Hugo Streekstra

Downstream processing, extraction, and purification of single cell oils.

Publisher Summary There is a common problem of biomass recovery from the fermenter and the subsequent extraction of the oil. Therefore, for the Single Cell Oils (SCOs) that are rich in a particular Polyunsaturated Fatty Acid (PUFA), there is a need to avoid sustained high temperatures or conditions that could lead to the oxidation and rancidity of the oils during their extraction. The first commercially viable SCO process was the production of an oil rich in Gamma-Linolenic Acid (GLA) from Mucor circinelloide . Examination of the first batch of oil extracted from M. circinelloides indicated the presence of free fatty acids at about 3%–5% of the total oil, which then contributed certain undesirable characteristics to the oil. These free fatty acids were quickly realized to be artifacts of the downstream processing system, as they were not present if the oil was quickly extracted from small samples of biomass taken from laboratory level fermenters. Over 98% of the oil within the cells of M. circinelloides could be extracted directly, using hexane, in one of the speciality extractors. Once the oil is extracted, its further refinement and purification follows conventional procedures.

Trichoderma longibrachiatum acetyl xylan esterase 1 enhances hemicellulolytic preparations to degrade corn silage polysaccharides.

Supplementation of a Trichoderma longibrachiatum preparation to an industrial Aspergillus niger/Talaromyces emersonii enzyme mixture demonstrated synergy for the saccharification of corn silage water-unextractable solids (WUS). Sub-fractions of the crude T. longibrachiatum preparation obtained after chromatography were analyzed regarding their hydrolytic activity. An acetyl xylan esterase 1 [Axe1, carbohydrate esterase (CE) family 5]-enriched sub-fraction closely mimicked the hydrolytic gain as obtained by supplementation of the complete, crude enzyme mixture (increase of 50%, 62% and 29% for Xyl, Ara and Glc, respectively). The acetic acid released from model polysaccharides (WUS) and oligosaccharides [neutral (AcXOS) and acidic (AcUXOS) xylo-oligosaccharides] by Axe1 was two and up to six times higher compared to the acetic acid released by acetyl xylan esterase A (AxeA, CE 1). Characterization of Axe1 treated AcXOS and AcUXOS revealed deacetylation of oligosaccharides that were not deacetylated by AxeA or the A. niger/T. emersonii preparation.

Arachidonic Acid: Fermentative Production by Mortierella Fungi

Publisher Summary Arachidonic Acid (ARA) is a Long-Chain Polyunsaturated Fatty Acid (LCPUFA) with 20 carbon atoms and four double bonds. Currently, the commercial demand for ARA is dominated by its application in infant formula. Plants do not contain significant levels of LCPUFA. In the case of ARA, well-accepted and concentrated animal sources are not available, even though most of the ARA in the diet does come from animal-derived foods. Therefore, microbial sources have been sought and found. ARA accounts for more than 25% of the fatty acids in Mortierella renispora lipids. The genus Mortierella is a place to search for ARA-producing strains, because the highest levels of ARA are found there. The vast majority of strains currently considered to belong to the genus Mortierella produce ARA and M. Alpina stands out as a high producer, with it often exceeding 50% of the total fatty acids found in this microorganism. This chapter discusses the fermentation conditions for ARA production with M. Alpina. The ARA production process with M. Alpina is the only current example of a commercial fungal lipid being produced by full-scale fermentation, extraction, and refining. The process takes place in 200 m3 fermenters in the U.S. An increasingly filled molecular biological toolbox would allow efficient production of a whole range of relevant LCPUFAs in this organism and in other fungi.

Fast and Robust Method To Determine Phenoyl and Acetyl Esters of Polysaccharides by Quantitative 1H NMR

The acetyl (AcE), feruloyl (FE), and p-coumaroyl (pCE) ester contents of different cereal and grass polysaccharides were determined by a quantitative ¹H NMR-based method. The repeatability and the robustness of the method were demonstrated by analyzing different plant polysaccharide preparations. Good sensitivity and selectivity for AcE, FE, and pCE were observed. Moreover, an optimized and easy sample preparation allowed for simultaneous quantification of AcE, FE, and pCE. The method is suitable for high-throughput analysis, and it is a good alternative for currently used analytical procedures. A comparison of the method presented to a conventional HPLC-based method showed that the results obtained are in good agreement, whereas the combination of the optimized sample preparation and analysis by the ¹H NMR-based methodology results in significantly reduced analysis time.