Shaojun Xiong

To enable support a growing global population (8.5 billion in 2030 and 10 billion in 2050), without further deteriorating Earth’s climate and biodiversity, it is pivotal to develop new technologies not only for sustainable production of healthy food, but also solutions to increase energy-and-resource efficiency and to reduce greenhouse gas emissions. One important strategy is to use local residual bioresources including crop and forest residues, for food, fuel and biomaterials in a circular economy approach. Today, food industries are energy intensive where fossil fuels are still the dominating energy resources. Existing technologies for producing second generation biofuel from biomass, e.g. bioethanol, and biomaterials are costly and have environmental issues typically due to chemical uses in the process. 

In last 15 years my research has been focused on development of biological/fungal pretreatment of lignocellulosic materials to utilize residual biomass for food and bio-based products. We believe the approach of “combined production of edible mushroom and biofuels/bio-based product” will be of importance not only in Sweden but also in global aspect. The basic scientific background is that edible mushrooms, such as shiitake (Lentinula edodes) and oyster (Pleurotos spp), are white-rot fungi and protein-rich food, but can also selectively degrade lignin and hemicellulose of lignocellulose substrate they grow on. Thus after a harvest of the mushrooms, the spent mushroom substrate (SMS) is cellulose-rich and ready to be bio-converted (e.g. through enzymatical or ferment processes) to cellulosic ethanol or other cellulosic-based bioproducts without chemical pretreatment.

One example of our R&D work is development of “Sustainable mushroom production for dual products – food and biofuel” (IVAs-100 lista 2021 and IVAs-100 lista 2022). It includes three major innovations:  

1)     An efficient fungal pretreatment of lignocellulose substrate by white-rot edible-fungi to maximize lignin degradation but minimize cellulose losses. This enables using SMS directly for cellulose ethanol production, without any chemical treatment. 

2)     Novel processes for automatic mushroom cultivation. A patented growing device and process will allow for a robotisation of production chain possible, thus considerably reduce the labour costs and cultivation time. 

3)     Climate smart pasteurisation of mushroom substrate method (patented). With this method, hot air (75 – 90 °C) instead of conventional pressurised steam (121°C, 2 bar) is used, which can reduce energy use by 60% and CO2 emission by 65%.  

These innovations can facilitate an industrial upscaling.

Recently, we have also explored possibilities to use SMS for functional biomaterials. It has been successfully shown that the SMS is ready to be directly processed without conventional chemical treatment to isolate cellulose and remove lignin in biomass for nanofiber production. The nanofibers are then used to produce, for example, packaging materials, film and foam. This approach can considerably reduce environmental impact related to toxic substances emitted to the environment, compared to chemical pretreatments.