Utilization of food waste-derived volatile fatty acids for production of edible Rhizopus oligosporus fungal biomass

Steven Wainaina,Afrilia Dwi Kisworini,Marizal Fanani,Rachma Wikandari,Ria Millati,Claes Niklasson,Mohammad J Taherzadeh

doi:10.1016/j.biortech.2020.123444

Steven Wainaina, Afrilia Dwi Kisworini + Show 5 more

Open Access

https://doi.org/10.1016/j.biortech.2020.123444

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Abstract

Rhizopus oligosporus is an edible filamentous fungus that can contribute to meet the growing demand for single-cell protein. Volatile fatty acids (VFAs) are favorable potential substrates for producing R. oligosporus biomass due to their capacity to be synthesized from a wide range of low-value organic solid wastes via anaerobic digestion. The goal of this work was to cultivate R. oligosporus using food waste-derived VFAs as the sole carbon source. To maintain the requisite low substrate concentrations, the fed-batch cultivation technique was applied. This resulted in a four-fold improvement in biomass production relative to standard batch cultivation. Maximum biomass yield of 0.21 ± 0.01 g dry biomass/g VFAs COD eq. consumed, containing 39.28 ± 1.54% crude protein, was obtained. In the bubble-column bioreactors, the complete uptake of acetic acid was observed, while the consumptions of caproic and butyric acids reached up to 97.64% and 26.13%, respectively.

Highlights

Enormous amounts of organic wastes and residues are produced daily from human activities
Anaerobic digestion process has been widely adopted to convert a wide range of abundantly available organic solid wastes, such as food waste, into biogas
Filamentous fungal biomass from edible species is a prospective feed substitute for animals owing to suitable nutritional properties

Summary

Introduction

Enormous amounts of organic wastes and residues are produced daily from human activities. Cultivation of filamentous fungi is one of the treatment options that solves the mentioned problems and yields value-added materials, creating promising pathways towards a circular economy. Because of their metabolic versatility, filamentous fungi have been identified as sources of a wide spectrum of essential bioproducts such as chitosan, industrial enzymes, adsorbents and animal feed (Ferreira et al, 2013; Ozsoy et al, 2008). Other complex organic solid waste streams originating from uncontrolled sources, such as mixed food waste from restaurants, households or retail stores, remain still unexploited for the production of filamentous fungal biomass in submerged fermentation systems

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