HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via CrossRef Citing Articles via Google Scholar Google Scholar Articles by Olofsson, A.-C. Articles by Hermansson, M. Search for Related Content PubMed PubMed Citation Articles by Olofsson, A.-C. Articles by Hermansson, M. Agricola Articles by Olofsson, A.-C. Articles by Hermansson, M.

Floc stability and adhesion of green-fluorescent-protein-marked bacteria to flocs in activated sludge

Department of Cell and Molecu'Baiorl ogyf General and Marine Microbiology, GBteborg University, Box 462, SE-40530 GBteborg, Sweden

ABSTRACT

Wastewater is often treated using the activated sludge process. Flocculation and subsequent sedimentation of flocs are vital steps in this process that have direct influence on the quality of the effluent water from wastewater treatment plants. Since cells that remain free-living will decrease the quality of the effluent water it is important to understand the mechanisms of bacterial adhesion to flocs. The green fluorescent protein (GFP) was used as a cellular marker to study bacterial adhesion to activated sludge flocs in situ in sludge liquor. Cell surface hydrophobicity (CSH) was shown to be an important factor that determined the relative bacterial adhesion potential. High CSH correlated with high numbers of attached cells. However, the absolute adhesion of two test bacteria to different sludge flocs varied and could not be explained by the floc characteristics. Confocal laser scanning microscopy of GFP-marked cells showed their position in the floc matrix in situ. Hydrophobic cells attached not only on the surface but also within the floc, whereas hydrophilic cells did not. This indicates that cells may penetrate the flocs through channels and pores and increase the effective surface, which in turn makes the clarification of the wastewater effluent more efficient. The addition of polymers is common practice in wastewater treatment and was shown to increase bacterial adhesion to the flocs. A decrease in surface tension caused by addition of DMSO decreased adhesion, indicating the detrimental effect of surfactants on flocculation. An understanding of basic bacterial adhesion and aggregation mechanisms is important for the managment and control of biotechnological wastewater treatment.

Malte Hermansson. Tel: +46 31 7732574. Fax: +46 31 7732599. e-mail: Malte.Hermansson@gmm.gu.se

This article has been cited by other articles:

				S. Timmusk, N. Grantcharova, and E. G. H. Wagner Paenibacillus polymyxa Invades Plant Roots and Forms Biofilms Appl. Envir. Microbiol., November 1, 2005; 71(11): 7292 - 7300. [Abstract] [Full Text] [PDF]

				A.-C. Olofsson, M. Hermansson, and H. Elwing Use of a Quartz Crystal Microbalance To Investigate the Antiadhesive Potential of N-Acetyl-L-Cysteine Appl. Envir. Microbiol., May 1, 2005; 71(5): 2705 - 2712. [Abstract] [Full Text] [PDF]

				A. Malik, M. Sakamoto, S. Hanazaki, M. Osawa, T. Suzuki, M. Tochigi, and K. Kakii Coaggregation among Nonflocculating Bacteria Isolated from Activated Sludge Appl. Envir. Microbiol., October 1, 2003; 69(10): 6056 - 6063. [Abstract] [Full Text] [PDF]

				N. Banning, S. Toze, and B. J. Mee Persistence of biofilm-associated Escherichia coli and Pseudomonas aeruginosa in groundwater and treated effluent in a laboratory model system Microbiology, January 1, 2003; 149(1): 47 - 55. [Abstract] [Full Text] [PDF]

				K. Otto, H. Elwing, and M. Hermansson Effect of Ionic Strength on Initial Interactions of Escherichia coli with Surfaces, Studied On-Line by a Novel Quartz Crystal Microbalance Technique J. Bacteriol., September 1, 1999; 181(17): 5210 - 5218. [Abstract] [Full Text]