Low GHG emissions and less nitrogen use in mushroom-based protein production from chitin-containing waste and cottonseed hull with two phase SSF

Mushroom cultivation with solid state waste from industrial crops has recently emerged as an innovative from of urban agriculture. This study aimed to bioconvert agricultural waste, including cottonseed hull, corncob, and chitin waste, into mushroom-derived nutrients through two phase solid state fermentation with the microbes. Here, we tested fungal community diversity and changes in physicochemical characteristics during phase I (fast composting) and nutrient recovery rates in phase II (fermentation with Pleurotus ostreatus (Jacq.) P. Kumm) in different N supplement formulas and then evaluated the potential to reduce greenhouse gas emissions of the diet by replacing animal-based protein sources with mushroom-based protein. Chitin waste as supplement in substrate has significantly increased the fungi community composition during fast composting. In phase II, the T3 with 20 % wheat bran had the highest yield, both with the first flush and second flush, which was 13.84 % more than T1 with 20 % chitin waste. The most degraded component was cellulose, which ranged from 43.94 % in T1 to 52.07 % in T3. Lignin degradation which mainly occurred in phase Ⅱ, ranged from 22.58 % to 28.69 %, and was 57.80 % higher than phase I. The present study showed that 12.71 mg trace element, 2.29 g major element, 13.81 g total amino acid, 267.16 g total sugar, 153.93 g crude protein, 27.11 g total flavonoids, and 10.80 g total phenolics (average in all formulas) were recycled into fruiting bodies from every kilogram of solid waste after two-phase fermentation. After mushroom-based protein added in diet, the value of protein GHG intensity declined in 14.99–23.71 %. The highest nitrogen use decreased was 13.01 % in diet. Adding chitin-containing waste from urban agriculture as N supplements to the substrate can promote the development of innovative urban agriculture in mushroom-based protein production.