Progress 09/15/05 to 09/14/09
Outputs
OUTPUTS: This project addresses the transmission of Salmonella enterica Serovar Enteritidis through chicken eggs. Before the start of the project, little is known about why Salmonella enterica Serovar Enteritidis is the only bacterium that routinely causes human infection through intact chicken eggs. During the funding period of this proposal, we have gained significant understanding on how Salmonella enterica Serovar Enteritidis survives in egg albumen for its transmission, and we published our findings in scientific journals for the agricultural and general scientific community. PARTICIPANTS: Raul Clavijo, undergraduate student, UC Berkeley Heijin Kang, undergraduate student, UC Berkeley Cindy Loui, UC Berkeley Lee Riley, UC Berkeley Sangwei Lu, UC Berkeley Gary Andersen, Lawrence Berkeley Laboratory, Berkeley, CA TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The long-term goal of this proposal is to understand how S. enteritidis survives in eggs, a characteristic important for the transmission of this bacterium. In this project, we have screened a transposon library to systematically identify genes necessary for S. enteritidis to survive in egg albumen and characterize the mechanisms of resistance mediated by these genes. We screened approximately 3,000 mutants and identified 32 egg-susceptible (ES) mutants. Of 33 ES mutants we identified, 16 (50%) have Tn insertions in genes expected to be involved in the structure and function of bacterial cell wall. Eight ES mutants (25%) have Tn insertions in genes involved in the metabolism, especially amino acid metabolism. Two ES mutants (ES16 and ES47) have insertions in genes unique to S. enteritidis; ES16 has a Tn insertion in a restriction endonuclease, and ES47 has a Tn insertion in the Prot6e that appears to be in an operon for fimbrial biosynthesis. Analysis of genes interrupted by Tn insertion in the ES mutants demonstrate that two systems, cell wall and amino acid metabolisms, play important roles in the survival of S. enteritidis in egg albumen. Twenty-four of the 32 ES mutants (75%) have Tn insertion in genes involved in either cell wall structure/function or amino acid metabolism. In addition, the two systems are related to one another. Therefore, cell wall structural and functional integrity and amino acid metabolism are essential for S. enteritidis to survive the stress of exposure to egg albumen. Characterization of the mechanisms of how these ES mutants become susceptible to egg albumen is ongoing. We have also systematically and quantitatively analyzed the survival properties of Salmonella enterica serovar Enteritidis in egg albumen and identified factors affecting its survival. Survival assays of Salmonella enterica serovar Enteritidis in egg indicate that egg albumen restricted the growth of Salmonella enterica serovar Enteritidis. A major factor that controlled Salmonella enterica serovar Enteritidis' growth in egg albumen was iron restriction, since egg albumen supplemented with iron allowed Salmonella enterica serovar Enteritidis to grow, and iron acquisition mutants of Salmonella enterica serovar Enteritidis showed decreased survival in egg albumen. In addition, low pH of albumen, high concentrations of bacteria and low incubation temperatures of bacteria with albumen facilitates the survival of Salmonella enterica serovar Enteritidis. Our results suggest that egg albumen uses multiple mechanisms to control Salmonella enterica serovar Enteritidis including iron limitation, surface interaction and possible enzymatic activities.
Publications
- Clavijo, R. I., Loui, C. S., Andersen, G. L., Riley, L. W. and Lu, S. (2006) Identification of genes associated with the survival of Salmonella enterica serovar Enteritidis in chicken egg albumen. Appl Environ Microbiol.72, 1055-1064.
- Kang, H., Loui, C. S., Clavijo, R. I., Riley, L. W. and Lu, S (2006). Survival characteristics of Salmonella enterica serotype Enteritidis in chicken egg albumen. Epidemiology and Infection 134, 967-976.
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Progress 09/15/06 to 09/14/07
Outputs
OUTPUTS: Continue atomization studies (ongoing evaluation). Currently we are comparing atomization data collected in the UCD wind tunnel during the phase I study with that of ARENA'S new wind tunnel and to measure atomization from several nozzles and chambers. The UCD wind tunnel uses the Particle Measuring System and we are now using SYMPATEC'S HELOS-VARIO/KF laser diffraction sensor and computer soft ware for particle size analysis (SYMPTEC system). While the two systems show similar atomization trends, there are differences in atomization values. The differences between the two systems need to be evaluated to provide both confidence in the data and an understanding of the differences in the data so that appropriate conclusions can be drawn when comparing results. Atomization in chambers with varying spray boom and nozzle locations has begun and this information will determine the optimal location of the spray boom and nozzle in the chamber. Five additional nozzles have been evaluated in the wind tunnel. These evaluations were conducted in ARENA Pesticide Management's new wind tunnel equipped with a SYPATEC system. ARENA has recently received a customized "Synchro System" (both the valve and controller) from Capstan Ag Service providing both better aerodynamics and increased liquid flow rates. This system is scheduled to be tested soon. This system enables the user to vary flow rate and pressure independent of each other giving better control over atomization. Chamber modifications. Chambers C-3, C-4 and C-7, were selected for testing because they have the most promising designs to date, each has been fitted with a movable spray boom with nozzle mounted aft of the spray boom in a zero degree deflection. Atomization profiles were then developed. Obtain Federal Aviation Administration (FAA) approvals. The PI has started working with Designated Engineering Representative (DER) Robert B. Poe, FAA DER. Mr. Poe feels there will be no significant obstacles to testing and eventual certification of the RVA system. We are currently in touch with Mr. Poe to move the aircraft into the experimental category and mount a one-half size chamber on the aircraft for in-flight testing. Mount the chamber on the aircraft. Chambers number C-3, C-4 and C-7 have been mounted on the wing of the aircraft along with a rake and manometer board (specifically engineered and constructed for this project) to measure air velocities while in flight. This was done to verify that the air velocities and flow inside the chamber while in the wind tunnel, i.e., a very controlled environment, would match those in actual flight. We did gain a great deal of valuable information from this testing. Perform swath testing. Not yet performed. We need to have a functional, near end-product, prototype completed to dedicate the time, effort and costs to this component of the project. Perform drift studies. Not yet performed. Same answer as above. Explore manufacturing and marketing strategies. Some preliminary work to the final design has been conducted. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: Nothing significant to report during this reporting period. PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
The variations between the Particle Measuring System used in the UCD wind tunnel for the phase I, and SYMPATEC'S HELOS-VARIO/KF laser diffraction sensor and computer soft ware for particle size analysis (SYMPTEC system) used in ARENA's wind tunnel were anticipated. The SYMATEC system is newer, more efficient, saves time and is more widely used in other testing facilities. These traits improve confidence in the data, have shown the data to be reproducible, and will allow others to validate the results of this study. The five nozzles tested have produced poor results when considering the amount of driftable fines produced. We have made many air velocity measurements at various locations in the chamber and tried to use that information to determine where best to locate the nozzle and spray boom which has been time consuming and most of the time a hit or miss ordeal. Because the SYMPATEC system can perform atomization test very rapidly we have been able to mount a movable spray boom with a nozzle mounted aft of spay boom in a zero degree deflection in varying locations and collect atomization data at many locations in the chamber in a short amount of time. This has allowed use to build a better picture of the atomization profile inside the chamber with the boom and nozzle at varying locations in less time and expense giving the ideal location for the spray boom and nozzle. Chamber modifications. Based on information gathered from Foresight Science and Technology, Inc. (hired by SBIR to aid in commercialization of technologies funded by SBIR) commercialization support program surveys indicated potential buyers of this system were concerned about drag on the aircraft, which will increase fuel consumption and operator costs. This was also one of our primary concerns. We then re-examined the differences between chambers already tested and decided that the reduction in driftable fines between chambers C-3 and C-7 was not enough of an improvement to justify the additional drag created by Chamber C7. Current and future efforts are and will be based on what we have learned from all the preceding chambers and put to use by increasing the length of the calming section and creating an overall chamber external profile between chambers C-3 and C-7. This modification will decrease drag while maintaining an acceptable reduction in driftable fines. Chamber mounted on the aircraft. Information obtained by multiple flight tests with the chambers attached to the wing of the aircraft has identified a potential problem. As the air passes over the chamber it is also effecting the angle that the air enters the chamber. This is having an effect on the air velocity profile inside the chamber. We have been able to make minor changes to the angle of the chamber relative to the bottom of the wing to solve this problem. This testing will need to be carried out on each different type wing design. At this point we are very encouraged by the findings. While we have had some setbacks, we are making positive progress overall and have moved forward. The ultimate goal of the finished product is taking shape.
Publications
- US Patent number 7,131,600 issued November 7, 2006
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Progress 09/15/05 to 09/15/06
Outputs
This has been a challenging year for the project team in that the PI had heart valve replacement surgery, complicated by a minor stroke. Mr. Akesson also had heart valve replacement surgery. Both required significant recovery time, but have both recovered and returned to work. In addition, the test aircraft proposed for flight testing encountered corrosion problems in the wing that had to be dealt with. Several valuable months were used up while it was down for repairs and then had to return commercial agricultural work. Accomplishments during project year 2006: 1. Modification and improvement of RVA (Reverse Venturi Atomization) chamber. The chamber developed in Phase II was modified by adding a spray boom within the chamber itself. This is a streamlined structure that traverses across the settling/calming area of the chamber. The spray boom delivers liquid to the spray nozzle and will become a structural component of the RVA chamber system. The placement of the spray
boom within the chamber is critical in providing the calm laminar flow of air at the site of atomization - a key goal for the entire project. The optimum location was determined by conducting wind tunnel tests using the same rake and manometer board used in Phase I & II studies. It is critical to understand the effect of the spray boom on the aerodynamics within the chamber and its effect on the liquid spray produced at the nozzle. The use of the spray boom in side the chamber is a key element in spray delivery to the spray nozzle and overall structure of the RVA system. 2. Testing of the modified chamber on the aircraft. The original chamber with and without spray boom have been mounted on the test aircraft. A portable manometer board and rake are currently being mounted on the test aircraft. The rake will be mounted in the RVA chamber at different locations as was done in the wind tunnel. Airspeeds will be taken both inside and outside the RVA chamber and this data will be analyzed
to see that the chamber is performing the same on the test aircraft as it did in the wind tunnel. This will allow a better understanding of any effects that the aircraft may be causing on performance of the chamber. Information from this testing will be used to enhance the final development and construction of a complete RVA system on the test aircraft. Other accomplishments, not originally proposed include: 1. It was determined that it would be advantageous to build our own wind tunnel, rather than depend on aging equipment, availability conflicts, and to better utilize time and effort. So, the PI built a wind tunnel at his location (Bob's Flying Service, Knights Landing, CA) at the expense of ARENA Pesticide Management. The wind tunnel is on line and being used to conduct atomization work for both this project and another project dealing with spray tank physical properties and atomization. 2. An additional RVA chamber was constructed and provided to another researcher who is testing
the unit in their wind tunnel. This individual will be providing comparison data (at no cost to the project) that will be used to validate and confirm our results.
Impacts
The use of the RVA system for aerial application of liquid materials will help mitigate the potential of off-site drift of pesticides. The minimization of off-site drift is beneficial to all concerned - the applicators of the material, the farmers whose crops are protected by the materials applied, the regulators who must monitor the materials and their drift, as well as the public and the environment who are protected from the off-site drift of materials by the use of this application strategy.
Publications
- No publications reported this period
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