Identifier

etd-04102017-095745

Degree

Master of Science (MS)

Department

Plant Pathology and Crop Physiology

Document Type

Thesis

Abstract

Floodwater can contain microbial contaminants such as plant and foodborne pathogens and can compromise the quality of fresh fruit and vegetables produced in Louisiana. The goal of this research was to determine the impact of flooding on microbial quality (foodborne and plant pathogens) of cantaloupe fruit produced on raised or flat beds. Cantaloupe fruit produced on 30 cm raised beds or flat ground, were flooded with a mixture of surface and well water spiked with three generic Escherichia coli strains (ATCC 23716, 25922, 11775). Mean baseline generic Escherichia coli and total coliform populations in flood water (mixture of spiked well and pond water) were 5.1±0.4 and 6.2±0.1 log10MPN/100ml respectively. There were no significant differences (p=0.7509 or p=0.4041 log10MPN/cm2 and log10MPN/100ml respectively) in generic Escherichia coli on fruits surface from raised or flat beds. Independent of bed type, total coliform populations on fruit surface were consistent (p=0.2324 or p=0.1865 log10MPN/cm2 and log10MPN/100ml respectively) over 72 hours, while generic Escherichia coli populations decreased significantly (p=<0.0001 or 0.0001 log10MPN/cm2 and log10MPN/100ml respectively). There were no significant differences in the number of fruits positive for Salmonella spp. over time (RapidChek, p=0.3916; Xylose lysine desoxycholate (XLD), p=0.0634; polymerase chain reaction (PCR), p=0.4100), and between flooded and non-flooded plot (RapidChek, p=0.3916; XLD, p=0.0634; PCR, p=0.4100). Fruits positive for L. monocytogenes did not differ significantly over time and between flooded and non-flooded plots based on listeria semi-selective agar medium (LSA, p=0.9196) and polymerase chain reaction (PCR; p=0.9289) and between flooded and non-flooded plots (LSA, p=0.5056 and PCR, p=0.4966). Independent of bed type, mean fruit rot incidence caused by Sclerotium rolfsii or Phytophthora spp. increased significantly by 17.6% (p=0.0001) and 20% (p=0.0001) respectively one week after flooding. No significant differences were detected in mean percent fruit rot incidence for Southern Blight (Sclerotium rolfsii) (p=0.4231) or Phytophthora fruit rot (Phytopthora capsici) (p=0.2657) between fruit produced on raised beds or flat ground. There is evidence that the quality of cantaloupe fruit might drop significantly with or without floods due to foodborne and plant pathogen contamination in production hence presenting a major public health risk to consumers.

Date

2017

Document Availability at the Time of Submission

Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.

Committee Chair

Ivey Melanie Lewis

Available for download on Saturday, February 23, 2019

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