The effect of production conditions on gene expression levels of inulinase of Aspergillus wentii NRLL 1778

In this study, the production of inulinase from Aspergillus wentii, the optimum conditions of that production and how those conditions influence gene expression levels of the enzyme were examined. For inulinase of A. wentii, the time of production was determined as 3 days, the temperature of production as 30°C, the starting pH of the production medium as 6.0, and concentration of Jerusalem artichoke added in to production medium as 3%. When the effect of C and N resources added to growth mediums on inulinase activity was investigated, the highest activity was observed in the medium containing 1% maltose. The medium containing 1% (NH4)2HPO4 was determined to be best growth medium. The enzyme was observed to be stable at pH 5.0-6.0 and to maintain its activity at 50°C for 30 minutes. It was found that gene expression was maximum at 2% Jerusalem artichoke concentration, pH 6.0, 35°C on the 1st day of production. The enzyme gene expression levels were higher compared to other studied resources when 1% cellulose was used as the carbon resource and 1% NH4H2PO4 as the nitrogen resource.

Structural Revision of Wentiquinone C and Related Congeners from Anthraquinones to Xanthones Using Chemical Derivatization and NMR Analysis

Wentiquinone C, which was previously isolated from the marine brown alga-derived endophytic fungus Aspergillus wentii EN-48, was found to be a potent antioxidant against α,α-diphenyl-picrylhydrazyl (DPPH) radical. The structure of wentiquinone C was originally assigned as an anthraquinone derivative (1,10-dihydroxy-3-(hydroxymethyl)-8-methoxydibenzo [b,e]oxepine-6,11-dione, 1) by 1D and 2D NMR experiments. However, the minor differences of the chemical shifts between xanthones and anthraquinones were queried, leading to the structure of 1 to be revised as a xanthone analog (8-hydroxy-6-(hydroxymethyl)-3-methoxy-9-oxo-9H-xanthene-1-carboxylic acid, 2) on the basis of a methylation and subsequent NMR measurements, and was confirmed by X-ray crystallographic analysis. The method established in this paper could be applied to the structural re-examination or revision for some of the reported seco-anthraquinone derivatives.

20-Nor-Isopimarane Epimers Produced by Aspergillus wentii SD-310, a Fungal Strain Obtained from Deep Sea Sediment

Four new uncommon 20-nor-isopimarane diterpenoid epimers, aspewentins I−L (1–4), together with a new methylated derivative of 3, aspewentin M (5), were isolated from the deep sea sediment-derived fungus Aspergillus wentii SD-310. The very similar structures of these epimers made the separation and purification procedures difficult. The structures of compounds 1–5 were illustrated based on spectroscopic analysis, and the absolute configurations of compounds 1–5 were unambiguously determined by the combination of NOESY, time-dependent density functional (TDDFT)-ECD calculations, and X-ray crystallographic analysis. These metabolites represented the rare examples of 20-nor-isopimarane analogues possessing a cyclohexa-2,5-dien-1-one moiety. These compounds were tested for antimicrobial activities against human and aquatic pathogenic bacteria, as well as plant-pathogenic fungi. While compounds 1 and 2 exhibited inhibitory activities against zoonotic pathogenic bacteria such as Escherichia coli, Edwardsiella tarda, Vibrio harveyi, and V. parahaemolyticus, compound 5 showed potent activity against the plant pathogen Fusarium graminearum.

Invertase Production by Fungi, Characterization of Enzyme Activity and Kinetic Parameters

The present paper presents the results of research carried out on 14 fungal isolates of various origins aiming to select new efficient sources for invertase production for further biotechnological application. Aspergillus flavus presented the highest protein content and Aspergillus niger, the most intense invertase activity. The relationship between enzyme concentration and enzymatic activity at 0.25 mM mL-1sucrose as substrate assayed for successive decimal dilutions of Aspergillus niger enzyme ranging from 0.1 to 1mlLrevealed a linear correspondence between 0.1 and 0.5mL. The kinetic parameters Michaelis-Menten constant (Km) and maximal velocity (Vmax) for invertase activity of Aspergillus niger, Penicillium aurantiogriseum, Aspergillus wentii and Rhizopus stolonifer were calculated. The determination coefficients R2 calculated from Lineweaver-Burk plots presented values very close or equal to 1.

Biotransformation of Androst-4-Ene-3,17-Dione by Some Fungi

The incubations of androst-4-ene-3,17-dione with Aspergillus candidus MRC 200634, Aspergillus tamarii MRC 72400, Aspergillus wentii MRC 200316 and Mucor hiemalis MRC 70325 for 5 days are reported. A. candidus MRC 200634 mainly hydroxylated androst-4-ene-3,17-dione at C-11α, C-15α and C-15β whilst A. wentii MRC 200316 hydroxylated it mainly at C-6β. A. tamarii MRC 72400 showed predominately a Baeyer–Villiger monooxygenase activity. M. hiemalis MRC 70325 hydroxylated the substrate at C-14α and reduced most of it at C-17.