Search

BACKGROUND: The present study explores the use of two different growth supports for the biocontrol yeasts Aureobasidium pullulans M13, C10, R34 and P17, by use of nutrient yeast glucose (NYDA) agar and hydrogel spheres as the support matrix, then evaluates their impact on the production of volatile compounds (VOCs) and the subsequent in vitro and in vivo antagonistic activity against Botrytis cinerea and Colletotrichum acutatum. RESULTS: For the in vitro assay, VOCs secreted by the isolates C10 and M13 encased in the hydrogel spheres showed greater inhibitory activity on the mycelial growth of B. cinerea (70.30%) and C. acutatum (52.35%), respectively, with respect to NYDA. For solid‐phase microextraction‐gas chromatography‐mass spectrometry, VOCs produced by the selected yeasts immobilized in the hydrogel spheres or cultured in the agar were identified. VOCs were grouped as alcohols, ketones, alkane and aldehyde, with phenylethyl alcohol and 1‐propanol‐2‐methyl being the most prominently produced. The analysis revealed variations in both quantity and composition of VOCs among the growth supports, indicating the hydrogel spheres as enhancer distinct metabolic pathways and substrate utilization of the isolates, particularly in the M13 isolate. CONCLUSION: The antifungal activity of the VOCs produced in the hydrogel spheres by the isolates C10 and M13 was assessed on strawberries, demonstrating a significant reduction in disease incidences. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Experimental evolution was carried out to investigate the adaptive responses of extremotolerant fungi to a stressful environment. For 12 cultivation cycles, the halotolerant black yeasts Aureobasidium pullulans and Aureobasidium subglaciale were grown at high NaCl or glycerol concentrations, and the halophilic basidiomycete Wallemia ichthyophaga was grown close to its lower NaCl growth limit. All evolved Aureobasidium spp. accelerated their growth at low water activity. Whole genomes of the evolved strains were sequenced. No aneuploidies were detected in any of the genomes, contrary to previous studies on experimental evolution at high salinity with other species. However, several hundred single‐nucleotide polymorphisms were identified compared with the genomes of the progenitor strains. Two functional groups of genes were overrepresented among the genes presumably affected by single‐nucleotide polymorphisms: voltage‐gated potassium channels in A. pullulans at high NaCl concentration, and hydrophobins in W. ichthyophaga at low NaCl concentration. Both groups of genes were previously associated with adaptation to high salinity. Finally, most evolved Aureobasidium spp. strains were found to have increased intracellular and decreased extracellular glycerol concentrations at high salinity, suggesting that the strains have optimised their management of glycerol, their most important compatible solute. Experimental evolution therefore not only confirmed the role of potassium transport, glycerol management, and cell wall in survival at low water activity, but also demonstrated that fungi from extreme environments can further improve their growth rates under constant extreme conditions in a relatively short time and without large scale genomic rearrangements. [ABSTRACT FROM AUTHOR]

In Poland's pine forests, mistletoe (Viscum album subsp. austriacum) abundance has increased over the past 20 years. This mistletoe infestation has decreased the growth and vigour of Scots pine trees. In this study, we surveyed the culturable fungi from healthy and diseased V. album subsp. austriacum leaves from two stands in Poland. In total, 63 distinct species were identified, 99.8% of which belonged to the phylum Ascomycota. The community compositions of fungi in mistletoe leaves were similar in healthy and diseased leaves as Alternaria alternata, Aureobasidium pullulans, Botryosphaeria visci, Fusarium paeoniae and Microsphaeropsis olivacea were consistently found in leaves of all symptom types. The most frequently isolated fungus from asymptomatic leaves was M. olivacea, followed by A. alternata, A. pullulans and Hypoxylon rubiginosum. In comparison, the most frequently isolated fungi from leaves with rusty‐brown necrotic spots were (in decreasing order) M. olivacea, B. visci, F. paeoniae and A. alternata, while the most frequently isolated fungi from leaves with black or dark brown spots were M. olivacea, A. alternata, A. pullulans, Epicoccum layuense and F. paeoniae. This study was the first comprehensive report showing that certain fungal species may be pathogens of V. album subsp. austriacum in Poland. This study was also the first report of F. paeoniae, F. juglandicola, Diaporthe vacuae and Heterotruncatella spartii from V. album, and the first report of D. vacuae and H. spartii in Poland. [ABSTRACT FROM AUTHOR]

The objective of this study was to optimize the fermentation parameters by using Response Surface Methodology for increasing melanin production in carrot peel extract by Aureobasidium pullulans NBRC 100716. The optimum conditions for melanin production by A. pullulans NBRC 100716 in carrot peel extract were determined as; the initial pH of the fermentation medium: 5.9, temperature: 29.9°C, agitation rate: 120 rpm, and fermentation time: 15 days. The estimated intracellular (Y1), extracellular (Y2), and total (Y3) melanin concentrations in optimum conditions were 2.44 ± 0.05, 1.95 ± 0.47, and 4.22 ± 0.74 g/L, respectively. As a result of confirmation experiments, the observed values of Y1, Y2, and Y3 were 2.23, 1.83, and 4.06 g/L, respectively. The optimization of melanin production conditions by A. pullulans NBRC 100716 caused an almost one‐fold increase in total melanin concentration. Besides, using carrot peel extract as an inexpensive substrate source for the production of high value‐added melanin, the optimization of the fermentation conditions is beneficial for the production of this product. [ABSTRACT FROM AUTHOR]

Introduction: Poor sleep quality is a major problem in patients with autism spectrum disorder (ASD), and is attributed to low melatonin levels. Melatonin supplementation is recommended; however, its effectiveness varies. β‐Glucans have previously been shown to improve melatonin levels in animal studies. Herein, we examined the effectiveness of Aureobasidium pullulans (Nichi Glucan), a species of black yeast that contains beta‐1,3/1,6‐glucan, in a pilot study of children with ASD. Methods: Thirteen children (age, 2.5–13 years) with ASD were recruited for the study. The control group consisted of four patients (Gr. 1), while nine patients were classified into the treatment group (Gr. 2). Gr. 2 received 1 g of Nichi Glucan along with conventional therapy, whereas the Gr. 1 (control) patients received conventional therapy alone for 90 days. Serum melatonin levels and sleep patterns, assessed using a subjective questionnaire, were evaluated before and after treatment. Results: In Gr. 2, the average serum melatonin level increased from 238.85 ng/L preintervention to 394.72 ng/L postintervention. Eight of nine participants (88%) in Gr. 2 showed improvements in sleep pattern and quality, while no improvement was observed in the participants in Gr. 1. Conclusion: The consumption of Nichi Glucan for 90 days resulted in visible improvement in sleep quality, sleep pattern, and serum melatonin levels, which was reported for the first time by our study. A larger multicenter study is required to validate our findings. [ABSTRACT FROM AUTHOR]

Iron is a fundamental element for plants as well as for microorganisms and several pathogens, including Rhizoctonia solani, one of the main soil‐borne pathogens of tomato. This study demonstrated the ability of Aureobasidium pullulans strain L1 to produce siderophores and how these molecules were, directly and indirectly, connected to its antagonistic activity and iron bioavailability. By ICP‐OES (Inductively Coupled Plasma—Optical Emission Spectroscopy) trace analysis, the strain displayed the ability to increase the bioavailability of Fe (II) in the soil by almost 50% 30 days after inoculation. Also, the bioavailability of Mn, Cu and Zn was increased after 30 days of incubation in the soil by 31.8, 38.4 and 27.1%, respectively. In in vivo assays, A. pullulans L1 strain showed a growth promotion of tomato roots length and stem diameter, respectively, by 19.1 and 27.3%, and acted as a biocontrol agent (BCA) against R. solani (80% of inhibition). The results demonstrate a new aspect of this microorganism, usually applied as an antagonist of postharvest fruit diseases, to explore in different environments and against different pathogens, such as soil‐borne pathogens. [ABSTRACT FROM AUTHOR]

The diversity and ecological contribution of the fungus kingdom in the marine environment remain understudied. A recent survey in the Atlantic (Woods Hole, MA, USA) brought to light the diversity and unique biological features of marine fungi. The study revealed that black yeast species undergo an unconventional cell division cycle, which has not been documented in conventional model yeast species such as Saccharomyces cerevisiae (budding yeast) and Schizosaccharomyces pombe (fission yeast). The prevalence of this unusual property is unknown. Here, I collected and identified 65 marine fungi species across 40 genera from the surface ocean water, sediment, and the surface of macroalgae (seaweeds) in the Pacific (Sugashima, Toba, Japan). The Sugashima collection largely did not overlap with the Woods Hole collection and included several unidentifiable species, further illustrating the diversity of marine fungi. Three black yeast species were isolated, two of which were commonly found in Woods Hole (Aureobasidium pullulans and Hortaea werneckii). Surprisingly, their cell division mode was dependent on cell density, and the previously reported unconventional division mode was reproduced only at a certain cell density. For all three black yeast species, cells underwent filamentous growth with septations at low cell density and immediately formed buds at high cell density. At intermediate cell density, two black yeasts (H. werneckii and an unidentifiable species) showed rod cells undergoing septation at the cell equator. In contrast, all eight budding yeast species showed a consistent division pattern regardless of cell density. This study suggests the plastic nature of the growth/division mode of marine‐derived black yeast. [ABSTRACT FROM AUTHOR]

Summary: Grapevine (Vitis vinifera) is a reservoir of fungal endophytes that may affect its growth, health status and grape production. Although there is growing interest in comparing fungal communities of mainly red grape varieties across various factors using only high‐throughput sequencing, the small‐scale mycobiome variations in geographically close vineyards need further examination. We aimed to characterize the fungal microbiome of the above‐ground tissues of V. vinifera cv. Furmint in different plant parts, seasons and sites using culture‐dependent and culture‐independent methods, and in planta fluorescent microscopic visualization techniques. Samples were collected from four sites of the Tokaj wine region in Mád and two reference sites in Eger, Hungary, across different seasons for 2 years. Fungal endophytes of young and mature leaves, flowers and grape bunches were collected at different phenological stages. Based on each technique, Aureobasidium pullulans, Cladosporium spp. and the complex species Alternaria alternata dominated the community at every site, season and plant organ. We found no significant difference among communities in distinct neighbouring vineyards, nor when compared with the distant reference sites. We can conclude that the different shoot parts of the Furmint grapevines harbour a common core group of fungal community in these regions. [ABSTRACT FROM AUTHOR]

Summary: The combined biochemical impact of carbon, nitrogen and temperature on the biosynthesis of the antifungal volatile organic compounds (VOCs): ethanol, 2‐methyl‐1‐propanol, 3‐methyl‐1‐butanol and 2‐phenylethanol produced by Aureobasidium pullulans A1 and A3 was investigated using a Box–Behnken experimental design and response surface methodology (RSM). Normalized peak areas derived from solid phase micro extraction‐gas chromatography–mass spectrometry (SPME‐GC–MS) analysis, indicated that initial carbon content had a significant influence on the biosynthesis of ethanol and alcohols with greater than three carbon atoms. This result suggests a dominant activity of the A. pullulans anabolic pathway to biosynthesize three higher alcohols via de novo biosynthesis of amino acids from sugar metabolism. Low concentrations of carbon (3–13 g l−1) with nitrogen as both ammonium and amino acids in the growth medium resulted in a higher number of significant linear and quadratic relationships. Nitrogen availability and growth temperature had significant negative linear and quadratic correlations with VOCs biosynthesis in most instances. Isolate‐dependant metabolic response was evident for all abiotic parameters tested on alcohol production. The findings of this study offer new perspectives to improve the production of key antifungal compounds by antagonists in biological control systems. [ABSTRACT FROM AUTHOR]

In this study, the mono‐, bi‐, and tri‐cultivation of Aureobasidium pullulans, Neurospora crassa, and Trichoderma reesei in solid‐state fermentation were applied to improve the nutritional values of hexane extracted canola meal (HECM) along with the reduction of antinutritional factors for animal feed applications. Static fermentation trials of 50% moisture content HECM were conducted in 500 mL Erlenmeyer flasks for 168 hours at 30 °C. The results showed that fungal cultivation had positive effects on the level of protein, fiber, and, glucosinolates (GLS). Monoculture of N. crassa exhibited the highest protein level of 49%. The combination of A. pullulans and N. crassa provided the highest reduction of crude fiber, acid detergent fiber and neutral detergent fiber by 21.9%, 1.7%, and 9.1%, respectively. Bi‐culture of A. pullulans and T. reesei resulted in the best GLS reduction by 81.3% (0.3 vs. 1.6 μM g−1 GLS of uninoculated control). These results indicate that each fungal strain possesses different enzymatic ability and selectively can work with other fungi in synergistic relationship for better fungal conversion of canola meal. [ABSTRACT FROM AUTHOR]

The objectives of the present study were to purify and assess the killer toxin effect produced by Aureobasidium pullulans under casual agents of green mold (Penicillum digitatum) and sour rot (Geotrichum citri‐aurantii). Initially, different methods of protein precipitation were tested. The proteolytic activity and the presence of proteins acting on cell wall receptors, β‐1,3‐glucanase and chitinase were determined, and toxin purification was conducted by Sephadex G‐75 gel exclusion chromatography and cellulose chromatography (medium fibers). Subsequently, purification was confirmed by polyacrylamide gel electrophoresis, and the detection of killer activity was performed in solid YEPD‐methylene blue buffered with citrate‐phosphate (0.1 M, pH 4.6). Toxin identification was performed by liquid chromatography–mass spectrometry. The results showed that the best protein precipitation method was 2:1 ethanol (vol/vol ethanol/supernatant). It was possible to observe the presence of enzymes with proteolytic activity, including β‐1,3‐glucanase and chitinase. During the purification process, it was verified that the killer toxin produced by the yeast has a low‐molecular‐weight protein belonging to the ubiquitin family, which presents killer activity against P. digitatum and G. citri‐aurantii. [ABSTRACT FROM AUTHOR]

Epiphytic yeasts were isolated from different cultivars of apples and lemons and identified by a combination of PCR‐RFLP of 5.8S rRNA region and sequencing of D1/D2 domain of the 26S rRNA gene. Among 69 isolates, Aureobasidium pullulans GE17 and Meyerozyma guilliermondii KL3 strains showed the greatest antagonistic activity against two significant apple and lemon postharvest pathogens, Penicillium expansum DSM62841 (blue mold) and Penicillium digitatum DSM2750 (green mold), after preliminary screening. Yeasts were applied as single and mixed cultures with two different cell concentrations of 106 and 108 cells/ml in the present study. It was determined that antagonistic activity of two yeast strains studied emerged with a combination of several mechanisms of action including competition for space and nutrients, production of volatile organic compounds (VOCs), secretion of extracellular lytic enzymes and inhibition of fungal spore germination. The highest inhibition of mycelial growth on P. expansum DSM62841 and P. digitatum DSM2750 (83.4% and 74.7%, respectively) was achieved by utilization of single culture of A. pullulans GE17. Otherwise, the application of mixed culture at the ratio of 108 cells/ml inhibited spore germination of both pathogens from 86% to 95%. Results of this study suggest that an increase in yeast cell concentrations positively affected their biocontrol activity against blue and green molds. According to the results, employing single culture of M. guilliermondii KL3 did not exhibit effective antagonistic activity against blue and green molds. However, utilization of A. pullulans GE17 alone and mixed culture showed succesfull controlling against both P. expansum DSM62841 and P. digitatum DSM2750. [ABSTRACT FROM AUTHOR]

Bioorganic asymmetric reduction of carbonyl compounds is one of the most important fundamental and practical reactions for producing chiral alcohols. The stereoselective bioreduction of prochiral ketones of benzofuran derivatives in the presence of yeast‐like fungus Aureobasidium pullulans contained in the antifungal Boni Protect agent was studied. Biotransformations were carried out under moderate conditions in an aqueous and two‐phase system and without multiplication of the bioreagent. Despite similar chemical structure, each of the used ketone has been reduced with varying efficiency and selectivity. One of the reasons for these results is the presence of a whole set of oxidoreductases in A. pullulans cells that are sensitive to the smallest changes in the structure of prochiral substrate. The unsymmetrical methyl ketones were biotransformed with the highest selectivity. Aureobasidium pullulans microorganism is less effective in the reduction of unsymmetrical halomethyl ketones. The presence of a heteroatom in the alkyl group significantly decreases the selectivity of the process. Finally, as a result of the preferred hydride ion transfer from the dihydropyridine ring of the cofactor to the carbonyl double bond on the re side, secondary alcohols of the S and R configuration were obtained with moderate to high enantioselectivity (55‐99%). [ABSTRACT FROM AUTHOR]

Summary: Polymalic acid (PMA) is a novel biopolymer produced by the polyextremotolerant fungus Aureobasidium pullulans. In this study, a GATA‐family transcriptional factor, Gat1, which regulates nitrogen uptake and PMA biosynthesis, was investigated. PMA production increased to 11.2% in the mutant overexpressing gat1 but decreased to 49.1% of the PMA titre when gat1 was knocked out from the genome of A. pullulans. Comparative transcriptome analysis of wild‐type and mutant strains (∆gat1 and OE::gat1) revealed that 23 common differentially expressed genes were related to oxidative phosphorylation, ribosome biogenesis, and nitrogen metabolism. Under nitrogen‐limited stress, regardless of the preferred nitrogen (glutamine, Gln) or non‐preferred nitrogen (proline, Pro), 70% of Gat1 in the cells was located in the nucleus–cytoplasm, which resulted in an increase in nitrogen uptake and PMA biosynthesis regulation. Quantitative RT‐PCR revealed that glucosekinase (GLK) in the glycolytic pathway and malate synthase (MLS) in the glyoxylate shunt pathway may be cross‐regulated by Gat1 and nitrogen concentration (Gln or Pro), Therefore, glk was overexpressed in mutant strain (OE::gat1), which resulted in an increased PMA titre and yield of 12.6% and 13.0% respectively. These findings indicate that Gat1 may play an important role in the dual regulation of the nitrogen and carbon metabolisms in PMA biosynthesis. [ABSTRACT FROM AUTHOR]

Summary: The black yeast Aureobasidium pullulans is a textbook example of a generalistic and ubiquitous fungus thriving in a wide variety of environments. To investigate whether A. pullulans is a true generalist, or alternatively, whether part of its versatility can be attributed to intraspecific specialization masked by cryptic diversification undetectable by traditional phylogenetic analyses, we sequenced and analysed the genomes of 50 strains of A. pullulans from different habitats and geographic locations. No population structure was observed in the sequenced strains. Decay of linkage disequilibrium over shorter physical distances (<100 bp) than in many sexually reproducing fungi indicates a high level of recombination in the species. A homothallic mating locus was found in all of the sequenced genomes. Aureobasidium pullulans appears to have a homogeneous population genetics structure, which is best explained by good dispersal and high levels of recombination. This means that A. pullulans is a true generalist that can inhabit different habitats without substantial specialization to any of these habitats at the genomic level. Furthermore, in the future, the high level of A. pullulans recombination can be exploited for the identification of genomic loci that are involved in the many biotechnologically useful traits of this black yeast. [ABSTRACT FROM AUTHOR]

Summary: Aureobasidium pullulans and A. melanogenum are black‐yeast‐like surface colonisers and are commonly encountered as contaminants in the hospital. The species are able to produce melanin which play a role in protection against environmental stress and irradiation. Aureobasidium melanogenum shows higher frequency in opportunistic infections compared to A. pullulans. Comparative pathogenicity of opportunistic black yeasts between Aureobasidium pullulans and A. melanogenum to explain the observed differences in frequency in infection. Degrees of melanisation and thermotolerance were measured, and virulence of strains from different sources was examined in Galleria mellonela and murine infection models. Aureobasidium melanogenum responds with increased melanisation to temperature stress and generally survives at 37°C, A. pullulans on average scored less on these parameters. In the murine model, differences between species were not significant, but the melanised A. melanogenum group showed the highest virulence. This result was not reproducible in Galleria mellonella larvae at 25°C. The A. melanogenum black group showed higher pathogenicity in murine model, indicating that the combination of melanisation and thermotolerance rather than species affiliation is instrumental. Galleria larvae did not survive very well at 37°C, and hence, this model is judged insufficient to detect the small virulence differences observed in Aureobasidium. [ABSTRACT FROM AUTHOR]

The goal of this study was to assess the performance of Aureobasidium pullulans in converting soybean meal (SBM) into high protein feed using the submerged and solid‐state processes. High solid loading rates (SLR) were evaluated for each process, i.e., 10–25% for submerged and 35–70% for static solid‐state fermentation. During the submerged fermentation, 10% SLR was considered the best performer due to the high amount of cell density, low residual carbohydrates, and high protein titers, while 40% SLR resulted in the high protein yields and low residual carbohydrates during the static solid‐state fermentation. The solid‐state fermentation was conducted in a 14‐L paddle‐type reactor at 50% SLR, and periodic mixing resulted in a protein titer of ~58% at 72 hours of fermentation. Overall, results showed the feasibility of scaling up these processes in converting SBM to a high protein feed ingredient for animal diet. [ABSTRACT FROM AUTHOR]

Summary: This microbiological survey was performed to determine the conservation state of a mummy in the Slovak castle of Krásna Hôrka and its surrounding environment. Culture‐dependent identification was coupled with biodegradation assays on keratin, gelatin and cellulose. Next Generation Sequencing (NGS) using Illumina platform was used for a deeper microbial investigation. Three environmental samples were collected: from the glass of the sarcophagus, from the air inside it, and from the air of the chapel where the mummy is located. Seven different samples were taken from mummy's surface: from the left ear, left‐hand palm, left‐hand nail, left instep, right hand, abdomen and mineral crystals embedded within the skin. Three internal organ samples, from the lung, pleura and stomach, were also included in this study. Together, the culture‐dependent and culture‐independent analyses revealed that the bacterial communities present had fewer taxa than the fungal ones. The mycobiome showed the largest variability and included Epicoccum nigrum, Penicillium spp., Alternaria spp., Aspergillus spp., Cladosporium spp. and Aureobasidium pullulans; many other Ascomycota and Basidiomycota genera were detected by NGS. The most interesting results came from the skin mineral crystals and the internal organs. The hydrolytic assays revealed those microorganisms which might be considered dangerous ‘mummy pathogens’. © 2018 Society for Applied Microbiology and John Wiley & Sons Ltd [ABSTRACT FROM AUTHOR]

Summary: Autophagy is a conserved degradation system in eukaryotic cells that includes non‐selective and selective processes. Selective autophagy functions as a selective degradation mechanism for specific substrates in which autophagy‐related protein 11 (ATG11) acts as an essential scaffold protein. In B. bassiana, there is a unique ATG11 family protein, which is designated as BbATG11. Disruption of BbATG11 resulted in significantly reduced conidial germination under starvation stress. The mutant ΔBbATG11 displayed enhanced sensitivity to oxidative stress and impaired asexual reproduction. The conidial yield was reduced by approximately 75%, and this defective phenotype could be repressed by increasing exogenous nutrients. The virulence of the ΔBbATG11 mutant strain was significantly impaired as indicated in topical and intra‐hemocoel injection bioassays, with a greater reduction in topical infection. Notably, BbATG11 was involved in pexophagy and mitophagy, but these two autophagic processes appeared in different fungal physiological aspects. Both pexophagy and mitophagy were associated with nutrient shift, starvation stress and growth in the host hemocoel, but only pexophagy appeared in both oxidation‐stressed cells and aerial mycelia. This study highlights that BbATG11 mediates pexophagy and mitophagy in B. bassiana and links selective autophagy to the fungal stress response, conidiation and virulence. [ABSTRACT FROM AUTHOR]

Abstract: Pullulan is a commercially important Exopolysaccharide (EPS) with wide‐spread applications which is produced by Aureobasidium pullulans. The alternative α (1 4) & α (1 6) configuration in pullulan provides it the specific structural and conformational properties. Pullulan is currently being exploited in food, health care, pharmacy, lithography, cosmetics. The fermented broth is processed by organic solvent precipitation for isolation and purification of pullulan. In this study, we have tried to analyze the potential of aqueous two phase system as an alternate technique to extract pullulan from fermented broth. Including this viability of ATPS was also compared with conventional organic solvent precipitation system in terms of cost and time. It was found that ATPS process produced a higher yield of pullulan (80.56%) than organic solvent precipitation method (71.6%). ATPS was also found more economical and less time consuming method. [ABSTRACT FROM AUTHOR]

Abstract: β‐poly (L‐malic acid) (PMLA) is a biopolyester which has attracted industrial interest for its potential application in medicine and other industries. A high dissolved oxygen concentration (DO) was beneficial for PMLA production, while the mechanisms of DO in PMLA biosynthesis by Aureobasidium pullulans are still poorly understood. In this work, the amount of PMLA was first compared when A. pullulans ipe‐1 were cultured under a high DO level (70% saturation) and a low DO level (10% saturation). Meanwhile, the key enzymes involved in different pathways of the precursor L‐malic acid biosynthesis were studied. The results revealed that the activities of glucose‐6‐phosphate dehydrogenase (G6PDH) and phosphoenolpyruvate carboxylase (PEPC) were positively correlated with cell growth and PMLA production, while the activities of phosphofructokinases (PFK), pyruvic carboxylase (PC) and citrate synthetase (CS) did no show such correlations. It indicated that the Pentose Phosphate Pathway (PPP) may play a vital role in cell growth and PMLA biosynthesis. Moreover, the precursor L‐malic acid for PMLA biosynthesis was mainly biosynthesized through phosphoenolpyruvic acid (PEP) via oxaloacetate catalyzed by PEPC. It was also found that low concentration of sodium fluoride (NaF) might impel carbon flux flow to the oxaloacetate through PEP, but inhibit the flux to the oxaloacetate via pyruvic acid. [ABSTRACT FROM AUTHOR]

Abstract: Renal transplant recipients are on long‐term potent immunosuppressive therapy, which makes them highly vulnerable to opportunistic fungal infections. Dematiaceous, or dark‐pigmented saprophytic fungi, are being increasingly seen as opportunistic pathogens of mycoses in immunosuppressed patients. One of these is Aureobasidium pullulans, which is a black yeast‐like dematiaceous fungus found ubiquitously in the environment that can cause various opportunistic human infections. Most infections occur by traumatic inoculation, such as keratitis and cutaneous lesions; disseminated mycoses are very rare and occur only in severely immunocompromised patients. We report a case of disseminated fungal infection due to A. pullulans in a pediatric patient who underwent renal transplant. The use of voriconazole and vacuum‐assisted closure along with surgical drainage most likely contributed to the patient's positive outcome. [ABSTRACT FROM AUTHOR]

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 [ABSTRACT FROM AUTHOR]

BACKGROUND β-Poly (L-malic acid) ( PMLA) can be used as a pro-drug or for a drug-delivery system, while the separation of PMLA producer cells of Aureobasidium pullulans from its fermentation broth is a challenge. This paper reports the separation of A. pullulans from PMLA fermentation broth by membranes technology. RESULTS The best separation efficiency was obtained by the membrane with a molecular weight cut off of 300 kDa, an initial feed volume of 1300 mL, a volume reduction ratio ( VRR) of 7.2, a cross-flow velocity of 6 m s−1, a trans-membrane pressure ( TMP) of 0.2 MPa, and a temperature of 40°C. The average flux reached 55.97 L m−2 h−1 with a VRR of 7.2. The main fouling mechanism during the filtration of cell suspension solution was cake layer formation, while it was pore blocking for fermentation broth and cell free broth. Since the cake layer induced by cells would reject some macromolecular substances (i.e. reduce the pore blocking and enhance the fluxes), one step separation of A. pullulans with a 300 kDa membrane was better than that with centrifugation followed by membrane filtration. CONCLUSION One step separation of A. pullulans by membranes technology would be beneficial for PMLA bio-refinery. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

This study explores the biotechnological potential for plant production of twelve psychrotolerant yeasts strains from Northwest-Patagonia. These strains were isolated from different substrates associated with Nothofagus sp. in native forests and Vaccinium sp. in a commercial plantation. Yeasts characterization was performed using in vitro assays to evaluate the production of auxin-like compounds and siderophores, ability to solubilize inorganic phosphate and to reduce common plant pathogen growth. Strain YF8.3 identified as Aureobasidium pullullans was the main producer of auxin-like and siderophores compounds. Phosphate solubilization was a characteristic observed by strains L8.12 and CRUB1775 identified as Holtermaniella takashimae and Candida maritima, respectively. Different yeast strains were able to inhibit the growth of Verticillium dahliae PPRI5569 and Pythium aphanidermatum PPRI 9009, but they all failed to inhibit the growth of Fusarium oxysporum PPRI5457. The present study, suggests that yeasts present in different environments in Northwestern-Patagonian have physiological in vitro features which may influence plant growth. These results are promising for the developing of biological products based on Patagonian yeasts for plant production in cold-temperate regions. [ABSTRACT FROM AUTHOR]

BACKGROUND Drosophila suzukii is a major pest of cherry in the western United States. We evaluated whether the addition of sugary baits could improve the efficacy of two classes of insecticides not considered to be sufficiently effective for this pest, diamides and spinosyns, in laboratory and field trials in cherry. RESULTS Adding cane sugar alone or in combination with the yeasts Saccharomyces cerevisiae or Aureobasidium pullulans significantly improved insecticide efficacy. However, the significance of adding yeasts to the sugar plus insecticide on fly mortality varied with respect to both the insecticide and yeast species. The addition of S. cerevisiae to sugar also did not significantly reduce egg densities in fruit compared with sugar alone. The addition of a yeast plus sugar significantly reduced egg densities in three field trials with cyantraniliprole and in two out of three trials with spinosad. CONCLUSION The addition of cane sugar with or without yeast can improve the effectiveness of diamide and spinosyn insecticides for D. suzukii in cherry. Inclusion of these two insecticides in D. suzukii management programs may alleviate the strong selection pressure currently being imposed on a few mode-of-action insecticide classes used by growers to maintain fly suppression over long continuous harvest periods of mixed cultivars. Published 2015. This article is a U.S. Government work and is in the public domain in the USA. [ABSTRACT FROM AUTHOR]

BACKGROUND Pullulan with high molecular weight (Mw) is attractive for industrial application. Previous studies indicated that high yield and high Mw of pullulan cannot be simultaneously obtained under constant agitation speeds or constant dissolved oxygen levels during batch pullulan fermentation. In this study, a two-stage agitation speed control strategy was developed to obtain pullulan with both high yield and high Mw. RESULTS Batch pullulan production at various constant agitation speeds ranging from 200 to 600 rpm was carried out in a 5 L stirred tank fermentor. Based on kinetic analysis of batch processes, activity assays of the enzymes associated with pullulan biosynthesis and biodegradation, and intracellular energy supply under different constant agitation speeds, a two-stage control strategy that shifted the agitation speed from 500 to 400 rpm at 18 h proved to effectively achieve simultaneous high yield of high Mw pullulan. CONCLUSION A maximum pullulan concentration of 27.4 g L−1 and final Mw of 3.09 × 106 Da were obtained using the two-stage agitation speed control strategy, which were both greatly improved compared with those obtained at constant agitation speeds. © 2014 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Because antioxidants from natural sources may be an effective approach to the treatment and prevention of UV radiation-induced skin damage, the effects of purified exopolymers from Aureobasidium pullulans SM-2001 ('E- AP-SM2001') were evaluated in UVB-induced hairless mice. E- AP-SM2001 consists of 1.7% β-1,3/1,6-glucan, fibrous polysaccharides and other organic materials, such as amino acids, and mono- and di-unsaturated fatty acids (linoleic and linolenic acids) and shows anti-osteoporotic and immunomodulatory effects, through antioxidant and anti-inflammatory mechanisms. Hairless mice were treated topically with vehicle, E- AP-SM2001 stock and two and four times diluted solutions once per day for 15 weeks against UVB irradiation (three times per week at 0.18 J/cm2). The following parameters were evaluated in skin samples: myeloperoxidase ( MPO) activity, cytokine levels [interleukin ( IL)-1β and IL-10], endogenous antioxidant content (glutathione, GSH), malondialdehyde ( MDA) levels, superoxide anion production; matrix metalloproteases ( MMP-1, -9 and -13), GSH reductase and Nox2 (gp91phox) mRNA levels, and immunoreactivity for nitrotyrosine ( NT), 4-hydroxynonenal ( HNE), caspase-3, and cleaved poly( ADP-ribose) polymerase ( PARP). Photoageing was induced by UVB irradiation through ROS-mediated inflammation, which was related to the depletion of endogenous antioxidants, activation of MMPs and keratinocyte apoptosis. Topical treatment with all three doses of E- AP-SM2001 and 5 n m myricetin attenuated the UV-induced depletion of GSH, activation of MMPs, production of IL-1β, the decrease in IL-10 and keratinocyte apoptosis. In this study, E- AP-SM2001 showed potent inhibitory effects against UVB-induced skin photoageing. Thus, E- AP-SM2001 may be useful as a functional ingredient in cosmetics, especially as a protective agent against UVB-induced skin photoageing. [ABSTRACT FROM AUTHOR]

The bioremediation of Pb2+, Cu2+, Ni2+, and Co2+ ions onto Aureobasidium pullulans biomass was studied in batch procedure. The extents to which the experimental variables such as pH, contact time, stirring rate, and temperature affect the efficiency of biosorption were examined. The optimum values of pH (pH = 5), amount of biomass, and contact time (1 day) were found to be 5.0, 1 g, and 24 h, respectively. The equilibrium data were fitted to the Langmuir and Freundlich isotherm models. The Freundlich model showed better (q = 75-82 for different metal ions and R = 1) fit and thus it was more suitable for the interpretation of experimental equilibrium data for Pb2+, Cu2+, Ni2+, and Co2+ ions adsorption onto A. pullulans. The kinetic data at various contact time were analyzed by applying different models which showed that the biosorption process of metal ions onto A. pullulans biomass obeys the first order kinetics Pb2+ and for Co2+ ions while it obeys the second order kinetics for Cu2+ and Ni2+ ions. © 2014 American Institute of Chemical Engineers Environ Prog, 33: 769-776, 2014 [ABSTRACT FROM AUTHOR]

In this study indigenous yeasts associated with wineries, grapes and Malbec fermented must from San Rafael viticulture region (Argentina) were isolated to select pectinolytic strains for their potential use in enology. Pectinolytic yeasts were identified by physiological and molecular methods. Among 78 isolates, only nine were able to produce extracellular pectinases. Six isolated from berry surface were identified as Aureobasidium pullulans and the remaining isolates, recovered from wineries, belonged to Saccharomyces cerevisiae and Filobasidium capsuligenum species. Pectinase production was evaluated under vinification-related conditions: pH 3.5, 12 and 28 °C. A. pullulans U-12 produced the highest pectinolytic activity at low temperature (1.16 U ml−1), while F. capsuligenum strains showed good activity at 12 and 28 °C (0.77 and 1.15 U ml−1, respectively) being this study the first report on the capacity of this species to produce pectinases. The pectinolytic activity of F. capsuligenum B-13 showed an optimum at pH 4.5 and two peaks at 20 and 50 °C. The enzyme half-life was 2 h at 40 °C and retained 65% of its activity at 40 °C after 1 h of incubation. This pectinolytic system displayed remarkable activity at pH and temperatures found in vinification, suggesting a potential candidate for applying to wine-making. [ABSTRACT FROM AUTHOR]

β-poly( l-malic acid) (PMLA) is a biopolyester, which has attracted growing attention due to its potential applications in medicine and other industries. In this study, the biosynthetic pathway of PMLA and the fermentation strategies with mixed sugars were both investigated to enhance PMLA production by Aureobasidium pullulans ipe-1. Metabolic intermediates and inhibitors were used to study the biosynthetic pathway of PMLA. It showed that exogenous addition of l-malic acid, succinic acid, TFA, and avidin had negligible effect on PMLA production, while pyruvic acid and biotin were the inhibitors, indicating that PMLA biosynthesis was probably related to phosphoenolpyruvate via oxaloacetate catalyzed by phosphoenolpyruvate carboxylase. Sucrose was suitable for achieving the highest PMLA concentration, while fructose generated a higher yield of PMLA (PMLA produced per biomass). Furthermore, the fed-batch culture using fed solution with different sugar mixture for PMLA production was implemented. During the fed-batch culture with mixed solution, fructose could increase PMLA production. Compared with the batch culture, the feeding with mixed sugar (sucrose and glucose) increased PMLA concentration by 23.9%, up to 63.2 g/L, and the final volume of the broth was increased by 25%. These results provide a good reference for process development and optimization of PMLA production. [ABSTRACT FROM AUTHOR]

BACKGROUND Polymalic acid ( PMA) is a water-soluble polyester with many attractive properties for biomedical application. Its monomer L-malic acid is widely used in the food industry and is also a potential C4 platform chemical. Hydrolysate of raw sweet potato as a low-cost renewable feedstock was applied for the production of PMA by immobilized Aureobasidium pullulans cells in an aerobic fibrous bed bioreactor system ( AFBB). RESULTS Under the initial hydrolysate sugar concentration 120 g L-1, yeast extract 5 g L-1, and citrate 7.5 g L-1, PMA production in a shake flask was improved. Comparison of the kinetics of fed-batch immobilized-cell fermentation using the AFBB with those of batch or fed-batch free-cell fermentation in a 5 L fermentor showed that immobilized-cell fermentation gave much higher PMA production and productivity. The maximum PMA production and productivity in AFBB were 57.5 g L-1 and 0.34 g L-1 h, which was 30.6% and 21.4% higher than that in free-cell mode. CONCLUSION Raw sweet potato is an efficient renewable feedstock for PMA fermentation. This present work demonstrated the great potential of AFBB and renewable feedstocks for the economical production of PMA and malic acid at industrial scale. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Malic acid is a dicarboxylic acid widely used in the food industry and also a potential C4 platform chemical that can be produced from biomass. However, microbial fermentation for direct malic acid production is limited by low product yield, titer, and productivity due to end-product inhibition. In this work, a novel process for malic acid production from polymalic acid (PMA) fermentation followed by acid hydrolysis was developed. First, a PMA-producing Aureobasidium pullulans strain ZX-10 was screened and isolated. This microbe produced PMA as the major fermentation product at a high-titer equivalent to 87.6 g/L of malic acid and high-productivity of 0.61 g/L h in free-cell fermentation in a stirred-tank bioreactor. Fed-batch fermentations with cells immobilized in a fibrous-bed bioreactor (FBB) achieved the highest product titer of 144.2 g/L and productivity of 0.74 g/L h. The fermentation produced PMA was purified by adsorption with IRA-900 anion-exchange resins, achieving a ∼100% purity and a high recovery rate of 84%. Pure malic acid was then produced from PMA by hydrolysis with 2 M sulfuric acid at 85°C, which followed the first-order reaction kinetics. This process provides an efficient and economical way for PMA and malic acid production, and is promising for industrial application. Biotechnol. Bioeng. 2013; 110: 2105-2113. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

β-Glucans, glucose polymers that are the main constituents of the outer cell walls of micro-organisms such as fungi and yeast, are known to play an immunostimulatory role. We prepared β-glucan (β-(1-3),(1-6)-D-glucan) from an edible cultured fungus through fermentation techniques using a strain of Aureobasidium pullulans ADK-34. The purity of this β-glucan preparation ( AP- FBG) was demonstrated to be high through various instrumental analyses. We then examined the effects of AP- FBG on intestinal immune systems. We prepared Peyer's patch ( PP) cells and measured interleukin ( IL)-5, IL-6, and IgA production in culture media with AP- FBG. We found that both cytokines and IgA increased; furthermore, IL-6 secreted by PP dendritic cells ( PPDCs) cultured in the presence of AP- FBG significantly increased. We tested IgA production after oral administration of AP- FBG for 2 weeks and found that AP- FBG tended to promote the production of IgA in the small intestine. Interestingly, we observed a significant increase in IgA production in the small intestines of mice treated with cyclophosphamide ( CY; an immunosuppressant) after oral administration of AP- FBG diet compared with CY-treated and control diet mice. Production of IL-6 and IgA by PP cells and IL-6 production by PPDCs in AP- FBG-fed and CY-treated mice also increased. These results demonstrate that AP- FBG has the ability to activate PPDC and induce IL-6 production and IgA secretion in PP cells. These abilities were more clearly expressed when AP- FBG was orally administered in a CY-induced immunosuppressed condition. Therefore, AP- FBG may be a useful ingredient for preparing functional foods with immunomodulatory activities. [ABSTRACT FROM AUTHOR]

BACKGROUND: β-poly(malic acid) (PMLA) can be used as a pro-drug or for a drug-delivery system. Effects of pH, dissolved oxygen concentration (DO) and stirring speed were investigated to improve PMLA production by A. pullulans ipe-1. RESULTS: The strain produced a high PMLA concentration when pH and DO remained at about 6.0 and above 70%, respectively, and the yeast-like cells were the main PMLA producers. To further promote PMLA production, the cultivation could be divided into three phases. In phase I, cell growth was accelerated by maintaining high DO (>70%) with a constant stirring speed of 800 rpm. In phase II, PMLA production was increased by controlling DO at 70% using the automatically controlled stirring speed. In phase III, PMLA production on per gram of glucose ( Y p/ s) was enhanced by keeping DO at 70%, and using a low stirring speed to decrease cell growth. Compared with batch cultures, a higher PMLA yield was obtained with this strategy, i.e. PMLA production and Y p/ s increased by 15% and 18%, respectively. CONCLUSION: Control strategies for pH, DO and stirring speed provide a good reference for process development and optimization of PMLA production. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Despite the ubiquity and importance of microbes in nature, little is known about their natural population dynamics, especially for those that occupy terrestrial habitats. Here we investigate the dynamics of the yeast-like fungus Aureobasidium pullulans (Ap) on apple leaves in an orchard. We asked three questions. (1) Is variation in fungal population density among leaves caused by variation in leaf carrying capacities and strong density-dependent population growth that maintains densities near carrying capacity? (2) Do resident populations have competitive advantages over immigrant cells? (3) Do Ap dynamics differ at different times during the growing season? To address these questions, we performed two experiments at different times in the growing season. Both experiments used a 2 X 2 factorial design: treatment 1 removed fungal cells from leaves to reveal density-dependent population growth, and treatment 2 inoculated leaves with an Ap strain engineered to express green fluorescent protein (GFP), which made it possible to track the fate of immigrant cells. The experiments showed that natural populations of Ap vary greatly in density due to sustained differences in carrying capacities among leaves. The maintenance of populations close to carrying capacities indicates strong density-dependent processes. Furthermore, resident populations are strongly competitive against immigrants, while immigrants have little impact on residents. Finally, statistical models showed high population growth rates of resident cells in one experiment but not in the other, suggesting that Ap experiences relatively ‘good’ and ‘bad’ periods for population growth. This picture of Ap dynamics conforms to commonly held, but rarely demonstrated, expectations of microbe dynamics in nature. It also highlights the importance of local processes, as opposed to immigration, in determining the abundance and dynamics of microbes on surfaces in terrestrial systems. [ABSTRACT FROM AUTHOR]

Background: Corneal ulcer caused by Aureobasidium pullulans is considered to be a rare entity. So far very few reports have appeared in the world literature and the authors’ hospital is the first to report from Nepal. Although A. pullulans is regarded as a contaminant, it should be considered as a pathogen if isolated from corneal ulcer specimen with clinical signs of infection and with growth of the organism on two or more culture media or growth in one medium with consistent direct microscopy findings or growth of the same organism on repeated corneal scrapings. In the present study, a series of proven cases of A. pullulans corneal ulcers at a tertiary eye care centre of Eastern Nepal is reported. Methods: A retrospective analysis of stored data of microbiological and clinical cases of corneal ulcer was carried out. All consecutive patients (447 patients) with presumed micorbial keratitis from 1 August 1998 to 31 July 2001 were evaluated with regards to clinical details, microbiological examination and management. Results: Of 200 fungal organisms isolated from the cultures, 25 were identified as A. pullulans. These ulcers showed negligible improvement to topical natamycin and required either topical fluconazole or topical itraconazole in all along with systemic intravenous fluconazole in eight patients. Of 25 eyes, 22 responded well to antifungal therapy and 2 required therapeutic penetrating keratoplasty. One patient was lost to follow up for 3 months and revealed phthisis bulbi on subsequent examination. Conclusions: Aureobasidium pullulans corneal infection should be considered as a cause of keratomycosis. [ABSTRACT FROM AUTHOR]

Fungi colonizing senescent chickpea ( Cicer arietinum) stems and postharvest debris from Pullman, WA, were enumerated and identified with the objective of finding species potentially useful for biological control of Didymella rabiei (conidial state = Ascochyta rabiei), causal agent of Ascochyta blight. In addition to D. rabiei, primary colonizers were, in order of decreasing abundance, Alternaria tenuissima, Al. infectoria, Ulocladium consortiale, Epicoccum purpurascens, U. atrum and Fusarium pseudograminearum. Present at lower frequencies were Al. malorum, Cladosporium herbarum, Aureobasidium pullulans, Clonostachys rosea and miscellaneous anamorphic ascomycetes. On agar media and autoclaved chickpea stems, Au. pullulans consistently grew faster than As. rabiei, and excluded As. rabiei from the substrate. When stems received prior inoculation with Au. pullulans or Cl. rosea, followed by inoculation with compatible mating types of D. rabiei, formation of pseudothecia and pycnidia of D. rabiei was suppressed. Results suggest that Au. pullulans and Cl. rosea can inhibit As. rabiei and its sexual stage, D. rabiei, on chickpea debris. Clonostachys rosea formed appressoria on, then invaded,hyphae of D. rabiei. Small-scale field experiments using Au. pullulans and Cl. rosea have been initiated. [ABSTRACT FROM AUTHOR]

DNA isolated and amplified higher plants may originate from symbiotic microbes occupying plant tissues. A recent report on the phylogeny of Picea contained sequence data that upon later analysis proved to originate for filamentous ascomycetes. Isolates of endophytic fungi from Picea foliage collected from thae same locations as the original samples were examined to identify the source of the contaminating DNA. The ITS region of solates was screened by Southern blotting using an oligonucleotide probe homologous to a unique portion of the reported ‘spruce’ sequences. This study identifies a DNA sequence originally attributed to Picea engelmannii (Engelmann spruce) as Hormonema dematioides, a ubiquitous foliar endophyte of conifers. Infections of plants by endophytic fungi are common anf their presence is not revealed by external symptoms. Plant molecular researchers should be aware of the potential for this type of DNA contamination. [ABSTRACT FROM AUTHOR]