Eduardo Caro

Date of Award


Degree Type


Degree Name

Doctor of Philosophy (PhD)




Roy Welch

Second Advisor

Yan-Yeung Luk


development;genotype-to-phenotype;microscopy;Myxococcus xanthus;sigma factors

Subject Categories

Life Sciences | Microbiology


The genotype-to-phenotype (G2P) problem is a fundamental challenge in understanding how genetic information controls the collective phenotypic outputs of multicellular organisms. To address this problem, this thesis focuses on Myxococcus xanthus, a model organism widely used for studying social behavior and morphological differentiation in bacteria. The social behaviors of M. xanthus are mediated by complex gene regulatory networks, making it an excellent model organism for studying the G2P problem. This thesis presents two studies that provide valuable insights into the G2P problem in M. xanthus. The first study investigates the dynamics of biofilm morphogenesis, an essential process for bacteria survival, using image capture and analysis techniques from custom-designed microscopes. Biofilms are complex structures composed of different cell types and gene expression patterns. The study produced a topological map of the process of biofilm formation in wild-type M. xanthus, which allowed the identification and characterization of even subtle mutations associated with different mutations with statistical significance. Stochastic variation was mapped, and this methodology allowed us to distinguish previously non-distinguishable genotypes of M. xanthus using phenotype data. The approach used in this study has the potential to enhance our understanding of the genetic and environmental factors that contribute to the development of M. xanthus and other organisms. The second study employs a "common garden" approach to investigate the impact of transcriptional regulators on development in M. xanthus. By recording subtle differences in traditional phenotype assays across a library of mutant transcriptional regulators, the study shows there are uncharacterized regulatory genes that play significant roles in regulating biofilm dynamics and gene expression during development. The study identified sigma factors that have an impact on sporulation fitness and characterized the effects of these regulators on the development pathways. The findings of this study supply a deeper understanding of the G2P problem in M. xanthus and could have broader implications for understanding the development of other organisms. By investigating the complex interplay between genotype and phenotype, this thesis aims to shed light on fundamental mechanisms underlying multicellular development, and the potential for these findings to be applied in the fields of biotechnology and medicine.


Open Access