RESUMO
BACKGROUND: The genus Blastobotrys consists of at least 20 species. Disease in humans has been reported with B adeninivorans, B raffinosifermentans, B proliferans and B serpentis, mostly in immunocompromised patients and those with cystic fibrosis. OBJECTIVE: We report a lung infection secondary to B raffinosifermentans in a cystic fibrosis patient successfully treated with isavuconazole and review the literature of invasive infections caused this genus. We also evaluated clinical isolates in our laboratory for species identification and antifungal susceptibility. METHODS: Phylogenetic analysis was performed on a collection of 22 Blastobotrys isolates in our reference laboratory, and antifungal susceptibility patterns were determined for nine clinically available antifungals against 19 of these isolates. RESULTS: By phylogenetic analysis, 21 of the 22 isolates in our collection were identified as B raffinosifermentans and only 1 as B adeninivorans. Most were cultured from the respiratory tract, although others were recovered from other sources, including CSF and blood. Isavuconazole, caspofungin and micafungin demonstrated the most potent in vitro activity, followed by amphotericin B. In contrast, fluconazole demonstrated poor activity. The patient in this case responded to isavuconazole treatment for breakthrough infection due to B raffinosifermentans that was cultured from pleural fluid while on posaconazole prophylaxis post-bilateral lung transplantation for cystic fibrosis. CONCLUSIONS: Blastobotrys species are rare causes of infections in humans and primarily occur in immunocompromised hosts. In our collection, the majority of isolates were identified as B raffinosifermentans. To our knowledge, this is the first report of successful treatment of such an infection with isavuconazole.
Assuntos
Fibrose Cística/complicações , Nitrilas/uso terapêutico , Pneumonia , Piridinas/uso terapêutico , Saccharomycetales , Triazóis/uso terapêutico , Adulto , Anfotericina B/uso terapêutico , Antifúngicos/uso terapêutico , Fibrose Cística/microbiologia , Feminino , Fluconazol/uso terapêutico , Genes Fúngicos , Humanos , Terapia de Imunossupressão/efeitos adversos , Testes de Sensibilidade Microbiana , Micoses/complicações , Micoses/tratamento farmacológico , Filogenia , Pneumonia/tratamento farmacológico , Pneumonia/microbiologia , Pneumonia/patologia , Saccharomycetales/genética , Saccharomycetales/isolamento & purificação , Saccharomycetales/patogenicidadeRESUMO
Pectin is synthesized in a highly methylesterified form in the Golgi cisternae and partially de-methylesterified in muro by pectin methylesterases (PMEs). Arabidopsis thaliana produces a local and strong induction of PME activity during the infection of the necrotrophic fungus Botrytis cinerea. AtPME17 is a putative A. thaliana PME highly induced in response to B. cinerea. Here, a fine tuning of AtPME17 expression by different defence hormones was identified. Our genetic evidence demonstrates that AtPME17 strongly contributes to the pathogen-induced PME activity and resistance against B. cinerea by triggering jasmonic acid-ethylene-dependent PDF1.2 expression. AtPME17 belongs to group 2 isoforms of PMEs characterized by a PME domain preceded by an N-terminal PRO region. However, the biochemical evidence for AtPME17 as a functional PME is still lacking and the role played by its PRO region is not known. Using the Pichia pastoris expression system, we demonstrate that AtPME17 is a functional PME with activity favoured by an increase in pH. AtPME17 performs a blockwise pattern of pectin de-methylesterification that favours the formation of egg-box structures between homogalacturonans. Recombinant AtPME17 expression in Escherichia coli reveals that the PRO region acts as an intramolecular inhibitor of AtPME17 activity.
Assuntos
Proteínas de Arabidopsis/metabolismo , Arabidopsis/enzimologia , Botrytis/fisiologia , Hidrolases de Éster Carboxílico/metabolismo , Defensinas/metabolismo , Pectinas/metabolismo , Doenças das Plantas/imunologia , Arabidopsis/genética , Arabidopsis/imunologia , Arabidopsis/microbiologia , Proteínas de Arabidopsis/genética , Hidrolases de Éster Carboxílico/genética , Ciclopentanos/metabolismo , Defensinas/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Etilenos/metabolismo , Expressão Gênica , Isoenzimas , Oxilipinas/metabolismo , Doenças das Plantas/microbiologia , Regiões Promotoras Genéticas/genética , Proteínas Recombinantes , Saccharomycetales/genética , Saccharomycetales/metabolismoRESUMO
The biosurfactants have extensive applications in food and petroleum microbiology. The aims of this research were isolation and characterization of thermo-tolerant biosurfactants from highly producing yeast strains. The Bushnell Hass medium was used for screening the biosurfactant-producing yeasts. Biosurfactant presence was evaluated using oil displacement assay and surface tension test. The best biosurfactant-producing strain was named Candida keroseneae GBME-IAUF-2 and its 5.8s-rDNA sequence was deposited in GenBank, NCBI, under the accession number MT012957.1. The thin layer chromatography and Fourier-transform infrared spectroscopy analysis confirmed that the extracted biosurfactant was sophorolipid with a significant surface activity. The purified sophorolipid decreased the surface tension of water from 72 to 29.1 mN/m. Its maximum emulsification index, E24%, was recorded as 60% and preserved 92.06-97.25% of its original activity at 110-120°C. It also preserved 89.11% and 84.73% of its original activity in pH of 9.3 and 10.5, respectively. It preserved 96.66-100% of its original activity in saline extreme conditions. This is the first report of sophorolipid production by the yeast C. keroseneae. According to the high thermal, pH and saline stability, the sophorolipid produced by C. keroseneae GBME-IAUF-2 could be highly recommended for applications in microbial enhanced oil recovery as well as food industries as an excellent emulsifying agent.
Assuntos
Microbiologia Industrial , Petróleo/microbiologia , Saccharomycetales/metabolismo , Ácidos Oleicos/química , Ácidos Oleicos/metabolismo , RNA Ribossômico 5,8S/genética , Saccharomycetales/genética , Especificidade da EspécieRESUMO
S-adenosyl-l-methionine (SAM) is a highly valued chemical that can be used as a dietary supplement and has been used to treat depression, osteoarthritis, and liver problems as well. We adopted systems metabolic engineering strategies to improve SAM production in a high-producing strain (GS115/DS56). First, the cystathionine ß-synthase gene CYS4 was downregulated using a weak promoter PG12 to reduce the removal of homocysteine from SAM cycle, thus leading to a 48.8% increase in the SAM titer (1.68 g/L) from the strain G12-CBS, while preventing cysteine auxotrophy induced by deletion of this essential gene. Subsequently, the SAM titer of G12-CBS was improved to 13.01 g/L in 15-L fed-batch fermentation using the optimal l-methionine feeding strategy. Finally, based on comparative transcriptomics, five genes were chosen and overexpressed for further enhancement of SAM production. Among them, GDH2 and ACS2 exhibited positive effects, and the additional overexpression of GDH2 led to a 52.3% increase of titer (2.71 g/L) in shake flask culture. Therefore, the engineered Pichia pastoris strains can be utilized in industrial production of SAM using a simple and cost-effective process, and these approaches could be employed for improving the production of other chemicals by P. pastoris.
Assuntos
Engenharia Metabólica/métodos , S-Adenosilmetionina , Saccharomycetales , Reatores Biológicos , Fermentação , Perfilação da Expressão Gênica , S-Adenosilmetionina/análise , S-Adenosilmetionina/metabolismo , Saccharomycetales/genética , Saccharomycetales/metabolismo , Transcriptoma/genéticaRESUMO
The estrogen-like mycotoxin zearalenone (ZEN) is one of the most widely distributed contaminants especially in maize and its commodities, such as corn oil. ZEN degrading enzymes possess the potential for counteracting the negative effect of ZEN and its associated high safety risk in corn oil. Herein, we targeted enhancing the secretion of ZEN degrading enzyme by Pichia pastoris through constructing an expression plasmid containing three optimized expression cassettes of zlhy-6 codon and signal peptides. Further, we explored various parameters of enzymatic detoxification in neutralized oil and analyzed tocopherols and sterols losses in the corn oil. In addition, the distribution of degraded products was demonstrated as well by Agilent 6510 Quadrupole Time-of-Flight mass spectrometry. P. pastoris GSZ with the glucoamylase signal was observed with the highest ZLHY-6 secretion yield of 0.39 mg/mL. During the refining of corn oil, ZEN in the crude oil was reduced from 1257.3 to 13 µg/kg (3.69% residual) after neutralization and enzymatic detoxification. Compared with the neutralized oil, no significant difference in the total tocopherols and sterols contents was detected after enzymatic detoxification. Finally, the degraded products were found to be entirely eliminated by washing. This study presents an enzymatic strategy for efficient and safe ZEN removal with relatively low nutrient loss, which provides an important basis for further application of enzymatic ZEN elimination in the industrial process of corn oil production.
Assuntos
Biotecnologia/métodos , Óleo de Milho/química , Contaminação de Alimentos/análise , Saccharomycetales/enzimologia , Zearalenona/análise , Biocatálise , Óleo de Milho/análise , Contaminação de Alimentos/prevenção & controle , Expressão Gênica , Glucana 1,4-alfa-Glucosidase/genética , Glicosídeo Hidrolases/genética , Hidrólise , Plasmídeos , Saccharomycetales/genética , Zearalenona/metabolismo , beta-Frutofuranosidase/genéticaRESUMO
To meet the challenges of global health, vaccine design and development must be reconsidered to achieve cost of goods as low as 15¢ per dose. A new recombinant protein-based rotavirus vaccine candidate derived from non-replicative viral subunits fused to a P2 tetanus toxoid CD4(+) T cell epitope is currently under clinical development. We have sought to simplify the existing manufacturing process to meet these aims. To this end, we have taken a holistic process development approach to reduce process complexity and costs while producing a product with the required characteristics. We have changed expression system from Escherichia coli to Pichia pastoris, to produce a secreted product, thereby reducing the number of purification steps. However, the presence of proteases poses challenges to product quality. To understand the effect of fermentation parameters on product quality small-scale fermentations were carried out. Media pH and fermentation duration had the greatest impact on the proportion of full-length product. A novel acidic pH pulse strategy was used to minimize proteolysis, and this combined with an early harvest time significantly increased the proportion of full-length material (60-75%). An improved downstream process using a combination of CIEX and AIEX to further reduce proteases, resulted in maintaining product quality (95% yield).
Assuntos
Técnicas de Cultura Celular por Lotes , Infecções por Rotavirus/prevenção & controle , Vacinas contra Rotavirus/biossíntese , Saccharomycetales/genética , Fermentação/efeitos dos fármacos , Humanos , Concentração de Íons de Hidrogênio , Proteólise , Rotavirus/patogenicidade , Infecções por Rotavirus/virologia , Vacinas contra Rotavirus/química , Vacinas contra Rotavirus/genética , Saccharomycetales/químicaRESUMO
Citrus black spot (CBS) and post-bloom fruit drop (PFD), caused by Phyllosticta citricarpa and Colletotrichum abscissum, respectively, are two important citrus diseases worldwide. CBS depreciates the market value and prevents exportation of citrus fruits to Europe. PFD under favorable climatic conditions can cause the abscission of flowers, thereby reducing citrus production by 80%. An ecofriendly alternative to control plant diseases is the use of endophytic microorganisms, or secondary metabolites produced by them. Strain LGMF1631, close related to Diaporthe cf. heveae 1, was isolated from the medicinal plant Stryphnodendron adstringens and showed significant antimicrobial activity, in a previous study. In view of the potential presented by strain LGMF1631, and the absence of chemical data for secondary metabolites produced by D. cf. heveae, we decided to characterize the compounds produced by strain LGMF1631. Based on ITS, TEF1, and TUB phylogenetic analysis, strain LGMF1631 was confirmed to belong to D. cf. heveae 1. Chemical assessment of the fungal strain LGMF1631 revealed one new seco-dihydroisocoumarin [cladosporin B (1)] along with six other related, already known dihydroisocoumarin derivatives and one monoterpene [(-)-(1S,2R,3S,4R)-p-menthane-1,2,3-triol (8)]. Among the isolated metabolites, compound 5 drastically reduced the growth of both phytopathogens in vitro and completely inhibited the development of CBS and PFD in citrus fruits and flowers. In addition, compound 5 did not show toxicity against human cancer cell lines or citrus leaves, at concentrations higher than used for the inhibition of the phytopathogens, suggesting the potential use of (-)-(3R,4R)-cis-4-hydroxy-5-methylmellein (5) to control citrus diseases.
Assuntos
Ascomicetos/efeitos dos fármacos , Citrus/microbiologia , Fungicidas Industriais/farmacologia , Isocumarinas/farmacologia , Saccharomycetales/química , Ascomicetos/fisiologia , Colletotrichum/efeitos dos fármacos , Colletotrichum/fisiologia , Fabaceae/microbiologia , Frutas/microbiologia , Fungicidas Industriais/química , Fungicidas Industriais/metabolismo , Isocumarinas/química , Isocumarinas/metabolismo , Filogenia , Doenças das Plantas/microbiologia , Folhas de Planta/microbiologia , Saccharomycetales/classificação , Saccharomycetales/genética , Saccharomycetales/isolamento & purificaçãoRESUMO
Fungal endophytes are known to secrete a large array of secondary metabolites (phenols, flavonoids, indole acetic acid (IAA) etc.) that facilitate crops under stress conditions. Considering this, a potent plant growth promoting endophyte (SXSp1) from the spines and leaves of Solanum xanthocarpum L. has been isolated. The isolated strain ably secreted high quantities of indole-3-acetic acid, phenols and flavonoids. Also, it exhibited phosphate solubilization, siderophore and had 2,2 diphenyl-1-picrylhydrazyl (DPPH) scavenging activity. The SXSp1 also resisted the salinity stress up to 150 mM. LC/MS analysis of SXSp1 culture filtrate (CF) revealed the presence of p-hydroxyl benzoic acid, diadzein, genistien, myricetin and caffeoyl-d-glucose. Moreover, the inoculation of maize plants with SXSp1 significantly (P=0.05) promoted the chlorophyll and carotenoid contents, root and shoot lengths, plant fresh and dry weights, catalase and peroxidase activities, proline, phenolics, flavonoids and relative water contents (RWCs) under salinity. More interestingly, SXSp1-associated plants showed lower endogenous abscisic acid (ABA) and higher endogenous IAA contents that helped the plants to resist salinity stress up to 100 mM. After sequencing, internal transcribed spacer (ITS) regions (ITS1 and ITS4) and phylogenetic analysis, the SXSp1 was identified as Meyerozyma caribbica.
Assuntos
Folhas de Planta , Brotos de Planta , Saccharomycetales/metabolismo , Estresse Salino , Solanum/microbiologia , Zea mays , Folhas de Planta/crescimento & desenvolvimento , Folhas de Planta/microbiologia , Brotos de Planta/crescimento & desenvolvimento , Brotos de Planta/microbiologia , Saccharomycetales/genética , Zea mays/crescimento & desenvolvimento , Zea mays/microbiologiaRESUMO
Free fatty acids are basic oleochemicals implemented in a range of applications including surfactants, lubricants, paints, plastics, and cosmetics. Microbial fatty acid biosynthesis has gained much attention as it provides a sustainable alternative for petrol- and plant oil-derived chemicals. The yeast Starmerella bombicola is a microbial cell factory that naturally employs its powerful lipid metabolism for the production of the biodetergents sophorolipids (> 300 g/L). However, in this study we exploit the lipidic potential of S. bombicola and convert it from the glycolipid production platform into a free fatty acid cell factory. We used several metabolic engineering strategies to promote extracellular fatty acid accumulation which include blocking competing pathways (sophorolipid biosynthesis and ß-oxidation) and preventing free fatty acid activation. The best producing mutant (Δcyp52m1Δfaa1Δmfe2) secreted 0.933 g/L (± 0.04) free fatty acids with a majority of C18:1 (43.8%) followed by C18:0 and C16:0 (40.0 and 13.2%, respectively). Interestingly, deletion of SbFaa1 in a strain still producing sophorolipids also resulted in 25% increased de novo sophorolipid synthesis (P = 0.0089) and when oil was supplemented to the same strain, a 50% increase in sophorolipid production was observed compared to the wild type (P = 0.03). We believe that our work is pivotal for the further development and exploration of S. bombicola as a platform for synthesis of environmentally friendly oleochemicals.
Assuntos
Ácidos Graxos/biossíntese , Glicolipídeos/metabolismo , Saccharomycetales/metabolismo , Glicolipídeos/química , Metabolismo dos Lipídeos , Engenharia Metabólica , Oxirredução , Saccharomycetales/genéticaRESUMO
Aconitum carmichaelii, commonly known as Fuzi, is a typical traditional Chinese medicine (TCM) herb that has been grown for more than one thousand years in China. Although root rot disease has been seriously threatening this crop in recent years, few studies have investigated root rot disease in Fuzi, and no pathogens have been identified. In this study, fungal libraries from rhizosphere soils were constructed by internal transcribed spacer (ITS) sequencing using the HiSeq 2500 high-throughput platform. A total of 948,843 tags were obtained from 17 soil samples, and these corresponded to 195,583,495 nt. At 97% identity, the libraries yielded 12,266 operational taxonomic units (OTUs), of which 97.5% could be annotated. In sick soils, Athelia, Mucor and Mortierella were the dominant fungi, comprising 10.3%, 10.1% and 7.7% of the fungal community, respectively. These fungi showed 2.6-, 1.53- to 6.31- and 1.38- to 2.65-fold higher enrichment in sick soils compared with healthy soils, and their high densities reduced the fungal richness in the areas surrounding the rotted Fuzi roots. An abundance analysis suggested that A. rolfsii and Mucor racemosus, as the dominant pathogens, might play important roles in the invading Fuzi tissue, and Phoma adonidicola could be another pathogenic fungus of root rot. In contrast, Mortierella chlamydospora, Penicillium simplicissimum, Epicoccum nigrum, Cyberlindnera saturnus and Rhodotorula ingeniosa might antagonize root rot pathogens in sick soils. In addition, A. rolfsii was further verified as a main pathogen of Fuzi root rot disease through hypha purification, morphological observation, molecular identification and an infection test. These results provide theoretical guidance for the prevention and treatment of Fuzi root rot disease.
Assuntos
Aconitum/microbiologia , DNA Fúngico/genética , DNA Intergênico/genética , Fungos/genética , Raízes de Plantas/microbiologia , Microbiologia do Solo , Biodiversidade , Etiquetas de Sequências Expressas , Fungos/classificação , Fungos/isolamento & purificação , Fungos/patogenicidade , Biblioteca Genômica , Sequenciamento de Nucleotídeos em Larga Escala , Mortierella/classificação , Mortierella/genética , Mortierella/isolamento & purificação , Mortierella/patogenicidade , Penicillium/classificação , Penicillium/genética , Penicillium/isolamento & purificação , Penicillium/patogenicidade , Filogenia , Doenças das Plantas/microbiologia , Rizosfera , Rhodotorula/classificação , Rhodotorula/genética , Rhodotorula/isolamento & purificação , Rhodotorula/patogenicidade , Saccharomycetales/classificação , Saccharomycetales/genética , Saccharomycetales/isolamento & purificação , Saccharomycetales/patogenicidade , Solo/químicaRESUMO
The fungus Ashbya gossypii is an important industrial producer of riboflavin, i.e. vitamin B2. In order to meet the constantly increasing demands for improved production processes, it appears essential to better understand the underlying metabolic pathways of the vitamin. Here, we used a highly sophisticated set-up of parallel 13C tracer studies with labeling analysis by GC/MS, LC/MS, 1D, and 2D NMR to resolve carbon fluxes in the overproducing strain A. gossypii B2 during growth and subsequent riboflavin production from vegetable oil as carbon source, yeast extract, and supplemented glycine. The studies provided a detailed picture of the underlying metabolism. Glycine was exclusively used as carbon-two donor of the vitamin's pyrimidine ring, which is part of its isoalloxazine ring structure, but did not contribute to the carbon-one metabolism due to the proven absence of a functional glycine cleavage system. The pools of serine and glycine were closely connected due to a highly reversible serine hydroxymethyltransferase. Transmembrane formate flux simulations revealed that the one-carbon metabolism displayed a severe bottleneck during initial riboflavin production, which was overcome in later phases of the cultivation by intrinsic formate accumulation. The transiently limiting carbon-one pool was successfully replenished by time-resolved feeding of small amounts of formate and serine, respectively. This increased the intracellular availability of glycine, serine, and formate and resulted in a final riboflavin titer increase of 45%.
Assuntos
Metaboloma , Metabolômica/métodos , Óleos de Plantas/metabolismo , Riboflavina/biossíntese , Saccharomycetales/metabolismo , Espectrometria de Massas/métodos , Ressonância Magnética Nuclear Biomolecular/métodos , Riboflavina/genética , Saccharomycetales/genéticaRESUMO
Tarballs, the remnants of crude oil which change into semi-solid phase due to various weathering processes in the sea, are rich in hydrocarbons, including toxic and almost non-degradable hydrocarbons. Certain microorganisms such as fungi are known to utilize hydrocarbons present in tarballs as sole source of carbon for nutrition. Previous studies have reported 53 fungal taxa associated with tarballs. There is apparently no gene sequence-data available for the published taxa so as to verify the fungal identification using modern taxonomic tools. The objective of the present study is to isolate fungi from tarballs collected from Candolim beach in Goa, India and investigate their phylogenetic diversity based on 5.8S rRNA gene and the flanking internal transcribed spacer regions (ITS) sequence analysis. In the ITS-based NJ tree, eight tarball-associated fungal isolates clustered with 3 clades of Dothideomycetes and 2 clades of Saccharomycetes. To the best of our knowledge, this is the first study that has employed ITS-based phylogeny to characterize the fungal diversity associated with tarballs. Further studies are warranted to investigate the role of the tarball-associated fungi in degradation of recalcitrant hydrocarbons present in tarballs and the role of tarballs as carriers of human pathogenic fungi.
Assuntos
Petróleo/microbiologia , Saccharomycetales/isolamento & purificação , Alcatrões/química , Poluentes Químicos da Água , Praias/normas , Biodegradação Ambiental , DNA Fúngico/genética , DNA Espaçador Ribossômico , Humanos , Índia , Filogenia , Saccharomycetales/genética , Análise de Sequência de DNARESUMO
Leptographium qinlingensis is a fungal associate of the Chinese white pine beetle (Dendroctonus armandi) and a pathogen of the Chinese white pine (Pinus armandi) that must overcome the terpenoid oleoresin defenses of host trees. L. qinlingensis responds to monoterpene flow with abundant mechanisms that include export and the use of these compounds as a carbon source. As one of the fungal cytochrome P450 proteins (CYPs), which play important roles in general metabolism, CYP51 (lanosterol 14-α demethylase) can catalyze the biosynthesis of ergosterol and is a target for antifungal drug. We have identified an L. qinlingensis CYP51F1 gene, and the phylogenetic analysis shows the highest homology with the 14-α-demethylase sequence from Grosmannia clavigera (a fungal associate of Dendroctonus ponderosae). The transcription level of CYP51F1 following treatment with terpenes and pine phloem extracts was upregulated, while using monoterpenes as the only carbon source led to the downregulation of CYP5F1 expression. The homology modeling structure of CYP51F1 is similar to the structure of the lanosterol 14-α demethylase protein of Saccharomyces cerevisiae YJM789, which has an N-terminal membrane helix 1 (MH1) and transmembrane helix 1 (TMH1). The minimal inhibitory concentrations (MIC) of terpenoid and azole fungicides (itraconazole (ITC)) and the docking of terpenoid molecules, lanosterol and ITC in the protein structure suggested that CYP51F1 may be inhibited by terpenoid molecules by competitive binding with azole fungicides.
Assuntos
Proteínas Fúngicas/química , Proteínas Fúngicas/genética , Saccharomycetales/enzimologia , Esterol 14-Desmetilase/química , Esterol 14-Desmetilase/genética , Proteínas Fúngicas/efeitos dos fármacos , Floema/química , Filogenia , Extratos Vegetais/química , Extratos Vegetais/farmacologia , RNA Fúngico/efeitos dos fármacos , RNA Fúngico/metabolismo , RNA Mensageiro/efeitos dos fármacos , RNA Mensageiro/metabolismo , Saccharomycetales/efeitos dos fármacos , Saccharomycetales/genética , Homologia de Sequência do Ácido Nucleico , Esterol 14-Desmetilase/efeitos dos fármacos , Homologia Estrutural de Proteína , Terpenos/farmacologiaRESUMO
Genome-scale metabolic network models represent the link between the genotype and phenotype of the organism, which are usually reconstructed based on the genome sequence annotation and relevant biochemical and physiological information. These models provide a holistic view of the organism's metabolism, and constraint-based metabolic flux analysis methods have been used extensively to study genome-scale cellular metabolic networks. It is clear that the quality of the metabolic network model determines the outcome of the application. Therefore, it is critically important to determine the accuracy of a genome-scale model in describing the cellular metabolism of the modeled strain. However, because of the model complexity, which results in a system with very high degree of freedom, a good agreement between measured and computed substrate uptake rates and product secretion rates is not sufficient to guarantee the predictive capability of the model. To address this challenge, in this work we present a novel system identification based framework to extract the qualitative biological knowledge embedded in the quantitative simulation results from the metabolic network models. The extracted knowledge can serve two purposes: model validation during model development phase, which is the focus of this work, and knowledge discovery once the model is validated. This framework bridges the gap between the large amount of numerical results generated from genome-scale models and the knowledge that can be easily understood by biologists. The effectiveness of the proposed framework is demonstrated by its application to the analysis of two recently published genome-scale models of Scheffersomyces stipitis.
Assuntos
Redes e Vias Metabólicas/genética , Modelos Biológicos , Saccharomycetales/genética , Saccharomycetales/metabolismo , Biologia Computacional/métodos , Simulação por Computador , Análise do Fluxo Metabólico , Biologia de Sistemas/métodosRESUMO
The yeast Arxula adeninivorans is considered to be a promising producer of recombinant proteins. However, growth characteristics are poorly investigated and no industrial process has been established yet. Though of vital interest for strain screening and production processes, rationally defined culture conditions remain to be developed. A cultivation system was evolved based on targeted sampling and mathematical analysis of rationally designed small-scale cultivations in shake flasks. The oxygen and carbon dioxide transfer rates were analyzed as conclusive online parameters. Oxygen limitation extended cultivation and led to ethanol formation in cultures supplied with glucose. Cultures were inhibited at pH-values below 2.8. The phosphorus demand was determined as 1.55 g phosphorus per 100 g cell dry weight. Synthetic SYN6 medium with 20 g glucose l(-1) was optimized for cultivation in shake flasks by buffering at pH 6.4 with 140 mmol MES l(-1). Optimized SYN6 medium and operating conditions provided non-limited cultivations without by-product formation. A maximal specific growth rate of 0.32 h(-1) and short fermentations of 15 h were achieved. A pH optimum curve was derived from the oxygen transfer rates of differently buffered cultures, showing maximal growth between pH 2.8 and 6.5. Furthermore, it was shown that the applied medium and cultivation conditions were also suitable for non-limiting growth and product formation of a genetically modified A. adeninivorans strain expressing a heterologous phytase.
Assuntos
Proteínas Recombinantes/metabolismo , Saccharomycetales/crescimento & desenvolvimento , Meios de Cultura , Fermentação , Expressão Gênica , Glucose/metabolismo , Concentração de Íons de Hidrogênio , Técnicas Microbiológicas , Oxigênio/metabolismo , Fósforo/metabolismo , Saccharomycetales/genética , Saccharomycetales/metabolismoRESUMO
Hyperuricemia and its symptoms are becoming increasingly common worldwide. Elevated serum uric acid levels are caused by increased uric acid synthesis from food constituents and reduced renal excretion. Treatment in most cases involves reducing alcohol intake and consumption of meat and fish or treatment with pharmaceuticals. Another approach could be to reduce uric acid level in food, either during production or consumption. This work reports the production of recombinant urate oxidase by Arxula adeninivorans and its application to reduce uric acid in a food product. The A. adeninivorans urate oxidase amino acid sequence was found to be similar to urate oxidases from other fungi (61-65% identity). In media supplemented with adenine, hypoxanthine or uric acid, induction of the urate oxidase (AUOX) gene and intracellular accumulation of urate oxidase (Auoxp) was observed. The enzyme characteristics were analyzed from isolates of the wild-type strain A. adeninivorans LS3, as well as from those of transgenic strains expressing the AUOX gene under control of the strong constitutive TEF1 promoter or the inducible AYNI1 promoter. The enzyme showed high substrate specificity for uric acid, a broad temperature and pH range, high thermostability and the ability to reduce uric acid content in food.
Assuntos
Manipulação de Alimentos/métodos , Saccharomycetales/enzimologia , Urato Oxidase/metabolismo , Ácido Úrico/metabolismo , Adenina/metabolismo , DNA Fúngico/química , DNA Fúngico/genética , Estabilidade Enzimática , Perfilação da Expressão Gênica , Concentração de Íons de Hidrogênio , Hipoxantina/metabolismo , Dados de Sequência Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Saccharomycetales/genética , Análise de Sequência de DNA , Homologia de Sequência de Aminoácidos , Especificidade por Substrato , Temperatura , Urato Oxidase/química , Urato Oxidase/genéticaRESUMO
Nine methanol-assimilating yeast strains isolated from olive oil sediments in Slovenia, extra virgin olive oil from Italy and rotten wood collected in Hungary were found to form three genetically separated groups, distinct from the currently recognized yeast species. Sequence analysis from genes of the small subunit (SSU) rRNA, internal transcribed spacer region/5.8S rRNA, large subunit (LSU) rRNA D1/D2 domains and translational elongation factor-1α (EF-1α) revealed that the three closely related groups represent three different undescribed yeast species. Sequence analysis of the LSU rRNA gene D1/D2 domains placed the novel species in the Ogataea clade. The three novel species are designated as Ogataea kolombanensis sp. nov. (type strain: ZIM 2322(T) = CBS 12778(T) = NRRL Y-63657(T)), Ogataea histrianica sp. nov. (type strain: ZIM 2463(T) = CBS 12779(T) = NRRL Y-63658(T)) and Ogataea deakii sp. nov. (type strain: NCAIM Y.01896(T) = CBS 12735(T) = NRRL Y-63656(T)).
Assuntos
Microbiologia de Alimentos , Filogenia , Saccharomycetales/classificação , DNA Fúngico/genética , DNA Espaçador Ribossômico/genética , Hungria , Itália , Dados de Sequência Molecular , Técnicas de Tipagem Micológica , Azeite de Oliva , Fator 1 de Elongação de Peptídeos/genética , Óleos de Plantas , RNA Ribossômico 5,8S/genética , Subunidades Ribossômicas Maiores de Eucariotos/microbiologia , Saccharomycetales/genética , Saccharomycetales/isolamento & purificação , Análise de Sequência de DNA , Eslovênia , Madeira/microbiologiaRESUMO
The Sporopachydermia cereana species lives in decaying stems of cactus and is exceptionally rare as a human pathogen. A 57-year-old man with therapy-refractory acute promyelocytic leukaemia developed severe neutropaenia. After about 3 weeks of micafungin used as prophylaxis, he developed high fever, multiple pulmonary nodular infiltrates and a painful leg lesion. Blood culture yielded a yeast which was not identified by the Vitek 2 system. On ITS1-5.8S-ITS2 gene sequencing, the isolate was identified as S. cereana. Antifungal sensitivity by the Etest showed that the minimum inhibitory concentration for fluconazole was 0.75 µg/mL, and for anidulafungin, it was >32 µg/mL. He responded to liposomal amphotericin B but later died of Escherichia coli septicaemia. There were no cactus plants in the vicinity, suggesting that S. cereana might have alternative habitats.
Assuntos
Antifúngicos/uso terapêutico , Quimioprevenção/métodos , Equinocandinas/uso terapêutico , Fungemia/diagnóstico , Leucemia Promielocítica Aguda/complicações , Lipopeptídeos/uso terapêutico , Infecções Oportunistas/diagnóstico , Saccharomycetales/isolamento & purificação , DNA Fúngico/química , DNA Fúngico/genética , DNA Ribossômico/química , DNA Ribossômico/genética , DNA Espaçador Ribossômico/química , DNA Espaçador Ribossômico/genética , Infecções por Escherichia coli/complicações , Infecções por Escherichia coli/diagnóstico , Evolução Fatal , Fungemia/complicações , Fungemia/microbiologia , Fungemia/patologia , Humanos , Hospedeiro Imunocomprometido , Masculino , Micafungina , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Neutropenia/complicações , Neutropenia/diagnóstico , Infecções Oportunistas/complicações , Infecções Oportunistas/microbiologia , Infecções Oportunistas/patologia , Radiografia Torácica , Saccharomycetales/classificação , Saccharomycetales/genética , Sepse/complicações , Sepse/diagnóstico , Análise de Sequência de DNA , Pele/patologia , Tomografia Computadorizada por Raios XRESUMO
During an investigation of olive oil microbiota, three yeast strains were found to be divergent from currently classified yeast species according to the sequences of the D1/D2 domain of the gene encoding the rRNA large subunit (LSU) and the internal transcribed spacer region including the gene for 5.8S rRNA. Phylogenetic analysis revealed that these strains, designated CBS 12509, CBS 12510(T) and CBS 12511, represent a novel anascosporogenous species described herein as Yamadazyma terventina sp. nov; the type strain is DAPES 1924(T) (= CBS 12510(T) = NCAIM Y.02028(T)). This novel species was placed in the Yamadazyma clade, with Yamadazyma scolyti, Candida conglobata and Candida aaseri as closest relatives. Y. terventina differs from the above-mentioned species in the ability to strongly assimilate dl-lactate and weakly assimilate ethanol.
Assuntos
Microbiologia de Alimentos , Olea/microbiologia , Filogenia , Óleos de Plantas , Saccharomycetales/classificação , DNA Fúngico/genética , DNA Espaçador Ribossômico/genética , Itália , Dados de Sequência Molecular , Técnicas de Tipagem Micológica , Azeite de Oliva , Saccharomycetales/genética , Saccharomycetales/isolamento & purificação , Análise de Sequência de DNARESUMO
Blastoschizomyces capitatus is a rare fungal pathogen that may lead to fatal infections especially in immunosuppressive individuals. In this report, three cases of B.capitatus were presented. The patients were under treatment for acute myeloid leukemia and their blood cultures yielded B.capitatus. The patients clinical conditions deteriorated and they died despite amphotericin B treatment. The isolates were identified by conventional mycological methods and API 20C AUX (Bio-Mérieux, France) system. Antifungal susceptibility test of the strains was performed with Sensititre Yeast One Panel (Trek Diagnostic Systems, USA) and minimum inhibitory concentration (MIC) ranges for amphotericin B, caspofungin, fluconazole, itraconazole, voriconazole, posaconazole, and flucytosine were found as 0.5-1; > 16; 8-16; 0.5; 0.25; 0.5-1 and 0.06-0.25 µg/ml, respectively. Isolated strains were genotyped with RAPD-PCR (Random Amplified Polymorphic DNA-Polymerase Chain Reaction) using Cnd-3, Cnd-4, OPE-03, OPE-18 primers. The strains isolated from the first two cases were found to be genotypically identical, while the strain isolated from the third case was different. Genotypically identical isolates belonged to two patients who were admitted to the hospital with approximately 18 months interval. The other strain with a unique genotype, was isolated from a patient who was admitted to the hospital about two years later than the other two patients. In conclusion, B.capitatus should be considered as an important opportunistic pathogen especially in patients with hematologic malignancies. The data of this study demonstrated that the lowest MIC values for B.capitatus strains were with voriconazole.