Biomedical subjects

T L Stamford

Publications and source records attributed to T L Stamford.

5 recordsLinked to original sources

PubMed2001

Production and characterization of a thermostable alpha-amylase from Nocardiopsis sp. endophyte of yam bean.

Thermostable amylolytic enzymes have been currently investigated to improve industrial processes of starch degradation. Studies on production of alpha-amylase by Nocardiopsis sp., an endophytic actinomycete isolated from yam bean (Pachyrhizus erosus L. Urban), showed that higher enzyme levels were obtained at the end of the logarithmic growth phase after incubation for 72 h at pH 8.6. Maximum activity of alpha-amylase was obtained at pH 5.0 and 70 degrees C. The isolated enzyme exhibited thermostable properties as indicated by retention of 100% of residual activity at 70 degrees C, and 50% of residual activity at 90 degrees C for 10 min. Extracellular enzyme from Nocardiopsis sp. was purified by fractional precipitation with ammonium sulphate. After 60% saturation produced 1130 U mg-1 protein and yield was 28% with purification 2.7-fold. The enzyme produced by Nocardiopsis sp. has potential for industrial applications.

Actinomycetales↗

PubMed1997

[Critical control points in the pasteurized milk processing fluxogram].

With the aim of evaluating the microbiological quality of raw and pasteurized milk and confirm the critical control points in a dairy processing industry (Recife-PE, Brazil), 84 samples of milk were collected from four points of the flow-chart considered critical (raw milk storage tank, outlet of the pasteurizer unit, pasteurized milk storage tank and packing filling machine). All samples were evaluated for the presence of mesophilic and psychotrophics microorganisms. The most probable number (MPN) of total and faecal coliforms were determined. Samples of raw and pasteurized milk (collected from the packing filling machine) were also assessed for the presence of Staphylococcus aureus. The preservation temperature of raw and pasteurized milk in the storage tanks and the MPN of total and faecal coliforms present in the water used by the industry were simultaneously evaluated. High counts of mesophilic and psychotrophics microorganisms, total and faecal coliforms and S. aureus were detect in raw milk production and processing. The pasteurization process reduced the microorganisms to acceptable numbers in the Brazilian standards, however, the statistics analysis showed that the number of microorganisms increased significantly (p < 0.01) in the pasteurized milk storage tank, representing an important point of contamination. The probable reason for this findings was the presence of coliforms in 60% samples of water which was used to clean the milk equipment and the inadequate temperatures in the storage tank. Therefore, the results of the microbiological analysis confirm that the milk maintenance temperature in the storage tanks, the pasteurization and the packaging are critical control points in the pasteurized milk processing fluxogram.

Animals↗

PubMed1995

[Nutritive value of collective meals: tables of food composition versus laboratory analysis].

A cycle of 13 basic meals lunches, planned and executed at an industrial feeding unit was studied, in order to verify the agreement between the nutritive value estimated by indirect analysis (Tables of chemical composition of foodstuffs), and by direct analysis in the laboratory. Two samples of each meal were taken, one consisting of raw unprocessed food and the other of prepared processed food. The following parameters were evaluated: weight, dry matter, humidity, proteins, lipids, fibers ashes, carbohydrates, calcium, iron and phosphorus. The results suggest that both the composition tables presented a weak correlation for calcium and phosphorus. Comparing processed with unprocessed meals, there was an increase in weight and humidity, and a considerable variation in protein, ash, iron and phosphorus, suggesting interference of the culinary process. The Food Composition Tables present limited reliability for the estimation of most nutrients in collective, prepared meals.

Analysis of Variance↗

PubMed1992

Fungal protein enrichment of residual liquor from a sugar-cane waste Saccharum officinarum.

The use of residual liquor obtained from cane-thrash, a sugar-cane waste Saccharum officinarum, L. , as a protein source was studied. The cane-thrash was available in local sugar-mills and the fungus utilized, the Aspergillus niger IZ-9, was provided by the University of São Paulo and derived from a strain under the number NRRL-337. The liquor was previously hydrolyzed and physicochemical analyses were performed. Total nitrogen and amino acid contents were measured in the final product. The synthetic medium of Pontecorvo et al. modified by Christias et al., was used for growth, maintenance and storage of the strain. The analysis of variance was used to determine the statistical significance of all results. Mean values were compared by the Tukey's test. According to our data, the residual liquor from the prehydrolyzed cane-thrash can be used as a medium for biomass production from the A. niger IZ-9 and that the highest biomass production was obtained when the synthetic medium was substituted for 100% treated liquor added with balanced salts and carbon, and pH adjusted to 5.0. The highest amino acid values were detected in the A. Niger grown in the medium containing 40% treated liquor added with balanced salts and carbon, with pH adjustment to 5.0 with exception of methionine, this fungal protein seems to provide all essential amino acids in a diet, and could certainly be considered of good biological value.

Amino Acids↗

PubMedDate not supplied

Changes in Saccharomyces cerevisiae development induced by magnetic fields.

Saccharomyces cerevisiae cultures exposed to 110 mT and 220 mT steady magnetic fields (SMF) were studied to observe eventual induced growth alterations and changes in metabolic activity. Cell mass (biomass) growth was evaluated by light spectrometry, and metabolic alterations were estimated on the basis of the CO2 pressure produced and by the culture media pH changes, measured at the beginning and the end of the observation. The yeast strain DAUFPE-1012, cultivated in a nonaerated liquid agar Sabouraud glucose medium, was exposed to SMF generated by NdFeBr magnets. Results showed alterations induced by 220 mT SMF as an increment in cell proliferation (1.84%) and an increased CO2 production (36.1%) as compared to control groups. Furthermore, the initial-to-final pH difference in 220 mT SMF exposed cultures was higher than the 110 mT SMF and the control values. The whole acidification and the rise in CO2 production observed after 220 mT SMF exposure did not correspond to the biomass growth values, as compared to the other cultures, and was apparently provoked by a enhancement in the cellular metabolic rate. This technique becomes very promising for future biotechnological applications in fermentative processes.

Biomass↗