Electrotransformation of Sphingomonas paucimobilis

Abstract

Bacterial strains of the new genus Sphingomonas (Yabuuchi et al 1990) are relatively ubiquitous in soil, water and sediments and have broad catabolic capabilities (Fredrickson et al. 1995; Dutta et al. 1998). Beside the high potential of Sphingomonas spp. for bioremediation and waste treatment, different strains of this genus produce at least eight extracellular acid heteropolysaccharides that have similar but not identical structures (Chandrasekaran and Radha 1995). These polysaccharides, the sphingans, exhibit properties which make them candidates for food and industrial applications such as thermoreversible gel formation and solution viscosity (Chandrasekaran and Radha 1995). The producing bacteria were originally classified into diverse genera (Pseudomonas, Alcaligenes,Azotobacter and Xanthobacter) but were later shown to be closely related to each other and to members of the genus Sphingomonas; most of them were identified as Sphingomonas paucimobilis (Pollock 1993). This is the case for the industrial strain ATCC 31461 (formerly Pseudomonas elodea) (Kang and Veeder 1982) that synthesize, in high yields, gellan gum. Gellan is currently produced by large scale aerobic fermentation for use as a gelling agent in foods and microbiological and plant tissue culture media and in other nonfood applications such as personal care products and controlled delivery of drugs.