Showing papers on "Biofilm published in 1983"

Biofilms and Microbial Fouling

Abstract: Publisher Summary This chapter presents a framework for understanding the process of biofilm development on a surface and the consequences of the accumulation on the environment. It begins by describing biofilm development in terms of selected fundamental rate processes and environmental parameters influencing their rate and extent. The physical, chemical, and biochemical properties of the biofilm that determine the influence of the biofilm on its microenvironment are discussed in the chapter. The properties of the biofilm and its microenvironment lead to a discussion of the microbial ecology within the biofilm and the physiology of the organisms immobilized within it. The effects of the biofilm on its environment, both beneficial and detrimental, are presented. There are many other questions and concerns stated in this chapter regarding biofilm processes.

Microbial fouling of reverse-osmosis membranes used in advanced wastewater treatment technology: chemical, bacteriological, and ultrastructural analyses.

Abstract: Biofouling of reverse-osmosis membranes was investigated at an advanced wastewater treatment facility. Cellulose diacetate membranes operated for approximately 4,000 h became uniformly coated with a mucilaginous fouling layer. The fouling material was approximately 93% water by weight, and nearly 90% of the dehydrated residue was organic in composition. Calcium, phosphorous, sulfur, and chlorine were the major inorganic constituents detected. Protein and carbohydrate represented as much as 30 and 17%, respectively, of the dry weight of the biofilm. Bacteriological plate counts indicated up to 5.6 X 10(6) CFU/cm2 of membrane surface. Accumulation of [3H]glucose in the biofilm and measurement of ATP indicated that the fouling bacteria were metabolically active in situ. The genus Acinetobacter and the Flavobacterium-Moraxella group were the major generic groups associated with the feedwater surface of the membrane, whereas species of the generic groups Acinetobacter, Pseudomonas-Alcaligenes, and Bacillus-Lactobacillus predominated on the permeate water surface. Electron microscopy revealed that the biofilm on the feedwater surface of the membrane was 10 to 20 microns thick and was composed of several layers of compacted bacterial cells, many of which were partially or completely autolyzed. The bacteria were firmly attached to the membrane surface by an extensive network of extracellular polymeric fibrils. Polyester (Texlon) support fibers located on the permeate surface of the reverse osmosis membranes were sparsely colonized, suggesting bacterial regrowth in the product water collection system.

Electron microscopic examination of wastewater biofilm formation and structural components.

Abstract: This research documents in situ wastewater biofilm formation, structure, and physiochemical properties as revealed by scanning and transmission electron microscopy. Cationized ferritin was used to label anionic sites of the biofilm glycocalyx for viewing in thin section. Wastewater biofilm formation paralleled the processes involved in marine biofilm formation. Scanning electron microscopy revealed a dramatic increase in cell colonization and growth over a 144-h period. Constituents included a variety of actively dividing morphological types. Many of the colonizing bacteria were flagellated. Filaments were seen after primary colonization of the surface. Transmission electron microscopy revealed a dominant gram-negative cell wall structure in the biofilm constituents. At least three types of glycocalyces were observed. The predominant glycocalyx possessed interstices and was densely labeled with cationized ferritin. Two of the glycocalyces appeared to mediate biofilm adhesion to the substratum. The results suggest that the predominant glycocalyx of this thin wastewater biofilm serves, in part, to: (i) enclose the bacteria in a matrix and anchor the biofilm to the substratum and (ii) provide an extensive surface area with polyanionic properties.

Influence of a calcium-specific chelant on biofilm removal.

Abstract: This paper describes the influence of ethylene glycol-bisβ-aminoethyl ether)- N, N-tetraacetic acid (EGTA) on biofilm removal. The addition of EGTA resulted in the immediate detachment of biofilm which suggests that the chelant removed essential calcium from the biofilm, causing it to detach.

Cellular reproduction and extracellular polymer formation in the development of biofilms

Abstract: Bacteria exhibit a tendency for attaching to and colonizing surfaces which are submerged in aquatic environments. Attachment is mediated by extracellular polymer material which is formed by the bacteria and extends from the cell to the attachment surface. The attached cells reproduce and form additional extracellular polymer increasing the mass of the deposit. The cellular-extracellular matrix is termed a biofilm. The purpose of this study was to investigate the kinetics and stoichiometry of cellular reproduction and extracellular formation in the development of biofilms. Experiments were conducted using pure cultures of Ps. aeruginosa with glucose and inorganic nutrients providing the necessary requirements for microbial growth. Both attached growth biofilm reactors ' and dispersed growth chemostat reactors were used as experimental systems. Rate and stoichiometric expressions which describe cellular re-' production and extracellular polymer formation in biofilms are presented. These expressions are compared with corresponding expressions describing the same processes in dispersed growth chemostat reactors. Results indicate that the rate and extent of cellular reproduction and extracellular polymer formation depend on Ps.. aeruginosa growth rate. At low growth rate, extracellular polymer formation exceeds cellular reproduction, whereas at high growth rate, the rate and extent of cellular reproduction exceed extracellular polymer formation. CELLULAR REPRODUCTION AND EXTRACELLULAR POLYMER FORMATION IN THE DEVELOPMENT OF BIOFILMS by Michael Gerald Trulear A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Civil Engineering MONTANA STATE UNIVERSITY Bozeman, Montana May 1983

Biofilm Fluidized‐Bed Reactors and Their Application to Waste Water Nitrification

Abstract: Necessite d'un recyclage rapide; vitesses de nitrification dans les biofilms; experiences au laboratoire sur la nitrification en lit fluidise

Effect of different environmental parameters on the biofilm build-up of Pseudomonas putida ATCC 11172 in chemostat

Abstract: The influence of carbon source, cell concentration, oxygen tension, pH and temperature on the biofilm build-up of Pseudomonas putida ATCC 11172 was studied. The experiments were performed in a carbon and energy limited chemostat (asparagine). When the asparagine was replaced by glucose the biofilm build-up was decreasing.

Electron Microscopic Examination ofWastewater Biofilm Formation andStructural Components

Abstract: Thisresearch documents insitu wastewater biofilm formation, structure, and physicochemical properties asrevealed byscanning andtransmission electron microscopy. Cationized ferritin wasusedtolabel anionic sites ofthebiofilm glycocalyx forviewing inthinsection. Wastewater biofilm formation paralleled theprocesses involved inmarine biofilm formation. Scanning electron microscopyrevealed adramatic increase incell colonization andgrowth overa 144-h period. Constituents included avariety ofactively dividing morphological types. Manyofthecolonizing bacteria wereflagellated. Filaments wereseenafter primary colonization ofthesurface. Transmission electron microscopy revealed a dominant gram-negative cell wallstructure inthebiofilm constituents. Atleast three typesofglycocalyces wereobserved. Thepredominant glycocalyx possessed interstices andwasdensely labeled withcationized ferritin. Twoofthe glycocalyces appeared tomediate biofilm adhesion tothesubstratum. Theresults suggest that thepredominant glycocalyx ofthis thin wastewater biofilm serves, in part, to:(i)enclose thebacteria ina matrix andanchorthebiofilm tothe substratum and(ii) provide anextensive surface areawithpolyanionic properties.