ß -glucan from saccharomyces cereviseae in skim yogurt production / ß-Glucana de Saccharomyces cereviseae na produção de iogurte desnatado

The demand for functional foods has increased in recent years, following a market trend in which the consumer values foods associated with health improvements. Skim milk yogurts were produced with yeast ß-glucan (YBG, 0.5 and 1.0 %) isolated from Saccharomyces cerevisiae and compared with full fat (FFY) and skim milk (SMY) yogurt as controls. The samples were analyzed for physical, chemical, color,syneresis, culture starter count, textural, microstructure and sensory attributes. Yeast ß-glucan was not able to retain the serum of yogurts during cold storage. Skim yogurt firmness increased with the addition of 0.5% yeast ß-glucan, presenting a more compact microstructure. Yogurts containing yeast ß-glucan had low scores by the untrained panelists in the sensorial analysis (0.5% YBG overall acceptance 5.2, FFY 6.8, SY 6.3) and low purchase intention. Thus, although similar characteristics were observed, low scores in the sensorial analysis and purchase intention were a barrier to commercializing skim milk yogurt with yeast ß-glucan developed in the present study

A demanda por produtos funcionais tem aumentado recentemente, seguindo um padrão no qual os consumidores valorizam os alimentos que são associados a melhoria da saúde. Iogurte desnatado foi produzido com ß-glucana extraída de Saccharomyces cerevisiae e comparado com iogurte integral e iogurte desnatado. O iogurte desnatado contendo ß-glucana não reteve soro durante a estocagem refrigerada. A firmeza do produto aumentou com a adição de 0,5% de ß-glucana e sua microestrutura foi mais compacta. Iogurtes contendo ß-glucana apresentaram menor escore na análise sensorial. Assim, embora características semelhantes tenham sido observadas, os baixos escores da análise sensorial são uma barreira para a comercialização de iogurte desnatado contendo ß-glucana produzido no presente estudo

Identification of Salmonella SPI-2 secretion system components required for SpvB-mediated cytotoxicity in macrophages and virulence in mice.

The Salmonella SpvB protein possesses ADP-ribosyl transferase activity. SpvB, acting as an intracellular toxin, covalently modifies monomeric actin, leading to loss of F-actin filaments in Salmonella-infected human macrophages. Using defined Salmonella mutants, different functional components of the SPI-2 type three secretion system (TTSS), ssaV, spiC, sseB, sseC, and sseD, were found to be required for SpvB-mediated actin depolymerization in human macrophages. Expression of SpvB protein in Salmonella was not affected by any of the SPI-2 mutants and the effects of these loci were not due to reduced numbers of intracellular bacteria. Interestingly, the major SPI-2 virulence effector, SifA, is not required for SpvB action. Further, caspase-3 activation is an additional marker of cytotoxicity in Salmonella-infected human macrophages. Caspase-3 activity depended on SpvB and SPI-2 TTSS function, but not on SifA. These human macrophage cell culture results were corroborated by virulence studies in mice. Using competitive infection of mice with mixed inocula of single and double mutants, spvBmut1 mutation did not have an effect independent of ssaJ mutation, essential for SPI-2 TTSS function. In contrast, competitive infection studies in mice confirmed that SpvB and SifA have independent virulence effects, as predicted by the macrophage studies.

Characterization of the spv locus in Salmonella enterica serovar Arizona.

Salmonella enterica serovar Arizona (S. enterica subspecies IIIa) is a common Salmonella isolate from reptiles and can cause serious systemic disease in humans. The spv virulence locus, found on large plasmids in Salmonella subspecies I serovars associated with severe infections, was confirmed to be located on the chromosome of serovar Arizona. Sequence analysis revealed that the serovar Arizona spv locus contains homologues of spvRABC but lacks the spvD gene and contains a frameshift in spvA, resulting in a different C terminus. The SpvR protein functions as a transcriptional activator for the spvA promoter, and SpvB and SpvC are highly conserved. The analysis supports the proposal that the chromosomal spv sequence more closely corresponds to the ancestral locus acquired during evolution of S. enterica, with plasmid acquisition of spv genes in the subspecies I strains involving addition of spvD and polymorphisms in spvA.