The native bacteria and yeasts present in Portuguese kefir grains stored under four distinct sets of environmental conditions have been isolated and identified on the basis of morphology and biochemical tests. The microbial population of the kefir grains as a whole has been characterized in terms of rates of biomass production and formation of lactic acid and ethanol. The rheological properties of the purified polysaccharide (kefiran) produced by the microflora of the grains and accumulated therein were studied in a low water activity solvent and as a component of a binary gel containing either -carrageenan or xanthan gum.

Mixed gels of kappa-carrageenan and locust bean gum (LBG) obtained from different varieties of Portuguese carob trees and commercial gums were compared. The viscoelastic properties of the gels were measured using dynamic parallel-plate geometry. Mixed gels at 1,0% of total polysaccharide concentration without addition of K Cl showed, whatever the LBG sample, a synergistic maximum when the ratio of kappacarrageenan to LBG was 80/20. The amplitude of this maximum varied with the LBG sample. The gels prepared at 0'3% total concentration with KCI added, showed a synergistic maximum at the same mixing ratio and the amplitude varied in a similar manner. Each sample was fractionated into the fraction soluble at 25°C and the fraction soluble at 9O°C.Mixed 253 CarbohydratePolymers 0144-8617/91/$03.50 -@ 1991 EIsevier Science Publishers Ltd, England. Printed in Great Britain P. B. Femandes, M. P. Gonçalves, J. L. Doublier ge/s of kappa-ea"ageenan with eold-water-soluble and hot-water-soluble fraetions, and a/so with tara gum and guar gum were prepared at the 801 20 ratio. [t was found that the synergistie maxima were related to the intrinsic viscosity and the MIG ratio. A linear relationship between the storage modulus G'maxat the synergistic maximum and the product of the intrinsie viscosity and the square of the mannose to galactose ratio was found, suggesting that the synergistie meehanism ean be aseribed to both the unsubstituted {galaetose-free} regions of the galaetomannan and the molecular weight. r-I , , , , J 274

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Many vaccines containing somatic and secreted antigens of Pseudomonas aeruginosa have been reported. The vaccines containing lipopolysaccharide have been found to provide type-specific protection, but the endotoxin content of these vaccines does not make it feasible to use them in patients who are already debilitated. Outer membrane proteins could be effective as vaccines, as they can be purified free of lipopolysaccharide, and also because they are common to all serotypes of P. aeruginosa. To be effective as a vaccine, such proteins must be immunogenic and accessible from the outside of the intact bacterial cell. In this study, we showed that systemic antibodies were produced frequently to two cell envelope proteins with masses of 58,500 and 37,500 daltons and occasionally to 34,000-dalton protein of P. aeruginosa in cystic fibrosis patients with chronic lung infections. In rabbits immunized with whole, fixed cells of P. aeruginosa, antibodies were also produced against the 58,500-dalton proteins. Thus, the 58,500-dalton cell envelope protein of P. aeruginosa was the only immunogenic protein that was accessible to the immune system when whole, fixed cells were used for immunization. These serum antibodies did not protect the cystic fibrosis patients against further lung infection with P. aeruginosa.

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