Enzyme formation and polysaccharide synthesis by bacteria

Abstract

IT is only comparatively recently that precise knowledge has been obtained in regard to the important problem of polysaccharide synthesis by bacteria. This advance has been due to the work of Hibbert and co-workers , who succeeded in isolating in the pure state and also on a large scale the polysaccharides formed by the activity of the micro-organisms B. mesentericUs, B. subtilis, and Acetobacter xylinum, and ascertaining their chemical structure.The polysaccharides synthesised by the closely related organisms, B. mesentericus and B. subtilis from sucrose and raffinose [1930; 1931, 1, 3; 1932] were found to be identical in chemical nature and to be "fructosans" of the laevan type. These laevans, consisting entirely of fructofuranose units are formed synthetically by the activity of a bacterial enzyme through the condensation of molecules of fructofuranose liberated in the nascent state in the initial hydrolysis of the sucrose and raffinose. The foregoing organisms were thus only able to produce a polysaccharide from carbohydrates, e.g. sucrose and raffinose, containing fructofuranose units; and such sugars as maltose, lactose, glucose, fructose (fructopyranose) were found to be unsuitable starting materials for synthesis. Ac. xylinum (the sorbose bacillus) synthesised cellulose [1931, 2, 4; 1934] from various carbohydrates and polyhydric alcohols, and it was discovered that the forms of cellulose produced by bacterial synthesis from glucose, fructose, galactose, sucrose, mannitol and glycerol were chemically identical, and also identical with cotton cellulose.The experimental work described in the present paper deals mainly with the problem of enzyme formation and polysaccharide synthesis by (1) bacteria related to B. mesentericus and (2) bacteria pathogenic to plants. Apart from the work of Ruhland [1906], no systematic researches appear to have been carried out, so far, in connection with polysaccharide formation in the latter group of micro-organisms.Ruhland studied the synthetic activities of B. spongiosWus, an organism causing disease in cherry trees in Germany, and stated that a pentosan of an araban type was formed by the growth of this organism in sucrose and raffinose agar media. On account, therefore, of the possible interest of the subject in plant pathology, and also because of the chemical interest of the phenomenon of pentosan formation by a micro-organism, an investigation on polysaccharide synthesis by plant pathogens has been carried out. Furthermore, very little information is available concerning the role of synthesising enzymes, the nutritional conditions essential for their formation in bacteria and also their activity. An investigation of the biochemical conditions influencing the develop- ( 2267 )

Studies on the Extracellular Polysaccharides (EPS) Produced in vitro by Pseudomonas phaseolicola I. Indications for a Polysaccharide Resembling Alginic Acid in Seven P. syringae Pathovars

“…The studies on EPS produced in vitro by P. phaseolicola revealed a more complex situation than previously described by EL-BANOBY (1980) who only found bacterial levan, (2-»6)-/S-D-fructofuranan. Levans are formed by many bacteria, especially by plant pathogens (COOPER and PRESTON 1935), and are widely used as a taxonomie criterion in phytobacteriology (SCHAAD 1980). However, our results indicate that levan is only produced in the presence of sucrose (Table 1).…”

Extracellular Polysaccharides of Rhizobium

“…Ash values for gums produced on Norris's medium were significantly lower than those found,by Bray et al (1944). This may be due to the absence of calcium salts from Norris's medium, since calcium is thought to combine with glucuronic acid in these polysaccharides (Cooper, Daker & Stacey, 1938). A fully defined medium, as used in the present study, eliminates the introduction of extraneoys carbohydrate.…”

Exopolysaccharides of the phytopathogen Pseudomonas syringae pv. glycinea

“…Typically, mucoid growth on sucrose-containing agar medium is used as the sole criterion of levan production (17). To syringae pathovars (23) except for aptata, morsprunorum, phaseolicola, syringae, and tabaci (1,5). In this study we characterized the EPS of several strains of P. syringae pv.…”