Animal Fat as a Substrate for Production of n-6 Fatty Acids by Fungal Solid-State Fermentation

The method of solid-state fermentation (SSF) represents a powerful technology for the fortification of animal-based by-products. Oleaginous Zygomycetes fungi are efficient microbial cell factories used in SSF to valorize a wide range of waste and rest cereal materials. The application of this fermentation technique for utilization and biotransformation of animal-based materials represents a distinguished step in their treatment. In this study, for the first time, the strain Umbelopsis isabellina CCF2412 was used for the bioconversion of animal fat by-products to the fermented bioproducts enriched with n-6 polyunsaturated fatty acids, mainly γ-linolenic acid (GLA). Bioconversion of both cereals and the animal fat by-product resulted in the production of fermented bioproducts enriched with not just GLA (maximal yield was 6.4 mg GLA/g of fermented bioproduct), but also with high yields of glucosamine. Moreover, the fermentation on the cornmeal matrix led to obtaining bioproduct enriched with β-carotene. An increased amount of β-carotene content improved the antioxidant stability of obtained fermented bioproducts. Furthermore, the application of Fourier-transform infrared spectroscopy for rapid analysis and characterization of the biochemical profile of obtained SSF bioproducts was also studied.

Effect of supplementation with solid-state fermented feed in the diet of laying hens on egg qualitative variables

   The aim of this experiment was to evaluate the effect of the supplementation of laying hens diet with solid-state fermented feed on egg qualitative variables. The diet of laying hens was supplemented with 10% and 15% of solid-state feed fermented by the low filamentous fungal strain Mortierella alpina CCF 2861. For the trial, 30 Lohmann Brown classic layers, aged 17 weeks, were selected and individually weighed and divided into three groups (control and two experimental groups). The control group of laying hens was fed with basic feed mixture and the experimental groups received the same diet as a control group, but enriched with supplementation of solid-state fermented feed. The first experimental group was fed a diet supplemented with 10% of fermented feed and the second experimental group with 15% supplementation. The following egg qualitative variables were observed: the egg weight, Haugh units, quality grade, air cell depth, percentage of the shell, yolk and albumen, eggshell breaking force, pH of egg yolk and albumen, egg yolk colour, and antioxidant activity with the extent of lipid oxidation in egg yolk samples. The pH of yolk and albumen did not show differences between all examined eggs originating from the experimental groups of laying hens (p >0.05). The eggs from both experimental groups had a significantly higher eggshell hardness than eggs produced by the hens of the control group (p <0.05). Antioxidant activity of egg yolk of experimental samples increased with the supplementation of fermented feed in the diet of laying hens (p <0.05). The specific lightness of egg yolk colour increased significantly in the experimental group with 15% of supplementation (p <0.01). The obtained results showed that feeding laying hens with fermented feed positively affected the quality of produced eggs. This was the first study and further investigation before using the fermented feed in commercial laying hen farms is necessary.

Correction to: Production of high-value bioproducts enriched with γ-linolenic acid and β-carotene by filamentous fungi Umbelopsis isabellina using solid-state fermentations

Following publication of the original article (Tao et al. 2020), the authors reported a missing funding source in the ‘Acknowledgements’ section.

Conversion of waste materials into very long chain fatty acids by the recombinant yeast Yarrowia lipolytica

Erucic acid (C22:1Δ13) has several industrial applications including its use as a lubricant, surfactant and biodiesel and composite material constituent. It is produced by plants belonging to the Brassicaceae family, especially by the high erucic acid rapeseed. The ability to convert oleic acid into erucic acid is facilitated by FAE1. In this study, FAD2 (encoding Δ12-desaturase) was deleted in the strain Po1d to increase oleic acid content. Subsequently, FAE1 from Thlaspi arvense was overexpressed in Yarrowia lipolytica with the Δfad2 genotype. This resulted in the YL10 strain producing very long chain fatty acids, especially erucic acid. The YL10 strain was cultivated in media containing crude glycerol and waste cooking oil as carbon substrates. The cells grown using glycerol produced microbial oil devoid of linoleic acid, which was enriched with very long chain fatty acids, mainly erucic acid (9% of the total fatty acids). When cells were grown using waste cooking oil, the highest yield of erucic acid was obtained (887 mg L–1). However, external linoleic and α-linolenic were accumulated in cellular lipids when yeasts were grown in an oil medium. This study describes the possibility of conversion of waste material into erucic acid by a recombinant yeast strain.

Production of high-value bioproducts enriched with γ-linolenic acid and β-carotene by filamentous fungi Umbelopsis isabellina using solid-state fermentations

Solid-state fermentation is a useful tool for utilizing different plant-based materials as cultivation substrates in order to produce potentially high-value fermented bioproducts. The aim of the present study was to successfully prepare various types of such bioproducts, using a zygomycetous strain Umbelopsis isabellina CCF2412. Various legume and cereal substrates were utilized effectively, while a few of them were obtained from agricultural waste, which is particularly advantageous from ecological and economic point of view. A common feature of the produced fermented materials was the increased content of different polyunsaturated fatty acids and carotenoid pigments in these bioproducts. Subsequent to the optimization of the solid-state fermentation process using cornmeal as the cultivation substrate, bioproducts enriched with γ-linolenic acid (11.45 mg γ-linolenic acid per gram of bioproduct), β-carotene (50.90 μg β-carotene per gram of bioproduct), and various microbial sterols were obtained. Appropriate n–6/n–3 acid ratio and enrichment of other microbial substances, such as the pigments and sterols mentioned above, in the fermented bioproducts widens the applicability of these bioproducts in different industries. The fermented cereal bioproducts produced in the present study from fermented wheat bran substrate were used for evaluating their application as feed for broiler chicken, and satisfactory results were obtained. Therefore, the present study creates novel opportunities for improving the quality of fermented bioproducts obtained during solid-state fermentation processes, especially for application in the feed industry.

Dual production of polyunsaturated fatty acids and beta-carotene with Mucor wosnessenskii by the process of solid-state fermentation using agro-industrial waste

Solid-state fermentation is a technique employing microorganisms grown on a solid substrate in the absence of free water. The substrates used in this process are mostly waste from the agro-industry (brans, spent malt grains, distiller grains, etc.) that improves not only the economy of the process but also has positive effect on waste management problems. Zygomycetous fungi are not only able to grow in such conditions but also enrich fermented materials with various types of bioactive compounds. Mucor sp. strains have been identified as producers of gamma-linolenic acid and beta-carotene in submerged fermentation. The aim of the present study was to identify the best microbial producer of gamma-linolenic acid and beta-carotene among four different Mucor strains and to study the requirements for the dual production of these metabolites. Mucor wosnessenskii was identified as the most suitable producer of both metabolites. After optimization of the fermentation conditions, the highest yields obtained were 10.7 g of gamma-linolenic acid/kg of fermented product and 261.5 mg of beta-carotene/kg of fermented product. This yield of beta-carotene is the highest among the results published so far.