César Milton Baratto

Resistance to Extended-Spectrum β-Lactamases in Salmonella from a Broiler Supply Chain

The prevalence of extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae varies worldwide, however, the incidence of ESBL-producing environmental Salmonella isolates is increasing. Salmonella is still one of the most important pathogens that occur in the poultry supply chain. Therefore, this study analyzed the susceptibility of Salmonella isolates collected from a poultry supply chain to β-lactam antibiotics, and examined the phenotypes of the isolates based on enzyme-inducible AmpC β-lactamase analysis. All analysis of the putative positive isolates in the current study confirmed that 27.02% (77/285 analysis) of all ESBL tests realized with the isolates produced a profile of resistance consistent with β-lactamase production. All isolates of S. Minnesota serotype had ESBL phenotype. Aztreonam resistance was the least common amongst the Salmonella isolates, followed by ceftazidime. The presence of inducible chromosomal ESBL was detected in 14 different isolates of the 19 serotypes investigated. These results are very indicatives of the presence of ESBL genes in Salmonella isolates from a broiler supply chain, reaffirming the growing global problem of ESBL resistance.

Influence of enzymes and ascorbic acid on dough rheology and wheat bread quality

The combined action of ascorbic acid and two commercial enzymatic complexes containing amylase and xylanase/amylase was analyzed to determine their effects on dough rheology and bread quality. Seven bread formulations containing different concentrations of these improvers were used in the analysis. The rheological properties of each dough formulation were determined by moisture, gluten and farinograph tests. The breads were also characterized in general aspect - especially shelf-life - based on the presence of fungi. The dough rheology results showed that the formulation developed in the presence of 0.01% xylanase/amylase and 200 ppm of ascorbic acid was more efficient. Improved shelf-life was obtained from the formulations containing xylanase. The results showed that some technological characteristics of dough rheology and gluten index produced from the combination of these improvers can indicate in order to obtain specific features of the bread. Key words: Food biotechnology, xylanase, amylase, dough properties, bread improvers.

Molecular and phenotypic characterization of Lactobacillus curvatus isolated from handmade Brazilian salami

17 Lactobacillus curvatus and one Lactobacillus brevis isolate were obtained from salami. The isolates were previously selected according to the desirable characteristics regarding technological criteria. Identification was based primarily on the biochemical carbohydrate assimilation profile, and later by amplified 16S rDNA restriction analysis (ARDRA). Due to inconsistencies in the results found by the identification methods employed, the 16S rRNA gene was partially sequenced and the result confirmed identity of L. curvatus, as predicted by ARDRA, which shows that this molecular technique is efficient in identifying the species. All isolates of L. curvatus were characterized by the molecular technique of random amplified polymorphic DNA (RAPD). In order to analyze the relationships existing between the isolates, taxonomic dendrograms were obtained based on molecular profile, what was suitable for the typing. The molecular techniques are efficient in the identification of Lactobacillus sp . isolates, which can be complementary or even substitute biochemical techniques. Thus, these molecular methods offer a fast and economic way for the identification and characterization of lactic acid bacterial with a potential use as starter cultures in the elaboration of handmade fermented products. Key words: 16S amplified ribosomal DNA restriction analysis (ARDRA), random amplified polymorphic DNA (RAPD), lactobacilli, microbial genetics.