Date of Award


Document Type

Doctoral Thesis

Degree Name

Doctor of Philosophy


Biological Sciences

First Advisor

Dr Olivia McAuliffe

Second Advisor

Dr Michael Callanan


The aim of this thesis is to characterize environmental Lactococcus strains to identify different and diverse metabolic capabilities that could be applied to microbial biotransformation, defined as the conversion of a cheap/waste substrate into a value-added product. Due to the increased amounts of food processing waste generated worldwide and the impact of climate change, new sustainable approaches are necessary to contribute to waste valorization and the circular bioeconomy. We ask to what extent and in what ways environment isolated Lactococcus strains could contribute to food biotransformation by metabolizing a different range of substrates. We do so to further understand and identify the variable metabolic capabilities that environment isolated Lactococcus strains possess, since this species has mostly been isolated from and studied within the dairy environment. Using different screening, molecular, enzymatic and genomic methods, the capabilities of these isolates to metabolize esters, lignocellulose-derived sugars, cellulose and starch were analyzed. Moreover, their ability to biotransform a waste stream generated in the dairy industry, acid whey, into value-added products, was evaluated. We show that some environmental Lactococcus strains possess esterolytic activity and have the ability to ferment lignocellulose-derived sugars, cellulose and starch. We also show that they can biotransform the waste stream acid whey into value-added products such as amino acids and vitamins. The significance of this study is that it expands our understanding of the diverse metabolic capabilities these environmental Lactococcus strains have. It also provides a potential future application of these strains to contribute to waste biotransformation and valorization, helping to mitigate the effects of food waste and climate change.

Creative Commons License

Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.

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