Production of Bioactive Metabolites with Pharmaceutical and Nutraceutical Interest by Submerged Fermentation of Pleurotus ostreatus in a Batch Stirred Tank Bioreactor

摘要

Mushrooms comprise a vast and yet largely untapped source of powerful new pharmaceutical and nutraceutical products. Submerged fermentation of the mycelial form of mushroom-producing fungi is viewed promising for efficient production of their biomass and active metabolites, comparing with the established time-consuming and labor-intensive field-cultivation of the fruiting bodies. The aim of this study was the isolation and identification of bioactive metabolites derived from the edible mushroom Pleurotus ostreatus (strain ATHUM 4438) biomass, produced by submerged fermentation in a batch stirred tank bioreactor. The biomass was initially extracted using a system of Accelerated Solvent Extraction (ASE). The dichloromethane extract was fractioned by medium pressure liquid chromatography (MPLC) and Sephadex LH-20 column chromatography. For extracting efficiently the phenolic compounds of the methanolic extract, an adsorption-desorption process, using XAD-4 type resin, was performed. The isolation procedure of the resulting phenolic fraction was accomplished by Fast Centrifugal Partition Chromatography (FCPC), Sephadex LH-20 column chromatography and preparative HPLC-TLC. The pure compounds were elucidated with 1D/2D NMR-spectroscopic analyses, NMR data comparisons, and chemical correlations combined with GC/MS-LC/MS experiments. The compounds afforded by the dichloromethane extract were identified as linoleic acid (1), oleic acid (2), stearic acid (3), palmitic acid (4) and their corresponding methyl esters (5-8, respectively), benzoic acid (9), trans 3, 4-dihydro-3, 4, 8-trihydroxynapthalen-1(2H)-one (10), 4-hydroxybenzaldehyde (11), indolo-3-carboxylic acid (12) and uracil (13). The investigation of the methanolic extract led to the isolation of 3-formyl-pyrrole (14), 4-hydroxy-benzoic acid (15), uridine (16), nicotinic acid (17) and nicotinamide (18). Based on existing literature data, all these compounds exhibit valuable biological properties. Most importantly, compounds (10), (12), (14) and (15) have not been reported again for this mushroom strain. The information obtained in this work is considered fundamental for the further investigation of the P. ostreatus fermentation process on an industrial scale for enhanced bioactive metabolite production.