Biotechnologie et biomatériaux

Abstrait

Xanthan pruni, a singular biopolymer produced by Brazilian bacterium strains ? 25 years of discovery

Moreira A da S

Scientifically and technologically the extracellular polysaccharide produced by bacteria of the Xanthomonas gender is called xanthan. Xanthan
is a biopolymer widely used by several industries as thickening, stabilizing, suspending agent and emulsifier additive. Traditionally the NRRL
B-1459 strain of Xanthomonas campestris pv campestris has been used for this industrial production of xanthan. In 1995 our research group
started the xanthan production by X. campestris pv pruni and in 2000 was reported internationally that xanthan produced by the pruni pathovar is
chemically different due to the presence of rhamnose, absent in commercial xanthans. Taking account of the chemical composition of its xanthan,
phytopatogenicity and genetic profile the bacterial was officially renamed as Xanthomonas arboricola pv pruni, and its polymer has been named
xanthan pruni by us. For the bacterial natural biopolymers such as xanthan pruni, the parameters utilized in the bioreactor (fermentation) such as
media, time, temperature, aeration and agitation must be extremely well defined and controlled so that the biosynthesized product has the desired
properties for each kind of application. In these 25 years we had studied how the specific bacteria that produce xanthan with different chemical
composition combined with fermentations with tailored parameters can result in specials xanthans. Generalizing, xanthan pruni is gelling, very
resistant to salt addition, posses high melting and degradation temperature, form strong physical or chemical crosslinking by interactions with
cations or chemical crosslinkers and posses higher antioxidant activity than the commercial xanthans. It has been successfully applied in foods,
vaccines, biodegradable eatable and pharmaceutics films (including an anesthetic bioadhesive for humidity areas) and as encapsulating agent
with high thermo and osmoprotectant effect to probiotic microcapsules for different applications. Now, experiments are being made with support of Procelys by Lesafre to reduce costs of fermentation media in scale transposition (from 14 to 1000L).