Production and rheological characteristics of the microbial polysaccharide gellan

Abstract

B. MANNA, A . GAMBHIR AND P. GHOSH. 1996. Sphingomonaspaucimobilis was used for the synthesis of the microbial polysaccharide gellan. In a 60 h fermentation, polysaccharide yield and productivity obtained were 0.45 g gellan per g glucose consumed and 0.21 g 1-' h-' respectively. T h e broth showed pseudoplastic behaviour with yield stress. The requirement of the solvent propanol to precipitate gellan from the broth depended on the volume of the broth rather than on gellan concentration. T h e addition of salt to the broth reduced the propanol requirement. Attempts to separate cells from the highly viscous broth by microfiltration were not successful. Ultrafiltration reduced the propanol requirement but appreciable membrane fouling and loss of gellan was observed.

Effects of carbon/nitrogen ratio, dissolved oxygen and impeller type on gellan gum production in Sphingomonas paucimobilis

“…To evaluate the effects of different types of impellers on gellan gum production, fed-batch fermentations were conducted with two RT (as control), AI and MI systems. As shown in Table 3, biomass (5.85±0.22 g DCW/L) and gellan gum concentration (12.5±0.1 g/L) with RT, which were similar to the data reported by Manna et al (1996), were lower than with AI or MI. Furthermore, values obtained with RT (Ox) were also lower than those exhibited by AI (Ox) and MI (Ox).…”

Optimization of Fermentation Conditions and Properties of an Exopolysaccharide from Klebsiella sp. H-207 and Application in Adsorption of Hexavalent Chromium

“…Maximum yield of HZ-7 (13.63 g/L) was achieved with 12% (v/v) of 15 h old inoculum. General studies have been carried out using 10% (v/v) 24-h-old inoculums [27], [28].…”

Cloning and knockout of phytoene desaturase gene in Sphingomonas elodea ATCC 31461 for economic recovery of gellan gum

“…Moreover, the carotenoids and gellan gum produced by ATCC 31461 were closely bound together, which also makes it difficult to recover gellan gum. Accordingly, large amounts of alcohol were often required in the conventional recovery method to dilute the fermentation broth [23], precipitate the biopolymer [4], and remove the carotenoid pigments. To the best of our knowledge, all gellan gum recovery methods reported include repetitive precipitation, in which a non-aqueous solvent, such as isopropanol, methanol, ethanol, dioxane, acetone, or tetrahydrofuran, is used [4].…”