14 that kill and bioconvert the insect host into nutritional components for both organisms (Boemare, Laumond, and Mauleon, 1996). Furthermore, P. luminescens secretes pigments and antimicrobials to ward off other contaminating microbes and as a result, ideal conditions are created for nematode growth and development (Waterfeld, Ciche and Clark, 2009). The symbiotic relationship between H. bacteriophora and P. luminescens is very intimate and complex as both partners are needed to support each other in many aspects. In this relationship, infective juvenile nematodes provide their bacterial symbionts with: 1) protection from environmental conditions; 2) a route to gain access to “food” (e.g. insect hemolymph); and 3) a mode of transportation from host to host. On the other hand, P. luminescens provides many benefts to its nematode partner such as: 1) protection from insect immunity, 2) growth Microbial Kinetics of Photorhabdus luminescens in Glucose Batch Cultures Matt Bowen University of North Carolina at Pembroke with Danica Co, William Peace University Faculty Mentors: Len Holmes with Floyd Inman University of North Carolina at Pembroke ABSTRACT Photorhabdus luminescens,an entomopathogenic bacterial symbiont of Heterorhabditis bacteriophora, was studied in batch cultures to determine the specifc growth rates of the bacterium in various glucose concentrations. P. luminescens was cultured in a defned liquid medium containing various concentrations of glucose. Culture parameters were monitored and controlled utilizing a Sartorius stedim Biostat® A plus fermentation system. Agitation and air fow remained constant; however, the pH of the media was chemically buffered and monitored over the course of bacterial growth. Measurements of culture turbidity were obtained utilizing an optical cell density probe. Specifc growth rates of P. luminescens were determined graphically and mathematically. The substrate saturation constant of glucose for P. luminescens was also determined along with the bacterium’s maximum specifc growth rate. 1. INTRODUCTION Photorhabdus luminescens is a Gram-negative, bioluminescent,entomopathogenic bacterium that is found to be a bacterial symbiont of the nematode Heterorhabditis bacteriophora (Inman, Singh and Holmes, 2012). These symbiotic partners serve as a bacto-helminthic complex that is considered to be a safe alternative to chemical insecticides. Through symbiosis and entomopathogenicity, these organisms are capable of infecting a broad range of insect hosts belonging to the orders of Coleoptera, Diptera, and Lepidoptera (Ehlers and Hokkanen, 1996). The infective juveniles of H. bacteriophora carry many cells of the bacterial symbiont in their upper digestive tract and upon entrance into the insect hemocoel; the juveniles regurgitate the cells into the insect hemolymph. As the cells proliferate, they produce biomolecules (toxins and digestive enzymes)