Improving the enantioselective bioreduction of aromatic ketones mediated by Aspergillus terreus and Rhizopus oryzae: the role of glycerol as a co-solvent

The improvement of the enzymatic performance of Aspergillus terreus and Rhizopus oryzae in enantioselective bioreductions by using glycerol as a co-solvent has been studied. In the most of the bioreductions, glycerol has demonstrated its potential for improved conversions (up to >99%) and enantioselectivities (up to >99%) when compared to reactions in aqueous or other aqueous-organic media (THF, diethyl ether, toluene, DMSO and acetonitrile). Moreover, high isolated yields of the desired chiral alcohols have been obtained on a preparative scale showing the great potential of this green solvent in biocatalysis. (C) 2009 Elsevier Ltd. All rights reserved.

Biotransformation of alpha-Bromoacetophenones by the Marine Fungus Aspergillus sydowii

The biotransformation reactions of alpha-bromoacetophenone (1), p-bromo-alpha-bromoacetophenone (2), and p-nitro-alpha-bromoacetophenone (3) by whole cells of the marine fungus Aspergillus sydowii Ce19 have been investigated. Fungal cells that had been grown in artificial sea water medium containing a high concentration of chloride ions (1.20 M) catalysed the biotransformation of 1 to 2-bromo-1-phenylethanol 4 (56%), together with the alpha-chlorohydrin 7 (9%), 1-phenylethan-1,2-diol 9 (26%), acetophenone 10 (4%) and phenylethanol 11 (5%) identified by GC-MS analysis. In addition, it was observed that the enzymatic reaction was accompanied by the spontaneous debromination of 1 to yield alpha-chloroacetophenone 5 (9%) and alpha-hydroxyacetophenone 6 (18%) identified by GC-FID analysis. When 2 and 3 were employed as substrates, various biotransformation products were detected but the formation of halohydrins was not observed. It is concluded that marine fungus A. sydowii Ce19 presents potential for the biotransformations of bromoacetophenone derivatives.

Pectinase production by solid fermentation from Aspergillus niger by a new prescription experiment

The Ordos Plateau in China is covered with up to 300,000 ha of peashrub (Caragana) which is the dominant natural vegetation and ideal for fodder production. To exploit peashrub fodder, it is crucially important to optimize the culture conditions, especially culture substrate to produce pectinase complex. In this study, a new prescription process was developed. The process, based on a uniform experimental design, first optimizes the solid substrate and second, after incubation, applies two different temperature treatments (30 °C for the first 30 h and 23°C for the second 42 h) in the fermentation process. A multivariate regression analysis is applied to a number of independent variables (water, wheat bran, rice dextrose, ammonium sulfate, and Tween 80) to develop a predictive model of pectinase activity. A second-degree polynomial model is developed which accounts for an excellent proportion of the explained variation (R² = 97:7%). Using unconstrained mathematical programming, an optimized substrate prescription for pectinase production is subsequently developed. The mathematical analysis revealed that the optimal formula for pectinase production from Aspergillus niger by solid fermentation under the conditions of natural aeration, natural substrate pH (about 6.5), and environmental humidity of 60% is rice dextrose 8%, wheat bran 24%, ammonium sulfate ((NH₄)₂SO₄) 6%, and water 61%. Tween 80 was found to have a negative effect on the production of pectinase in solid substrate. With this substrate prescription, pectinase produced by solid fermentation of A. niger reached 36.3 IU/(g DM). Goats fed on the pectinase complex obtain an incremental increase of 0:47 kg day^-1 during the initial 25 days of feeding, which is a very promising new feeding prospect for the local peashrub. It is concluded that the new formula may be very useful for the sustainable development of arid and semiarid pastures such as those of the Ordos Plateau.

Purification and characterization of naringinase from a newly isolated strain of Aspergillus niger 1344 for the transformation of flavonoids

An extracellular naringinase (an enzyme complex consisting of α-L-rhamnosidase and β-D-glucosidase activity, EC 3.2.1.40) that hydrolyses naringin (a trihydroxy flavonoid) for the production of rhamnose and glucose was purified from the culture filtrate of Aspergillus niger 1344. The enzyme was purified 38-fold by ammonium sulphate precipitation, ion exchange and gel filtration chromatography with an overall recovery of 19% with a specific activity of 867 units per mg of protein. The molecular mass of the purified enzyme was estimated to be about 168 kDa by gel filtration chromatography on a Sephadex G-200 column and the molecular mass of the subunits was estimated to be 85 kDa by sodium dodecyl sulphate-Polyacrylamide gel electrophoresis (SDS-PAGE). The enzyme had an optimum pH of 4.0 and temperature of 50 °C, respectively. The naringinase was stable at 37 °C for 72 h, whereas at 40 °C the enzyme showed 50% inactivation after 96 h of incubation. Hg2+, SDS, p-chloromercuribenzoate, Cu2+ and Mn2+ completely inhibited the enzyme activity at a concentration of 2.5–10 mM, whereas, Ca2+, Co2+ and Mg2+ showed very little inactivation even at high concentrations (10–100 mM). The enzyme activity was strongly inhibited by rhamnose, the end product of naringin hydrolysis. The enzyme activity was accelerated by Mg2+ and remained stable for one year after storage at −20 °C. The purified enzyme preparation successfully hydrolysed naringin and rutin, but not hesperidin.

Optimization of process parameters for the production of naringinase by Aspergillus niger MTCC 1344

Aspergillus niger MTCC 1344 was used to produce extracellular naringinase in a complex (molasses, yeast extract and salts) medium. An initial medium pH 4.5 and cultivation temperature 30 °C were optimal for enzyme production. Among various carbon and organic nitrogen sources used, molasses and peptone were the most effective for enzyme yield. The rate of enzyme production was enhanced when metal ions were added to the medium. Fermentation conditions are described which produced a higher rate of enzyme synthesis. An increase in initial sugar concentration from 6 to 10 g l⁻¹ in the fermentation medium produced decreased naringinase synthesis while cell mass growth increased with the increase of sugar concentration. At a higher sugar level (10 g l⁻¹) the production of cell mass decreased.

Aspergillus species, cyclic dimeric dipeptide derivative substance P antagonist biosynthetic products thereof, and process for preparation thereof

A novel Aspergillus species, cyclic dimeric dipeptide derivatives which are biosynthetic products thereof and are useful as Substance P antagonists and therefore as analgesic and/or antiinflammatory agents, and a process for preparation of the biosynthetic products are disclosed.

Plant extract assisted extracellular tannase production by Aspergillus sp MIK 23

An extracellular tannase (E.C. 3.1.1.20) producing fungal strain was isolated from soil and identified as Aspergillus sp MIK23. Out of various plant extracts, Terminalia chebula powder (TCP) in the optimized medium enhanced enzyme production. Maximum yield of tannase (3 IU ml-1) was obtained with glucose (10 g/L), urea (2 g/L), and yeast extract (2.5 g/L) when inoculated with 10% inoculum in 48 h. An initial medium at pH 6.0 and a cultivation temperature of 37 0C was found to be optimum for enzyme production. Metal ions Mg2+, Zn2+, Ca2+, Cu2+ and Cd2+ did not improve enzyme activity, whereas, Ca2+, Fe2+ and Hg2+ repressed enzyme activity. The enzyme was purified using ammonium sulfate precipitation followed by Q-sepharose ion-exchange chromatography. The enzyme was purified to 42-fold with an overall recovery of 20. The pH and temperature optima of the purified tannase were found to be 7.0 and 37°C, respectively.

Growth inhibition of Candida species and Aspergillus fumigatus by statins

Statins are a class of drugs widely used for lowering high cholesterol levels through their action on 3-hydroxy-3-methylglutaryl-CoA reductase, a key enzyme in the synthesis of cholesterol. We studied the effects of two major statins, simvastatin and atorvastatin, on five Candida species and Aspergillus fumigatus. The statins strongly inhibited the growth of all species, except Candida krusei. Supplementation of Candida albicans and A. fumigatus with ergosterol or cholesterol in aerobic culture led to substantial recovery from the inhibition by statins, suggesting specificity of statins for the mevalonate synthesis pathway. Our findings suggest that the statins could have utility as antifungal agents and that fungal colonization could be affected in those on statin therapy.

Invasive infections due to filamentous fungi other than Aspergillus: epidemiology and determinants of mortality

The epidemiology of invasive fungal disease (IFD) due to filamentous fungi other than Aspergillus may be changing. We analysed clinical, microbiological and outcome data in Australian patients to determine the predisposing factors and identify determinants of mortality. Proven and probable non-Aspergillus mould infections (defined according to modified European Organization for Research and Treatment of Cancer/Mycoses Study Group criteria) from 2004 to 2012 were evaluated in a multicentre study. Variables associated with infection and mortality were determined. Of 162 episodes of non-Aspergillus IFD, 145 (89.5%) were proven infections and 17 (10.5%) were probable infections. The pathogens included 29 fungal species/species complexes; mucormycetes (45.7%) and Scedosporium species (33.3%) were most common. The commonest comorbidities were haematological malignancies (HMs) (46.3%) diabetes mellitus (23.5%), and chronic pulmonary disease (16%); antecedent trauma was present in 21% of cases. Twenty-five (15.4%) patients had no immunocompromised status or comorbidity, and were more likely to have acquired infection following major trauma (p <0.01); 61 (37.7%) of cases affected patients without HMs or transplantation. Antifungal therapy was administered to 93.2% of patients (median 68 days, interquartile range 19-275), and adjunctive surgery was performed in 58.6%. The all-cause 90-day mortality was 44.4%; HMs and intensive-care admission were the strongest predictors of death (both p <0.001). Survival varied by fungal group, with the risk of death being significantly lower in patients with dematiaceous mould infections than in patients with other non-Aspergillus mould infections. Non-Aspergillus IFD affected diverse patient groups, including non-immunocompromised hosts and those outside traditional risk groups; therefore, definitions of IFD in these patients are required. Given the high mortality, increased recognition of infections and accurate identification of the causative agent are required.

Colonizacao intracavitaria pulmonar por aspergillus niger : analise de suas peculiaridades

Trezentos pacientes portadores de colonização intracavitária pulmonar (pelos exames soro lógico e/ou tecidual) foram investigados num período de 10 anos. Os casos foram classificados como: Aspergillus fumigatus (246 casos); Ao niger (21 casos); A. flavus (7 casos); Pseudallescheria boydii (1 caso); colonização fúngica não especificada (21 casos) e colonização actinomicética (4 casos). os grupos A. niger (çasos)e A. fumigatus (controles) foram comparados a respeito de variáveis clínicas e laboratoriais, por serem os mais freqUentes e pela pobreza da literatura sobre A. niger. Esta análise mostrou associações estatisticamente significativas com o A. niger para;sexo masculino (Razão de Chances = 3,28; p <0,05); infecção nosocomial, ocorrendo em hospitais de conservação precária (RC = 150,8; p< 0,001); tuberculose ativa (RC = 8,03; P <0,001); diabete mélito tipo 11 (RC = 10,67; p

Avaliação micológica de rações comerciais para cães e gatos e potencial micotoxinogênico de espécies selecionadas

A eficácia dos meios ágar batata acidificado, ágar dicloram rosa de bengala e cloranfenicol e ágar dicloram glicerol 18% foi comparada para isolamento e quantificação de fungos a partir da análise de 54 amostras de rações comerciais secas para cães e gatos (34 para cães e 20 para gatos), produzidas por 9 empresas. A atividade de água das amostras foi quantificada, apresentando valores entre 0,45 e 0,82. Em 74% das amostras foi detectada a presença fúngica, onde, além de fungos com micélio estéril e leveduras, 23 gêneros de fungos foram identificados. As 40 amostras positivas apresentaram níveis de contaminação, com contagens variando entre 101 e 103 UFC/g. Não se verificou correlação entre atividade de água e contaminação fúngica e não se observou diferença significativa entre o número de colônias isoladas e os diferentes meios de cultivo utilizados. Apesar disto, o DG18 foi o meio que apresentou melhores resultados tanto na quantidade quanto na variedade de fungos isolados. Comparando-se os resultados obtidos com diferentes meios observa-se que os microrganismos isolados dependem dos meios de cultivo empregados. O gênero Aspergillus e a espécie Aspergillus niger foram os mais freqüentemente isolados. Isolados pertencentes a espécies potencialmente produtoras de aflatoxinas e ocratoxina A foram avaliados através do método de ágar plug-TLC. Vinte por cento dos A. flavus isolados produziram aflatoxina B1, todos os isolados de A. ochraceus produziram ocratoxina A e nenhum isolado de A. niger foi detectado como produtor de ocratoxina através do método de screening utilizado. A avaliação fúngica realizada com o emprego de 3 meios de cultura tornou claro que a detecção de fungos é dependente do meio de cultura utilizado. A Aw do alimento e do meio também devem ser consideradas para que as análises microbiológicas possam detectar ou valorar a micobiota que, efetivamente, está contaminando o alimento.

Transcription of the Hsp30, Hsp70, and Hsp90 heat shock protein genes is modulated by the PalA protein in response to acid pH-sensing in the fungus Aspergillus nidulans

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Solubilization of CaHPO4 and AlPO4 by Aspergillus niger in culture media with different carbon and nitrogen sources

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Enhanced solubilization of iron and calcium phosphates by Aspergillus niger by the addition of alcohols

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Production of fibrolytic enzymes by Aspergillus japonicus C03 using agro-industrial residues with potential application as additives in animal feed

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)