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Factors preventing the metabolism of carbohydrates by Bacillus sphaericus 2362

Bacillus sphaericus 2362 is a mosquito pathogenic bacterium. Its greatest industrial potential may be in developing countries where mosquitos are often vectors for diseases. This strain is typical of the species in that it is unable to grow using carbohydrates as a sole source of carbon. The goal of this research was to determine the metabolic deficiency(s) responsible for the inability of this organism to grow on carbohydrates. Compounds that supported light growth of this organism on an agar-solidified, defined medium included acetate, glycerol, and gluconate. Growth in a defined liquid medium with acetate as the source of carbon was much slower than growth in a complex, protein-based broth. B. sphaericus grew poorly in a defined, liquid medium with glycerol or gluconate as the carbon source. Activity of enzymes responsible for the initiation of metabolism of some substrates was not detected in cell extracts. These enzymes were: glucokinase, hexokinase, beta-galactosidase, and amylase. Growth of this bacterium on glycerol as a sole source of carbon implies the presence of the enzymes from the lower half of the Embden-Meyerhof-Parnas (EMP) pathway. Two enzymes of the upper half of the EMF pathway, phosphofructokinase and fructose diphosphate aldolase, were undetected in cell extracts. In addition, glucose dehydrogenase activity was not detected. The inability to form glucose-6-phosphate from glucose prevents the catabolism of this and related substrates via the Entner-Doudoroff (ED), hexose monophosphate (HMP), and EMF pathways. Oxygen uptake studies indicated that B. sphaericus oxidized gluconate slightly but only when the cells were grown in a complex, protein-based medium supplemented with gluconate. Although gluconokinase activity was detected in cell extracts, no activity was detected for the key enzymes of the ED (phosphogluconate dehydratase/KDPG aldolase), or HMP (6-phosphogluconate dehydrogenase) pathway. It is unclear how B. sphaericus grows on a defined medium with gluconate as the sole source of carbon. In addition to enzymatic deficiencies, whole cells were unable to accumulate [¹⁴C]glucose or [¹⁴C]sucrose. / Master of Science

Identiferoai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/45179
Date13 October 2010
CreatorsRussell, Brenda Lurline
ContributorsMicrobiology
PublisherVirginia Tech
Source SetsVirginia Tech Theses and Dissertation
Detected LanguageEnglish
TypeThesis, Text
Formatix, 82 leaves, BTD, application/pdf, application/pdf
RightsIn Copyright, http://rightsstatements.org/vocab/InC/1.0/
RelationOCLC# 17729497, LD5655.V855_1988.R877.pdf

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