Fermentation, vol.9, no.7, pp.1-14, 2023 (SCI-Expanded)
The increase in the wastage of bread, representing 12.5 million tons per year, causes
ecological problems, such as the production of methane and CO2
, when that waste bread (WB)
is improperly managed. To reduce this ecological footprint, a more sustainable system of WB
management must be set up. Based on its chemical composition, WB has a high potential to be used
as feedstock for microbial growth and conversion into value-added bio products. The microbial
valorisation of WB is a novel biotechnological approach to upgrading a waste into a renewable
feedstock for bio-based industry, thus favouring the circular economy concept. Based on this, the aim
of this study was to test WB as a feedstock for biomass production by Yarrowia lipolytica, which can
be considered as a promising supplement for animal and human dietary products. The enzymatic
hydrolysis of WB was primarily optimized for large-scale production in a bioreactor. The biomass
production of Y. lipolytica strain K57 on WB hydrolysate-based media in batch bioreactor culture was
then investigated. As a result, a very high starch to glucose conversion yield of 97% was obtained
throughout optimised hydrolysis. At the end of 47 h of batch culture, a biomass higher than 62 g/L,
specific growth rate of 0.37 h−1 and biomass yield of 0.45 g/g were achieved from a WB hydrolysate.
Therefore, this study demonstrates that WB hydrolysate has a promising potential to be used as a
feedstock for biomass production by Y. lipolytica strain K57 for food and animal diet applications.