Gellan Gum

Abstract

For decades microbial exopolysaccharides have been invaluable ingredients in the food industry, as well as having many attractive pharmaceutical and chemical applications. Gellan gum is a comparatively new gum elaborated by the Gram-negative bacterium Sphingomonas paucimobilis. Although its physico-chemical properties have been well characterized, the ecology and physiology of Sphingomonas, and the factors influencing the fermentation process for production of this gum have received much less attention. This review focuses on the metabolism and the enzymic activity of this bacterium, as well as the factors that influence gellan production, including process temperature, pH, stirring rate, oxygen transfer, and composition of the production medium. Potential strategies for improving the production process are discussed in the context of processes for the production of other microbial biopolymers, particularly exopolysaccharides. In addition, the importance and potential utility of gellan lyases in modification of gellan and in other applications is critically evaluated.

Goma xantana: produção, recuperação, propriedades e aplicação

“…Quando o caldo é tratado sob condições apropriadas (80 -130°C, 10 -20 min, pH 6,3 -6,9), a dissolução da goma xantana ocorre sem degradação térmica, e o rompimento das células é observado (Smith e Pace, 1982). O aumento da temperatura também diminui a viscosidade do meio, facilitando a remoção dos insolúveis por centrifugação (Giavasis et al, 2000;Moreira et al, 2003;Boza et al, 2004) ou filtração (Giavasis et al, 2000).…”

“…A precipitação do polímero é realizada por diminuição da solubilidade do colóide dissolvido, usandose métodos tais como adição de sais, de solventes miscíveis em água e concentração por evaporação, além da precipitação com solventes orgânicos, tais como o etanol e o isopropanol, o uso de misturas de álcool e sais (Giavasis et al, 2000;Moreira et al, 2003;Boza et al, 2004) e da precipitação com sais trivalentes e tetravalentes (Kennedy e Bradshaw, 1984). Também o uso de ultrafiltração tem sido relatado (Lo et al, 1997).…”

Physiological and biochemical characterization of the two α-l-rhamnosidases of Lactobacillus plantarum NCC245

“…It is produced by a number of animal tissues, plants, fungi, bacteria and bacteriophage (Hashimoto et al, 2003). The physiological role of a-L-rhamnosidase is not well understood but is probably linked to the broad distribution of L-rhamnose as a component in bacterial and plant cell walls, glycosides, biofilms and glycolipids (Bader et al, 1998;Giavasis et al, 2000). a-L-Rhamnosidase has been implicated in invasion processes of plant-pathogenic fungi, infection of bacteria by bacteriophages and metabolism of bacterial biofilms (Hashimoto et al, 1999;Hashimoto & Murata, 1998;Steinbacher et al, 1996).…”

Preparation and characterisation of graphene composite hydrogels

“…Gellan gum (GG) is a high molecular weight, linear anionic extracellular polysaccharide secreted by the bacterium Sphingomonas elodea (ATCC 31461) [18] . Structurally, it is built up of tetrasaccharide repeat units containing β-D-glucose, β-D-glucoronic acid and α-Lrhamnose monomers.…”

“…GG has been approved in the US (FDA) and in the EU for food and medical usage as a gelling, stabilizing, and suspending agent [31] . It is commonly used within foods such as dessert gels, icings, puddings and glazes [32] and its ideal film forming properties led to its use in coatings and preservation of fruits [33] .…”