Spruce sugars and poultry hydrolysate as growth medium in repeated fed-batch fermentation processes for production of yeast biomass

David Lapeña,Vincent G H Eijsink,Pernille M Olsen,Svein J Horn,Magnus Ø Arntzen,Volkmar Passoth,Gergely Kosa

doi:10.1007/s00449-019-02271-x

Abstract

The production of microbial protein in the form of yeast grown on lignocellulosic sugars and nitrogen-rich industrial residues is an attractive approach for reducing dependency on animal and plant protein. Growth media composed of enzymatically saccharified sulfite-pulped spruce wood, enzymatic hydrolysates of poultry by-products and urea were used for the production of single-cell protein. Strains of three different yeast species, Cyberlindnera jadinii, Wickerhamomyces anomalus and Blastobotrys adeninivorans, were cultivated aerobically using repeated fed-batch fermentation up to 25 L scale. Wickerhamomyces anomalus was the most efficient yeast with yields of 0.6 g of cell dry weight and 0.3 g of protein per gram of glucose, with cell and protein productivities of 3.92 g/L/h and 1.87 g/L/h, respectively. Using the conditions developed here for producing W. anomalus, it would take 25 industrial (200 m3) continuously operated fermenters to replace 10% of the fish feed protein used in Norway.

Highlights

A possible future shortage of feed protein will force mankind to explore alternative protein sources that could replace conventional soymeal or fish meal [1]
This study demonstrates that W. anomalus is better suited than and B. adeninivorans and the well-established C. jadinnii to produce microbial protein in a medium composed of a mixture of organic and inorganic nitrogen sources and spruce-derived sugars in a semi-continues mode
The protein content of the yeast biomass produced in the 42 L fermenter was high, and the amino-acid profile of W. anomalus was reasonable, albeit with the deficit in sulfur-containing amino acids, which is common for yeast and bacterial biomasses

Summary

Introduction

A possible future shortage of feed protein will force mankind to explore alternative protein sources that could replace conventional soymeal or fish meal [1]. Continuous fermentation has been the preferred strategy to produce SCP industrially [20, 21] Another good strategy is called repeated fed-batch fermentation, which is a semi-continuous system of operation where a portion of culture is harvested at regular intervals and replaced by an equal volume of fresh medium [22]. It is considered as one of the best fermentation set-ups for economical SCP production [23]. The effect of several cell disruptive methods on the yeast morphology was investigated using autolysis, exogenous enzymes and mechanical force

Materials and methods

Results and discussion

42 L Bioreactor run

Conclusions

Compliance with ethical standards