Rapeseed meal hydrolysate as substrate for microbial astaxanthin production

Abstract

Rapeseed meal, a by-product of oil processing industry, was evaluated as a substrate for astaxanthin production by the yeast Xanthophyllomyces dendrorhous DSMZ 5626. Four commercial enzymes were tested at different concentrations (1-15 %, v/v) for their ability to break down the cellulosic and hemicellulosic compounds of rapeseed meal into fermentable sugars. Viscozyme® L and cellulase demonstrated the highest glucose recovery yields (47-52%, w/w for 15 % (v/v) of enzyme loading) with 7-11 g/l of net glucose released in the hydrolysates. Pectinase and Accellerase® hydrolysates supported the best cell growth and astaxanthin production in batch shake flask cultures, with maximum biomass of 26 g/l and 15 g/l, respectively, and astaxanthin yields (YP/X) of 258 to 332 µg per g of biomass. In batch bioreactor trials, pectinase hydrolysates resulted in high biomass (42 g/l) and astaxanthin production (11 mg/l) aided by the presence of glycerol (originating from the enzyme formulation) which served as additional energy and carbon source. Finally, simple glass beads disruption lead into satisfactory astaxanthin extraction (95 %, w/w) in acetone. The findings of this study generate knowledge towards scale-up potential of microbial astaxanthin production using rapeseed meal hydrolysate as fermentation feedstock.

Importance of Downstream Processing of Natural Astaxanthin for Pharmaceutical Application

“…In the case of N-ASX extraction, ethanol, acetone, hexane, isopropyl alcohol, dichloromethane, and dimethyl sulfoxide (DMSO) are the most used, and the FDA classifies them as low risk to human health; they are approved, under certain limits, for their use in pharmaceuticals (FDA, 2020). The solvents' effectiveness is related to their polarity and their capacity to permeate through the cell wall and cell membrane (Harith et al, 2019). Harith et al (2019) compared ethanol, methanol, DMSO, and acetone, combined with simple glass beads disruption, in N-ASX extraction from P. rhodozyma.…”

“…The solvents' effectiveness is related to their polarity and their capacity to permeate through the cell wall and cell membrane (Harith et al, 2019). Harith et al (2019) compared ethanol, methanol, DMSO, and acetone, combined with simple glass beads disruption, in N-ASX extraction from P. rhodozyma. Although N-ASX was shown to have a lower solubility in acetone than in DMSO, the extraction efficiency was 95% and 40%, respectively.…”

Use of the Versatility of Fungal Metabolism to Meet Modern Demands for Healthy Aging, Functional Foods, and Sustainability

“…A yeast species, Yarrowia lipolytica , was engineered by introducing genes for the production of β-ketolase and β-hydroxylase of seaweed and bacteria origin, increasing the yield of astaxanthin (7) (285 ± 19 mg/L; 47% of total carotenoids) [ 54 ]. This was a great achievement, given the lower productivity of astaxanthin (7) by yeasts like Xanthophyllomyces dendrorhous (10.2 mg/L) [ 55 ] and microalgae like Haematococcus pluvialis (84.8 mg/L) [ 56 ] and Chlorella zofingiensis (12.5 mg/L) [ 57 ]. Astaxanthin (7) has a high market value (USD 2500–7000/kg), 5–20 times higher than that of β-carotene (6) produced by the microalga Dunaliella salina (USD 300–500/kg) [ 54 , 58 ].…”

Anaerobic Digestion of Steam-Exploded Wheat Straw and Co-Digestion Strategies for Enhanced Biogas Production

“…The significantly lower concentration of lignin and higher presence of hemicellulosic carbohydrates that are present in DDGS and RM (Table 1) can partially explain the enhanced methane production. RM and DDGS also contain other, more assimilable carbohydrates, such as pectin [37], as well as beta-glucans [20]. It is possible that due to the differences in the hemicellulosic carbohydrates of the feedstocks, the microorganisms of the system had increased affinity towards pectin or beta-glucans, as opposed to arabinoxylans in straw, leading into enhanced biomethanation.…”