This study evaluated the thermal drying process commonly used by small and very small beef jerky operations in Texas. It was intended to determine the impact of relative humidity on the production of beef jerky and to provide documentation to beef jerky producers to support their Hazard Analysis and Critical Control Point programs. This project was divided into two phases: Phase I provided a low level of relative humidity (15-25%), whereas Phase II provided a high level (100%) for 25% of the cooking cycle. Both phases consisted of three trials, each representing one of the treatments (n=18) applied to the samples. The first treatment served as the control group and included samples that were non-inoculated, while the other two treatments included inoculations of samples with a bovine fecal slurry and rifampicin-resistant Salmonella Typhimurium. Each of the three treatments for both phases was analyzed for reduction of microbial levels in addition to temperature and product composition. Once the two phases had been completed and all data were analyzed, it was concluded that there was not a statistical difference between the level of reduction for Aerobic Plate Counts, coliforms, Escherichia coli and Salmonella provided by Phase I with low humidity and Phase II with high humidity. Both levels of humidity provided similar levels of reduction within each trial, suggesting that the level of humidity does not have a great impact on the level of microbial reduction achieved. However, this study did not provide the adequate level of initial inoculation levels to support the required 6.5 log reduction stated in 9 CFR 318.7. Inoculation levels were lower than 6.5 logs for all three treatments in both phases, resulting in lower levels of overall reduction. Therefore, based upon the information provided by this study, it cannot be concluded that a low level of humidity will achieve a 6.5 log reduction as mandated in 9 CFR 318.17.

This study measured and compared different temperatures and dwell times of hot water treatment on the reduction of Escherichia coli O157:H7 and Salmonella Typhimurium on beef carcass surfaces. Two different types of beef surfaces, lean and fat, were inoculated with a fecal slurry containing E. coli O157:H7 and S. Typhimurium at ca. 7-log CFU/g, washed to remove gross fecal matter, and rinsed with hot water between 66 and 82 degrees C (150 to 180 degrees F water) for either 5, 10, or 15 s. There were no differences (P > 0.05) in the log reductions of S. Typhimurium and E. coli O157:H7 on the lean surfaces for all three temperature treatments (66, 74, and 82 degrees C). Although the 15 s treatment resulted in a numerically higher log reduction than the other treatments, each of the times resulted in at least a 1 log reduction of both S. Typhimurium and E. coli O157:H7 for lean surfaces. For the fat surfaces, all time treatments for the 82 degrees C and the 10 and 15 s treatments for the 74 degrees C resulted in the highest log reduction for S. Typhimurium. The 5 and 10 s dwell times for treatments at 66 degrees C and the 5 s dwell time at 74 degrees C resulted in the lowest log reduction of S. Typhimurium and E. coli O157:H7. For E. coli O157:H7 all temperature and time treatments resulted in at least a 1 log reduction for the fat surfaces of the outside round. Therefore, hot water treatment is a proven method for reducing both coliforms and pathogenic bacteria.

Due to the seasonal nature of E. coli O157:H7 shedding and of hormone production by the thyroid gland, two studies were initiated to determine whether chemical inhibition of the thyroid gland influences fecal shedding of Escherichia coli O157:H7. Twenty-four crossbred sheep (68.6 kg BW) were randomly assigned to pen and either 0.0 mg/kg BW PTU or 20 mg/kg BW PTU for 5, 11, or 14 days. Sheep were experimentally infected (d 0) with E. coli O157:H7 11 days prior to PTU treatment. Fecal and serum samples were collected for bacterial enumeration and for analysis of T3 and T4, respectively. Sheep were humanely euthanized and tissue and content samples were collected from the rumen, ileum, colon and rectum. Detection of E. coli O157:H7 increased toward the terminal end of the GI tract. In the treatment group, serum T3 levels decreased to an overall lower level than the control group. A correlation was seen between T3 levels and daily O157:H7 bacterial shedding (P=0.003; r=0.37). In experiment 2, 12 growing lambs (41.04 kg BW) were exposed to either 0.0 mg/kg BW PTU or 40 mg/kg BW PTU for 21 days. Fecal samples were collected for analysis of generic E. coli and body weights were recorded on days 0, 7, 14, and 21. Feed intake was recorded throughout the experiment. Animals were experimentally infected with E. coli O157:H7 on day 15. Sheep were humanely euthanized on day 21 and GI tract tissue and content was collected from the rumen, ilium, colon and rectum. A date by treatment interaction was observed for T4 (P=0.0016) and hormone levels decreased in treated animals. Thyroxine and E. coli O157:H7 display a multivariate treatment (P=0.0005) and date effect (P=0.0174) but no significant interaction. Triiodothyronine and E. coli O157:H7 shedding have a slight date trend (P=0.065) but no significant treatment or treatment by date interaction. Generally, the treatment group shed genreric E. coli at higher levels throughout the study period with slightly more than a log count difference between groups at the last collection point (control = 3.8 CFU/gram of feces (log10); treatment = 4.9 CFU/gram of feces (log10)). Results from these experiments suggest that correlations exist between both E. coli O157:H7 and generic E. coli shedding in sheep.

Microbiological detection of foodborne pathogens is ineffective for monitoring critical control points (CCP) within a slaughter/processing Hazard Analysis and Critical Control Point (HACCP) system. Pathogens are usually absent from carcass surfaces and their uneven distribution makes it difficult to obtain a representative sample. However, microbiological testing can be applied within a HACCP plan to validate and verify the effectiveness of decontamination procedures designed to control hazards. With proper data collection, the reduction of an indicator group at a point in processing can indicate that a specific pathogen is being effectively controlled, especially when pathogen levels are too low to allow confirmation of process control, as they typically are in beef slaughter processing. Since E. coli O157:H7 has been shown to have some acid resistance, the ability of typical indicator organisms to accurately predict the reduction of this pathogen by carcass decontamination procedures has been a concern. Obtaining potential indicator bacteria from the same environmental reservoir as E. coli O157:H7 may provide non-pathogenic indicators with similar heat- and acid-resistance characteristics suitable for use in processing plant environments for validation and verification of carcass decontamination treatments within HACCP plans. Potential indicator bacteria were isolated from hides of cattle at slaughter facilities in Arizona, Georgia, and Texas and compared with isolates of E. coli O157:H7 from the same locations to determine similarity in acid- and heat-resistance characteristics. After evaluation at 2 heating temperatures (55 and 65??C) and 3 pH levels (3.0, 4.0, and 5.0), it was determined that several potential indicator bacteria were slightly more resistant than E. coli O157:H7 to heating and acid treatment. The greatest reduction in numbers for E. coli O157:H7 and indicator bacteria occurred at pH 3.0 and temperature of 65??C. Counts of bacteria grown at pH 4.0 and 5.0 were not significantly different. Testing indicated that several of the isolates from cattle hides would make good process control indicators since the indicator bacteria were reduced by heating or acid conditions at similar or greater rates when compared to E. coli O157:H7, providing an increased level of security that pathogens have been reduced in processing.

This manuscript presents a thorough investigation and description of metabolic control dynamics in vivo and in silico using as a model de novo pyrimidine biosynthesis. Metabolic networks have been studied intensely for decades, helping develop a detailed understanding of the way cells carry out their biosynthetic and catabolic functions. Biochemical reactions have been defined, pathway structures have been proposed, networks of genetic control have been examined, and mechanisms of enzymatic activity and regulation have been elucidated. In parallel with these types of traditional biochemical analysis, there has been increasing interest in engineering cellular metabolism for commercial and medical applications. Several different mathematical approaches have been developed to model biochemical pathways by combining stoichiometric and/or kinetic information with probabilistic analysis, or deciphering the comparative logic of metabolic networks using genomic-derived data. However, most of the research performed to date has relied on theoretical analyses and non-dynamic physiological states. The studies described in this dissertation provide a unique effort toward combining mathematical analysis with dynamic transition experimental data. Most importantly these studies emphasize the significance of providing a quantitative framework for understanding metabolic control. The pathway of de novo biosynthesis of pyrimidines in Escherichia coli provides an ideal model for the study of metabolic control, as there is extensive documentation available on each gene and enzyme involved as well as on their corresponding mechanisms of regulation. Biochemical flux through the pathway was analyzed under dynamic conditions using middle-exponential growth and steady state cultures. The fluctuations of the biochemical pathway intermediates and end products transitions were quantified in response to physiological perturbation. Different growth rates allowed the comparison of rapid versus long-term equilibrium shifts in metabolic adaptation. Finally, monitoring enzymatic activity levels during metabolic transitions provided insight into the interaction of genetic and biochemical mechanisms of regulation. Thus, it was possible to construct a robust mathematical model that faithfully represented, with a remarkable predictability, the nature of the metabolic response to specific environmental perturbations. These studies constitute a significant contribution to the fields of quantitative biochemistry and metabolic control, which can be extended to other cellular processes as well as different organisms.

HDGF (hepatoma-derived growth factor) is a novel growth factor,identified from conditioned medium of hepatoma cell line. HDGF has growth stimulating activity for fibroblast and some hepatoma cells. HDGF, a novel defined growth factor with mitogenic effect, has homology protein sequence as HMG (high mobility group) protein and their three dimension structures appeared to be similar to each other. Recently, elevated HDGF expression was found in developing kidneys but less was found in adult kidney. In addition, HDGF expression was found to be correlated with angiogenic status of tissues. Thus, it is speculated that HDGF plays a role during embryonic development and angiogenesis. HDGF also plays a role in cell-cell interaction and cell migration. HDGF is a growth factor that is involved in stimulating vascular smooth muscle cells (SMCs)proliferation during development and in disease. HDGF contains a true bipartite nuclear localization sequence necessary for nuclear targeting. HDGF is sciential factor in stimulating DNA replication and cell proliferation of vascular smooth muscle cell.In this study,we used E. coli strain BL21 (DE3) to express the recombinant protein hepatoma derived growth factor(HDGF). To find out the optimal production conditions,we studied on the different temperature and fermentor to calculate all cost .

Thèse de doctorat : Sciences agronomiques : INPL : 2008. / Titre provenant de l'écran-titre.

Zugl.: Berlin, Freie Universiẗat, Diss., 2009.

Thesis (Ph.D.)--University of Wyoming, 2008. / Title from PDF title page (viewed on August 5, 2009). Includes bibliographical references (p. 123-138).

Diss. (sammanfattning) Göteborg : Göteborgs universistet, 2009. / Härtill 4 uppsatser.