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The affects of hydrodynamic shock wave treatment on the bacterial flora of raw beef and poultry were evaluated. Hydrodynamic shock waves were generated in an aqueous treatment medium by either the detonation of two types of explosive charges (explosively-generated hydrodynamic shock waves [EHSW]) (a binary or a molecular explosive) or by electrical discharge (high voltage arc discharge Hydrodyne (TM [HVADH; Hydrodyne, Inc.]). A variety of sample types (whole steaks, ground beef, a water and ground beef slurry) were used to determine the lethality affects of EHSW on cells of the marker microorganism Listeria innocua suspended in a simple broth medium. These sample types were used in order to evaluate the affects of the process not only on the surface, but throughout the bulk of the samples in order to determine whether EHSW could also be used as a non-thermal alternative to reduce the bacterial flora of non-intact or ground meats. The levels of psychrotrophic, lactic, and coliform populations on the surface of whole eye of round steaks submitted to EHSW processing did not differ (P> 0.05) from those of untreated whole eye of round steaks. Parameters expected to influence the nature, magnitude, and propagation of the hydrodynamic shock wave were also varied and evaluated in order to determine which individual parameter or combination of parameters affected the bactericidal potential of EHSW or HVADH processing. Treatment with EHSW failed (P > 0.05) to produce lethality effects on the psychrotrophic, lactic, and coliform populations of ground beef, regardless of the composition and mass of explosive used, the number of successive EHSW treatments used, the relative distance between the explosive charge and the top surface of the sample, or the temperature of the water used in the treatment chamber. EHSW processing did not change (P >0.05) the bacterial population of treated ground beef samples when compared to untreated controls during a five day refrigerated storage study. No lethality effects were observed (P >0.05) in ground beef samples treated by HVADH when samples were subjected to one, two, or three successive HVADH treatments. Minimal penetration of surface inoculated bacteria was observed for both beef steaks and boneless skinless chicken breasts subjected to EHSW and HVADH, respectively. In EHSW-treated beef eye of round steaks, marker bacteria were detected within the first 300 um of tissue below the inoculated surface, 50-100 um beyond the depth of untreated surface inoculated steaks. In HVADH-treated boneless skinless chicken breasts, marker bacteria were detected within the first 200 um below the inoculated surface, 50-100 um beyond the depth of untreated surface inoculated boneless skinless chicken breasts. This suggests that although no difference in the bacteriological populations was observed between EHSW treated, HVADH treated, and untreated control samples of whole steaks (and ground beef treated with both HVADH and EHSW), HVADH and EHSW treatments affect the movement of surface bacteria. United States Department of Agriculture (USDA) guidelines suggest intact beef steaks be cooked to achieve a cooked color appearance on the surface and raw poultry be cooked to an internal temperature of 77° C to inactivate the pathogens Escherichia coli O157:H7 and salmonellae which are of concern in beef and poultry, respectively. By following these guidelines during proper cooking, consumers achieve thermal inactivation of these pathogens. Since the movement of the marker bacterium observed in treated steaks and boneless skinless chicken breasts was minimal, proper cooking of the products would be expected to inactivate vegetative bacterial cells at this depth. Therefore, EHSW and HVADH treated whole beef steaks and boneless skinless chicken breasts would not be expected to pose a bacterial hazard if the products were properly cooked. / Ph. D.

PURPOSE: The purpose of this study is to describe the subgingival bacterial biodiversity in untreated chronic periodontitis patients through the use of next generation 16S rRNA molecular analysis, and to determine similarities or differences between deep and shallow pockets within the same patients. METHODS: The analysis involved paired subgingival plaque samples from 24 subjects diagnosed with Generalized Moderate to Severe Chronic Periodontitis. One sample was selected from a single site having a probing depth >5 mm (i.e. Deep Site), and the other from a site with a probing depth <3mm (i.e. Shallow Site) within each subject. Bacterial DNA amplification of the V4-V6 region of the 16S rRNA was performed. The amplicons were sequenced via 454 Roche Genome Sequencer FLX System. The identified sequences were evaluated, and then compared to calculated false discovery rates. RESULTS: A total of 119 independent microbial genera were identified within the samples analyzed. Seven genera were identified to be statistically significant (p<0.05) in their association to deep or shallow sites following t-test and boot strap randomization: Actinomyces (p=0.004), Methylobacterium (p=0.028), Veillonella (p=0.028), and Rothia (p=0.038), and Streptococcus (p=0.033) in Shallow sites; while Mycoplasma (p=0.007) and Fusobacterium (p=0.016) were associated with deep sites. However, taking into account the calculated false discovery rates, it is suggested that none of the 119 microbial genera identified in this study were significantly associated with either deep nor shallow sites. CONCLUSION: The microbial genera identified within this study to be associated with deep and shallow sites follows the traditional pattern anticipated from the literature. However, the calculated false discovery rates suggest that these results may have occurred by chance and not due to a true difference.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

One of the factors that maintains fruit quality is its microbial flora. Fruit holds a natural non-pathogenic epiphytic microflora but can become contaminated with pathogenic microorganisms during export, causing either postharvest decay or possibly resulting in a food safety risk. In order to study microbial dynamics on fruit surfaces and the environment fruit moves through in the export chain, fruit washings were made, surfaces were sampled and total populations and diversities determined per cm2. Hygiene and safety levels for fruit export environments were hereby determined by sampling various points along the apple export chain, which included two farms and a harbour in South Africa and two harbours, two repacking facilities and two retail centres in Europe. In this first study of its kind, all the surfaces that were sampled exceeded the international standard for cleaning efficacy of food-processing equipment that is <5 cfu/cm2, while several areas exceeded the maximum acceptable index level of microbial air contamination of 22 cfu/h in food industries. Washing of containers on a harbour in South Africa did not have a significant impact on microbial populations. Regarding fruit quality, it was determined that apple microflora fluctuate throughout the export process and that postharvest pathogens that are known to cause great economic losses in the apple industry, proved to be of little significance in this investigation. The presence of six foodborne pathogens i.e. Shigella sonnei, Salmonella muenchen, Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Staphylococcus epidermidi/s was monitored throughout the chain. Of these, only S. aureus and E. coli were recorded, although pathogenicity was not confirmed for the latter. Staphylococcus aureus was found in containers and at a retail centre in Europe, and S. aureus and S. epidermidis were recorded on apple surfaces for the first time. Escherichia coli was present in great numbers in fruit washing water on a farm in South Africa. Since the standard for food premises is very stringent and perhaps inapplicable for fresh fruit handling and holding facilities, future research should include development of a more realistic hygiene standard for fresh fruit environments. / Dissertation (MSc(Agric) : Plant Pathology)--University of Pretoria, 2006. / Microbiology and Plant Pathology / unrestricted

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2004. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2006. / Härtill 4 uppsatser.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniv. / Härtill 4 uppsatser.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2007. / Härtill 3 uppsatser.

Объектом исследования являются бактерии Staphylococcus aureus в модельных суспензиях. Цель работы— апробация разработанных алгоритмов определения Staphylococcus aureus с использованием электрохимической системы на основе бесферментных электрохимических иммуносенсоров в модельных суспензиях. Определение чувствительности микробной флоры к антибактериальному препарату.В процессе работы должны быть проведены исследования синтезированных наночастиц магнетита, изучен характер электропревращений модифицированных наночастиц. Должен быть осуществлен выбор рабочего электрода и оптимальных условий анализа для количественного определения Staphylococcus aureus в модельных суспензиях. Должна быть проведена апробация разработанных алгоритмов по определению Staphylococcus aureus в модельных образцах. Определена чувствительность микробной микрофлоры к антибактериальному препарату мазь «Новокомб – 50%». В результате исследования были синтезированы наночастицы магнетита (Fe3O4), наличие полимерного покрытия подтверждено методом ИК - спектроскопии. В результате проведенных экспериментов был получен электрохимический аналитический отклик от модифицированных наночастиц магнетита. Были выбраны оптимальные условия регистрации аналитического сигнала. В качестве рабочего электрода был выбран планарный платиновый электрод, в качестве метода иммобилизации - метод физической сорбции антител на рабочую зону электрода. Был получен электрохимический отклик от иммунокомплекса антитело-бактерия, меченая наночастицами магнетита. Были выбраны оптимальные условия проведения количественного определения Staphylococcus aureus в модельных суспензиях. При данных условиях была выполнена оценка результатов в отношении таких показателей, как воспроизводимость и специфичность. По результатам апробации алгоритмов на модельных образцах было выявлено, что результаты данного метода коррелируют с методами ИФА и бактериального посева. Точность метода с использованием электрохимического иммуносенсора удовлетворительная. Данный метод может быть рекомендован для определения чувствительности микробной флоры к антибактериальным препаратам при их разработке, исследовании и на этапах серийного производства и обращения Основные конструктивные и технико-эксплуатационные показатели: предел обнаружения для бактерий Staphylococcus aureus составил 8.7 КОЕ/мл. Относительное стандартное отклонение не превышает 10%.Эффективность метода определяется возможностью его применения для определения чувствительности микробной флоры к антибактериальным препаратам при их разработке, исследовании и на этапах серийного производства и обращения. / Object of research are the bacteria Staphylococcus aureus in model suspensions. The purpose of testing the developed algorithms work- determining Staphylococcus aureus using electrochemical systems based on electrochemical besfermentnyh immunosensors in model suspensions. Determination of the sensitivity of the microbial flora to antibacterial preparatu.V during operation should be studied synthesized nanoparticles of magnetite, studied character elektroprevrascheny modified nanoparticles. Selection is to be made the working electrode and optimal assay conditions for quantitative determination of Staphylococcus aureus in model suspensions. It must be carried out testing of the developed algorithms to identify Staphylococcus aureus in model samples. Determine the sensitivity of the microbial microflora antimicrobial ointment "Novokomb - 50%." The study nanoparticles of magnetite (Fe3O4) were synthesized, the presence of the polymer coating was confirmed by IR - spectroscopy. As a result of the experiments was obtained from the electrochemical analytical response modified magnetite nanoparticles. optimal conditions for the registration of the analytical signal were selected. The working electrode was selected planar platinum electrode, as a method of immobilization - the method of physical adsorption of antibodies to the working electrode area. electrochemical response by the bacterium-antibody immunocomplex, labeled magnetite nanoparticles was obtained. the optimal conditions were selected quantitative determination of Staphylococcus aureus in model suspensions. Under these conditions, evaluation of the results was carried out in relation to indicators such as reproducibility and specificity. According to the results of testing of algorithms to model samples it was found that the results of this method correlate with the ELISA and bacterial seeding. Accuracy of the method using an electrochemical immunosensor satisfactory. This method can be recommended for the determination of the sensitivity of the microbial flora to antibiotics when they are developing, researching and on the stages of mass production and circulation of basic design and technical and operational parameters: detection limit for bacteria Staphylococcus aureus was 8.7 CFU / ml. The relative standard deviation does not exceed 10% g? O FIG method determined by the possibility of its application for the determination of the sensitivity of the microbial flora to antibiotics when they are developing, researching and on the stages of mass production and circulation.