Graduate Thesis Or Dissertation
 

Bacteriophages for Leuconostoc oenos : a survey of Oregon wineries

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/6q182p39j

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  • A study of malolactic bacteria of the Leuconostoc genus, especially L. oenos, and their bacteriophages was conducted. A search for the presence of infectious bacteriophages in grapes, musts, and juices employed in malo-lactic fermentation (MLF) was conducted; no evidence, either physical or biological, was found for the existence of these phages. A screening of three varieties of fermenting wine from Oregon wineries also produced no physical or biological evidence for the presence of these phages. Electron microscopy of one wine sample which had failed in the MLF provided evidence of the presence of bacteriophages. These phages were of the Bradley type E variety. The effect of a previously isolated bacteriophage, lco 23, was tested on several commercial strains of malolactic bacteria and two Oregon-derived strains. It was found that this phage infected the homologous bacterial strain Lco 23 as well as one Oregon-derived strain, .ER-1A. Electron microscopy revealed that these phages were Bradley type B , consisting of an icosohedral head 50 nanometers in diameter, and a striated tail 150 nanometers long with a triangular baseplate at the distal end. These phages were inhibited by 1% ethanol and rendered non-infectious at 15 %. The effect of grape juices, used in MLF, on phage viability was tested. It was found that. 15 % juice of the Pinot Noir variety was inhibitory to phages and rendered them non-infectious in the undiluted form. The juice from the Chardonnay grape also rendered the phages non-infectious in the undiluted form. The existence of bacteriophages specific for MLF starter bacteria was proven to be a potential hazard to the winemaker using juice inoculation to induce the MLF. Suggestions for control of these phage in the starter culture have been provided.
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file details EschelbachMatthewM1984.pdf 2017-08-16 Público Descargar