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Selected AbstractsProduction of delta-endotoxin by Bacillus thuringiensis subsp kurstaki and overcoming of catabolite repression by using highly concentrated gruel and fish meal media in 2- and 20-dm3 fermentersJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 8 2002Nabil Zouari Abstract Delta-endotoxin production by a strain of Bacillus thuringiensis subsp kurstaki exhibiting larvicidal toxicity towards lepidoptera was investigated in 2- and 20-dm3 fermenters, using gruel- and fish meal-based media. The results show clearly that in such complex media, aeration plays an important role in bioinsecticide production. Optimal aeration led to improvement of delta-endotoxin concentrations with decreases of final spore count and proteolytic activity. Moreover, in order to use high gruel concentrations, a fermenter configuration with an efficient aeration system should be used. In a 20-dm3 Biolafite fermenter, 59,g,dm,3 or 75,g,dm,3 gruel was used to produce bioinsecticides with a significant reduction of carbon catabolite repression of delta-endotoxin synthesis. This result is very interesting in order to produce high final delta-endotoxin concentrations in the culture broth. It was also concluded, by considering the key role of oxidative pathways in delta-endotoxin synthesis, that oxygen supply must be adequate for bioinsecticide production at high substrate concentrations. Moreover, the role of sodium chloride in improving delta-endotoxin production is dependent not only on protease synthesis and its effect on crystal stability, but also on the aeration level of the production medium. © 2002 Society of Chemical Industry [source] The relationship between flesh quality and numbers of Kudoa thyrsites plasmodia and spores in farmed Atlantic salmon, Salmo salar L.JOURNAL OF FISH DISEASES, Issue 8 2003J A Dawson-Coates Abstract Atlantic salmon, Salmo salar L., were exposed to Kudoa thyrsites (Myxozoa, Myxosporea)-containing sea water for 15 months, and then harvested and assessed for parasite burden and fillet quality. At harvest, parasites were enumerated in muscle samples from a variety of somatic and opercular sites, and mean counts were determined for each fish. After 6 days storage at 4 °C, fillet quality was determined by visual assessment and by analysis of muscle firmness using a texture analyzer. Fillet quality could best be predicted by determining mean parasite numbers and spore counts in all eight tissue samples (somatic and opercular) or in four fillet samples, as the counts from opercular samples alone showed greater variability and thus decreased reliability. The variability in both plasmodia and spore numbers between tissue samples taken from an individual fish indicated that the parasites were not uniformly distributed in the somatic musculature. Therefore, to best predict the probable level of fillet degradation caused by K. thyrsites infections, multiple samples must be taken from each fish. If this is performed, a mean plasmodia count of 0.3 mm,2 or a mean spore count of 4.0 × 105 g,1 of tissue are the levels where the probability of severe myoliquefaction becomes a significant risk. [source] Reduction of Microflora of Whole Pickling Cucumbers by BlanchingJOURNAL OF FOOD SCIENCE, Issue 8 2000F. Breidt ABSTRACT: There is increasing interest in developing methods to control the presence of pathogenic and spoilage microorganisms on fresh fruits and vegetables. Blanching whole pickling cucumbers for 15 s at 80 °C reduced microbial cell counts by 2 to 3 log cycles from an initial population of typically 106 CFU/g. Vegetative microorganisms survived this blanching process (10,fold greater in number than the spore count), presumably because they were located beneath the surface of the cucumber. The sensitivity to heat of selected populations was measured by determining D values for pooled microorganisms (termed D values) isolated from fresh cucumbers. The Enterobacteriaceae population and the total aerobic microflora had similar Dp values to each other and to the D value for a selected lactic acid bacterium. [source] A - scab (Apple-scab), a simulation model for estimating risk of Venturia inaequalis primary infections,EPPO BULLETIN, Issue 2 2007V. Rossi A-scab (Apple-scab) is a dynamic simulation model for Venturia inaequalis primary infections on apple. It simulates development of pseudothecia, ascospore maturation, discharge, deposition and infection during the season based on hourly data of air temperature, rainfall, relative humidity and leaf wetness. A-scab produces a risk index for each infection period and forecasts the probable periods of symptoms appearance. The model was validated under different epidemiological conditions: its outputs were successfully compared with daily spore counts and actual onset and severity of the disease under orchard conditions, and neither corrections nor calibrations have been necessary to adapt the model to different apple-growing areas. Compared to other existing models, A-scab: (i) combines information from literature and data acquired from specific experiments; (ii) is completely ,open' because both model structure and algorithms have been published and are easily accessible; (iii) is not written with a specific computer language but it works on simple-to-use electronic sheets. For these reasons the model can be easily implemented in the computerized systems used by warning services. [source] The relationship between flesh quality and numbers of Kudoa thyrsites plasmodia and spores in farmed Atlantic salmon, Salmo salar L.JOURNAL OF FISH DISEASES, Issue 8 2003J A Dawson-Coates Abstract Atlantic salmon, Salmo salar L., were exposed to Kudoa thyrsites (Myxozoa, Myxosporea)-containing sea water for 15 months, and then harvested and assessed for parasite burden and fillet quality. At harvest, parasites were enumerated in muscle samples from a variety of somatic and opercular sites, and mean counts were determined for each fish. After 6 days storage at 4 °C, fillet quality was determined by visual assessment and by analysis of muscle firmness using a texture analyzer. Fillet quality could best be predicted by determining mean parasite numbers and spore counts in all eight tissue samples (somatic and opercular) or in four fillet samples, as the counts from opercular samples alone showed greater variability and thus decreased reliability. The variability in both plasmodia and spore numbers between tissue samples taken from an individual fish indicated that the parasites were not uniformly distributed in the somatic musculature. Therefore, to best predict the probable level of fillet degradation caused by K. thyrsites infections, multiple samples must be taken from each fish. If this is performed, a mean plasmodia count of 0.3 mm,2 or a mean spore count of 4.0 × 105 g,1 of tissue are the levels where the probability of severe myoliquefaction becomes a significant risk. [source] Environmental Allergens and Irritants in Schools: A Focus on AsthmaJOURNAL OF SCHOOL HEALTH, Issue 1 2002Susan R. Tortolero ABSTRACT: As part of the Partners in School Asthma Management Program, environmental data were collected from 385 rooms in 60 elementary schools in southeast Texas, using an Environmental Observation Checklist and a Q-TRAK Indoor Air Quality Monitor. Dust samples for allergen analysis were collected from floors, carpets, and area rugs in 80 classrooms in a subset of 20 schools. CO2 levels >1,000 ppm were found in 86% of rooms; 69% had indoor humidity above recommended levels. Der p I dust mite allergen levels >2,000 ng/g were present in 20% of rooms, but only 2.5% of rooms had Der f I mite allergen levels exceeding recommended tolerances. Detectable levels of cockroach allergen (Bla g II) were found in all schools (median 5.5 ng/g), with 10% of rooms over the recommended threshold. Almost two-thirds of classrooms had mold spore counts >10,000 col/g (median, 14,400 col/g; range, 2,000 , 52,000 col/g). [source] |