Abstract
One of the most addressed topics today is the transfer from a linear model of economics to a model of circular economics. It is a discipline that seeks to eliminate waste produced by various industries. The food industry generates huge amounts of waste worldwide, particularly the coffee industry, and related industries produce millions of tons of waste a year. These wastes have potential utility in biotechnology, and in the production of energy, fuels, fertilizers and nutrients, using green techniques such as anaerobic digestion, co-digestion, composting, enzymatic action, and ultrasonic and hydrothermal carbonization. This work is focused on the biotechnological use of processed spent coffee grounds (SCG) and waste fat/oil materials by some Sporidiobolus sp. carotenogenic yeasts in the model of circular economics. The results show that selected yeast strains are able to grow on SCG hydrolysate and are resistant to antimicrobial compounds present in media. The most productive strain Sporidiobolus pararoseus CCY19-9-6 was chosen for bioreactor cultivation in media with a mixture of coffee lignocellulose fraction and some fat wastes. Sporidiobolus pararoseus CCY19-9-6 was able to produce more than 22 g/L of biomass in mixture of SCG hydrolysate and both coffee oil and frying oil. The combined waste substrates induced the production of lipidic metabolites, whereby the production of carotenoids exceeded 5 mg/g of dry biomass. On media with coffee oil, this strain produced high amounts of ubiquinone (8.265 ± 1.648 mg/g) and ergosterol (13.485 ± 1.275 mg/g). Overall, the results prove that a combination of waste substrates is a promising option for the production of carotenoid- and lipid-enriched yeast biomass.
Highlights
Today, it is important to pay attention to the carbon footprint of humanity in the environment; for this reason, it is necessary to focus on the quality of waste material management and their re-integration into the circular economy in the form of usable waste substrates [1,2]
We propose the use of combined waste substrates; first, a simple carbon source promotes high and fast biomass production, and second, a complex source induces the production of stress response metabolites
The experiment started with cultivation at the lowest C/N ratio, which is more suitable for the production of carotenoids [19]
Summary
It is important to pay attention to the carbon footprint of humanity in the environment; for this reason, it is necessary to focus on the quality of waste material management and their re-integration into the circular economy in the form of usable waste substrates [1,2]. Such wastes have a significant impact on the quality of the environment, as there is an over-generation of greenhouse gases, an accumulation of waste in landfills and in water, land occupation, and overall environmental pollution. The development in the field of biotechnology has created a new way to use these materials as cheap substrates for the growth of microorganisms
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