Date of Submission
8-2024
Document Type
Thesis
Degree Name
Master of Science in Cellular and Molecular Biology
Department
Biology and Environmental Sciences
Advisor
Nikolas M. Stasulli, Ph.D.
Committee Member
Anthony Melillo, M.S.
Committee Member
Anna Kloc, Ph.D.
Keywords
Chromobacterium Violaceum, Light exposure, Pigment Production, Violacein, Gene Transcription, Metabolite Clusters
MeSH
Chromobacterium, Gene Expression Regulation, Bacterial
LCSH
Chromobacterium violaceum, Gene expression, Microbial metabolites
Abstract
An environmental isolate of Chromobacterium violaceum produces a previously uncharacterized orange pigment when exposed to light on select media. This pigmentation phenotype was discovered serendipitously when an ISP2 agar plate with C. violaceum growth was exposed to sunlight, resulting in an orange ring of new growth surrounding the older purple colony. This suggests that light exposure may influence the transcription of pigment production in C. violaceum. Typically, C. violaceum produces a purple pigment called violacein, a secondary metabolite known for its diverse biological activities. Since light is known to alter transcription and regulate gene expression in bacteria, we hypothesize that differential light levels induce transcriptomic changes in C. violaceum, leading to altered pigment production. To investigate, C. violaceum was grown at 30°C under different light spectrums and media compositions to observe pigment production. Various media types were tested to determine if a specific nutrient component contributes to orange pigment production, as nutrient availability can modulate gene activation and transcription. Additionally, different wavelengths of light were tested to identify differential pigment production, as specific light wavelengths can activate photoreceptors and trigger signal transduction pathways that lead to transcriptional changes. Once optimal growth conditions for orange pigment production were established, RNA was isolated from C. violaceum grown under selected conditions. RNA from five replicates of each condition were pooled for cDNA library construction and sequencing using Oxford Nanopore Technology MinION system. Data analysis resulted in 368 differentially expressed genes between light and dark conditions. In conclusion, two genes of the violacein gene cluster, three genes from the chromobactin gene cluster, two genes from the viobactin gene cluster, and four genes from the hydrogen-cyanide gene cluster were differentially expressed. Our results suggest that light has a role in regulating the expression of specialized metabolite clusters in C. violaceum, demonstrating the ability to adapt its secondary metabolism in response to environmental conditions.
Recommended Citation
Cook, Greta D., "The Role of Light in Regulating the Transcription of Specialized Metabolite Clusters in Chromobacterium Violaceum Relating to Pigment Production" (2024). Master's Theses. 231.
https://digitalcommons.newhaven.edu/masterstheses/231