title: Membrane-aerated biofilm proton and oxygen flux during chemical toxin exposure.
abstract: Bioreactors containing sessile bacteria (biofilms) grown on hollow fiber membranes have been used for treatment of many wastestreams. Real time operational control of bioreactor performance requires detailed knowledge of the relationship between bulk liquid water quality and physiological transport at the biofilm-liquid interface. Although large data sets exist describing membrane-aerated bioreactor effluent quality, very little real time data is available characterizing boundary layer transport under physiological conditions. A noninvasive, microsensor technique was used to quantify real time (≈1.5 s) changes in oxygen and proton flux for mature Nitrosomonas europaea and Pseudomonas aeruginosa biofilms in membrane-aerated bioreactors following exposure to environmental toxins. Stress response was characterized during exposure to toxins with known mode of action (chlorocarbonyl cyanide phenyl-hydrazone and potassium cyanide), and four environmental toxins (rotenone, 2,4-dinitrophenol, cadmium chloride, and pentachlorophenol). Exposure to sublethal concentrations of all environmental toxins caused significant increases in O(2) and/or H(+) flux (depending on the mode of action). These real time microscale signatures (i.e., fingerprints) of O(2) and H(+) flux can be coupled with bulk liquid analysis to improve our understanding of physiology in counter-diffusion biofilms found within membrane aerated bioreactors; leading to enhanced monitoring/modeling strategies for bioreactor control.
authors.affiliation: Physiological Sensing Facility, Purdue University, 1203 West State Street, West Lafayette, Indiana 47907-2057, USA. emclamor@purdue.edu
authors.forename: E S
authors.initials: ES
authors.lastname: McLamore
authors.forename: W
authors.initials: W
authors.lastname: Zhang
authors.forename: D M
authors.initials: DM
authors.lastname: Porterfield
authors.forename: M K
authors.initials: MK
authors.lastname: Banks
mesh_terms: D018441:Biofilms / Q000187:drug effects; D004785:Environmental Pollutants / Q000633:toxicity*; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D008567:Membranes, Artificial; D043370:Nitrosomonas europaea / Q000187:drug effects / Q000502:physiology*; D010100:Oxygen / Q000378:metabolism*; D011190:Potassium Cyanide / Q000633:toxicity; D011522:Protons; D011550:Pseudomonas aeruginosa / Q000187:drug effects / Q000502:physiology*; D013312:Stress, Physiological / Q000187:drug effects
chemical_list: D004785:Environmental Pollutants; D008567:Membranes, Artificial; D011522:Protons; D011190:Potassium Cyanide; D010100:Oxygen