title: Interaction of Klebsiella oxytoca and Burkholderia cepacia in dual-species batch cultures and biofilms as a function of growth rate and substrate concentration.
abstract: Dual-species microbial interactions have been extensively reported for batch and continuous culture environments. However, little research has been performed on dual-species interaction in a biofilm. This research examined the effects of growth rate and substrate concentration on dual-species population densities in batch and biofilm reactors. In addition, the feasibility of using batch reactor kinetics to describe dual-species biofilm interactions was explored. The scope of the research was directed toward creating a dual-species biofilm for the biodegradation of trichloroethylene, but the findings are a significant contribution to the study of dual-species interactions in general. The two bacterial species used were Burkholderia cepacia PR1-pTOM(31c), an aerobic organism capable of constitutively mineralizing trichloroethylene (TCE), and Klebsiella oxytoca, a highly mucoid, facultative anaerobic organism. The substrate concentrations used were different dilutions of a nutrient-rich medium resulting in dissolved organic carbon (DOC) concentrations on the order of 30, 70, and 700 mg/L. Presented herein are single- and dual-species population densities and growth rates for these two organisms grown in batch and continuous-flow biofilm reactors. In batch reactors, planktonic growth rates predicted dual-species planktonic species dominance, with the faster-growing organism (K. oxytoca) outcompeting the slower-growing organism (B. cepacia). In a dual-species biofilm, however, dual-species planktonic growth rates did not predict which organism would have the higher dual-species biofilm population density. The relative fraction of each organism in a dual-species biofilm did correlate with substrate concentration, with B. cepacia having a greater proportional density in the dual-species culture with K. oxytoca at low (30 and 70 mg/L DOC) substrate concentrations and K. oxytoca having a greater dual-species population density at a high (700 mg/L DOC) substrate concentration. Results from this research demonstrate the effectiveness of using substrate concentration to control population density in this dual-species biofilm.
authors.affiliation: Center for Biofilm Engineering, Montana State University, Bozeman, MT 59717-3980, USA. jkomlos@princeton.edu
authors.forename: J
authors.initials: J
authors.lastname: Komlos
authors.forename: A B
authors.initials: AB
authors.lastname: Cunningham
authors.forename: A K
authors.initials: AK
authors.lastname: Camper
authors.forename: R R
authors.initials: RR
authors.lastname: Sharp
mesh_terms: D001673:Biodegradation, Environmental; D018441:Biofilms; D016956:Burkholderia cepacia / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D002244:Carbon / Q000378:metabolism; D003470:Culture Media; D041121:Klebsiella oxytoca / Q000254:growth & development / Q000378:metabolism / Q000502:physiology*; D011156:Population Density; D011157:Population Dynamics; D013045:Species Specificity
chemical_list: D003470:Culture Media; D002244:Carbon