Cell surface hydrophobicity and mycolic acid composition of Rhodococcus strains isolated from activated sludge foam

2002 ◽  
Vol 28 (5) ◽  
pp. 264-267 ◽  
Author(s):  
H M Stratton ◽  
P R Brooks ◽  
P C Griffiths ◽  
R J Seviour
Keyword(s):  
Cell Surface ◽  
Activated Sludge ◽  
Acid Composition ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Mycolic Acid

Activated sludge foaming: what causes hydrophobicity and can it be manipulated to control foaming?

1998 ◽  
Vol 37 (4-5) ◽  
pp. 503-509 ◽  
Author(s):  
Helen Stratton ◽  
Bob Seviour ◽  
Peter Brooks
Keyword(s):  
Activated Sludge ◽  
Control Strategies ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Mycolic Acid ◽  
Current Control ◽  
Operating Costs ◽  
Foam Formation ◽  
Rhodococcus Rhodochrous ◽  
Stable Foam

Activated sludge aeration tanks frequently suffer from the formation of a stable foam on their surfaces, a problem which results in increased operating costs and reduces performance. Current control strategies are often unsuccessful, mainly because of a lack of understanding of the microbes involved, and often employ expensive and environmentally undesirable procedures, such as the addition of chemicals. Here we have attempted to better understand the mechanism(s) involved in foam formation. We have investigated the possible relationship between the mycolic acid content in a Rhodococcus rhodochrous strain isolated from foam, its cell surface hydrophobicity (CSH) and ability to form stable foam. Results show that mycolic acid composition is not the only contributor to CSH, nor is the CSH the only factor responsible for foam formation and stabilisation. Other possible explanations for mechanisms of foaming and ways to control it are addressed.

Cell surface and exopolymer characterization of laboratory stabilized activated sludge from a beverage bottling plant

2001 ◽  
Vol 43 (6) ◽  
pp. 175-184 ◽  
Author(s):  
S. M. Boyette ◽  
J. M. Lovett ◽  
W. G. Gaboda ◽  
J. A. Soares
Keyword(s):  
Cell Surface ◽  
Activated Sludge ◽  
Surface Charge ◽  
Electrophoretic Mobility ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Food Sources ◽  
Colloid Titration ◽  
High Concentrations

Fermentor-stabilized activated sludge from an industrial beverage bottling plant was grown on three different food sources: normal plant wastewater, plant wastewater containing high sucrose concentrations, and a synthetic glucose-based feed stock. Surface charge, hydrophobicity, and exopolysaccharide composition were measured on the stabilized bacterial flocs. Cell surface charge was measured by electrophoretic mobility, dye exchange titration, and a standard colloid titration, while cell hydrophobicity was determined using the bacterial adhesion to hydrocarbons (BATH) test. Exopolysaccharide profiles were determined by measuring concentrations of glucose, galactose, mannose, glucuronic, and galacturonic acids in digested exopolymer extractions using HPLC. Changes in the physical surface properties of the bacteria and the chemical composition of the extracted exopolymers were correlated with differences in the three food sources. Cell surface hydrophobicity was similar for cultures grown on different plant wastewaters, while the culture grown on synthetic food produced less floc hydrophobicity. Electrophoretic mobility measurements, charge titrations, and dye exchange titrations showed different total surface charge as well as varying charge availability. Additionally, total surface charge and total exopolysaccharide concentrations appeared less dependent on food source than the food-to-mass ratio. High concentrations of biodegradable food produced dispersed growth and high concentrations of exopolysaccharides that contributed to poor settling.

Influence of oxygen limitation on the cell surface properties of bacteria from activated sludge

1998 ◽  
Vol 37 (4-5) ◽  
pp. 349-352 ◽  
Author(s):  
R. Palmgren ◽  
F. Jorand ◽  
P. H. Nielsen ◽  
J. C. Block
Keyword(s):  
Cell Surface ◽  
Activated Sludge ◽  
Surface Properties ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Growth Conditions ◽  
Oxygen Limitation ◽  
Cell Surface Properties ◽  
Number Of Factors ◽  
Math Test

Cell surface hydrophobicity is believed to be important to flocculation in activated sludge and biofilm systems. Optimization of these processes includes changes in the growth conditions of the bacteria. A number of factors influence cell surface hydrophobicity. The influence of oxygen on the cell surface hydrophobicity of 4 bacteria isolated from activated sludge was tested. The bacteria were grown in batch cultures with and without oxygen limitation. It was found that oxygen limitation generally caused a lowering of the cell surface hydrophobicity. The study also showed that there are many difficulties in measuring cell surface hydrophobicity since other cell surface properties, such as surface charge, influence the measurement methods. The MATH test was employed to establish how assay conditions influenced the results.

scholarly journals Starvation Improves Survival of Bacteria Introduced into Activated Sludge

2000 ◽  
Vol 66 (9) ◽  
pp. 3905-3910 ◽  
Author(s):  
Kazuya Watanabe ◽  
Mariko Miyashita ◽  
Shigeaki Harayama
Keyword(s):  
Population Density ◽  
Cell Surface ◽  
Activated Sludge ◽  
Ralstonia Eutropha ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Luria Bertani ◽  
Exponential Growth Phase ◽  
Degrading Bacterium ◽  
Metabolic Activities

ABSTRACT A phenol-degrading bacterium, Ralstonia eutropha E2, was grown in Luria-Bertani (LB) medium or in an inorganic medium (called MP) supplemented with phenol and harvested at the late-exponential-growth phase. Phenol-acclimated activated sludge was inoculated with the E2 cells immediately after harvest or after starvation in MP for 2 or 7 days. The densities of the E2 populations in the activated sludge were then monitored by quantitative PCR. The E2 cells grown on phenol and starved for 2 days (P-2 cells) survived in the activated sludge better than those treated differently: the population density of the P-2 cells 7 days after their inoculation was 50 to 100 times higher than the population density of E2 cells without starvation or that with 7-day starvation. LB medium-grown cells either starved or nonstarved were rapidly eliminated from the sludge. The P-2 cells showed a high cell surface hydrophobicity and retained metabolic activities. Cells otherwise prepared did not have one of these two features. From these observations, it is assumed that hydrophobic cell surface and metabolic activities higher than certain levels were required for the inoculated bacteria to survive in the activated sludge. Reverse transcriptase PCR analyses showed that the P-2 cells initiated the expression of phenol hydroxylase within 1 day of their inoculation into the sludge. These results suggest the utility of a short starvation treatment for improving the efficacy of bioaugumentation.

Autecology of scum producing bacteria

1998 ◽  
Vol 37 (4-5) ◽  
pp. 527-530 ◽  
Author(s):  
Hilde Lemmer ◽  
George Lind ◽  
Margit Schade ◽  
Birgit Ziegelmayer
Keyword(s):  
Wastewater Treatment ◽  
Cell Surface ◽  
Wastewater Treatment Plants ◽  
Cell Surface Hydrophobicity ◽  
Surface Hydrophobicity ◽  
Residence Times ◽  
Loading Conditions ◽  
Emulsifying Activity ◽  
Substrate Preferences

Non-filamentous hydrophobic scum bacteria were isolated from scumming wastewater treatment plants (WWTP) by means of adhesion to hydrocarbons. They were characterized with respect to taxonomy, substrate preferences, cell surface hydrophobicity, and emulsification capability. Their role during flotation events is discussed. Rhodococci are selected by hydrolysable substrates and contribute to flotation both by cell surface hydrophobicity and emulsifying activity at long mean cell residence times (MCRT). Saprophytic Acinetobacter strains are able to promote flotation by hydrophobicity and producing emulsifying agents under conditions when hydrophobic substrates are predominant. Hydrogenophaga and Acidovorax species as well as members of the Cytophaga/Flavobacterium group are prone to proliferate under low loading conditions and contribute to flotation mainly by emulsification.

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