Research Program

The Cao lab investigates microbial symbiosis between the insect-parasitic nematodes in the genus of Steinernema and their mutualistic bacterial partners from the genus Xenorhabdus. In addition to their ecological importance in soil ecosystems and practical value in promoting sustainable agriculture, these symbiotic pairs are valuable models for studying how animals and microbes adapt to changing environments. The Cao group is focused on establishing Steinernema hermaphroditum as a genetic model, with particular emphasis on its interactions with the mutualistic symbiotic bacterium Xenorhabdus griffiniae and the mild pathogen E. coli Nissle. Our current research investigates how X. griffiniae and E. coli Nissle colonize distinct intestinal tissues in S. hermaphroditum and elicit unique host responses at the transcriptional, biochemical, and behavioral levels.

To further investigate the immunological and neurological responses of Steinernema nematodes to both symbionts and pathogens, a major hurdle has been the lack of molecular genetic tools—particularly on the host side. To address this, our group began developing such tools, including CRISPR-Cas9–based genome editing in Steinernema. On the symbiotic bacterial side, we are building a synthetic biology toolkit by establishing a modular library in Xenorhabdus, which enables microbial engineering with broad applications, including the potential of RNAi delivery to the host. Together, these toolkits will accelerate our efforts to answer fundamental questions in microbial symbiosis and translate our findings into innovative strategies for environmental engineering—for example, designing bacterial biosensors capable of detecting nematodes in the soil ecosystem. 

CV

Recent Publications