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dc.contributor.advisor Bozak, Kristin R. en
dc.contributor.author Chung, Kevin en
dc.date.accessioned 2018-07-10T22:41:56Z en
dc.date.available 2018-07-10T22:41:56Z en
dc.date.issued 2018-07-10 en
dc.identifier.uri http://hdl.handle.net/10211.3/204269 en
dc.description.abstract Juglone (5-hydroxy-1,4-naphthoquinone) is the allelopathic compound produced by plants in the family Juglandaceae, which includes pecans, hickory, and walnuts. Throughout history, walnuts were observed to decrease the growth and fitness of neighboring plants. This effect was termed “walnut wilt” or when more broadly attributed to various organisms, “soil sickness”. The mechanism of the toxicity is not fully understood, though our lab results have demonstrated cellular respiration may be inhibited in seedlings, bacteria, and fungi. The compound is found in various concentrations throughout the plant, but highest concentrations are found within the hulls of the green fresh fruit. Juglone has been shown in literature to be somewhat toxic against many different organisms including crops, invasive plants, insects, and microorganisms. The study I conducted focused on three main objectives which included (1) the effect of juglone on 2 invasive plant seed germination, (2) the effect of juglone on 5 human pathogenic bacterial species, and (3) the effect of juglone on plant pathogenic fungal or oomycete species (Phytophthora, Pythium, and Rhizoctonia). Objective (1) was studied by saturating filter papers inside sterile petri dishes with 5 mls of dilutions up to 1 mM concentrations of juglone, where after three days, juglone inhibited germination of B. diandrus completely at 1 mM and of B. nigra significantly by 0.01 mM juglone. Objective (2) was studied by three primary methods: (a) Well Diffusion Assay, (b) Minimal Inhibitory Concentration (MIC) Assay based upon turbidity and plating, and (c) Time-kill test. The well diffusion assay was performed for each of 5 bacteria grown on LB agar plates with standardized wells containing water, 1 mM juglone, or an antibacterial control. Zones of inhibition were measured, and the following was ranked from most sensitive to least sensitive: M. luteus, S. epidermidis, S. aureus, A, hydrophilia, and E. coli. MIC assays were quantified by growing 5 different bacteria in concentrations of juglone up to 1 mM juglone then determining which concentration inhibited growth, with M. luteus and E. coli in the same respective sensitivity ranks as observed with the well diffusion assays. Time kill assay was conducted by exposing bacteria to LB amended to concentration with juglone, then plating on nutrient plates and calculating percent coverage by growth after incubation. All bacteria experienced decreased vitality by the third hour. Directly exposing bacteria to pure 1 mM juglone solution showed death within 30 minutes. Objective (3) was tested with well diffusion assays against hyphal structures and spores. Well diffusion assays produced zones of inhibition similar to bacteria. Based on the data collected it seems to indicate that juglone is bactericidal at upper limit of solubility likely by targeting cellular respiration and bactericidal instead of bacteriostatic. However, difficulties with solubility, cost, and its hydrophobic nature prevents it from being a good candidate for herbicidal or antibacterial application. It costs 6 dollars to produce one liter of 1 mM juglone. However, with the development of resistance against common drugs, it is still important to continue studying the potential uses of naphthoquinones like juglone and other similar compounds. en
dc.format.extent 52 pgs. en
dc.language.iso en en
dc.publisher California State Polytechnic University, Pomona en
dc.rights.uri http://www.cpp.edu/~broncoscholar/rightsreserved.html en
dc.subject juglone en
dc.subject walnut en
dc.subject microorganisms en
dc.subject seed en
dc.subject allelopathy en
dc.title Investigating the Biocidal Properties of Juglone Against Weedy Invasives and Microorganisms en
dc.type Thesis en
dc.contributor.department Department of Biological Sciences en
dc.description.degree M.S. en
dc.contributor.committeeMember Mellano, Valerie J. en
dc.contributor.committeeMember Snyder, Jamie C. en
dc.rights.license All rights reserved en

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