Influence of arginine on the biocontrol efficiency of Metschnikowia citriensis against Geotrichum citri-aurantii causing sour rot of postharvest citrus fruit.

This study investigated the effect of arginine (Arg) on the antagonistic activity of Metschnikowia citriensis against sour rot caused by Geotrichum citri-aurantii in postharvest citrus, and evaluated the possible mechanism therein. Arg treatment up-regulated the PUL genes expression, and significantly induced the pulcherriminic acid (PA) production of M. citriensis, which related to the capability of iron depletion of M. citriensis. By comparing the biocontrol effects of Arg-treated and untreated yeast cells, it was found that Arg treatment significantly enhanced the biocontrol efficacy of M. citriensis, and 5 mmol L-1 Arg exerted the best effect. Additionally, the biofilm formation ability of M. citriensis was greatly enhanced by Arg, and the higher population density of yeast cells in citrus wounds was also observed in Arg treatment groups stored both at 25 °C and 4 °C. Moreover, Arg was shown to function as a cell protectant to elevate antioxidant enzyme activity [including catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPX)] and intracellular trehalose content to resist oxidative stress damage, that directly helped to enhance colonization ability of yeasts in fruit wounds. These results suggest the application of Arg is a useful approach to improve the biocontrol performance of M. citriensis.

Genome sequencing and transcriptome analysis of Geotrichum citri-aurantii on citrus reveal the potential pathogenic- and guazatine-resistance related genes.

Sour rot, caused by Geotrichum citri-aurantii, is a major postharvest disease of citrus，and it causes serious economic losses. In this study, a high-quality genome sequence of G. citri-aurantii was obtained by Single Molecule Real-Time Sequencing (SMRT). Approximately 5.43 Gb of clean data were obtained and a total of 27.94-Mb genomic sequence was mapped to 10 chromosome groups after high-through chromosome conformation capture (Hi-C) assembly. In addition, three polygalacturonase genes which were related to pathogenicity in G. citri-aurantii genome were discovered. And transcriptome data of guazatine-resistance had been analyzed, the results showed that the guazatine-resistance of G. citri-aurantii was related to two ATP-binding cassette (ABC) transporter family genes, six major facilitator superfamily (MFS) transporter family genes and two multidrug and toxic compound extrusion (MATE) transporter family genes. In summary, our research may provide novel insights into the effective control of this pathogen.

Saprochaete capitata (Geotrichum capitatum), an emerging fungal infection in kidney transplant recipients.

We are reporting the case of an 82-year-old Yemeni patient, renal transplant recipient who was admitted to our institution and who subsequently developed disseminated infection with Saprochaete capitata. This pathogenic fungus is rarely reported in patients with solid organ trans-plants. Saprochaete capitata is an emerging fungal pathogen, ubiquitously spread in the environment. This is the second case to our knowledge of infection with Saprochaete capitata in a renal transplant patient. Our patient was treated for multiple nosocomial infections with prolonged antibiotic courses. He succumbed to the infection with Saprochaete capitate after several weeks spent in the intensive care unit.

Biofilm production by Aureobasidium pullulans improves biocontrol against sour rot in citrus.

The biocontrol efficiency of Aureobasidium pullulans strain ACBL-77 against Geotrichum citri-aurantii, causal agent of sour rot in citrus, and their interactions were evaluated. For this, were evaluated the incorporation of nutrients in optimizing the antagonistic activity of the yeast, the competition for nutrients between microorganisms, the effect of nutrients on yeast cell and biofilm production and their correlation in the biocontrol of disease, the survival of yeast in citrus fruits and the interaction between microorganisms using scanning electron microscopy. Micronutrients (boric acid, cobalt chloride and ammonium molybdate) favoured the antagonistic action of A. pullulans. Ammonium sulfate 1% and sucrose 0.5% favoured the yeast during the competition between the microorganisms. The addition of ammonium sulfate (1%) in the yeast culture stimulated biofilm production and increased the antagonistic activity against the disease, as also allowed the better survival of yeast in wounded sites of citrus fruit. The yeast was found to be able to form biofilms on citrus, deforming the pathogen hyphae. These results showed the importance of the addition of nutrients in A. pullulans based-formulations when aiming for their use on a commercial scale. This is the first report of a positive correlation between the increase in the quantity of biofilm produced by A. pullulans, with increased antagonistic activity.

Biodiversity in targeted metabolomics analysis of filamentous fungal pathogens by 1H NMR-based studies.

The taxonomical classification among fungi kingdom in the last decades was evolved. In this work the targeted metabolomics study based on 1H NMR spectroscopy combined with chemometrics tools was reported to be useful for differentiation of three model of fungal strains, which represent various genus of Ascomycota (Aspergillus pallidofulvus, Fusarium oxysporum, Geotrichum candidum) were selected in order to perform metabolomics studies. Each tested species, revealed specific metabolic profile of primary endo-metabolites. The species of A. pallidofulvus is represented by the highest concentration of glycerol, glucitol and Unk5. While, F. oxysporum species is characterised by increased level of propylene glycol, ethanol, 4-aminobutyrate, succinate, xylose, Unk1 and Unk4. In G. candidum, 3-methyl-2-oxovalerate, glutamate, pyruvate, glutamine and citrate were elevated. Additionally, a detailed analysis of metabolic changes among A. pallidofulvus, F. oxysporum and G. candidum showed that A. pallidofulvus seems to be the most pathogenic fungi. The obtained results demonstrated that targeted metabolomics analysis could be utilized in the future as a supporting taxonomical tool for currently methods.

Geotrichum capitatum septicaemia in a haematological patient after acute myeloid leukaemia relapse: identification using MALDI-TOF mass spectrometry and review of the literature.

Emerging fungal pathogens, such as Geotrichum capitatum, are often associated with poor prognosis and represent a new challenge in modern medicine. Invasive Geotrichum capitatum infection is rare and has been reported exclusively in patients who showed signs of severe immunodeficiency, particularly those affected by haematological malignancies. The optimal therapy against systemic geotricosis has not yet been identified due to limited data about its antifungal susceptibility. The use of several therapeutic strategies and the low number of cases treated does not allow identification of specific therapeutic protocols. Furthermore, in spite of antifungal therapy, mortality rates reach very high levels. We report a case of systemic Geotrichum capitatum infection in a 78-year-old male treated with salvage therapy after acute myeloid leukaemia (AML) relapse. Geotrichum capitatum was isolated from his blood culture and identified by using Vitek 2 and Maldi time-of-flight system (MALDI-TOF). The infection was unsuccessfully treated, despite in vitro susceptibility, with micafungin and liposomal amphotericin B.

[Pulmonary infection by Geotrichum capitatum about a case and review of the literature]. / Infection pulmonaire à Geotrichum capitatum à propos d'un cas et revue de la littérature.

Pulmonary geotrichosis is a rare mycosis caused by an arthrospore filamentous fungi of the genus Geotrichum. It is an opportunistic infection that develops when underlying conditions are present, particularly immunosuppression including neutropenia. Pulmonary mycoses in non-neutropenic patients affect two main populations: the solid organ transplanted patients and patients whose local pulmonary defenses are altered by a chronic underlying lung pathology. We report a case of pulmonary infection Geotrichum capitatum in an old tuberculosis patient.

Geotrichum candidum as etiological agent of horse dermatomycosis.

Fungi of the genus Geotrichum are commonly found in the environment and, in some circumstances, they may cause diseases in humans and animals. Although these fungi have been isolated from skin lesions of some animal species, their pathogenic role in horses remains uncertain. With the aim to investigate the role of Geotrichum candidum as etiological agent of dermatomycoses, a retrospective study of 64 horses presenting skin lesions and suspected to have fungal infections was carried out. For each animal, anamnestic data were recorded and fungal culture were performed using hair. Out of 64 cases, 18 (28.1%) were positive for G. candidum and only two (3.1%) for dermatophytes (i.e., one for Microsporum equinum and the other for Microsporum canis). Alopecia, desquamation, and pruritus localized mainly on head and neck were frequently observed in G. candidum infected animals. Most of G. candidum infections were recorded during spring (44.4%). Out of the 18 animals presenting G. candidum infections, eight were treated using a disinfectant with antifungal properties. After one month of treatment, the clinical lesions were healed and fungal cultures resulted negative. The high prevalence of G. candidum in skin lesions of horses and the clinical recover following antifungal treatment indicated that these yeast-like fungi might play a role as etiological agents of horse cutaneous mycoses.

Breakthrough Saprochaete capitata infections in patients receiving echinocandins: case report and review of the literature.

We report a rare case of a fatal Saprochaete capitata breakthrough infection in a patient with acute myeloid leukemia receiving empirical caspofungin therapy. S. capitata is an uncommon, yet emerging cause of invasive infections, especially in patients with haematological malignancies. Blood cultures from our patient yielded S. capitata which was found to be resistant, in vitro, to caspofungin. We consecutively reviewed all published cases of breakthrough infections caused by S. capitata in patients receiving echinocandins. S. capitata should be considered in those patients who remain febrile or who develop invasive mould infections while under echinocandin therapy.

A new report of pre-harvest ear rot of corn caused by Geotrichum candidum from Iran.

In summer of 2004, samples of husk looseness ear of corn (Zea mays) (cv. 700-Karaj) were collected from corn fields in Ali-Abad (Jiroft region), Kerman province, Southeastern Iran, for diagnosis of an unusual ear decay. A fungus was isolated from the rotting kernels and subsequently identified as Geotrichum candidum. The fungal pathogen was found to be closely related to G. citri-aurantii (citrus race) based on morphological, physiological and pathogenicity properties. The fungal pathogenicity test was demonstrated by fulfilling Koch's postulates. The pathogen caused rot disease on husk looseness corn kernels in soft-dough stage of ripening. The fungus was also pathogenic on ripe lemon and green and ripe tomato fruits. Fungal isolates of corn were compared to isolates from soft-rotten potato tubers. These two groups of isolates were highly similar on the basis of their morphological, biochemical and pathogenicity characteristics. To our knowledge, this is the first known report of corn ear rot caused by G. candidum in the world.

Genetic variability among Blastoschizomyces capitatus isolates from different clinical sources.

Sixteen clinical isolates and nine ATCC reference strains of Blastoschizomyces capitatus were analysed genetically, examined for the cellobiose, arbutin and salicin assimilation and tested for the aspartyl-proteinase secretion. The restriction endonuclease analysis (REA) with HpaII and HinfI enzymes and the electrophoretic karyotype (EK) were investigated. Both the restriction enzymes revealed two groups (I, II) constituted by the same isolates: 17 isolates (68%) in group I and 8 (32%) in group II. The EK analysis revealed sixteen groups. These data prompts for a genetic variability of the isolates of Blastoschizomyces capitatus and their account in two distinct genetic groups as suggested by REA. This grouping was confirmed by examining the utilisation of cellobiose, arbutin and salicin. The tests for secretory aspartyl proteinase (Sap) were positive only for three isolates, suggesting a marginal role of this specific enzyme in pathogenesis for these isolates.

Invasive infections caused by Trichosporon species and Geotrichum capitatum in patients with hematological malignancies: a retrospective multicenter study from Italy and review of the literature.

Trichosporonosis is an uncommon but frequently fatal mycosis in immunocompromised patients. A multicenter retrospective study was conducted to characterize cases of proven or probable invasive trichosporonosis diagnosed over the past 20 years in Italian patients with hematological diseases. Of the 52 cases identified, 17 were classified as Trichosporon sp. infections and 35 were attributed to Geotrichum capitatum. Acute myeloid leukemia accounted for 65.4% of the cases. The incidence rates of Trichosporon sp. and G. capitatum infections in acute leukemia patients were 0.4 and 0.5%, respectively. Overall, 76.9% of cases had positive blood cultures. Pulmonary involvement was documented in 26.9% of cases. Death was reported for 57.1% of G. capitatum infections and for 64.7% of Trichosporon sp. infections. A literature review on trichosporonosis in patients with any underlying disease or condition reveals G. capitatum as a predominantly European pathogen, particularly in certain Mediterranean areas, while Trichosporon sp. infections are seen with similar frequencies on all continents. The majority of published Trichosporon sp. and G. capitatum infections occurred in patients with hematological diseases (62.8 and 91.7%, respectively). Well over half of these were suffering from acute leukemia (68 and 84% of patients with Trichosporon sp. and G. capitatum infections, respectively). Crude mortality rates were 77% for Trichosporon spp. and 55.7% for G. capitatum. The optimal therapy for trichosporonosis has yet to be identified; however, in vitro experiences are providing encouraging evidence of the potential role of the new triazoles, in particular, voriconazole.

CPR1: a gene encoding a putative signal peptidase that functions in pathogenicity of Colletotrichum graminicola to maize.

Colletotrichum graminicola causes anthracnose leaf blight and stalk rot of maize. We used restriction-enzyme mediated insertional (REMI) mutagenesis to identify a gene in this fungus that is required for pathogenicity to both stalks and leaves. The predicted polypeptide encoded by this gene, which we have named CPR1, is similar to a family of proteins that comprise one subunit of the eukaryotic microsomal signal peptidase. The nonpathogenic CPR1 REMI mutant contains a plasmid integration in the 3' untranslated region of the gene, 19 bp downstream from the stop codon. The result is a significant reduction in transcript levels in comparison to the wild type, perhaps as a result of increased transcript instability. We were unable to knock out the CPR1 gene, and it may be essential for viability. Microscopic examination of the REMI mutant on maize leaves revealed that it is fully capable of penetrating and colonizing host cells during the initial, biotrophic phases of the disease interaction but, unlike the wild type, it appears to be unable to switch to a necrotrophic mode of growth. We suggest that the CPR1 REMI mutant may be unable to secrete sufficient quantities of degradative enzymes to support that transition. The CPR1 REMI mutant provides us with a useful tool for future studies of the role of fungal protein transport in this important stalk rot disease of maize.

Isolation and identification of Geotrichum candidum as an etiologic agent of geotrichosis in Bulgaria.

Geotrichosis affects mainly patients with systemic diseases like diabetes mellitus, leukoses, neoplasms etc. Clinically, it is similar to candidiasis and may occur as an oral, vaginal, skin, or systemic infection. Clinical specimens (98 sputa and 67 oral smears) were collected and studied using microscopic examination of Gram stained preparations and culture sampling between 1995 and 1997. Geotrichum candidum was isolated as a single pathogen in 8 sputum and 7 oral smear samples. Ten-day antifungal treatment with Nizoral was applied and resulted in relatively quick clinical improvement. The presented cases are the first cases of pulmonary and oral infections reported in our home practice in which Geotrichum candidum species was identified as a pathogen. The identification of Geotrichum candidum using combination of colonial and microscopic morphologic features increase the possibilities for diagnostic decision.

Pathogenicity of yeasts and algae isolated from bovine mastitis secretions in a murine model.

The pathogenicity of strains of yeasts and algae isolated from bovine mastitis secretions was evaluated in immunosuppressed mice. Strains of Candida tropicalis (n = 3) were the most pathogenic, but all strains of Geotrichum capitatum (n = 5) and the colourless alga Prototheca zopfii (n = 5) were also lethal to mice at the highest dose of 1 x 10(7) CFU per mouse. Reisolation of the inoculated micro-organisms and the occurrence of histopathological lesions within organs of mice challenged with 1 x 10(3) to 1 x 10(7) CFU per animal revealed strains of C. krusei (n = 17), C. kefyr (n = 6) and C. rugosa (n = 6) to have a moderate pathogenicity, whereas strains of C. valida (n = 1) and C. catenulata (n = 2) were weakly pathogenic and non-pathogenic respectively.