Studies on the extracelluar polysaccharides (EPS) produced in vitro by Pseudomonas phaseolicola. 1. Indication for a polysaccharide resembling alginic acid in seven P. syringae pathovars
1987
Gross, M. (GOettingen Univ. (Germany, F.R.). Inst. fuer Pflanzenpathologie und Pflanzenschutz) | Rudolph, K.
Extracellular polysaccharides (EPS) produced by Pseudomonas syringae pv. phaseolicola are obviously composed of two main components: the long known levan consisting of fructose, and a mannuronan consisting mainly od mannuronic acid (manA), thus resembling alginic acid (alginate). The identification of manA was established by TLC utilizing different developing systems, and by cellulose acetate electrophoresis in different buffers. References were authentic uronic acids and hydrolyzed authentic alginate. A rough quanitfication of the 'alginate' present in crude EPS was achieved with a selective colour reaction which largely excluded compounds other than uronic acids. Levan was only synthesized with sucrose as primary carbon source. When grown on several other sugars and related compounds 'alginate' was the predominant component of the EPS. Additionally, rhamnose, fucose, glucose and amino sugars were found in some instances in hydrolystates of crude EPS, suggesting the release of lippolysaccharides (LPS) from the bacterial cell walls during culture. Growth on carbon sources not related to sugars resulted in these 'LPS' as the main constituent of EPS. After cultivation with sucrose, the 'alginate' was restricted to the 'slime' fraction of the EPS. In the 'capsular' fraction, levan was predominating. A screening program revealed the capacity to synthesize the 'alginate' in six additional P. syringae pathovars: pisi, lachrymans, aptata, syringae, and glycinea. All of the stains tested so far produced levan from sucrose, however, the 'alginate' was formed not by all of them. There was a tendency that fresh isolates produced more 'alginate' than strains subcultured for an extended time in vitro. This was also true for the total amount of EPS
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