High temperature-induced changes in exopolysaccharides, lipopolysaccharides and protein profile of heat-resistant mutants of Rhizobium sp. (Cajanus)

Abstract

A thermosensitive wild-type strain (PP201) of Rhizobium sp. (Cajanus) and its 14 heat-resistant mutants were characterized biochemically with regard to their cell surface (exopolysaccharides (EPSs) and lipopolysaccharides (LPSs)) properties and protein profile. Differences were observed between the parent strain and the mutants in all these parameters under high temperature conditions. At normal temperature (30 degrees C), only half of the mutant strains produced higher amounts of EPSs than the parent strain, but at 43 degrees C, all the mutants produced higher quantities of EPS. The LPS electrophoretic pattern of the parent strain PP201 and the heat-resistant mutants was almost identical at 30 degrees C. At 43 degrees C, the parent strain did not produce LPS but the mutants produced both kinds of LPSs. The protein electrophoretic pattern showed that the parent strain PP201 formed very few proteins at high temperature, whereas the mutants formed additional new proteins. A heat shock protein (Hsp) of 63-74 kDa was overproduced in all mutant strains.

Kinetics and physico-chemical characterization of exopolysaccharides produced by the cyanobacterium Oscillatoria formosa

“…ATCC 33047 decreased with decrease in its optimal growth temperature from 40-45 to 30-35°C. Nandal et al (2005) reported high temperature On day zero, absorbance of the culture was set at A 660 , 0.1. In control cultures, medium contained 1.5 mM CaCl 2, 10 mM NO À 3 and no sodium chloride Data in the columns marked with similar lower case alphabets are not significantly different from one another at P \ 0.05 induced changes in exopolysaccharides, lipopolysaccharides and protein profile of heat-resistant mutants of Rhizobium sp.…”

Environmental conditions affecting exopolysaccharide production by Pseudomonas aeruginosa, Micrococcus sp., and Ochrobactrum sp.

“…The ionizable functional groups of EPS such as carboxyl, phosphoric, amine, and hydroxyl groups aid in metal chelation. Different types of microorganisms have previously been studied in terms of their ability to produce EPS [14][15][16][17][18]. In these studies, EPS formation was strictly affected by environmental conditions such as heavy metal concentration, salt ions, pH level, temperature, oxygen concentration, or medium composition.…”

Extracellular polysaccharide production byRhizobium ciceri from Turkey

“…Similar results have been reported for Azotobacter vinelandii grown on sucrose (Vermani et al, 1995) and for other EPS producting bacteria (Duta et al, 2004(Duta et al, , 2006. Although some studies have indicated that environmental conditions do not affect EPS biosynthesis (Jarman et al, 1978), others had opposite results (Nandal et al, 2005;Duta et al, 2006). pH and agitation have been described as the most influential factors on EPS yields (Vermani et al, 1995).…”