, have a similar function in A. niger, we performed a short in silico search for homologues of these genes in the A. niger and several related genomes. For het-c, pin-c and vib-1 we did indeed identify putative orthologues. We then screened a genetically diverse worldwide collection of incompatible black Aspergilli for polymorphisms in the het-c orthologue. No size variation was observed in the variable het-c indel region that determines the specificity in N. crassa. Sequence comparison showed only minor variation in the number of glutamine coding triplets. However, introduction of one of the three N. crassa alleles (het-c2) in A. niger by transformation resulted in an abortive phenotype, reminiscent of the heterokaryon incompatibility in N. crassa. We conclude that although the genes required are present and the het-c homologue could potentially function as a heterokaryon incompatibility gene, het-c has no direct function in heterokaryon incompatibility in A. niger because the necessary allelic variation is absent.

Since the first description of a linear mitochondrial plasmid in Podospora anserina, pAL2-1, and homologous plasmids have gone from being considered beneficial longevity plasmids, via neutral genetic elements, toward mutator plasmids causing senescence. The plasmid has an invertron structure, with terminal inverted repeats and encodes a DNA and a RNA polymerase. Here we test whether pAL2-1 homologs cause rapid aging independent of intrinsic and external conditions. We first analyzed a natural population of P. anserina and in 40% of the 112 isolates we detected pAL2-1 homologous plasmids. Though the lifespan varied considerably among the strains, plasmid-infected wild-type strains are on average shorter lived than plasmid-free strains and typically show a reduced lifespan extending effect of calorie restriction (CR). However, interesting exceptions were found, inviting further study. To further investigate the effect of pAL2-1 homologs under various conditions, we constructed and analyzed isogenic lines with and without the plasmid. We found that the presence of pAL2-1 homologs did not significantly affect growth rate as suggested by the population analysis, but reduced lifespan under all conditions. This effect was particularly clear for the lifespan extending conditions tested (CR, low temperature, antibiotics) supporting the idea that pAL2-1 homologs are additional senescence factors independent of the intrinsic senescence determinants.

The primary objective of this study was to determine the possibility of internalization of GFP-expressing Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium (S. Typhimurium) strains MAE 110 (multi-cellular morphology) and 119 (wild type morphology) into lettuce seedlings (Lactuca sativa cv. Tamburo) grown in an inoculated hydroponic and soil system. The second aim was to quantify the level of contamination with the use of a proper surface sterilization method. Silver nitrate was superior in reducing the number of viable bacteria on leave surfaces compared to sodium hypochlorite and ethanol. With the hydroponic system internal colonization of lettuce only occurred at high densities with S. Typhimurium MAE 119. With the soil system E. coli O157:H7, S. Typhimurium 110 and S. Typhimurium 119 were found at considerable densities in sterilized leaf samples (respectively, 3.95, 2.57 and 2.37 log cfu/g on average) with prevalences of 0.29, 0.23 and 0.15, respectively. No statistical differences were observed between the Salmonella strains. A negative correlation was observed between shoot weight and leaf contamination. The observed presence of the pathogens in lettuce, after thorough surface sterilization, demonstrates the possible presence of human pathogens in locations were they are unlikely to be removed by the actions of consumer washing and therefore pose a serious threat when occurring in field situations.

Gene flow within populations can occur by sexual and/or parasexual means. Analyses of experimental and in silico work are presented relevant to possible gene flow within the aspergilli. First, the discovery of mating-type (MAT) genes within certain species of Aspergillus is described. The implications for self-fertility, sexuality in supposedly asexual species and possible uses as phylogenetic markers are discussed. Second, the results of data mining for heterokaryon incompatibility (het) and programmed cell death (PCD) related genes in the genomes of two heterokaryon incompatible isolates of the asexual species Aspergillus niger are reported. Het-genes regulate the formation of anastomoses and heterokaryons, may protect resources and prevent the spread of infectious genetic elements. Depending on the het locus involved, hetero-allelism is not tolerated and fusion of genetically different individuals leads to growth inhibition or cell death. The high natural level of heterokaryon incompatibility in A. niger blocks parasexual analysis of the het-genes involved, but in silico experiments in the sequenced genomes allow us to identify putative het-genes. Homologous sequences to known het- and PCD-genes were compared between different sexual and asexual species including different Aspergillus species, Sordariales and the yeast Saccharomyces cerevisiae. Both het- and PCD-genes were well conserved in A. niger. However some point mutations and other small differences between the het-genes in the two A. niger isolates examined may hint to functions in heterokaryon incompatibility reactions.

Approximately 10% of all examined 668 representatives of black Aspergillus species, independent of worldwide location, were infected with double-stranded RNA (dsRNA) mycoviruses. These isometric viruses (25-40 nm diameter) contained a variety of often multiple segments of different dsRNA sizes ranging from 0.8 to 4.4 kb in size. In one strain the virus shows clear visible effects on its host with non-sporulating sectors. We quantified the fitness costs of these and more 'cryptic' virus infections on mycelial growth rate and spore production, and on competitive ability with respect to other strains under different growth conditions. Mycovirus infection proved detrimental in all these measures. The reduced success in interference competition due to mycovirus infection belies co-evolution of mycovirus and host to a mutually beneficial symbiosis, like in killer virus systems in yeast and smut and agrees more to recent infections. For a stable virus infection frequency in the black Aspergillus population, fitness costs and spontaneous loss should be balanced with new infections. Implications of even small viral fitness effects combined with the observed transmission limits for host and mycovirus are discussed.

Survival of the green fluorescent protein-transformed human pathogens Escherichia coli O157:H7 and Salmonella enterica serovar Typhimurium was studied in a laboratory-simulated lettuce production chain. Dairy cows were fed three different roughage types: high-digestible grass silage plus maize silage (6:4), low-digestible grass silage, and straw. Each was adjusted with supplemental concentrates to high and low crude protein levels. The pathogens were added to manure, which was subsequently mixed (after 56 and 28 days for E. coli O157:H7 and Salmonella serovar Typhimurium, respectively) with two pairs of organically and conventionally managed loamy and sandy soil. After another 14 days, iceberg lettuce seedlings were planted and then checked for pathogens after 21 days of growth. Survival data were fitted to a logistic decline function (exponential for E. coli O157:H7 in soil). Roughage type significantly influenced the rate of decline of E. coli O157:H7 in manure, with the fastest decline in manure from the pure straw diet and the slowest in manure from the diet of grass silage plus maize silage. Roughage type showed no effect on the rate of decline of Salmonella serovar Typhimurium, although decline was significantly faster in the manure derived from straw than in the manure from the diet of grass silage plus maize silage. The pH and fiber content of the manure were significant explanatory factors and were positively correlated with the rate of decline. With E. coli O157:H7 there was a trend of faster decline in organic than in conventional soils. No pathogens were detected in the edible lettuce parts. The results indicate that cattle diet and soil management are important factors with respect to the survival of human pathogens in the environment.

Previously, we showed that bacterial populations oscillate in response to a moving substrate source such as a root tip, resulting in moving wavelike distributions along roots. For this article, we investigated if bacterial communities fluctuate as a whole or if there is a succession in bacterial composition from peak to peak or within peaks. Rhizosphere microbial communities along roots of wheat Triticum aestivum L. were studied in detail (20-25 rhizosphere and bulk soil samples along the total root length) in two related soils by colony enumeration and culture-independent DNA analysis. Similar to our previous findings, the numbers of copiotrophic and oligotrophic bacteria oscillated with significant harmonics along each root, independent of soil moisture or lateral roots. Shifts in amplified eubacterial 16S rDNA fragments from denaturing gradient gel electrophoresis (DGGE) analysis were detected along the roots. The most abundant and intensively amplified fragments fluctuated in phase with colony-forming unit (CFU) oscillations; fewer amplified fragments with less intensive bands fluctuated out of phase or were restricted to certain root zones. The bacterial species richness along the root was negatively correlated with the numbers of oligotrophic bacterial CFUs. Discriminant analyses on DGGE patterns distinguished between soil types, rhizosphere and bulk soil, and waxing and waning phases in the oscillations along roots. Bacterial compositions shifted within oscillations but were repeated from oscillation to oscillation, supporting the idea that the most abundant bacterial taxa were growing and dying over time and consequently in space, whereas other taxa counterfluctuated or hardly responded to the substrate supplied by the passing root tip.

A comparative study of 13 organic and 13 neighboring conventional arable farming systems was conducted in the Netherlands to determine the effect of management practices on chemical and biological soil properties and soil health. Soils were analyzed using a polyphasic approach combining traditional soil analysis, culture-dependent and independent microbiological analyses, a nematode community analysis and an enquiry about different management practices among the farmers. Organic management resulted in significantly lower levels of both nitrate and total soluble nitrogen in the soil, higher numbers of bacteria of different trophic groups, as well as larger species richness in both bacteria and nematode communities and more resilience to a drying-rewetting disturbance in the soil. All factors together indicating a higher level of soil health under organic management.

A set of aspergillus strains from culture collections and wild-type black aspergilli isolated on non-selective media were used to validate the use of media with 20% tannic acid for exclusive and complete selection of the black aspergilli. The 20% tannic acid medium proved useful for both quantitative and qualitative selection of all different black aspergilli, including all recognized species: A. carbonarius, A. japonicus, A. aculeatus, A foetidus, A. heteromorphus, A. niger, A. tubingensis and A. brasiliensis haplotypes. Even higher concentrations of tannic acid can be utilized by the black aspergilli suggesting a very efficient tannic acid-degrading system. Colour mutants show that the characteristic ability to grow on high tannic acid concentrations is not causally linked to the other typical feature of these aspergilli, i.e. the formation of brown-black pigments. Sequence analysis of the A. niger genome using the A. oryzae tannase gene yielded eleven tannase-like genes, far more than in related species. Therefore, a unique ecological niche in the degradation of tannic acid and connected nitrogen release seems to be reserved for these black-spored cosmopolitans.