Stimulation of exopolysaccharide production by fluorescent pseudomonads in sucrose media due to dehydration and increased osmolarity

Abstract

Exopolysaccharides produced by plant pathogenic bacteria are thought to play an important role in both the general ecology and the virulence of the producing organism. The environmental factors affecting exopolysaccharide production in planta by Pseudomonas syringae pathovars are not known. We tested the effect of increased medium osmolarity and dehydration on exopolysaccharide production in a sucrose‐containing medium by three P. syringae pathovars, one (P. syringae pv. phaseolicola) capable of levan and alginate production and two (P. syringae pv. papulans and pv. savastanoi) capable of only alginate production. Addition of NaCl and ethanol to the medium led to increased accumulation of alginate by all three pathovars as well as increased levan production by P. syringae pv. phaseolicola. Culture fluids of the two non‐levan producers also contained increased amounts of neutral carbohydrate which was not levan. Based on sugar compostion this material may have originated from outer membrane lipopolysaccharide. In addition, the ratio of neutral material (levan or not) to alginate varied dependent on culture conditions.

Production in vitro, on different solid culture media, of two distinct exopolysaccharides by a mucoid clinical strain ofBurkholderia cepacia

“…the Pseudomonas isolation agar (PIA) medium and the King A medium, possess the question of their production, alone or together, on other culture conditions. The concomitant production of two distinct EPS by the same bacterium is a known phenomenon and has been previously reported in different species of the genera Pseudomonas , Agrobacterium , Azotobacter , Clavibacter , Erwinia and Rhizobium [10–13] as well as in extremophile microorganisms like Bacillus thermoantarcticus [14]. In the present study, we examined the in vitro production of these two distinct EPS, PS‐I and PS‐II, by the BC1 strain grown on different solid nutrient media.…”

Priming Soilless Growing Medium with Disaccharides Stimulated Microbial Biofilm Formation, and Increased Particle Aggregation and Moisture Retention during Muskmelon Transplant Production

“…B. megaterum has other documented agricultural benefits, such as an ability to solubilize inorganic phosphate (Cakmakci et al, 1992) and suppress Rhizoctonia root rot of soybean (Glycine max) (Zheng and Sinclair, 2000). The production of biofilms has been characterized in other prokaryotes, including the Pseudomonads (Singh and Fett, 1995). The terrestrial cyanobacterium Nostoc commune excretes large amounts of glucan polysaccharide with unusual properties, including maintenance of secreted enzymes in an active state during long-term, air-dried storage, and accommodation of rapid biophysical and physiological changes upon rehydration (Helm et al, 2000).…”