A pilot-scale sustainable biorefinery, integrating mushroom cultivation and in-situ pretreatment-cum-saccharification for ethanol production

Abstract

Biomass pretreatment incurs 40% of the overall cost of biorefinery operations. The usage of mushroom cultivation as a pretreatment/delignification technique, and bio-ethanol production from spent mushroom substrates, after subsequent pretreatment, saccharification and fermentation processes, have been reported earlier. However, the present pilot-scale, entirely-organic demonstration is one of the very first biorefinery models, which efficiently consolidates: biomass pretreatment; in-situ cellulase production and saccharification; mushroom cultivation, thereby improving the overall operational economy. During pretreatment, the oyster mushroom, Pluerotus florida VS-6, matures into distinct substrate mycelia and fruiting bodies. Consequential variations in the kinetics of growth, biomass degradation/substrate utilization, oxygen uptake and transfer rates, and enzyme production, have been analyzed. Signifying the first-time usage of a biomass mixture, comprising vegetative waste and e-commerce packaging waste, the 30 day-long, bio-economical, non-inhibitor-generating, catabolite repression-limited, solid-state in-situ pretreatment-cum-saccharification, resulted in: 78% lignin degradation; 13.25% soluble-sugar release; 18.25% mushroom yield; 0.88 FPU/g.ds cellulase secretion. The in-situ saccharified biomass, when sequentially subjected to ex-situ enzymatic hydrolysis and fermentation, showed 37.35% saccharification, and a bio-ethanol yield of 0.425 g per g of glucose, respectively. Apart from yielding engine-ready bio-ethanol, the model doubles as an agripreneurial proposition, and encourages mushroom cultivation and consumption.

Keywords:

• Biomass pretreatment
• biorefinery
• enzymatic hydrolysis
• in-situ and ex-situ
• mushroom’s fruiting body
• mycelia

Acknowledgement

The authors would like to thank the Department of Biotechnology and the Department of Biochemistry and Molecular Biology, Pondicherry University, for providing the laboratory facilities. Thanks to M/s VS Mushroom farms, Puducherry, India, for providing us with the Oyster mushroom’s mother culture, and the workspace.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was funded by the Dr. D.S. Kothari Post-Doctoral Fellowship scheme [No.F.4-2/2006 (BSR)/BL/20-21/0315], and the first author is thankful to the agency for the support provided. This work was supported by University Grants Commission.