Yeast Single-Cell Proteins (SCP) production using various agro-industrial byproducts and wastes have significant potential as an alternative to the soy meal, and fish meal protein used for livestock and aquaculture feeds. The use of organic wastes as a substrate in the fermentation processes can be accepted as one of the solutions to reduce the total price of the culture and an environmentally friendlier method of removing these residues. This review article focuses on the yeast biomass yield and protein content increase strategies, which is impossible without understanding metabolic pathways and switching mechanisms. The present work discusses optimization strategies for protein-enriched yeast biomass production, such as fermentation medium composition, including a selection of carbon and nitrogen sources and their ratio, supplemented trace elements, and cultivation conditions such as pH, temperature, time of cultivation, and inoculum size. This review summarizes the theoretical knowledge and experimental results of other researchers that provide an overview of the achievements of the last decades in the production of SCP.

Cooking oils are widely used in food preparation. During cooking, harmful compounds are formed in oils, therefore utilization of used cooking oils (waste cooking oils) is limited. Single cell protein (SCP) is dietary protein, which can be produced from various protein-rich microorganisms that are capable of utilizing industrial by-products such as waste cooking oil (WCO). In this study the utilization of industrial WCO (obtained from local potato chips manufacturer) as a carbon source for single cell protein production by yeast Yarrowia lipolytica was assessed. The medium containing 27.5 g/L WCO and C/N ratio of 5–10 for batch fermentations was determined to be the optimal composition for SCP production. In this study, the highest reported Yarrowia lipolytica biomass concentration (57.37 g/L) was achieved when WCO was used as the main carbon source. Protein concentrations were relatively low (12.6 %), which also affected the final protein yield (7.23 g/L). The resulting biomass accumulated low concentrations of toxic malondialdehyde (MDA) (2.32 mg MDA/kg) compared to concentrations initially detected in the WCO itself (30.87 mg MDA/kg). To the best of the authors knowledge this is the first study to report on MDA decrease via microbial fermentations.

Biomethanation is a prospective biogas upgrading method to integrate renewable energy grid with existing biogas grid. Biomethane can directly substitute fossil natural gas and be used in all energy sectors. The selection of packing material for the ex-situ biomethanation in biotrickling filter reactors can be based on the physical and chemical characterization of the carrier material. The packing material selected for biotrickling filter reactors supports hydrogenotrophic methanogenic growth and thereby increases the area for H2 mass transfer. Chemical components and melting temperature analysis of wood ash material are carried out to determine optimal parameters for producing wood ash filter material. Physical characteristics of new wood ash filter material such as volume-specific surface area (m2 m−3), the external porosity (vol. %) and bulk density (kg m−3) are carried out to compare this material with other carrier materials that have been used in biotrickling filter reactors before.

As humanity sets its sights on establishing a sustainable and prosperous colony on Mars, the main challenges to be overcome are ensuring a reliable and nutritious food supply for settlers, feedstock for 3D printing, fuel and pharmaceuticals. While various solutions for production of essential products on Mars have been proposed, there is growing interest in the use of microorganisms as the main production units. This scientific review article proposes a novel concept of using single cell oil (SCO) as a versatile feedstock for various applications in a bioregenerative life support system (BLSS) for space missions. The authors suggest using outputs from autotrophic systems, such as cyanobacteria biomass and oxygen, to cultivate SCO-producing microorganisms from the class Labyrinthulomycetes. The produced SCO can be used for food, fuel, 3D printing materials, and pharmaceuticals. This approach can potentially reduce the importance of carbohydrates in space foods, offering various benefits, including a reduction in food weight, simpler, lightweight, more compact bioreactors, launch cost reduction, potentially improved mental and cognitive performance, and reduced fatigue for the crew. The authors also suggest using SCO as the feedstock for the production of 3D printable filaments and resins and as a supplementary fuel source for space colonies. While the concept is hypothetical, the theoretical foundation is solid, and this approach could potentially become an important element required for the establishment of a successful Mars colony.

The research and development of carotenoids production have a long history, and interest in this group of pigments has not decreased to this day. Among all existing carotenoids, six are considered industrially important: astaxanthin, β-carotene, lutein, zeaxanthin, canthaxanthin, and lycopene. These carotenoids have a wide range of application and are used as additives in food and beverage, feed, nutraceuticals, pharmaceuticals, and cosmetics due to their bioactive and colour properties. An undisputed leader in the global pigment market is chemically synthesized carotenoids. To a lesser extent, carotenoids derived from natural sources as plants and microorganisms. Currently, the market of natural carotenoids is mainly represented by microalgae Haematococcus pluvialis, Dunaliella salina, Botryococcus braunii, fungus Blakeslea trispora, yeast Phaffia rhodozyma and bacteria Paracoccus carotinifaciens. These microorganisms afford the production of astaxanthin, βcarotene, canthaxanthin, and lycopene. In turn, lutein is obtained by extracting marigold flowers Tagetes eracta L. and there is no other competitive source yet. Therefore, the potential of microorganisms to synthesize and accumulate lutein and other equally important carotenoids in their cells has been actively studied. Several yeast and bacteria species from Rhodosporidium, Rhodotorula, Sporobolomyces, Sphingomonas, Gordonia, and Sphingobacterium genus have a potential to replenish the diversity of sources of industrially important natural pigments, but available technologies still need improving. This paper reviews strategies for increasing of competitiveness of fungal and bacterial carotenoids production. Strategies such as selection of carotenogenic strain, use of low-cost substrates, simultaneous production of carotenoids and other value-added compounds, and optimization of fermentation medium and conditions are considered.