An Extracellular Polysaccharide Produced by Zoogloea ramigera 115

Abstract

A weakly acidic polysaccharide was purified from the extracellular zoogloeal matrix produced by Zoogloeal ramigera 115. The purified polysaccharide was homogeneous as judged by sedimentation analysis, and the average molecular weight was estimated to be about lo5 by gel permeation chromatography of the fully methylated preparation. The polysaccharide was composed of D-glucose, D-gahCtOSe and pyruvic acid in an approximate molar ratio of 11 : 3 : 1.5. On the basis of methylation, periodate oxidation, Smith degradation and partial hydrolysis, the following highly branched structure was deduced for the polysaccharide : a long chain mainly consisting of fl1-+4-linked glucose residues branching at the C-3 or C-6 position of galactose residues which are present in D l -+ 4 or P I + 3 linkages as the minor component of the long chain; pyruvic acid residues, the sole acidic component, are linked to the nonreducing end and/or 1,3-linked glucose residues through 4,6-ketal linkages. The purified polysaccharide was not readily soluble in water and had a high affinity for several metallic ions (e.g. 0.25 pmol Fe3+/mg, and 0.17 pmol Fe2+ mg). Upon addition of metallic ions (1 mM) to a gelatinous aqueous solution of the polysaccharide (K' form, 0.125 %), more than 80% of it immediately coprecipitated out with them.Among a group of floc-forming bacteria indigenous to activated sludges or organically polluted water, Zoogloea ramigera I-16-M produces no gelatinous matrix [l], while Zoogloea ramigera 1 15, isolated by Friedman and Dugan, produces an extracellular zoogloeal matrix in which the cells are embedded [2]. Although the gelatinuous matrix polymer is known to have a remarkably high affinity for several metallic ions [ 3 ] and organic compounds such as amino acids [4], its chemical nature has not been fully elucidated yet. Dugan and his coworkers [5,6] reported that the extracellular polymer was composed of fibrillar strands of polysaccharide which consisted of glucose and galactose, and also contained carboxyl functions or terminal aldehyde groups. The purpose of this study was to investigate further the chemical structure of the extracellular polysaccharide purified from Z. ramigera 11 5 , which forms a gelatinous aqueous solution and shows a high affinity for several metallic ions. EXPERIMENTAL PROCEDURES Culture of OrganismZoogloea ramigera 11 5, kindly provided by Dr P. R. Dugan (Ohio State University, Columbus, OH, USA) was maintained on Trypticase soy agar slants at room temperature. The bacterium was grown on a reciprocal shaker at 30°C for 72 h in a basal medium (500 ml in 2000-ml Sakaguchi flasks) containing 0.1 % casamino acids, 0.05 % yeast extract, 0.1 % K2HP04, 0.05 % KH2P04 and 30 mM glucose, until the culture liquor became very viscous.

Bacterial colonization of early stages of limnetic diatom microaggregates

“…These observations suggest that these bacteria are already present on senescent diatoms and are actively involved in the aggregation process. D. zoogloeoides is known to produce mucopolysaccharides, occurs on activated sludge flocs in sewage treatment plants and has also been found on mucilage of filamentous cyanobacteria (Caldwell & Caldwell 1978, Ikeda et al 1982, Dugan et al 1992. α-and β-Proteobacteria also dominated on natural lake snow aggregates in Lake Constance collected at 25 m depth and on lake snow aggregates 2 to 3 d old and formed in rolling tanks ).…”

α- and β- Proteobacteria Control the Consumption and Release of Amino Acids on Lake Snow Aggregates

“…D. zoogloeoides metabolizes labile DOM such as amino acids, proteins, and carbohydrates and produces mucopolysaccharides. It has been found on the mucilage of filamentous cyanobacteria and occurs on activated sludge flocs in sewage treatment plants (13,17,31). Interestingly, D. zoogloeoides, formerly assigned to the polyphyletic species Zoogloea ramigera, could not be detected in various sewage treatment plants even though it exhibits the greatest physiological diversity of the three strains known (46,47).…”

Hahella chejuensis gen. nov., sp. nov., an extracellular-polysaccharide-producing marine bacterium.

“…They have been found in various microorganisms including Alteromonas, Cyanothece, Pseudomonas, Vibrio and Zoogloea (Ikeda et al, 1982 ;Rodrigues & Bhosle, 1991 ;Matsuda & Worawattanamateekul, 1993 ;Philippis et al, 1993 ;Raguenes et al, 1996). Microbial EPSs have an advantage over polysaccharides from other sources, as they can be produced in large quantity using a relatively simple purification process.…”