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Background Chenopodium album L. is one of the most important threat weeds affecting crops productivity in the fields. Control of this weed is complex and currently, lies in the use of chemical methods, although this method has not proven to be fully effective. The utilization of microorganisms has emerged as a means of simultaneously controlling this weed with high-efficiency, and friendly to the environment. In this regard, this study used LC-MS/MS and RNA-Seq technology to gain insights into the molecular herbicidal mechanisms underlying strain Aureobasidium pullulans PA-2 on C. album . Results Physiological and biochemical tests showed that compared with the control group (CK), the content of chlorophyll, soluble protein, soluble sugar and phenylalanine ammonia-lyase (PAL) activity in C. album leaves in the pot show a decreasing trend under the infection of PA-2. Transmission electron microscopy (TEM) observation revealed that abnormal shapes of chloroplast, incomplete intracellular structure and gradual disintegration of the outer membrane in the cells of C. album are observed at the third day after inoculation. A total of 69,404 unigene was obtained, among which 35,950 were differentially expressed genes (DEGs), and most of them were enriched plant secondary metabolite biosynthesis, phytohormone signaling, and carotenoid biosynthesis. Moreover, the analysis of 8 candidate genes showed that the content of photosynthesis indices was significantly decreased, which was resulted from the down-regulation of photosynthesis-related genes expression levels after PA-2 infection. During the PA-2 infection phase, a total of 14,521 and 13,211 differentially accumulated metabolites (DAMs) were identified using the ESI + and ESI − modes, respectively. Significant differences were observed in the content of DAMs at the five stages of PA-2 infection, especially photosynthesis, purine metabolism, and carotenoid biosynthesis. Further correlation analysis of major DAMs and DEGs showed that 19 key DEGs were involved in photosynthesis, 10 key DEGs in carotenoid biosynthesis, and 3 key DEGs in purine metabolism. Conclusion These findings have paved way in further functional characterization of candidate genes and subsequently can be better understanding of molecular mechanism of PA-2 infection on C. album .

Polymalic acid (PMA) is a linear anionic polyester composed of l-malic acid monomers, which have potential applications as drug carriers, surgical suture, and biodegradable plastics. In this study, a novel strain of Aureobasidium pullulans var. melanogenum GXZ-6 was isolated and identified according to the morphological observation and deoxyribonucleic acid internal-transcribed spacer sequence analysis, and the product of PMA was characterized by FT-IR, 13C-NMR, and 1H-NMR spectra. The PMA titer of GXZ-6 reached 62.56 ± 1.18 g L−1 with productivity of 0.35 g L−1 h−1 using optimized medium with addition of metabolic intermediates (citrate and malate) and inhibitor (malonate) by batch fermentation in a 10-L fermentor. Besides that the malate for PMA synthesis in GXZ-6 might mainly come from the glyoxylate cycle, based on results, citrate, malate, malonate, and maleate increased while succinate and fumarate inhibited the production of PMA, which was different from that of other A. pullulans. This study provided a potential strain and a simple metabolic control strategy for high-titer production of PMA and shared novel information on the biosynthesis pathway of PMA in A. pullulans.

This work aims to separate antimicrobial lipopeptides from fermentation by Aureobasidium pullulans PA-2, and verify its antimicrobial activity and the optimum condition of lipopeptide production. Using high performance liquid chromatography (HPLC) analysis, the lipopeptides with antimicrobial activity was evaluated with the agar well diffusion test. Response surface methodology (RSM) was used to determine optimum conditions for lipopeptides from A. pullulans PA-2. The lipopeptides with antimicrobial activity in the fermentation supernatant of the PA-2 strain was found to be the Aureobasidin A (AbA). In vitro antagonistic tests showed that the minimal inhibitory concentration (MIC) of AbA against Staphylococcus aureus and Escherichia coli was 0.5 and 1.0 mg/mL, respectively. The optimal fermentation conditions were: inoculum size 6.8 % (v/v)(OD600=0.25), rotation speed 216 rpm, culture temperature 26 ℃, liquid volume 125 mL and initial pH7. Under this condition, predicting yield of the antimicrobial lipopeptides by the model was 940 mg/L, observed yield 920 mg/L, which was 51 % more than that of before optimization (610 mg/L).

Microbial oils can be used for biodiesel production and fumaric acid (FA) is widely used in the food and chemical industries. In this study, the production of lipids and FA by Aureobasidium pullulans var. aubasidani DH177 was investigated. A high initial carbon/nitrogen ratio in the medium promoted the accumulation of lipids and FA. When the medium contained 12.0% glucose and 0.2% NH4NO3, the yeast strain DH177 accumulated 64.7% (w/w) oil in its cells, 22.4 g/l cell biomass and 32.3 g/l FA in a 5-L batch fermentation. The maximum yields of oil and FA were 0.12 g/g and 0.27 g/g of consumed sugar, respectively. The compositions of the produced fatty acids were C14:0 (0.6%), C16:0 (24.9%), C16:1 (4.4%), C18:0 (2.1%), C18:1 (57.6%), and C18:2 (10.2%). Biodiesel obtained from the extracted oil burned well. This study provides the pioneering utilization of the yeast strain DH177 for the integrated production of oil and FA.

Abstract In this study, the yeast strain P5 isolated from a mangrove system was identified to be a strain of Aureobasidium pullulans var. melanogenum and was found to be able to secrete a large amount of heavy oil into medium. After optimization of the medium for heavy oil production and cell growth by the yeast strain P5, it was found that 120.0 g/l of glucose and 0.1 % corn steep liquor were the most suitable for heavy oil production. During 10-l fermentation, the yeast strain P5 produced 32.5 g/l of heavy oil and cell mass was 23.0 g/l within 168 h. The secreted heavy oils contained 66.15 % of the long-chain n-alkanes and 26.4 % of the fatty acids, whereas the compositions of the fatty acids in the yeast cells were only C16:0 (21.2 %), C16:1(2.8 %), C18:0 (2.9 %), C18:1 (39.8 %), and C18:2 (33.3 %). We think that the secreted heavy oils may be used as a new source of petroleum in marine environments. This is the first report of yeast cells which can secrete the long-chain n-alkanes.

Yeasts occur in all environments and have been described as potent antagonists of various plant pathogens. Due to their antagonistic ability, undemanding cultivation requirements, and limited biosafety concerns, many of these unicellular fungi have been considered for biocontrol applications. Here, we review the fundamental research on the mechanisms (e.g., competition, enzyme secretion, toxin production, volatiles, mycoparasitism, induction of resistance) by which biocontrol yeasts exert their activity as plant protection agents. In a second part, we focus on five yeast species (Candida oleophila, Aureobasidium pullulans, Metschnikowia fructicola, Cryptococcus albidus, Saccharomyces cerevisiae) that are or have been registered for the application as biocontrol products. These examples demonstrate the potential of yeasts for commercial biocontrol usage, but this review also highlights the scarcity of fundamental studies on yeast biocontrol mechanisms and of registered yeast-based biocontrol products. Yeast biocontrol mechanisms thus represent a largely unexplored field of research and plentiful opportunities for the development of commercial, yeast-based applications for plant protection exist.

Background Aureobasidium pullulans is a black-yeast-like fungus used for production of the polysaccharide pullulan and the antimycotic aureobasidin A, and as a biocontrol agent in agriculture. It can cause opportunistic human infections, and it inhabits various extreme environments. To promote the understanding of these traits, we performed de-novo genome sequencing of the four varieties of A. pullulans. Results The 25.43-29.62 Mb genomes of these four varieties of A. pullulans encode between 10266 and 11866 predicted proteins. Their genomes encode most of the enzyme families involved in degradation of plant material and many sugar transporters, and they have genes possibly associated with degradation of plastic and aromatic compounds. Proteins believed to be involved in the synthesis of pullulan and siderophores, but not of aureobasidin A, are predicted. Putative stress-tolerance genes include several aquaporins and aquaglyceroporins, large numbers of alkali-metal cation transporters, genes for the synthesis of compatible solutes and melanin, all of the components of the high-osmolarity glycerol pathway, and bacteriorhodopsin-like proteins. All of these genomes contain a homothallic mating-type locus. Conclusions The differences between these four varieties of A. pullulans are large enough to justify their redefinition as separate species: A. pullulans , A. melanogenum , A. subglaciale and A. namibiae . The redundancy observed in several gene families can be linked to the nutritional versatility of these species and their particular stress tolerance. The availability of the genome sequences of the four Aureobasidium species should improve their biotechnological exploitation and promote our understanding of their stress-tolerance mechanisms, diverse lifestyles, and pathogenic potential.

Aureobasidium pullulans is a yeast-like fungus known for its commercial biomanufacturing of pullulan. This study explores the genome of A. pullulans NRRL 62031, highlighting its biosynthetic potential, metabolic pathways, and physiological traits. Additionally, it demonstrates actual product formation and links molecular features to biotechnological applications. Phylogenetic analysis suggested it might be closely related to Aureobasidium melanogenum . While the functional annotation revealed a wide carbohydrate catabolism, growth evaluation demonstrated that the microbe can utilize not only saccharides but also polyols and organic acids. The extracellular cellulolytic, xylanolytic, and pectinolytic activities were indicated by the formation of visible halos on agar plates. The antiSMASH pipeline, NCBI Blastp alignment, and product qualification confirmed that A. pullulans NRRL 62031 can produce melanin, pullulan, polymalate, and polyol lipids. Moreover, yanuthone D, burnettramic acid A, choline, fructooligosaccharides, gluconic acid, and β-glucan might be synthesized by A. pullulans NRRL 62031. The results clearly show the extraordinary potential of A. pullulans NRRL 62031 as a microbial chassis for valorizing biomass residues into value-added bioproducts. The strong catabolic and anabolic capacities indicate significant promise for biotechnological applications. The results are discussed in the context of metabolic engineering of Aureobasidium .

Aureobasidium is omnipresent and can be isolated from air, water bodies, soil, wood, and other plant materials, as well as inorganic materials such as rocks and marble. A total of 32 species of this fungal genus have been identified at the level of DNA, of which Aureobasidium pullulans is best known. Aureobasidium is of interest for a sustainable economy because it can be used to produce a wide variety of compounds, including enzymes, polysaccharides, and biosurfactants. Moreover, it can be used to promote plant growth and protect wood and crops. To this end, Aureobasidium cells adhere to wood or plants by producing extracellular polysaccharides, thereby forming a biofilm. This biofilm provides a sustainable alternative to petrol-based coatings and toxic chemicals. This and the fact that Aureobasidium biofilms have the potential of self-repair make them a potential engineered living material avant la lettre. Key points • Aureobasidium produces products of interest to the industry • Aureobasidium can stimulate plant growth and protect crops • Biofinish of A. pullulans is a sustainable alternative to petrol-based coatings • Aureobasidium biofilms have the potential to function as engineered living materials

Honeybee ( Apis mellifera ) is an important agricultural pollinator and a model for sociality. In this study, a deep knowledge on yeast community characterizing the honeybees’ environmental was carried out. For this, a total of 93 samples were collected: flowers as food sources, bee gut mycobiota, and bee products (bee pollen, bee bread, propolis), and processed using culture-dependent techniques and a molecular approach for identification. The occurrence of yeast populations was quantitatively similar among flowers, bee gut mycobiota, and bee products. Overall, 27 genera and 51 species were identified. Basidiomycetes genera were predominant in the flowers while the yeast genera detected in all environments were Aureobasidium , Filobasidium , Meyerozyma , and Metschnikowia . Fermenting species belonging to the genera Debaryomyces , Saccharomyces , Starmerella , Pichia , and Lachancea occurred mainly in the gut, while most of the identified species of bee products were not found in the gut mycobiota. Five yeast species, Meyerozyma guilliermondii , Debaryomyces hansenii , Hanseniaspora uvarum , Hanseniaspora guilliermondii , and Starmerella roseus , were present in both summer and winter, thus indicating them as stable components of bee mycobiota. These findings can help understand the yeast community as a component of the bee gut microbiota and its relationship with related environments, since mycobiota characterization was still less unexplored. In addition, the gut microbiota, affecting the nutrition, endocrine signaling, immune function, and pathogen resistance of honeybees, represents a useful tool for its health evaluation and could be a possible source of functional yeasts. Key points • The stable yeast populations are represented by M. guilliermondii, D. hansenii, H. uvarum, H. guilliermondii, and S. roseus. • A. pullulans was the most abondance yeast detective in the flowers and honeybee guts. • Aureobasidium , Meyerozyma, Pichia, and Hanseniaspora are the main genera resident in gut tract.