Researcher ORCID Identifier

https://orcid.org/0009-0007-7747-0122

Graduation Year

2026

Document Type

Campus Only Senior Thesis

Rights Information

2026 Alyssa E Welch

Abstract

J. lividum is a Gram-negative, rod-shaped, motile bacterium that produces the antifungal compound violacein via quorum sensing and in response to environmental stress. Violacein is also documented to have antitumor, antiparasitic, and antioxidant activity. J. lividum can grow in a wide range of environments with various temperature, pH, and salinities, but most studies examine these factors independently, rather than together. Given that in natural environments bacteria experience multiple stressors at once, this study aims to address the question: how do combinations of temperature, pH, and salinity affect J. lividum growth? It is hypothesized that the highest mean growth yield after 48 hours would occur at 25°C, pH 7.0, and 0.5% NaCl. Growth yield was calculated to determine differences in growth across conditions, and a one-way ANOVA was conducted to determine whetherthose differences between conditions were significant (or not). Results indicated that the highest growth occurred under ~19°C, pH 7.0, and 0.5% salinity, not fully supporting the hypothesis. The results suggest that J. lividum grows best at moderate to higher temperatures, and that combined environmental conditions matter and may affect J. lividum growth differently than expected compared to studies of single variables. This study can inform future research about J. lividum adaptability, the maximization of violacein production, and its potential applications to pharmaceutical, medical, and environmental fields.

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