Abstract
The escalating demand for palm oil since the 1980s has resulted in a 17-foldproduction increase, with dire environmental consequences such as extensive
deforestation. This crisis underscores the urgency for sustainable alternatives.
Oleaginous yeasts like Metschnikowia pulcherrima present a promising substitute,
capable of yielding microbial oils akin to palm oil without the geographical
constraints. However, the scale-up of oleaginous yeasts is hindered by their fragility
and production costs.
This research addresses the gap in the fermentation downstream process—
specifically, the under investigated area of cell disruption to release lipids from
oleaginous yeasts. Various cost-effective cell disruption techniques were tested on
M. pulcherrima, leading to the innovation of a novel system that curtails the
necessity of biomass desiccation pre-lipid extraction.
Trials involving inexpensive disruption methods (acid, alkaline, salt, bead milling,
and thermal lysis) at different yeast concentrations identified bead milling as a
promising and economical method for cell lysis. The subsequent development of a
vortex separator—traditionally used for lysing bacteria in wastewater treatment—
proved capable of lysing M. pulcherrima cells effectively, influenced by factors such
as bead and yeast concentrations and impeller velocity.
A techno-economic model based on annual lipid production of 3,000 metric tons
revealed that optimising cell disruption can positively impact economic outcomes,
albeit with a modest 2% cost reduction. Hence, to achieve significant cost savings,
a more holistic approach to process optimisation is warranted.
Abstract
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The concluding part of the study screened potential by-products, discovering
several secondary metabolites including 2-phenyl ethanol. These compounds offer
additional avenues for economic optimisation and scalability, bolstering the
proposition that yeast-based biorefineries could viably replace traditional vegetable
oils. However, the limited oxygen may have influenced the quantity of secondary
metabolites formed as 2 phenyl ethanol was below the expected amount.
In summary, this investigation not only proves the effectiveness of a vortex
separator for extracting lipids from M. pulcherrima but also highlights critical process
enhancements needed to lower the production costs of yeast-derived lipids,
supporting the concept of a sustainable biorefinery model.
| Date of Award | 13 Nov 2024 |
|---|---|
| Original language | English |
| Awarding Institution |
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| Supervisor | Daniel Henk (Supervisor) & Chris Chuck (Supervisor) |