Browsing by Author "Siebel, M. A."

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Accumulation of a biofilm of k. pneumoniae and p. aeruginosa
(1989-12) Siebel, M. A.; Characklis, William G.
Observations of binary population biofilms
(1991-04) Siebel, M. A.; Characklis, William G.
Biofilm research has focused on studies of undefined mixed microbial populations and, more recently, on investigations of monopopulation biofilms. In the first case, the biofilm is considered a homogeneous mass, ignoring the properties of individual species. The second case concentrates on the properties and processes of one microbial species in the biofilm. This article describes biofilm experiments conducted with monopopulations of Klebsiella pneumoniae and Pseudomonas aeruginosa and with binary populations of K. pneumoniae and P. aeruginosa. Process rates and stoichiometric coefficients were determined for the monopopulation and for the binary population biofilms and evaluated in light of the species distribution in the latter. Results indicate that neither the specific cellular product formation rate nor the glucose–oxygen stoichiometric ratio of K. pneumoniae or P. aeruginosa in the binary biofilm is affected by the presence of the other species. Consequently, species interaction was not observed. Although the specific cellular growth rate of K. pneumoniae is five times that of P. aeruginosa, the former species did not dominate the microbial population in the biofilm. Possible reasons for this unexpected behavior are discussed.
Seasonal Variations in Bacterial Colonization of Stainless Steel, Aluminum and Polycarbonate Surfaces in a Seawater Flow System
(1989-03) Fera, P.; Siebel, M. A.; Characklis, William G.; Prieur, D.
Before the construction of an Ocean Thermal Energy Conversion (OTEC) power plant, an experimental station was built near the entrance of the Bay of Brest (France) in order to perform preliminary studies. Bacterial colonisation of three substrata (stainless steel UB6, aluminium AG4 and polycarbonate filters) was observed in a continuous flow seawater system. The study was performed between May 1983 and May 1984 and included seven experiments of 15 days each. The early events in bacterial colonisation of these materials may be affected by both water quality and type of substratum. If these two parameters influence the adsorption step of the biological process (0 to 1 h), seasonal variation in water quality seems to be more important during the accumulation step (1 h to 6 days), because of its effect on bacterial metabolism.