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Purpose:
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The growing world population, along with a shift towards diets richer in animal protein has led to a steep increase in global protein demand. A global shift towards diets richer in plant-based ingredients (i.e. strictly following the recommended meat consumption or flexitarian) would not be sufficient to enable operation within the planetary boundaries, while a global switch to fully vegetarian diets is an unlikely scenario. Microbial biomass from bacteria, yeasts, filamentous fungi and microalgae, used as food, could be a key solution to enable food security. However, despite the renewed interest in the use of microbial biomass in food, many aspects have been neglected, including changes in nucleic acid composition and amino acid and protein profiles that could impact the properties of the microbial biomass and the processing required to convert it into edible food. The cultivation conditions of microorganisms play a crucial role in determining the composition and size of the cells and, therefore, the nutritional quality of microbial biomass. In addition, the diversity and versatility of microorganisms allow for the adjustment of the nutritional quality and physical and chemical properties of microbial biomass to meet a wide range of food applications. While information on the food properties of microbial biomass is currently limited, there is significant potential for microorganisms to be used as a versatile ingredient in the food industry. It is therefore essential to study and improve the food quality properties of microbial biomass to make it a viable and high-quality alternative to animal proteins. This work is a critical contribution to this field and combines principles of bioprocess engineering, microbiology and cell biology to address this knowledge gap. Microbial biomass has emerged as a promising sustainable protein alternative. The cultivation conditions affect the composition of microbial cells, and hence their quality and nutritional value. Here, we investigated the relationship between growth rate, substrate availability and cell composition and size of Cupriavidus necator and Komagataella phaffii. |
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Conclusion:
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Biomass with decreased nucleic acid and increased protein content was produced at low growth rates. Conversely, high rates resulted in larger cells, which could enable more efficient biomass harvesting. The proteome allocation varied across the different growth rates, with more ribosomal proteins at higher rates. Considering the distinct amino acid profiles established for the different cellular components, variations in their abundance impacts the product quality leading to higher cysteine and phenylalanine content at low growth rates. In summary, we demonstrate tradeoffs between nutritional quality and production rate, and we discuss that techno-functional food properties should be considered when designing microbial biomass production processes.
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