Microbial food: microorganisms repurposed for our food

Abstract

Sustainable food production is a key to solve complicated and intertwined issues of overpopulation, climate change, environment and sustainability. Microorganisms, which have been routinely consumed as a part of fermented foods and more recently as probiotic dietary supplements, can be repurposed for our food to present a sustainable solution to current food production system. This paper begins with three snapshots of our future life with microbial foods. Next, the importance, possible forms, and raw materials (i.e. microorganisms and their carbon and energy sources) of microbial foods are discussed. In addition, the production strategies, further applications and current limitations of microbial foods are discussed.

Fig. 1

Nutritional facts of various biomasses. The contents of protein, fat and carbohydrate in animal‐, plant‐ and microorganism‐derived biomass. The content of each nutrient is calculated based on dry weight (Lee et al., ; USDA, 2021).

Fig. 2

Possible sources of carbon and energy for microbial food production. A. Carbohydrates derived from edible biomass can serve as carbon and energy source of food microbes. B. Non‐edible materials, including lignocellulosic biomass, food waste and plastic, can be consumed by food microorganisms for sustainable production of microbial foods. C. Light energy derived from sunlight or other forms of renewable energy can directly drive fixation of CO₂ to biomass through photosynthesis. In addition, renewable energy can be converted to chemical energies (e.g. H₂, reduced metal ions, reduced sulfur compounds) and provide reducing power to food microorganisms for CO₂ fixation. D. Renewable energy can be used to reduce CO₂ into organic compounds, such as methane (CH₄), formaldehyde (CH₂O), methanol (CH₃OH) and formic acid (HCOOH), that are easier to be consumed by microorganisms. The resulting products can serve as both carbon source and reducing power, enabling indirect fixation of CO₂ into biomass. rAcetyl‐CoA cycle, reductive acetyl‐CoA cycle; rTCA cycle, reductive TCA cycle; RuMP cycle, ribulose monophosphate cycle; rGlyP, reductive glycine pathway.

Fig. 3

Further application of food microorganisms beyond microbial food production. Beyond the production of microbial foods, live food microorganisms can be exploited as probiotics and live medicine. In addition, food microorganisms can be designed to be suitable for their use as animal feed and fertilizer. Moreover, food microorganisms that are safe to both human and environment can be further exploited to degrade environmental pollutants and produce valuable chemicals in an environment‐friendly manner.