A linhagem Klebsiella sp. K18 produz a enzima glicosiltransferase que catalisa a conversão de sacarose em palatinose, um açúcar alternativo que apresenta baixa cariogenicidade. Metodologia de Superfície de Resposta foi empregada com sucesso para determinar a concentração ótima dos componentes do meio de cultivo. A máxima produção de glicosiltransferase (21,78 U mL-1) foi obtida utilizando o meio de cultivo otimizado composto por melaço de cana de açúcar (80 g L-1), peptona bacteriológica (7 g L-1) e extrato de levedura (20 g L-1), após 8 horas de fermentação a 28°C. A conversão de sacarose em palatinose foi estudada utilizando células imobilizadas em alginato de cálcio. Os efeitos da concentração de alginato (2-4%), concentração de massa celular (20-40%) e concentração de substrato (25-45%) foram avaliados e a porcentagem de palatinose foi de aproximadamente 62,5%.

The strain Klebsiella sp. K18 produces the enzyme glucosyltransferase and catalyses the conversion of sucrose to palatinose, an alternative sugar that presents low cariogenicity. Response Surface Methodology was successfully employed to determine the optimal concentration of culture medium components. Maximum glucosyltransferase production (21.78 U mL-1) was achieved using the optimized medium composed by sugar cane molasses (80 g L-1), bacteriological peptone (7 g L-1) and yeast extract (20 g L-1), after 8 hours of fermentation at 28°C. The conversion of sucrose to palatinose was studied utilizing immobilized cells in calcium alginate. The effects of the alginate concentration (2-4%), cell mass concentration (20-40%) and substrate concentration (25-45%) were evaluated and the yield of palatinose was approximately 62.5%.

Structural features of segmental parts of the aorta of rabbit were studied by light, scanning and transmission electron microscospies. The variabilities in architectural composition and thicker of the vascular coats as well as in vascular diameters at the ascendent (T2-3 level), thoracic (T6-7 level) and abdominal (L5-6 level) segments of the aorta were verified. Morphological features such as presence of intimal folds; occurrence of medial myo-elastic connections with segmental variations in the number of elastic lamellae, whose relative number was major in the ascendent and thoracic parts relatively to the abdominal part, and predominance of a network of stromal elements (connective fibers) in the adventitia were characterized. Also, the morphological findings were discussed at histophysiological base, because small but significative segmental differences were observed in the mural aortic structure of the rabbit

La estructura microscópica de la aorta de conejo fue estudiada, con recursos de microscopías óptica, electrónica de barrido y de transmisión, en las porciones ascendente torácica y abdominal, observándose variaciones morfométricas en el diámetro vascular y espesor de las capas de la pared aórtica. Los valores obtenidos fueron, generalmente, mayores en la porción ascendente. Características estructurales de la pared vascular fueron descritas, destacándose la presencia de pliegues en la túnica íntima; la formación de conexiones mioelásticas en la túnica media, variaba el número de lamelas elásticas en distintos segmentos, siendo mayor en las porciones torácicas ascendente y descendente, en relación a la porción abdominal. En la túnica adventicia predominaban las fibras del conjuntivo, dispuestas de forma variada, constituyendo una red. Los resultados fueron discutidos en términos morfofuncionales, teniendo presentes las pequeñas, pero significativas, variaciones segmentares observadas en la estructura de la pared aórtica de conejo