Browsing by Author "Banks, M. K."

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Assessment of biofilm ecodynamics
(1990) Bryers, James D.; Banks, M. K.
Bacterial species dominance within a binary culture biofilm
(1991-07) Banks, M. K.; Bryers, James D.
Studies with two species of bacteria, Pseudomonas putida and Hyphomicrobium sp. strain ZV620, were carried out to evaluate the overall net rate of accumulation of biofilm, the biofilm species composition, and individual species shear-related removal rates. Bacterial cells of either or both species were deposited onto glass or biofilm surfaces to initiate multispecies biofilms. Subsequent biofilm development was carried out under known conditions of nutrient concentration and laminar flow. Establishment of a depositing organism in a biofllm composed of another species was found to be a function of the relative growth rates of the bacterial species. In the case of simultaneous species deposition and subsequent binary culture development, the fastergrowing organisms rapidly became the dominant biofilm species, but the slower-growing organisms remained established within the biofilm and continued to increase in numbers over time. The results also indicated that the rate of cell removal by fluid shear for a species was a function of biofilm cell number only if the species concentration was uniform with depth; in essence, only the upper layers of the biofilm were sheared off.
Cryptic growth within a binary bacterial culture
(1990-08) Banks, M. K.; Bryers, James D.
The ability of viable cells of the species Pseudomonas putida and Hyphomicrobium sp. to metabolize the particulate and soluble cellular organic constituents of both species was studied in a series of batch experiments. Both P. putida and Hyphomicrobium sp. were grown in individual batch reactors on either the 14C-labelled soluble or the particulate debris of sonicated cells of each species derived from steady-state chemostat cultures. Cell generation times (tg)observed for P. putida cultivated on soluble organic material originating from either sonicated P. putida or Hyphomicrobium sp. cells, were tg= 2.0 h and tg= 6.3 h, respectively. Corresponding tgvalues of Hyphomicrobium sp. on soluble organic material originating from sonicated P. putida and Hyphomicrobium so. were, respectively, 11.6 h and 4.3 h. While particulate debris originating from either species was solubilized by both P. putida and Hyphomicrobium sp., no increases in cell numbers were observed for either species. The data indicate that bacteria are capable of scavenging soluble material released upon cell lysis at near maximal rates; solubilization of debris also occurred but at much slower overall rates with no observable cell replication. The results reaffirm that cryptic growth and turnover of cellular biomass can be significant under situations of low substrate flux or starvation conditions.
Deposition of bacterial cells onto glass and biofilm surfaces
(1992-07) Banks, M. K.; Bryers, James D.
Deposition rates of Pseudomonas putida and Hyphomicrobium ZV620 onto glass and biofilm surfaces were quantified. Both species deposited to glass at a much slower rate than to biofilm. A definite bias by depositing cells for biofilms of their own species was evident in the highest attachment rates observed in this study.