Showing papers on "Biofilm published in 1982"

Processes governing primary biofilm formation.

Abstract: Biofilm accumulation under turbulent flow condition on the surface of a circular tube is the net result of several process including the following: (1) transport and firm adhesion of soluble components and microbial cell to the surface; (2) metabolic conversions within the biofilm in cluding growth and maintenance decay process; (3) detachment of portions of the biofilm and reentrainment in the bulk fluid. Experiments in tabular reactor were designed to measure the rates of these process during the early stages of biofilm accumulation as a function of the Reynolds number and suspended biomass concentration. Results indicate deposition (i.e., combined transport and adsorption) is only important in the very early stages of biofilm accumulation and is significantly influenced by negligible for the thin biofilms encountered in these experiments. Net biofilm production rates in all experiments decrease to same level and this level is not affected by changes in Reynolds number or suspended biomass concentration. Biofilm detachment rate increases continuously with biofilm accumulation and with increasing Reynolds number.

Method for studying microbial biofilms in flowing-water systems.

Abstract: A method for the study of microbial biofilms in flowing-water systems was developed with special reference to the flow conditions in electrochemical concentration cells. Seawater was circulated in a semiclosed flow system through biofilm reactors (3 cm s−1) with microscope cover slips arranged in lamellar piles parallel with the flow. At fixed time intervals cover slips with their biofilm were removed from the pile, stained with crystal violet, and mounted on microscope slides. The absorbances of the slides were measured at 590 nm and plotted against time to give microbial biofilm development. From calibration experiments a staining time of 1 min and a rinse time of 10 min in a tap water flow (3 cm s−1) were considered sufficient. When an analysis of variance was performed on biofilm development data, 78% of the total variance was found to be due to random natural effects; the rest could be explained by experimental effects. The absorbance values correlated well with protein N, dry weight, and organic weight in two biofilm experiments, one with a biofilm with a high (75%) and one with a low (∼25%, normal) inorganic content. Comparisons of regression lines revealed that the absorbance of the stained biofilms was an estimate closely related to biofilm dry weight.

Factors regulating microbial biofilm development in a system with slowly flowing seawater.

Abstract: Microbial biofilm development was followed under growth conditions similar to those of a projected salinity power plant. Microscope glass cover slips were piled in biofilm reactors to imitate the membrane stacks in such a plant. A staining technique closely correlating absorbance values with biofilm dry weight was used for the study. Generally, the biofilms consisted of solitary and filamentous bacteria which were evenly distributed with considerable amounts of various protozoa and entrapped debris of organic origin. Protozoa predation was shown to decrease the amount of biofilm produced. The biofilm development lag phase was longer at lower temperatures. The subsequent growth phase was approximately arithmetic until stationary phase appeared. Adaptation of a hyperbolic saturation function gave curves that agreed well with the logarithm of the amount of biofilm as a function of time. Increased flow velocity, temperature, and nutrient concentration increased the biofilm production rate. An exponential relationship was shown between biofilm production rate and flow velocity within the range of 0 to 15 cm s−1. Intervals in which the biofilms were exposed to fresh water decreased the biofilm production rate more than four times. If the cover slips were inoculated with untreated seawater for 24 h, subsequent UV treatment had an insignificant effect on the biofilm formation.

Viability of a marine microbial biofilm

Abstract: The formation of a microbial biofilm on glass surfaces arranged in lamellar piles parallel with circulating sea water (3 cm·sec−1) was studied. The increase in dry weight, protein content, nucleotide content (ATP, ADP), and diatoms was followed over a period of 62 days. Dry weight and protein were estimates of the total biofilm development, whereas the nucleotide measurements revealed the viability of the biofilm and reflected the dynamics in the community structure.

Effect of Polyelectolytes on Biofilm Growth

Abstract: In certain biofilm processes, such as nitrification and anaerobic carbon removal, biofilm attachment and growth may take several weeks or even months. This research focuses on determining the effect of synthetic and naturally produced polymers, used as surface conditioners, on the rate of biofilm attachment and growth. Partial success was obtained, and the only practical alternative seems to be to precondition the surface of the media by growing an easy-to-develop biological film before the final biofilm is induced to grow. This paper also reviews the literature which describes the factors affecting the attached growth of bacteria.

Processes of aerobic/anaerobic biofilm development

Abstract: The constitutive response of an aerobic/anaerobic composite annular biofilm reactor was modeled with fundamental kinetic parameters obtained independently from a completely aerobic, reactor utilizing glucose, a completely anaerobic reactor utilizing glucose, and a completely aerobic reactor utilizing products formed in the anaerobic reactor. The model satisfactorily predicted the biofilm areal carbon density dependence of the specific glucose removal rate, the specific suspended biomass production rate, and the specific oxygen removal rate. Specific product formation rate and specific biofilm accumulation rate were not predicted satisfactorily as a function of biofilm areal carbon density. STATEMENT OF PERMISSION TO COPY In presenting this thesis in partial fulfillment of the requirements for an advanced degree at Montana State University, I agree that the Library shall make it freely available for inspection. I further agree that permission for extensive copying of this thesis for scholarly pur­ poses may be granted by my major professor, or, in his absence, by the Director of Libraries. It is understood that any copying or publication of this thesis for financial gain shall not be allowed without my written permission.