Publications by Colleges and Departments (MSU - Bozeman)
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Item Antiviral Activity of the PropylamylatinTM Formula against the Novel Coronavirus SARS-CoV-2 In Vitro Using Direct Injection and Gas Assays in Virus Suspensions(MDPI, 2021-03) Brown, Ashley N.; Strobel, Gary; Hanrahan, Kaley C.; Sears, JoeSevere acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of novel coronavirus disease 2019 (COVID-19), has become a severe threat to global public health. There are currently no antiviral therapies approved for the treatment or prevention of mild to moderate COVID-19 as remdesivir is only approved for severe COVID-19 cases. Here, we evaluated the antiviral potential of a Propylamylatin formula, which is a mixture of propionic acid and isoamyl hexanoates. The Propylamylatin formula was investigated in gaseous and liquid phases against 1 mL viral suspensions containing 105 PFU of SARS-CoV-2. Viral suspensions were sampled at various times post-exposure and infectious virus was quantified by plaque assay on Vero E6 cells. Propylamylatin formula vapors were effective at inactivating infectious SARS-CoV-2 to undetectable levels at room temperature and body temperature, but the decline in virus was substantially faster at the higher temperature (15 min versus 24 h). The direct injection of liquid Propylamylatin formula into viral suspensions also completely inactivated SARS-CoV-2 and the rapidity of inactivation occurred in an exposure dependent manner. The overall volume that resulted in 90% viral inactivation over the course of the direct injection experiment (EC90) was 4.28 ls. Further investigation revealed that the majority of the antiviral effect was attributed to the propionic acid which yielded an overall EC90 value of 11.50 ls whereas the isoamyl hexanoates provided at most a 10-fold reduction in infectious virus. The combination of propionic acid and isoamyl hexanoates was much more potent than the individual components alone, suggesting synergy between these components. These findings illustrate the therapeutic promise of the Propylamylatin formula as a potential treatment strategy for COVID-19 and future studies are warranted.Item An Endophytic Nodulisporium sp. from Central America Producing Volatile Organic Compounds with Both Biological and Fuel Potential(2013) Hassan, Syed R.-U.; Strobel, Gary A.; Geary, Brad; Sears, JoeA Nodulisporium sp. (Hypoxylon sp.) has been isolated as an endophyte of Thelypteris angustifolia (Broadleaf Leaf Maiden Fern) in a rainforest region of Central America. It has been identified both on the basis of its morphological characteristics and by scanning electron microscopy as well as ITS sequence analysis. The endophyte produces volatile organic compounds (VOCs) that have both fuel (mycodiesel) and use for biological control of plant disease. When grown on potato dextrose agar, the organism uniquely produces a series of ketones, including acetone; 2-pentanone; 3-hexanone, 4-methyl; 3-hexanone, 2,4- dimethyl; 2-hexanone, 4-methyl, and 5-hepten, 2-one and these account for about 25% of the total VOCs. The most abundant identified VOC was 1,8 cineole, which is commonly detected in this group of organisms. Other prominent VOCs produced by this endophyte include 1-butanol, 2- methyl, and phenylethanol alcohol. Moreover, of interest was the presence of cyclohexane, propyl, which is a common ingredient of diesel fuel. Furthermore, the VOCs of this isolate of Nodulisporium sp. were selectively active against a number of plant pathogens, and upon a 24 h exposure caused death to Phytophthora palmivora, Rhizoctonia solani, and Sclerotinia sclerotiorum and 100% inhibition to Phytophthora cinnamomi with only slight to no inhibition of the other pathogens that were tested. From this work, it is becoming increasingly apparent that each isolate of this endophytic Nodulisporium spp., including the Daldina sp. and Hypoxylon spp. teleomorphs, seems to produce its own unique set of VOCs.Item Control of microbial souring by nitrate, nitrite or glutaraldehyde injection in a sandstone column(1996-08) Reinsel, Mark A.; Sears, Joe; Stewart, Philip S.; McInerney, Michael J.Microbial souring (production of hydrogen sulfide by sulfate-reducing bacteria, SRB) in crushed Berea sandstone columns with oil field-produced water consortia incubated at 60°C was inhibited by the addition of nitrate (NO3) or nitrite (NO2−). Added nitrate (as nitrogen) at a concentration of 0.71 mM resulted in the production of 0.57–0.71 mM nitrite by the native microbial population present during souring and suppressed sulfate reduction to below detection limits. Nitrate added at 0.36 mM did not inhibit active souring but was enough to maintain inhibition if the column had been previously treated with 0.71 mM or greater. Continuous addition of 0.71–0.86 mM nitrite also completely inhibited souring in the column. Pulses of nitrite were more effective than the same amount of nitrite added continuously. Nitrite was more effective at inhibiting souring than was glutaraldehyde, and SRB recovery was delayed longer with nitrite than with glutaraldehyde. It was hypothesized that glutaraldehyde killed SRB while nitrite provided a long-term inhibition without cell death. Removal of nitrate after as long as 3 months of continuous addition allowed SRB in a biofilm to return to their previous level of activity. Inhibition was achieved with much lower levels of nitrate and nitrite, and at higher temperatures, than noted by other researchers.Item Partition coefficients for acetic, propionic, and butyric acids in a crude oil/water system(1994-07) Reinsel, Mark A.; Borkowski, J. J.; Sears, JoeItem A computer investigation of chemically mediated detachment in bacterial biofilms(2003-05) Hunt, Stephen Michael; Hamilton, Martin A.; Sears, Joe; Harkin, Gary; Reno, JasonA three-dimensional computer model was used to evaluate the effect of chemically mediated detachment on biofilm development in a negligible-shear environment. The model, BacLAB, combines conventional diffusion-reaction equations for chemicals with a cellular automata algorithm to simulate bacterial growth, movement and detachment. BacLAB simulates the life cycle of a bacterial biofilm from its initial colonization of a surface to the development of a mature biofilm with cell areal densities comparable to those in the laboratory. A base model founded on well established transport equations that are easily adaptable to investigate conjectures at the biological level has been created. In this study, the conjecture of a detachment mechanism involving a bacterially produced chemical detachment factor in which high local concentrations of this detachment factor cause the bacteria to detach from the biofilm was examined. The results show that the often observed ‘mushroom’-shaped structure can occur if detachment events create voids so that the remaining attached cells look like mushrooms.Item Urnula sp., an Endophyte of Dicksonia antarctica, Making a Fragrant Mixture of Biologically Active Volatile Organic Compounds(2017-08) Strobel, Gary A.; Ericksen, Amy; Sears, Joe; Xie, Jie; Geary, Brad; Blatt, BryanUrnula sp. was isolated as an endophyte of Dicksonia antarctica and identified primarily on the basis of its ITS sequence and morphological features. The anamorphic state of the fungus appeared as a hyphomyceteous-like fungus as based on its features in culture and scanning electron microscopy examination of its spores. On potato dextrose agar (PDA), the organism makes a characteristic fragrance resembling peach pie with vanilla overtones. A GC/MS analysis done on the volatile organic compounds (VOCs) of this organism, trapped by carbotrap methodology, revealed over 150 compounds with high MS matching quality being noted for 44 of these. Some of the most abundantly produced compounds included 4-decene, tridecane, 2-decene (E), 2-dodecene, (Z,E)-alpha-farnesene, butanoic acid, pentyl ester, and 1-hexanol,2-ethyl. In addition, vanillin, methyl vanillin, and many other fragrant substances were noted including isomenthol, pyrazine derivatives, and 3-decanone. In split plate bioassay tests on potato dextrose agar (PDA), Botrytis cinerea, Ceratocystis ulmi, Pythium ultimum, Fusarium solani, and Rhizoctonia solani were inhibited at levels of 24 to 50% of their normal growth on this medium. Bioreactors supporting fungal growth on 50g of beet pulp waste, using stainless steel carbotraps, yielded over 180mg of hydrocarbon-based products collected over 6weeks of incubation. Similarly, because this organism is making one of the largest sets of VOCs as any fungus examined to date, producing many compounds of commercial interest, it has enormous biotechnical potential. The role of the VOCs in the biology and ecology of this endophyte may be related to the antimicrobial activities that they possess.Item Quantifying selected growth parameters of leptothrix discophora sp-6 in biofilms from oxygen concentration profiles(2003-10) Yurt, Nurdan; Beyenal, Haluk; Sears, Joe; Lewandowski, ZbigniewIt is a dubious but common practice to use growth parameters measured in suspended cultures to predict substrate concentration profiles in biofilms. To obtain biofilm biokinetic parameters that apply to biofilms, a reliable method is needed that allows the computation of biokinetic parameters from substrate concentration profiles measured directly in biofilms. We have developed such a method and demonstrated its utility by evaluating biokinetic parameters from oxygen concentration profiles measured in biofilms of Leptothrix discophora SP-6 grown on a membrane, which was placed on top of an agar plate by fitting the data to Monod or Tessier growth kinetics, including maintenance substrate consumptions. We found that the Monod model represented the growth of L. discophora SP-6 biofilms marginally better than the Tessier model. The Monod half saturation coefficient was 0.333 ± "0.077 mg/l.Item Passive film chemistry on 316l stainless steel ennobled by biomineralized manganese(2002-04) Yurt, Nurdan; Avci, Recep; Lewandowski, Zbigniew; Sears, JoeThe effect of ennoblement on chemistry of passive films on 316L stainless steel (SS) was quantified using surface-sensitive analytical techniques. Under well-defined laboratory conditions, SS coupons were ennobled to ~ +350Vsce by biofilms of manganese-oxidizing bacterium Leptothrix discophra SP-6. Ennobled coupons were analyzed by x-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectroscopy (TofSIMS). From the XPS depth profiles of Fe, Cr, O, Ni, C and Mn, we evaluated thickness of the passive layers before and after ennoblement, while the TofSIMS depth profiles were used to evaluate spatial distribution of Mn, Cr, Fe and Ni on the surface. Because the ennobled coupons were covered with biomineralized deposits, sputtering was used to remove these deposits under ultrahigh vacuum (UHV) conditions before probing the chemistry of the underlying passive layers. The main conclusion of the paper is that oxide layers on the ennobled coupons are significantly thinner that those on the pre-ennobled coupons, which may, hypothetically, contribute to their susceptibility to localized corrosion.Item Adhesion and biofilm formation of Candida albicans on native and pluronic-treated polystyrene(2005-01) Wesenberg-Ward, Karen E,; Tyler, Bonnie J.; Sears, JoeCandida albicans forms part of the normal human flora whose growth is usually restricted by the normal flora bacteria and the host's immune system. It is an opportunistic fungal pathogen that causes infections in immunocompromised individuals, mechanical trauma victims and iatrogenic patients. Candida albicans can ingress the human host by adhering to a plastic surface (i.e., prosthetic devices, catheters, artificial organs, etc.) that is subsequently implanted, and forms a protective biofilm that provides a continuous reservoir of yeast to be hematogenously dispersed. In order for the medical profession to battle device-related infections, initial adhesion and biofilm formation of C. albicans needs to be better understood. There has been some skepticism as to whether the initial adhesion events bear any relationship to subsequent biofilm formation. Thus, to better comprehend the relationship between the initial adhesion rates and growth rate and biofilm formation, these events were studied on two different, well-defined culture surfaces, native polystyrene and Pluronic F127-conditioned polystyrene. The adhesion studies determined that Pluronic F127 adsorption dramatically reduced the adhesion of C. albicans to polystyrene. The biofilm growth studies, analyzed by confocal scanning laser microscopy, revealed that Pluronic F127 decreased the biofilm surface coverage, cluster group size, thickness and the presence of hyphal elements over the untreated polystyrene. These findings indicate that the effect of a material's surface chemistry on the initial adhesion process has a direct influence on subsequent biofilm formation.Item Volatile antimicrobials from Muscodor crispans, a novel endophytic fungus(2009-01) Mitchell, Angela M.; Strobel, Gary A.; Moore, Emily; Robison, Richard; Sears, JoeMuscodor crispans is a recently described novel endophytic fungus of Ananas ananassoides (wild pineapple) growing in the Bolivian Amazon Basin. The fungus produces a mixture of volatile organic compounds (VOCs); some of the major components of this mixture, as determined by GC/MS, are propanoic acid, 2-methyl-, methyl ester; propanoic acid, 2-methyl-; 1-butanol, 3-methyl-;1-butanol, 3-methyl-, acetate; propanoic acid, 2-methyl-, 2-methylbutyl ester; and ethanol. The fungus does not, however, produce naphthalene or azulene derivatives as has been observed with many other members of the genus Muscodor. The mixture of VOCs produced by M. crispans cultures possesses antibiotic properties, as does an artificial mixture of a majority of the components. The VOCs of the fungus are effective against a wide range of plant pathogens, including the fungi Pythium ultimum, Phytophthora cinnamomi, Sclerotinia sclerotiorum and Mycosphaerella fijiensis (the black sigatoka pathogen of bananas), and the serious bacterial pathogen of citrus, Xanthomonas axonopodis pv. citri. In addition, the VOCs of M. crispans killed several human pathogens, including Yersinia pestis, Mycobacterium tuberculosis and Staphylococcus aureus. Artificial mixtures of the fungal VOCs were both inhibitory and lethal to a number of human and plant pathogens, including three drug-resistant strains of Mycobacterium tuberculosis. The gaseous products of Muscodor crispans potentially could prove to be beneficial in the fields of medicine, agriculture, and industry.