Comparative transcriptome analysis between original and evolved recombinant lactose-consuming Saccharomyces...

Area of Science:

• Biotechnology
• Microbial Engineering
• Molecular Biology

Background:

• Developing efficient alcoholic fermentation of cheese whey requires yeast strains that can utilize lactose.
• Previous work engineered a recombinant Saccharomyces cerevisiae strain for improved lactose fermentation, but its performance was suboptimal.
• Evolutionary engineering yielded a superior flocculent strain from the original recombinant, necessitating investigation into the underlying molecular mechanisms.

Purpose of the Study:

• To compare the transcriptomes of an original and an evolved recombinant Saccharomyces cerevisiae strain during lactose fermentation.
• To identify genes and pathways responsible for the enhanced lactose utilization and ethanol production in the evolved strain.
• To generate hypotheses explaining the physiological and molecular differences observed between the two recombinant strains.

Main Methods:

• Utilized cDNA microarrays to perform comparative transcriptomic analysis.
• Cultured original and evolved recombinant Saccharomyces cerevisiae strains on lactose-containing media.
• Analyzed microarray data to identify genes with significantly altered expression levels ( >1.5-fold difference).

Main Results:

• Identified 173 genes with differential expression between the original and evolved strains.
• Approximately half of the differentially expressed genes were associated with RNA-mediated transposition.
• Observed alterations in genes related to DNA repair, stress response, chromatin remodeling, cell cycle control, mitosis, glycolysis, and alcoholic fermentation.

Conclusions:

• Transcriptomic data provide molecular insights into the enhanced lactose fermentation capabilities of the evolved Saccharomyces cerevisiae strain.
• The significant changes in gene expression, particularly in transposition and metabolic pathways, contribute to the improved performance.
• These findings support previous physiological observations and offer new hypotheses for further research into yeast strain engineering for industrial applications.