Microscale to pilot-scale submerged fermentation of mycelia from the edible mushroom Laetiporus sulphureus using by-products from the food industry

In view of the growing demand for vegan meat substitutes, research into alternative plant-based and microbial protein sources is on the rise. Mushrooms are a particular focus of this Transformation of the food market. Thanks to their rich nutritional profile and structural properties, mushrooms can mimic the taste and texture of meat very authentically.

The common sulphur polypore (Laetiporus sulphureus) is also known as ‘Chicken of the Woods’ due to its texture and its flavour, which is reminiscent of chicken. In the wild, this edible mushroom usually grows on living or dead deciduous trees and is easily recognisable by its bright yellow-orange colour.

However, the fruiting body – familiar to mushroom foragers and gourmets – represents only part of the fungus. The vast majority of the fungus consists of microscopic fungal filaments, known as mycelium, which thrives hidden within the wood of trees. The mycelium of the sulphur polypore possesses sensory and nutritional properties that are very similar to those of the mushroom’s fruiting body and, moreover, offers enormous potential for future, sustainable and scalable biotechnological production.

A key obstacle to the development of fungal mycelium as a food raw material has so far been the lack of understanding of its industrial production in bioreactors. As fungi in stirred-tank bioreactors suffer from hydrodynamic stress and the breakdown of their hyphae (cell filaments), the project aims to encourage the sulphur polypore to grow attached to small substrate particles. This technology is expected to represent an important milestone in increasing the productivity and cost-effectiveness of the production process. A further aim of the project is to make the cultivation process sustainable. To this end, by-products from the food industry are to be used as alternative substrates, and spent fermentation media from mushroom cultivation are to be reused for the stabilisation and enzymatic breakdown of by-products. The planned work is intended to make a decisive contribution towards a sustainable and carbon-neutral bioeconomy with closed material cycles.