Type of Document Master's Thesis Author Miles, Jacquelyn Marie URN etd-12012006-144716 Title Salmonella Internalization From Contaminated Seeds or Irrigation Water in Greenhouse Tomatoes Degree Master of Science In the Life Sciences Department Food Science and Technology Advisory Committee
Advisor Name Title Sumner, Susan S. Committee Chair Latimer, Joyce G. Committee Member Williams, Robert C. Committee Member Keywords
Date of Defense 2006-11-17 Availability unrestricted AbstractAbstract
Greenhouse grown tomato fruits and tissues were tested for the presence of
Salmonella after the plants had been treated with Salmonella contaminated irrigation
water or grown from contaminated seeds. Greenhouse grown tomato plants were placed
into eight different groups. Groups one through six consisted of five plants each and were
treated with 350 ml of 10^6 Salmonella contaminated irrigation water over a course of 70
days; group one received one 350 ml 10^7 Salmonella treatment, group two received two
treatments, and so on, the treatments were scheduled every 14 days. Group seven was the
control that consisted of five plants and received no Salmonella treatment. Group eight
was grown from seeds that had been contaminated with Salmonella by soaking the seeds
in a 10^8 Salmonella suspension for 24 hours at room temperature, and received no
Salmonella watering treatment. A total of 128 tomatoes were sampled from the tomato
plants of all three groups and none tested positive for Salmonella. Tissue samples
consisting of roots, leaves, and stems, and were collected from one plant per each of three
replications. No leaves or stems contained Salmonella, however, five of the twenty-four
root samples were positive for Salmonella.
In a second study, Salmonella was tested for its ability to survive in three
concentrated fertilizer stock solutions and 1.6% diluted solutions of the fertilizer.
Fertilizer sample CF-S was a stock solution of commercial 20N-4.4P-16.6K fertilizer,
US-S was a mix of 11.3 kg UltraSol, 4.5 kg Epsom Salts, and 2.3 kg 0N-0P-43.2K in
114 L water, Fertilizer CN-S is a mix of 11.3 kg Calcium Nitrate and 56.7 g Iron chelate
(10%) to 30 L water; Fertilizers CF-1.6, US-1.6, and CN-1.6 were the 1.6% fertilizer
dilutions respectively. There was no significant difference (p<0.05) between the survival
of Salmonella in fertilizer groups CF-1.6, US-S, US-1.6, CN-1.6, and the sterile distilled
water control; all but US-S yielded less than a one log reduction in Salmonella over a
period of 72 hours. US-S yielded over a two log reduction in Salmonella and was not
significantly different than CN-S which had over a four log reduction. CF-S was
significantly different than all samples and led to over a 6 log reduction of Salmonella.
The results of this study showed no evidence that Salmonella was able to
internalize in Cultiver trust tomato fruit or tissues above the root line when irrigated with
contaminated water into the pine medium under greenhouse conditions. There was also
no evidence that Salmonella is able to internalize in any tissues or fruit from
contaminated seeds. The results also show that Salmonella was not able to survive in the
commercial fertilizer stock solution (CF-S), and had limited survival in CN-S tomato
fertilizer solution. The diluted fertilizer solution and US-S stock solution showed no
significance in survival of Salmonella when compared to the sterile water control.
Filename Size Approximate Download Time (Hours:Minutes:Seconds)
28.8 Modem 56K Modem ISDN (64 Kb) ISDN (128 Kb) Higher-speed Access MilesThesis.pdf 358.74 Kb 00:01:39 00:00:51 00:00:44 00:00:22 00:00:01
If you have questions or technical problems, please Contact DLA.