Enumeration of bacterial and yeast colonists of apple fruits and identification of epiphytic yeasts on pear fruits in the Pacific Northwest United States

Yeasts associated with mines on tree leaves in the urban areas

Mines on tree leaves and undamaged leaves were studied to investigate yeast complexes in urban areas (Aesculus hippocastanum, miner - Cameraria ohridella; Betula verrucosa, miner - Caloptilia betulicola; Populus nigra, miner - Lithocolletis populifoliella; Quercus robur, miner - Tischeria companella; Salix caprea, miner - Trachys minuta; Syringa vulgaris, miner - Caloptilia syringella; Tilia cordata, miner - Phyllonorycter issikii; Ulmus laevis, miner - Carpatolechia fugitivella). The abundance and taxonomic structure of yeasts were studied using a surface plating method on solid media (GPY agar). Identification of yeast species was based on the ITS rDNA nucleotide sequence. The average abundance of yeasts during the first stages of mine formation in the internal tissues of leaves was 103 cfu/g. After 23-25 days, during the last stage of larval metamorphosis before mine destruction, the abundance of yeasts in the mines increased by two orders of magnitude to 105 cfu/g. No significant differences were observed in the abundance of yeasts in mines formed by different insects on different trees. A total of twelve yeast species were observed. The fast-growing ascomycetous yeasts Hanseniaspora uvarum and H. occidentalis dominated the mines. On undamaged leaves, the basidiomycetous yeasts Papiliotrema flavescens and Rhodotorula mucilaginosa, typical in the phyllosphere, dominated. The opportunistic yeast Candida parapsilosis was detected in the yeast complexes of all mines examined and was not found on the surface of leaves. Comparison of the relative abundance of yeast species between the studied mines and undamaged leaves using principal component analysis showed that all studied yeast communities in the mines were significantly different from the epiphytic yeast complexes of the undamaged leaves. Thus, miners in urban environments provoke the formation of short-lived endophytic yeast complexes with high abundance of Hanseniaspora. For leaf miners, the yeasts serve primarily as a food source for insect larvae rich in vitamins and amino acids. The adult leaf miners, in turn, contribute to the reproduction of the yeasts and create favorable conditions for their development.

Pseudozyma aphidis Suppresses Microbe-Associated Molecular Pattern (MAMP)-Triggered Callose Deposition and Can Penetrate Leaf Tissue

Beneficial microorganisms need to overcome the plant defense system to establish on or within plant tissues. Like pathogens, beneficial microbes can manipulate a plant's immunity pathways, first by suppressing and hiding to establish on the host and then by inducing resistance to protect the plant. In the current study, we demonstrated that although Pseudozyma aphidis can activate microbe-associated molecular pattern (MAMP)-associated genes, it does not activate MAMP-triggered callose deposition and can, moreover, suppress such deposition triggered by Flg22 or chitin. While MAMP-associated gene activation by P. aphidis was not dependent on salicylic acid, jasmonic acid, or ethylene signaling, suppression of MAMP-triggered callose deposition required the salicylic acid and jasmonic acid signaling factors JAR1-1 and E3 ubiquitin ligase COI1 yet did not rely on EIN2, NPR1, or the transcription factor JIN1/MYC2. We also demonstrated the ability of P. aphidis, known to be an epiphytic yeast-like organism, to penetrate the stomata and establish within plant tissues, as do endophytes. These results thus demonstrate the potential of P. aphidis to suppress MAMP-elicited defenses in order to establish on and within host plant tissues. IMPORTANCE Our study demonstrates the ability of P. aphidis to penetrate into plant tissues, where it avoids and overcomes plant defense systems in order to establish and subsequently protect the plant.

Search for Cryptococcus neoformans/gattii Complexes and Related Genera (Filobasidium, Holtermanniella, Naganishia, Papiliotrema, Solicoccozyma, Vishniacozyma) spp. Biotope: Two Years Surveillance of Wild Avian Fauna in Southern France

Fungi belonging to the Cryptococcus genus and related genera (Filobasidium, Holtermanniella, Naganishia, Papiliotrema, Solicoccozyma, Vishniacozyma) are encapsulated yeasts found in either the environment or animal sources. However, the precise biotopes of most species remain poorly defined. To assess whether wild birds from southern France can carry or spread the most pathogenic species (i.e., species belonging to the C. neoformans and C. gattii complexes), as well as lesser-studied species (non-neoformans/gattii Cryptococcus and former Cryptococcus spp.), 669 birds belonging to 89 species received for care over a two-year period at the Centre de Protection de la Faune Sauvage of Villeveyrac (Bird Protection League nongovernmental organization (NGO) care center) were sampled. Samples were cultured, and Cryptococcus and former Cryptococcus yeasts were identified by PCR sequencing. The purpose was to evaluate whether there was any health risk to local populations or care personnel in aviaries and gather new data on the ecological niches of lesser-known species. One hundred and seven birds (16%) were found to be positive for at least one Cryptococcus or former Cryptococcus species. No yeasts belonging to the highly pathogenic C. neoformans or C. gattii complexes were isolated. However, diversity was notable, with 20 different Cryptococcus or former Cryptococcus species identified. Furthermore, most bird–yeast species associations found in this study have never been described before.

Variations in the Community Structure of Fungal Microbiota Associated with Apple Fruit Shaped by Fruit Bagging-Based Practice

The various fungal communities that adhere to apple fruit are influenced by agricultural practices. However, the effects of fruit bagging-based management practice on the fungal microbiota are still unknown, and little is known about the fungal communities of bagged apple fruit. We conducted a study using apple fruit grown in a conventionally managed orchard where pesticide use is an indispensable practice. Fungal communities were collected from the calyx-end and peel tissues of bagged and unbagged fruit and characterized using barcode-type next-generation sequencing. Fruit bagging had a stronger effect on fungal richness, abundance, and diversity of the fungal microbiota in comparison to non-bagging. In addition, bagging also impacted the compositional variation of the fungal communities inhabiting each fruit part. We observed that fruit bagging had a tendency to maintain ecological equilibrium since Ascomycota and Basidiomycota were more distributed in bagged fruit than in unbagged fruit. These fungal communities consist of beneficial fungi rather than potentially harmful fungi. Approximately 50 dominant taxa were detected in bagged fruit, for example, beneficial genera such as Articulospora, Bullera, Cryptococcus, Dioszegia, Erythrobasidium, and Sporobolomyces, as well as pathogenic genera such as Aureobasidium and Taphrina. These results suggested that fruit bagging could significantly increase fungal richness and promote healthy fungal communities, especially the harmless fungal communities, which might be helpful for protecting fruit from the effects of pathogens. This study provides a foundation for understanding the impacts of bagging-based practice on the associated fungal microbiota.

Yeasts Associated with Various Amazonian Native Fruits

Yeasts, commonly present on the surface of fruits, are of industrial interest for the production of enzymes, flavorings, and bioactive compounds, and have many other scientific uses. The Amazonian rainforest may be a good source of new species or strains of yeasts, but their presence on Amazonian fruits is unknown. The aim of this study was to identify and characterize yeasts isolated from Amazonian native fruits using molecular and phenotypic methods. In total, 81 yeast isolates were obtained from 10 fruits species. Rep-PCR showed 29 strain profiles. Using a combination of restriction-fragment length polymorphism (RFLP) of the 5.8S-ITS region and D1/D2 sequencing of the 26S rRNA gene, 16 species were identified belonging to genera Candida, Debaryomyces, Hanseniaspora, Kodamaea, Martiniozyma, and Meyerozyma. The most dominant species were Candida tropicalis, Debaryomyces hansenii, Hanseniaspora opuntiae, and Hanseniaspora thailandica. H. opuntiae and H. thailandica showed the highest number of the strain profiles. Phenotypic profiles were variable between species, and even among strains. Screening for hydrolases showed lipolytic activity in only one isolate, while proteolytic, cellulolytic and amylolytic capabilities were not detected. Yeast presence among fruits varied, with cidra (Citrus medica) and ungurahui (Oenocarpus bataua) having the highest number of species associated. This investigation broadens the understanding and possible biotechnological uses of yeast strains obtained from Amazonian native fruits.

Yeasts, commonly present on the surface of fruits, are of industrial interest for the production of enzymes, flavorings, and bioactive compounds, and have many other scientific uses. The Amazonian rainforest may be a good source of new species or strains of yeasts, but their presence on Amazonian fruits is unknown. The aim of this study was to identify and characterize yeasts isolated from Amazonian native fruits using molecular and phenotypic methods. In total, 81 yeast isolates were obtained from 10 fruits species. Rep-PCR showed 29 strain profiles. Using a combination of restriction-fragment length polymorphism (RFLP) of the 5.8S-ITS region and D1/D2 sequencing of the 26S rRNA gene, 16 species were identified belonging to genera Candida, Debaryomyces, Hanseniaspora, Kodamaea, Martiniozyma, and Meyerozyma. The most dominant species were Candida tropicalis, Debaryomyces hansenii, Hanseniaspora opuntiae, and Hanseniaspora thailandica. H. opuntiae and H. thailandica showed the highest number of the strain profiles. Phenotypic profiles were variable between species, and even among strains. Screening for hydrolases showed lipolytic activity in only one isolate, while proteolytic, cellulolytic and amylolytic capabilities were not detected. Yeast presence among fruits varied, with cidra (Citrus medica) and ungurahui (Oenocarpus bataua) having the highest number of species associated. This investigation broadens the understanding and possible biotechnological uses of yeast strains obtained from Amazonian native fruits.

Metagenomics analysis of fungal communities associated with postharvest diseases in pear fruits under the effect of management practices

An amplicon metagenomic approach based on the ITS1 region of fungal rDNA was employed to identify the composition of fungal communities associated with diseases of pear fruits during postharvest storage. The sampled fruits were harvested at an orchard using routine management practices involving treatments with various chemical fungicides and were transferred to a storage packinghouse. Effective tags of reading sequences clustered into 53 OTUs whereas Ascomycota was the dominant phylum (83.4%) followed by Basidiomycota (15.8%). Our results revealed that four genera, Penicillium, Rhodotorula, Alternaria and Cladosporium were the most abundant representing 59-95% of the relative abundance per sample. The interruption of chemical treatments during the last month before harvest altered the structure of the fungal community of fruits among untreated and treated samples, mainly in cases of relative abundance of Penicillium and Rhodotorula genera. We hypothesize that various antagonistic interactions might occur on fruit surfaces among the detected fungal genera whose relative abundances were affected by fungicide treatments. Interestingly, some common pre- and postharvest pear fungal pathogens were either less present (such as Moniliana), or undetected (such as Aspergillus, Venturia and Septoria) in untreated and treated samples.

Effects of Pre-Processing Short-Term Hot-Water Treatments on Quality and Shelf Life of Fresh-Cut Apple Slices

Processing, especially cutting, reduces the shelf life of fruits. In practice, fresh-cut fruit salads are, therefore, often sold immersed in sugar syrups to increase shelf life. Pre-processing short-term hot-water treatments (sHWT) may further extend the shelf life of fresh-cuts by effectively reducing microbial contaminations before cutting. In this study, fresh-cut ‘Braeburn’ apples, a major component of fruit salads, were short-term (30 s) hot water-treated (55 °C or 65 °C), partially treated with a commercial anti-browning solution (ascorbic/citric acid) after cutting and, thereafter, stored immersed in sugar syrup. To, for the first time, comprehensively and comparatively evaluate the currently unexplored positive or negative effects of these treatments on fruit quality and shelf life, relevant parameters were analyzed at defined intervals during storage at 4 °C for up to 13 days. Compared to acid pre-treated controls, sHWT significantly reduced the microbial loads of apple slices but did not affect their quality during the 5 day-standard shelf life period of fresh-cuts. Yeasts were most critical for shelf life of fresh-cut apples immersed in sugar syrup. The combination of sHWT and post-processing acid treatment did not further improve quality or extend shelf life. Although sHWT could not extend potential maximum shelf life beyond 10 d, results highlighted the potentials of this technique to replace pre-processing chemical treatments and, thus, to save valuable resources.

Survey of conspecific herbivore-induced volatiles from apple as possible attractants for Pandemis pyrusana (Lepidoptera: Tortricidae)

BACKGROUND

Studies were conducted to identify volatiles released by apple foliage untreated or sprayed with a yeast and from untreated and sprayed foliage with actively feeding larvae of Pandemis pyrusana Kearfott. Field studies then evaluated various combinations of these volatiles when paired with acetic acid as possible adult attractants.

RESULTS

The most abundant volatiles released following herbivore feeding were four green leaf volatiles (GLVs) and acetic acid. Nineteen volatiles were found to be released in significantly higher amounts from foliage with herbivore damage than from intact leaves. The combination of yeast followed by herbivore injury increased the levels of methyl salicylate and phenylacetonitrile compared with herbivory alone. Levels of acetic acid released were not significantly different among the four treatments. Only phenylacetonitrile and 2-phenylethanol with acetic acid caught similar and significantly more total and female moths than acetic acid alone. Moth catches with 12 other volatiles plus acetic acid were not significantly higher than with acetic acid alone, and were lower than with acetic acid and 2-phenylethanol.

CONCLUSION

These data show that herbivore injury does not create a unique chemical signal for adults to locate oviposition or rendezvous sites. Instead, moths may cue to the aromatic-acetic acid combination as a nutritional cue to locate sugary resources. © 2017 Society of Chemical Industry.

Characterization of microbial population of breba and main crops (Ficus carica) during cold storage: Influence of passive modified atmospheres (MAP) and antimicrobial extract application

The purpose of this work was to study the changes of bacterial and fungal population of breba fruits such as 'Banane' and 'San Antonio' as well as 'Cuello Dama Negro', 'Cuello Dama Blanco' and 'San Antonio' fig cultivars stored in passive modified atmospheres (MAP) by the use of three different microperforated films (M10 with 16 holes; M30 with five holes and M50 with three holes). Moreover the effects of the application of aqueous soy polyphenolic antimicrobial extract (APE), alone or combined with MAP, were also studied for 'Cuello Dama Negro' and 'Cuello Dama Blanco' fig cultivars. Bacteria and fungi isolates were identified by PCR-RFLP of 16S rRNA and ITS regions, respectively, and subsequently sequence of the different patterns obtained. The results indicated that Pseudomonas gessardii, Pantoea agglomerans and Enterobacter asburiae were the main species of bacteria found in all the treatments studied. The fungal species identified were Aureobasidium pulullans, Cladosporium cladosporioides and Alternaria alternata, which were found in a lower percentage in fruit stored in MAP and fruits treated with antimicrobial extracts, as this treatments allowed to reduce the microbial growth of moulds and yeasts. Thus, the application of treatments such as M30, M50 or the combination of MAP with antimicrobial extract was highly effective to control fruit spoilage in fig and breba crops.

A Case of Disseminated Infection with Skin Manifestation due to Non-neoformans and Non-gattii Cryptococcus in a Patient with Refractory Acute Myeloid Leukemia

Cryptococcus spp. other than Cryptococcus neoformans or Cryptococcus gattii were previously considered saprophytes and thought to be non-pathogenic to humans. However, opportunistic infections associated with non-neoformans and non-gattii species, such as Cryptococcus laurentii and Cryptococcus albidus, have increased over the past four decades. We experienced a case of cryptococcosis caused by non-neoformans and non-gattii spp. in a 47-year-old female with refractory acute myeloid leukemia after allogeneic hematopoietic stem cell transplantation. The patient underwent salvage chemotherapy with fluconazole prophylaxis and subsequently developed neutropenic fever with multiple erythematous umbilicated papules. A skin biopsy revealed fungal hyphae and repetitive blood cultures showed yeast microorganisms that were identified later as C. laurentii by Vitek-II^®. Skin lesions and fever began to improve with conventional amphotericin B therapy. The treatment regimen was continued for 21 days until the disseminated cryptococcosis was completely controlled.

Identification and characterization of epiphytic yeasts on apples in China

The first report regarding yeast diversity on apples from the two largest producing areas in China.

Pseudozyma aphidis Induces Salicylic-Acid-Independent Resistance to Clavibacter michiganensis in Tomato Plants

The ability of plant pathogens to rapidly develop resistance to commonly used pesticides challenges efforts to maximize crop production. Fungal biocontrol agents have become an important alternative to chemical fungicides as a result of environmental concerns regarding conventional pesticides, including resistance issues. The complex mode of action of biocontrol agents reduces the likelihood that pathogens will develop resistance to them. We recently isolated a unique, biologically active isolate of the epiphytic fungus Pseudozyma aphidis. We show that the extracellular metabolites secreted by our P. aphidis isolate can inhibit Xanthomonas campestris pv. vesicatoria, X. campestris pv. campestris, Pseudomonas syringae pv. tomato, Erwinia amylovora, Clavibacter michiganensis, and Agrobacterium tumefaciens in vitro. Moreover, application of Pseudozyma aphidis spores on tomato plants in the greenhouse significantly reduced (by 60%) the incidence of bacterial wilt and canker disease caused by C. michiganensis subsp. michiganensis on those plants as well as disease severity by 35%. Furthermore, infected plants treated with P. aphidis were 25% taller than control infected plants. We found that P. aphidis activates PR1a-and other pathogenesis-related genes in tomato plants-and can trigger an induced-resistance response against C. michiganensis that proceeds in a salicylic-acid-independent manner, as shown using NahG-transgenic tomato plants.

Microbes Associated with Freshly Prepared Juices of Citrus and Carrots

Fruit juices are popular drinks as they contain antioxidants, vitamins, and minerals that are essential for human being and play important role in the prevention of heart diseases, cancer, and diabetes. They contain essential nutrients which support the growth of acid tolerant bacteria, yeasts, and moulds. In the present study, we have conducted a microbiological examination of freshly prepared juices (sweet lime, orange, and carrot) by serial dilution agar plate technique. A total of 30 juice samples were examined for their microbiological quality. Twenty-five microbial species including 9 bacterial isolates, 5 yeast isolates, and 11 mould isolates were isolated from juices. Yeasts and moulds were the main cause of spoilage of juices. Aspergillus flavus and Rhodotorula mucilaginosa were observed in the maximum number of juice samples. Among bacteria Bacillus cereus and Serratia were dominant. Escherichia coli and Staphylococcus aureus were detected in few samples. Candida sp., Curvularia, Colletotrichum, and Acetobacter were observed only in citrus juice samples. Alternaria, Aspergillus terreus, A. niger, Cladosporium, and Fusarium were also observed in tested juice samples. Some of the microorganisms detected in these juice samples can cause disease in human beings, so there is need for some guidelines that can improve the quality of fruit juices.

Yeasts associated with plums and their potential for controlling brown rot after harvest

Bacterial and yeast antagonists isolated from fruit surfaces have been effective in controlling various post-harvest diseases, and several microbial antagonists have been developed into commercial products. Our knowledge of the fruit microbial community, with the exception of grapes, apples and some citrus fruit, is rudimentary and the potential of the resident yeasts for biocontrol remains largely unknown. We determined the occurrence of yeasts on plum surfaces during fruit development from the pre-hardening stage until harvest for 2 years. A total of 16 species from 13 genera were isolated. Species from three genera, basidiomycetes Rhodotorula (29.5%) and Sporidiobolus (24.7%) and the dimorphic ascomycete genus Aureobasidium (24.7%), constituted 78.7% of all isolations and were recovered throughout fruit development, while Cryptococcus spp. constituted only 6.2% of the total plum isolates. The yeast community in the final sampling was significantly different from the first three samplings, reflecting a rapidly changing fruit habitat during the maturation of fruit. For example, Hanseniaspora, Pichia, Zygosaccharomyces and Wickerhamomyces occurred only on the most mature fruit. Screening of the yeasts for antagonistic activity against Monilinia fructicola, a fungus that causes brown rot, revealed a range of biocontrol activities. Several isolates provided complete control of the decay on plums, challenged with a pathogen suspension of 10(3) conidia/ml and > 90% of control on fruit inoculated with the pathogen at a concentration 10 times higher. Some of the best antagonists included A. pullulans and R. phylloplana. Populations of both of these antagonists increased rapidly by several orders of magnitude in wounds of plums incubated at 24ºC and 4ºC. Our results indicate that plum surfaces harbour several yeast species, with excellent potential for use in biological control of brown rot of stone fruits.

Development of PMA real-time PCR method to quantify viable cells of Pantoea agglomerans CPA-2, an antagonist to control the major postharvest diseases on oranges

Dilution plating is the quantification method commonly used to estimate the population level of postharvest biocontrol agents, but this method does not permit a distinction among introduced and indigenous strains. Recently, molecular techniques based on DNA amplification such as quantitative real-time PCR (qPCR) have been successfully applied for their high strain-specific detection level. However, the ability of qPCR to distinguish viable and nonviable cells is limited. A promising strategy to avoid this issue relies on the use of nucleic acid intercalating dyes, such as propidium monoazide (PMA), as a sample pretreatment prior to the qPCR. The objective of this study was to optimize a protocol based on PMA pre-treatment samples combined with qPCR to distinguish and quantify viable cells of the biocontrol agent P. agglomerans CPA-2 applied as a postharvest treatment on orange. The efficiency of PMA-qPCR method under the established conditions (30μM PMA for 20min of incubation followed by 30min of LED light exposure) was evaluated on an orange matrix. Results showed no difference in CFU or cells counts of viable cells between PMA-qPCR and dilution plating. Samples of orange matrix inoculated with a mixture of viable/dead cells showed 5.59log10 CFU/ml by dilution plating, 8.25log10 cells/ml by qPCR, and 5.93log10 cells/ml by PMA-qPCR. Furthermore, samples inoculated with heat-killed cells were not detected by dilution plating and PMA-qPCR, while by qPCR was of 8.16log10 cells/ml. The difference in quantification cycles (Cq) among qPCR and PMA-qPCR was approximately 16cycles, which means a reduction of 65,536 fold of the dead cells detected. In conclusion, PMA-qPCR method is a suitable tool for quantify viable CPA-2 cells, which could be useful to estimate the ability of this antagonist to colonize the orange surface.

Trichotillomania in a young male complicated by tinea capitis associated with Cryptococcus laurentii and Candida parapsilosis

This is the first case report of tinea capitis associated with Cryptococcus laurentii as well as Candida parapsilosis in an eleven year old male which responded to treatments with griseofulvin, lamisil, as well as fluconazole only to show recurrent alopecia from an underlying problem of trichotillomania. When confronted with the biopsy diagnosis of trichotillomania, the family admitted knowledge of the hair pulling disorder for at least five years. It took three providers to finally solve the question of the recalcitrant alopecia.

Yeasts and yeast-like organisms associated with fruits and blossoms of different fruit trees

Yeasts are common inhabitants of the phyllosphere, but our knowledge of their diversity in various plant organs is still limited. This study focused on the diversity of yeasts and yeast-like organisms associated with matured fruits and fully open blossoms of apple, plum, and pear trees, during 2 consecutive years at 3 localities in southwest Slovakia. The occurrence of yeasts and yeast-like organisms in fruit samples was 2½ times higher and the yeast community more diverse than that in blossom samples. Only 2 species (Aureobasidium pullulans and Metschnikowia pulcherrima) occurred regularly in the blossom samples, whereas Galactomyces candidus, Hanseniaspora guilliermondii, Hanseniaspora uvarum, M. pulcherrima, Pichia kluyveri, Pichia kudriavzevii, and Saccharomyces cerevisiae were the most frequently isolated species from the fruit samples. The ratio of the number of samples where only individual species were present to the number of samples where 2 or more species were found (consortium) was counted. The occurrence of individual species in comparison with consortia was much higher in blossom samples than in fruit samples. In the latter, consortia predominated. Aureobasidium pullulans, M. pulcherrima, and S. cerevisiae, isolated from both the fruits and blossoms, can be considered as resident yeast species of various fruit tree species cultivated in southwest Slovakia localities.

Antifungal activity of Wickerhamomyces anomalus and Lactobacillus plantarum during sourdough fermentation: identification of novel compounds and long-term effect during storage of wheat bread

This study aimed at investigating the antifungal activity of Wickerhamomyces anomalus and sourdough lactic acid bacteria to extend the shelf life of wheat flour bread. The antifungal activity was assayed by agar diffusion, growth rate inhibition, and conidial germination assays, using Penicillium roqueforti DPPMAF1 as the indicator fungus. Sourdough fermented by Lactobacillus plantarum 1A7 (S1A7) and dough fermented by W. anomalus LCF1695 (D1695) were selected and characterized. The water/salt-soluble extract of S1A7 was partially purified, and several novel antifungal peptides, encrypted into sequences of Oryza sativa proteins, were identified. The water/salt-soluble extract of D1695 contained ethanol and, especially, ethyl acetate as inhibitory compounds. As shown by growth inhibition assays, both water/salt-soluble extracts had a large inhibitory spectrum, with some differences, toward the most common fungi isolated from bakeries. Bread making at a pilot plant was carried out with S1A7, D1695, or a sourdough started with a combination of both strains (S1A7-1695). Slices of the bread manufactured with S1A7-1695 did not show contamination by fungi until 28 days of storage in polyethylene bags at room temperature, a level of protection comparable to that afforded by 0.3% (wt/wt) calcium propionate. The effect of sourdough fermentation with W. anomalus LCF1695 was also assessed based on rheology and sensory properties.

Culturable bacterial microflora associated with nectarine fruit and their potential for control of brown rot

Microflora of fruit surfaces have been the best source of antagonists against fungi causing postharvest decay of fruit. However, there is little information on microflora colonizing surfaces of fruits other than grape, apple, and citrus. We characterized bacterial microflora on nectarine fruit surfaces from the early stage of development until harvest. Identification of bacterial strains was made using MIDI (fatty acid methyl ester analysis) and Biolog systems. Biolog identified 35% and MIDI 53% of the strains. Thus results from MIDI were used to determine the frequency of occurrence of genera and species. The most frequently occurring genera were Curtobacterium (21.31%), followed by Pseudomonas (19.99%), Microbacterium (13.57%), Clavibacter (9.69%), Pantoea (6.59%), and Enterobacter (4.26%). The frequency of isolations of some bacteria - for example, the major pseudomonads (Pseudomonas syringae, Pseudomonas putida, and Pseudomonas savastanoi) or Pantoea agglomerans - tended to decline as fruit developed. As Pseudomonas declined, Curtobacterium became more dominant. Time of isolation was a significant factor in the frequency of occurrence of different bacteria, indicating succession of the genera. Throughput screening of the bacterial strains against Monilinia fructicola on nectarine fruit resulted in the detection of strains able to control brown rot. The 10 best-performing antagonistic strains were subjected to secondary screening. Four strains reduced decay severity by more than 50% (51.7%-91.4% reduction) at the high pathogen inoculum concentration of 105 conidia/mL.

Fungaemia due to Cryptococcus laurentii as a complication of immunosuppressive therapy--a case report

Recently, infections caused by cryptococci non-neoformans have been increasingly recognized. Cryptococcus laurentii was previously considered saprophyte and thought to be non-pathogenic to humans. However, in favorable circumstances like diminished immunity, it seems to be an important pathogen. We present a case of fungaemia caused by Cryptococcus laurentii in a young man with membranoproliferative glomerulonephritis on aggressive immunosuppressive therapy. We also considered a tick-borne infection because of the endemic area of ticks' occurrence. Most cases of fungaemia caused by Cryptococcus laurentii were successfully treated with fluconazole. We still observed septic fever and positive microbiological blood tests after 3 weeks of treatment with fluconazole in our patient. Therefore, among the others, a computer tomography of abdomen was done, which revealed an inflammatory (presumably mycotic) focus near right lobe of the liver. Accordingly, we started treatment with itraconazole. Controlled microbiological blood tests after 5 weeks of itraconazole therapy were negative. Until now, only one case of fungaemia caused by Cryptococcus laurentii with use of itraconazole was reported. Such an unusual fungal infection needs guidelines dealing with earlier diagnosis, treatment and prophylaxis to protect immunocompromised hosts.

Culturable fungi of stored 'golden delicious' apple fruits: a one-season comparison study of organic and integrated production systems in Switzerland

The effects of organic and integrated production systems on the culturable fungal microflora of stored apple fruits from five matched pairs of certified organic and integrated 'Golden Delicious' farms were studied at five representative production sites in Switzerland. Isolated fungi were identified morphologically. Colonization frequency (percentage of apples colonized), abundance (colony numbers), and diversity (taxon richness) were assessed for each orchard. The standard quality of the stored fruits was comparable for both organic and integrated apples and complied with national food hygiene standards. Yeasts (six taxa) and the yeast-like fungus Aureobasidium pullulans were the dominant epiphytes, filamentous fungi (21 taxa) the dominant endophytes. The most common fungi occurred at all sites and belonged to the "white" and "pink" yeasts, yeast-like A. pullulans, filamentous fungi Cladosporium spp., Alternaria spp., and sterile filamentous fungi. Canonical correspondence analysis of the total fungal community revealed a clear differentiation among production systems and sites. Compared to integrated apples, organic apples had significantly higher frequencies of filamentous fungi, abundance of total fungi, and taxon diversity. The effects of the production system on the fungal microflora are most likely due to the different plant protection strategies. The incidence of potential mycotoxin producers such as Penicillium and Alternaria species was not different between production systems. We suggest that higher fungal diversity may generally be associated with organic production and may increase the level of beneficial and antagonistically acting species known for their potential to suppress apple pathogens, which may be an advantage to organic apples, e.g., in respect to natural disease control.

Yeasts and lactic acid bacteria microbiota from masau (Ziziphus mauritiana) fruits and their fermented fruit pulp in Zimbabwe

Masau are Zimbabwean wild fruits, which are usually eaten raw and/ or processed into products such as porridge, traditional cakes, mahewu and jam. Yeasts, yeast-like fungi, and lactic acid bacteria present on the unripe, ripe and dried fruits, and in the fermented masau fruits collected from Muzarabani district in Zimbabwe were isolated and identified using physiological and molecular methods. The predominant species were identified as Saccharomyces cerevisiae, Issatchenkia orientalis, Pichia fabianii and Aureobasidium pullulans. A. pullulans was the dominant species on the unripe fruits but was not isolated from the fermented fruit pulp. S. cerevisiae and I. orientalis were predominant in the fermented fruit pulp but were not detected in the unripe fruits. S. cerevisiae, I. orientalis, P. fabianii and S. fibuligera are fermentative yeasts and these might be used in the future development of starter cultures to produce better quality fermented products from masau fruit. Lactic acid bacteria were preliminary identified and the predominant strains found were Lactobacillus agilis and L. plantarum. Other species identified included L. bifermentans, L. minor, L. divergens, L. confusus, L. hilgardii, L. fructosus, L. fermentum and Streptococcus spp. Some of the strains of LAB could also potentially be used in a mixed-starter culture with yeasts and might contribute positively in the production of fermented masau fruit products.

Pneumonia and pleural effusion due to Cryptococcus laurentii in a clinically proven case of AIDS

Non-neoformans cryptococci were previously considered to be saprophytes and nonpathogenic to humans. Cryptococcus laurentii is frequently used as a biological means to control fruit rot. Interestingly, C laurentii has recently been reported to be a rare cause of infection in humans. The authors report a case of pulmonary cryptococcosis caused by C laurentii in a diabetic AIDS patient who was on antituberculosis and antiretroviral treatments. The sputum smear revealed capsulated yeast cells that were identified as C laurentii. Repeated pleural fluid culture revealed growth of C laurentii. Both respiratory samples were negative for acid-fast bacilli. Moraxella catarrhalis and Klebsiella pneumoniae were also found in the sputum, but not in the pleural fluid. The patient had a good response to oral fluconazole therapy at 600 mg/day for five weeks and was then discharged. The present article is the first to report on the rare pulmonary involvement of C laurentii in the Indian HIV population. These unusual forms of cryptococci create a diagnostic predicament in the rapid diagnosis of pulmonary cryptococcosis. A high degree of suspicion and improvement of techniques for culture and identification will contribute to the early diagnosis and treatment of unusual fungal infections.

Emergence of amphotericin B-resistant Cryptococcus laurentii meningoencephalitis shortly after treatment for Cryptococcus neoformans meningitis in a patient with AIDS

A unique occurrence of two subsequent episodes of HIV-associated Cryptococcus neoformans followed by C. laurentii meningoencephalitis (successfully cured with fluconazole after demonstrated amphotericin B resistance) is presented and discussed. The available literature reported only two cases of HIV-associated C. laurentii infection to date, while a concurrent infection by C. neoformans and C. laurentii has been reported only once in a patient without HIV disease. The absence of prior descriptions of documented central nervous system infection by C. laurentii in non-HIV-infected patients is emphasized as well as the unpredictable in vitro and in vivo antifungal susceptibility of this non-neoformans Cryptococcus spp., and its apparent prevalence in hospitalized patients who received prior antifungal treatments. All epidemiologic, diagnostic, clinical, and therapeutic implications are discussed on the basis of the evolving characteristics of opportunism in the era of highly active antiretroviral therapy (HAART).

Effects of Sequential Calcium Chloride, Ziram, and Yeast Orchard Sprays on Postharvest Decay of Pear

The most effective nutritional, fungicidal, and biological control treatments previously evaluated for control of postharvest decay in pear were evaluated for 3 years as factorial treatments to determine the best combinations for an integrated program. Calcium chloride sprays during the growing season reduced incidence of side rot in each year and of blue mold in 1 year, while ziram was effective against side rot in 1 year and blue mold in 2 years. Ziram, but not calcium chloride, provided control of gray mold and bull's-eye rot. Application of the yeast Cryptococcus infirmominiatus to pear fruit 1 week before harvest at a concentration of 1.0 to 1.5 × 10⁸ CFU/ml resulted in establishment of large populations of yeast on fruit surfaces, but did not reduce postharvest fungal decay incidence in 3 years of testing. In 1 year, ziram sprays applied 2 weeks before harvest significantly reduced yeast populations on fruit subsequently treated with C. infirmo-miniatus. Sequential treatments with calcium chloride and ziram are indicated in an integrated program to take advantage of their differential effectiveness to broaden the range of control of pear postharvest decay pathogens.

Infections due to non-neoformans cryptococcal species

The incidence of infections due to non-neoformans cryptococcal species is increasing. Risk factors associated with infections due to these organisms include immunosuppression and clinical syndromes are similar to those encountered with Cryptococcus neoformans. Therapy with antifungal agents is often successful.

Edible dates (Phoenix dactylifera), a potential source of Cladosporium cladosporioides and Sporobolomyces roseus: implications for public health

Edible dates (Phoenix dactylifera) were examined for the presence of endogenous yeasts and filimentous fungi. Mean counts of fungi were 530 colony forming units (cfu) per gram of fruit, representing a mixture of two phenotypic colony types. Subsequent DNA extraction and PCR amplification of these two morphotypes yielded an amplicon of approximately 350 bp with the 5.8S-28S rRNA ITS region. Sequence analysis identified these to be Cladosporium cladosporioides (230 cfu/g) and Sporobolomyces roseus. Both organisms have been previously reported in opportunistic infections involving skin or in immunocompromised patients. This is the first report of edible dates being a source of these organisms and we emphasize the importance of the common practice of washing hands following the consumption of these fruits by hand.

Involvement of Aureobasidium pullulans and Rhodotorula glutinis in Russet of d'Anjou Pear Fruit

d'Anjou pear, the main cultivar grown in the Mid-Columbia Region of Oregon, is subject to russeting of the fruit surface, resulting in reduced quality and value. The role of Aureobasidium pullulans and Rhodotorula glutinis in russet of pear fruit was studied. Inoculations were done at full bloom in 1998 and 1999 and petal fall in 1999 with a log range of concentrations up to 10⁸CFU/ml. Populations of A. pullulans on floral and fruit tissue were monitored during spring 1999 and 2000 in six orchards with a history of russet. Russet of fruit in both studies was evaluated at harvest. In 1998 neither fungus increased russet. In 1999, inoculation with two strains of each fungus at 10⁸ CFU/ml increased russet. Inoculation with 10⁴ or 10⁶ CFU/ml did not increase russet in either year. In commercial orchards, there was no correlation between fruit russet and the populations of A. pullulans on floral and fruit tissue. Populations were less than 10³ CFU/g of tissue. We conclude that A. pullulans and R. glutinis are not major contributors to russet of d'Anjou pear fruit in the Mid-Columbia Region.

Debaryomyces hansenii growth in nonsterile seawater ClO2-peptone-containing medium

We found that the marine yeast Debaryomyces hansenii strain C-11 (CIBNOR yeast collection, La Paz, Mexico) is highly tolerant to chlorine dioxide (ClO2), a powerful biocide agent. A direct application of this observation is the fermentation of the yeast in a nonsterile medium with an initial concentration of 0.3 mg/L of ClO2. The disinfectant helps to avoid the growth of unwanted microorganisms while allowing the development of the yeast. Because the concentration of ClO2 decreases during the fermentation, we ascribe to D. hansenii cells a "biocontrol" action that contributes to the collection of a contaminant-free yeast cell biomass.

Cryptococcus laurentii fungemia in a premature neonate

Cryptococcus spp. other than Cryptococcus neoformans are generally considered nonpathogenic to humans. There are only 15 case reports of disease in humans caused by Cryptococcus laurentii infection. Underlying diseases and predisposing risk factors seem to play an important role in these cases. Our patient is the first case of an extremely low birth weight infant with C. laurentii fungemia reported in the English literature. In our case, the MIC of amphotericin B for C. laurentii was 0.25 to 1 microg/ml and the patient had a good outcome following the administration of amphotericin B at 10 mg/kg combined with central venous catheter removal. There will undoubtedly be an increasing occurrence of unusual fungal infections accompanying further advances in medicine. A high degree of suspicion and improvements in the techniques for culture and identification will contribute to the earlier diagnosis and treatment of unusual fungal infections.

Diversity in the yeast Cryptococcus albidus and related species as revealed by ribosomal DNA sequence analysis

Evidence accumulated from studies based on physiological, biochemical, and molecular characteristics has pointed to the heterogeneity of the ubiquitous anamorphic basidiomycetous yeast species Cryptococcus albidus (Saito) Skinner, with its current varieties and synonyms. The taxonomic status of this species has not been reappraised because different studies, mostly involving limited numbers of strains, have not been integrated. To assess species diversity within the clade containing Cryptococcus albidus and other phylogenetically related Cryptococcus and Filobasidium species, we determined ribosomal DNA (rDNA) sequences of 69 strains from the 5prime end of the 26S gene, D1/D2 region, and in some cases, the non-coding ITS2 region. Analysis of the sequence data together with available physiological, biochemical, and molecular characteristics, showed the segregation of C. albidus into at least 12 species, leading to the elevation of former varieties to the rank of species (C. aerius, C. diffluens), the reinstatement of synonyms (C. liquefaciens, C. terricola), and the proposal of new species (C. arrabidensis, C. chernovii, C. cylindricus, C. oeirensis, C. phenolicus, C. saitoi, C. uzbekistanensis, C. wieringae). The overall analyses of the results argue in favour of the use of rDNA sequence data to improve species delineation when integrated with other available physiological and molecular characteristics.Key words: basidiomycetous yeasts, taxonomy, Cryptococcus albidus, ribosomal DNA, molecular systematics.

Fruit Surface Colonization and Biological Control of Postharvest Diseases of Pear by Preharvest Yeast Applications

The yeasts Cryptococcus infirmo-miniatus, Cryptococcus laurentii, and Rhodotorula glutinis, applied to Bosc and d'Anjou pear fruit in the field 3 weeks prior to harvest, maintained high population levels through harvest, while populations of Candida oleophila declined after 1 and 2 weeks, and by harvest were not significantly different from total yeast populations on untreated fruit. Yeasts were sprayed individually on fruit at concentrations of 1 to 3 × 10⁸ CFU/ml, with approximately 2 ml applied per fruit. Initial population sizes for all four species averaged 5 × 10⁶ CFU per fruit. C. infirmo-miniatus provided the most consistent decay control in fruit treated 3 weeks before harvest. C. infirmo-miniatus and R. glutinis also provided significant postharvest decay control in Bosc fruit treated 1 day before harvest.

Role of adhesion in the colonization of barley leaves by the yeastRhodosporidium toruloides

To investigate whether leaf-surface yeasts adhere to the phylloplane in a two-phase manner, with weak, nonspecific attachment followed by stronger, time-dependent adhesion, we observed adhesion kinetics of the basidiomycete yeast Rhodosporidium toruloides to barley. While 50-60% of the cells adhered in short-term assays (up to 3 h), fewer than 10% were adherent after 10 days. Ten attachment-minus (Att-) mutants, deficient in phase I attachment, did not adhere after 5-day incubations, further suggesting a lack of stronger, independent phase II adhesion. Long-term (5 day) adhesion was similar for two isolates of R. toruloides and the ubiquitous leaf-surface fungus Aureobasidium pullulans. Long-term adhesion of R. toruloides to leaves of a waxless barley mutant was significantly greater than to leaves of the wild-type cv. Bonus. Application of exogenous nutrients (dilute yeast carbon base) to resident, wild-type R. toruloides populations resulted in both a rapid recolonization to the apparent carrying capacity of the leaves and an increase in the total adherent populations. Att-mutants recolonized barley segments, when supplied with nutrients, after more than 99% of the cells had been removed by agitation. Therefore, adhesion of R. toruloides to leaves was not required for subsequent colonization of the phylloplane. Overall, these data suggest that the frequency of yeast emigration from leaf surfaces, microbial growth rates, and leaf surface characteristics are major factors influencing colonization of leaf surfaces.Key words: epiphyte, phylloplane, Rhodotorula glutinis.

Control of Postharvest Decay in Pear by Four Laboratory-Grown Yeasts and Two Registered Biocontrol Products

Control of blue mold decay in Bosc pears was studied with the laboratory-grown yeasts Rhodotorula glutinis, Cryptococcus infirmo-miniatus, and two strains of Cryptococcus laurentii, as well as registered biocontrol products Aspire, containing the yeast Candida oleophila, and Bio-Save 11 (now Bio-Save 110), containing the bacterium Pseudomonas syringae. Both thiabendazole (TBZ)-sensitive and TBZ-resistant strains of Penicillium expansum were used. Aspire treatment reduced the average lesion diameter by approximately 65 and 45%, and reduced decay incidence by 27 and 9% with TBZ-resistant and TBZ-sensitive P. expansum, respectively, in the first year of the study, but did not result in significant decay control in the second year. Bio-Save 11 reduced decay lesion diameter by 32 to 72% and incidence by 21 to 40% over the 2 years. In both years, TBZ-sensitive P. expansum was completely controlled by the combination of either C. laurentii (both strains), R. glutinis, or C. infirmo-miniatus with 100 ppm TBZ. With TBZ-resistant P. expansum, control of wound infection with these yeasts alone or with 100 ppm TBZ ranged from 62.9 to 100%. In a packinghouse trial, control by Bio-Save 110 + 100 ppm TBZ and Aspire + 100 ppm TBZ was not different than control by TBZ at 569 ppm, the maximum label rate. The amount of decay following Aspire + 100 ppm TBZ treatment was significantly less than the amount of decay following Bio-Save 110 + 100 ppm TBZ treatment.

A method for studying the population dynamics of Candida oleophila on oranges in the grove, using a selective isolation medium and PCR technique

Populations of the biological control agent Candida oleophila on fruit in an orange grove were monitored by plating fruit washes and peel homogenates on a selective medium, followed by PCR analysis of DNA from yeast colonies resembling C. oleophila. The C. oleophila transformant ADGus-10 formed colonies on a selective medium that suppressed the development of 99% of the filamentous fungi and the indigenous yeasts, Aureobasium (a yeast-like fungus) and Rhodotorula. Only 6-8 indigenous yeasts/cm2 fruit surface gave rise to colonies that resembled C. oleophila on the selective medium. The identity of the C. oleophila transformant colonies was verified by PCR analysis of yeast DNA. The presence of a 599-bp band in the PCR product primed by beta-glucuronidase gene primers, confirmed the identity of C. oleophila transformant ADGus-10. Colony-forming units of C. oleophila were recovered efficiently from fortified washes of the fruit surface and from homogenates of wounds excised from fruit sprayed in the grove with C. oleophila.

Control of Brown Rot and Blue Mold of Sweet Cherry with Preharvest Iprodione, Postharvest Cryptococcus infirmo-miniatus, and Modified Atmosphere Packaging

The effectiveness of preharvest iprodione and postharvest Cryptococcus infirmo-miniatus treatments alone and in combination for control of decay of sweet cherry fruit was studied. Also, the effect of a modified atmosphere on brown rot control was evaluated as a part of the iprodione-C. infirmo-miniatus combinations. A single preharvest application of iprodione at 1.13 kg a.i./ha reduced brown rot in stored sweet cherry fruit in both years of this study. Significantly better control of brown rot was obtained when cherry fruit that received a preharvest iprodione application also were treated with a postharvest dip in a suspension of C. infirmo-miniatus containing 0.5 to 1.5 × 10⁸ CFU/ml. Brown rot was reduced by modified atmosphere packaging (MAP) alone and further reduced as a result of a C. infirmo-miniatus-MAP synergism. Incidence of brown rot was reduced from 41.5% in the control to 0.4% by combining preharvest iprodione and postharvest C. infirmo-miniatus treatments with MAP.