Short communicationγ-Linolenic acid production by solid-state fermentation of Mucorales strains on cereals
Introduction
γ-Linolenic acid (GLA, cis,cis,cis-6,9,12-octadecatrienoic acid), is an intermediate in the transformation of linolenic acid into prostaglandins, which play an important physiological role in the organism. In certain pathological conditions, such as diabetes, cancer, virus infection, as well as ageing, the enzyme Δ-6 desaturase that catalyses the conversion of linoleic acid into GLA is less active, thus leading to deficient prostaglandins synthesis. Furthermore, GLA deficiency has been associated with some skin disorders (Horrobin, 1992). This dietary supply of GLA has been suggested as useful to prevent these situations, but GLA is very rare in common food, so that specific sources of this fatty acid need to be provided. The GLA used in pharmacological preparations is generally obtained from the seed oil of several plants such as evening primrose, borage and blackcurrants. The first industrial process for the production of GLA by cultivation of oleaginous fungi was developed in the UK using Mucor circinelloides (Ratledge, 1993). Despite the good yields and quality of the product, the process proved unprofitable, due to marketing difficulties. Currently, a biotechnological process is successfully applied on the industrial scale in Japan using GLA producers of the genus Mortierella and Mucor. A further improvement in productivity was recently obtained growing a new mutant of Mortierella ramanniana in a Maxblend fermentor (Certik and Shimizu, 1999). Other fungi of the order Mucorales have been reported as promising GLA producers and various substrates and fermentation techniques have been applied in the attempt to enhance GLA production and make the fermentation process competitive with the traditional extraction from plant sources. In particular, fermentation on various solid substrates such as cereals (Emelyanova, 1996) and apple pomace (Stredansky et al., 2000) may be of potential use on the industrial scale. Solid-state fermentation (SSF) offers several advantages over the more commonly applied liquid submerged fermentation (LSF). Solid fermentation techniques entail low capital cost and low energy expenditure. The solid substrates are normally obtained at a low price as raw products or residues of agro and food-industries, yet they provide a concentrated source of most nutrients required for microbial growth and metabolite production. Furthermore, the environmental impact of the SSF process is usually lower than for LSF, since low wastewater is produced in the former, while the exhausted biomass, rich in assimilable proteins, can often be used to feed farm animals. In this work, various cereals were supplied as nutrient substrates to a number of fungal strains of the Mucorales, that were screened for GLA production. The fermentation process was optimised using the producing strain Cunninghamella elegans CCF 1318.
Section snippets
Methods
Micro-organisms maintenance and inoculum preparation. The fungal strains screened for GLA production are listed in Table 1. Stock cultures were maintained on Czapek–Dox agar slants at 4°C. The spore suspension used as inoculum was prepared by washing the mycelium, grown on Sabouraud agar for 4 days at 28°C, with a sterile aqueous solution of Tween 80 (0.1% w/v), obtaining ca. 1×105 spores/ml.
Cultivation in Erlenmeyer flasks. For strain screening and substrate selection, 500 ml Erlenmeyer flasks
Results and discussion
Screening of strains and substrate selection. Fungal strains of the order Mucorales were screened for GLA production on solid substrate consisting of pearl barley impregnated with a nutrient solution. Cunninghamella elegans CCF 1318 yielded the highest amounts of oil, with a favourable GLA content (Table 1), and was used in cultivations with various cereal substrates, as well as with combinations of cereals and oil (Table 2). Pearl barley cultivations resulted in the highest yields of fungal
References (11)
- et al.
Biosynthesis and regulation of microbial polyunsaturated fatty acid production
Journal of Bioscience and Bioengineering
(1999) γ-linolenic acid production by Cunninghamella japonica in solid state fermentation
Process Biochemistry
(1996)Nutritional and medical importance of γ-linolenic acid
Progress in Lipid Research
(1992)Recent process developments in solid state fermentations
Process Biochemistry
(1992)Single cell oils – have they a biotechnological future?
Trends in Biotechnology
(1993)
Cited by (56)
Biomanufacturing of γ-linolenic acid-enriched galactosyldiacylglycerols: Challenges in microalgae and potential in oleaginous yeasts
2023, Synthetic and Systems BiotechnologyFostering single cell oil synthesis by de novo and ex novo pathway in oleaginous microorganisms for biodiesel production
2022, Biofuels and Bioenergy: Opportunities and ChallengesMicrobial lipids for foods
2022, Trends in Food Science and TechnologyRecent advancements in biofuels production with a special attention to fungi
2021, Sustainable Biofuels: Opportunities and ChallengesBio-enrichment of oilseed cakes by Mortierella alpina under solid-state fermentation
2020, LWTCitation Excerpt :Oleaginous microorganisms that can accumulate up to 80% of their biomass as lipids are recognized as a good alternative to PUFAs production due to their capacity to produce, absorb and transform exogenous fatty acids (Béligon et al., 2016; Cantrell & Walker, 2009). Several microorganisms have already been used to produce PUFAs, such as mycobacteria (Mycobacterium phlei and M. smegmatis) and fungi, such as Cunninghamella elegans (Conti et al., 2001) and M. alpina (Jang et al., 2000). Fungi have some particularities that made them a potentially good source of PUFAs since they accumulate a high concentration of lipids with a certain fatty acid profile that may be modulated by the manipulation of the growth medium (Dyal & Narine, 2005; Mamani et al., 2019).