Date of Award

8-2013

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Microbiology

Advisor

Dr. J. Michael Henson

Committee Member

Dr. Jeremy Tzeng

Committee Member

Dr. Sarah Harcum

Abstract

Bacteria that utilize methane as a sole source of carbon and energy are referred to as methanotrophs. Industrial uses of these types of organisms include the production of poly-hydroxybutyrate as well as the degradation of some chlorinated hydrocarbons that are considered pollutants in the environment. Methanotrophs also play an important role in methane cycling in the environment. Methane gas has the ability to trap 20 times more heat than carbon dioxide, which makes it a potent greenhouse gas. A defining characteristic of methanotrophs is the production of extensive intracytoplasmic membranes composed of lipids that are 16 or 18 carbons in length, similar to those of soy biodiesel. Therefore, considering the existing abundant supply of methane gas, another potential industrial application of these organisms is to utilize the intracytoplasmic membrane lipids as a source of components similar to biodiesel. In this study, we hypothesized that by optimizing the growth temperature as well as the copper concentration, a greater amount of desired lipids would be produced. Results indicated that the production of total lipids and specifically the fatty acid methyl ester (FAME)16:1 was greater at 25 °C while lower amounts of 16:1 were produced at 30 °C and 33 °C. Bacterial growth was not observed at 20 °C and the bacterial cells clumped together at 35 °C. M. methanica was then grown at 25 °C in the presence of six concentrations of copper ranging from 0 to 50 µM, with 5 µM yielding the highest production of 16:1. No growth occurred with 50 µM copper at 25 °C. Based on these results, M. methanica was grown in a 2 L flask at 5 µM copper at 25 °C. The weight of total biodiesel-like lipids under these growth conditions was 4.8% of the total biomass, with C16:1 comprising 70% of the total FAMES. Results of this research indicate that temperature affects the lipid profile and that copper concentration affects the amount of lipids produced. Thus, it is possible for M. methanica to produce biodiesel-like lipids from methane gas.

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Microbiology Commons

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