Extracellular polymeric substance

McEldowney (2000) reported that 65% of Cd2+ was associated with the cell walls of Pseudomonas fluorescens, while 33% was present in the cytoplasm, and 2% was bound to extracellular polymeric substances (EPS) excreted by the bacteria. EPS include polyssacharides, proteins and siderophores. Organic matter, derived from dead microbes, can also form extracellular complexes with metals. 

All types of sewer biofilms are produced at surfaces exposed to the water phase and also, to some extent, at the sewer air surfaces where aerosols are present and the humidity is high. Biofilms in sewers are often referred to as slimes and consist mainly of microorganisms, extracellular polymeric substances (EPS) produced by the microorganisms and adsorbed organic and inorganic compounds from the wastewater. 

Christensen, B. E. (1999). Physical and chemical properties of extracellular polysaccharides associated with biofilms and related systems. In Microbial Extracellular Polymeric Substances. Characterization, Structure and Function, eds. Wingender, J., Neu, T. R. and Flemming, H.-C., Springer-Verlag, Berlin, pp. 143-154. 

C.S. Laspidou, E.R. Bruce, A unified theory for extracellular polymeric substances, soluble microbial products, active and inert biomass, Water Res. 11 (2002) 2711-2720. 

Flemming, H.-C., and J. Wingender. 2001a. Relevance of microbial extracellular polymeric substances (EPS) — Part II Technical aspects. Water Science and Technology 43 9-16. 

Sutherland, I. W. 1999. Polysaccharases in biofilms — sources — action — consequences In Microbial Extracellular Polymeric Substances Characterization, Structure, and Function (J. Wingender, T. R. Neu, and H.-C. Flemming, Eds.), pp. 201-216. Springer-Verlag, Berlin. 

Jahn, A., and R H. Neilsen. 1993. Extraction of extracellular polymeric substances (EPS) from biofilms using a cation exchange resin. Water Science and Technology 32 157-164. 

Nuengjamnong, C., Cho, J., Polprasert, C. and Ahn, K.H. (2006) Extracellular polymeric substances s influence on membrane fouling and cleaning during microfiltration process. Water Science and Technology Water Supply, 6, 141-148. 

Microbial mats and biofilms, defined as surface layers of microbes entrained in a matrix of extracellular polymeric substances (EPS) (Characklis and Marshall, 1989), are also important in changing the surface texture and erodibility of sediments in estuaries (de Beer and Kiihl, 2001). The EPS are primarily composed of cellular-derived polysaccharides, polyuronic acids, proteins, nucleic acids, and lipids (Decho and Lopez, 1993 Schmidt and Ahring, 1994). The EPS can serve as a cementing agent for surface sediment particles, thereby affecting the erodibility of sediments as well as the flux of dissolved constituents across the sediment-water interface (de Beer and Kiihl, 2001). 

Biofilms defined as surface layers of microbes entrained in a matrix of extracellular polymeric substances (EPS)—same as microbial mats. 

Strong attachment or anchoring of microorganisms to the substratum surface through the production of extracellular polymeric substances (EPS), mostly composed of polysaccarides [8] and proteins [9],... 

Extending this idea one step further, bacteria may have evolved to produce extracellular polymeric substances (EPSs) in order to make mineral surfaces more favorable for attachment. This would be an important evolutionary step, especially if the earliest bacteria utilized minerals for respiration and nutrition.25 According to the present model, oxides other than quartz also have unfavorable entropic interactions with the head group PL (AS°adsi < 0). EPSs should then be exuded on the surfaces of many oxide (and silicate) minerals. As discussed above, quartz is the most harmful, so greater production of EPSs should be expected on quartz, all other factors being equal. Consistent with this hypothesis, the nature of the substrate and of the bacterial surfaces does, in fact, affect the amount of EPS produced.60-62 The idea that surfaces become more hydrophilic by bacterial attachment also underlies the biobeneflciation of ores during mineral separation by floatation. 

Flemming H-C and Wingender J. Relevance of microbial extracellular polymeric substances (EPSs). Part II. Technical aspects. Water Sci Technol. 2001 43(6) 9-16. 

Sutherland IW (1999) In Wingender J, Neu TR, Llemming HC (eds) Microbial Extracellular Polymeric Substances. Springer, Berlin Heidelberg New York, p 73-92... 

Chlorination of secondary effluent prior to membrane pretreatment may extend membrane run times between clean. Over 90 h of MF operation was achieved with prechlorinated secondary effluent compared to 42 h operation reported when secondary effluent was not chlorinated (72,73). Similar observations were reported with dosage of chloramine prior to microfiltration pretreatment (77). It was speculated that preoxidation due to chlorination altered the chemistry of extracellular polymeric substance (EPS) produced by the microorganisms in the secondary effluent. This could weaken the attachment of the EPS on the membrane and thus offset the detrimental effect on the membrane flux. However, care must be taken to verify compatibility of membrane with chlorination as some membranes are not tolerant to the aggressive action of chlorine. 

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