Presentation Title

Determining the Carbon Source Hierarchy of Sinorhizobium meliloti using 1H NMR Spectroscopy and CRAFT analysis

Faculty Mentor

Daniel Wacks, David Soulsby

Start Date

17-11-2018 2:00 PM

End Date

17-11-2018 2:15 PM

Location

C335

Session

Oral 3

Type of Presentation

Oral Talk

Subject Area

physical_mathematical_sciences

Abstract

Sinorhizobium meliloti is a species of bacteria that forms a symbiotic relationship with alfalfa. Throughout their symbiotic relationship, S. melilotiencounters different environments that contain various amounts and types of carbon sources. The goal of this project is to determine the carbon source hierarchy of S. meliloti, since this has yet to be fully explored. To accomplish this goal, we grew S. melilotion the carbon sources that included succinate, glucose, sucrose, lactose, cellobiose, glycerol, galactose, fumarate, and malate either singly or in pairs. We then directly studied the consumption of each carbon source using 1H NMR spectroscopy. Samples of the cultures were taken periodically and cell growth measured using the optical density at 600 nm. After centrifugation, the supernatant was then examined directly by 1H NMR spectroscopy and the data analyzed using Complete Reduction to Amplitude Frequency Table (CRAFT). The data was then modeled using Gompertz bacterial growth modeling to better determine how carbon sources affect growth and consumption. Growth rates and lag times for single carbon sources have been determined, allowing us to develop an expanded carbon source hierarchy for S. meliloti. Carbon source pairs have also been investigated, allowing us to quantitate the magnitude of succinate-mediated catabolite repression, and observe systems where no repression occurs.

Summary of research results to be presented

We have determined growth rates, lag times, and consumption rates for single carbon sources, which allow for a more thorough understanding of the carbon hierarchy of S. meliloti. The carbon preferences that we have determined based on the consumption rate fall into three groupings: fast consumption, average consumption and slow consumption. Fumarate, malate, and succinate show fast consumption, galactose, sucrose, and cellobiose show average consumption, and glycerol, glucose and lactose show slow consumption. We have studied the succinate/sucrose, succinate/glucose, succinate/cellobiose, and cellobiose/lactose carbon source pairings. Using the consumption rates for the carbon source pairings we have determined how the consumption rate for a carbon source changes on a mM of carbon basis with a second carbon source. For the succinate/sucrose pairing the consumption rate of succinate, the preferred carbon source, is halved when paired, while sucrose’s consumption rate is quartered when paired. Conversely, for the cellobiose/lactose pairing the consumption rates for cellobiose and lactose do not change when paired.

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Nov 17th, 2:00 PM Nov 17th, 2:15 PM

Determining the Carbon Source Hierarchy of Sinorhizobium meliloti using 1H NMR Spectroscopy and CRAFT analysis

C335

Sinorhizobium meliloti is a species of bacteria that forms a symbiotic relationship with alfalfa. Throughout their symbiotic relationship, S. melilotiencounters different environments that contain various amounts and types of carbon sources. The goal of this project is to determine the carbon source hierarchy of S. meliloti, since this has yet to be fully explored. To accomplish this goal, we grew S. melilotion the carbon sources that included succinate, glucose, sucrose, lactose, cellobiose, glycerol, galactose, fumarate, and malate either singly or in pairs. We then directly studied the consumption of each carbon source using 1H NMR spectroscopy. Samples of the cultures were taken periodically and cell growth measured using the optical density at 600 nm. After centrifugation, the supernatant was then examined directly by 1H NMR spectroscopy and the data analyzed using Complete Reduction to Amplitude Frequency Table (CRAFT). The data was then modeled using Gompertz bacterial growth modeling to better determine how carbon sources affect growth and consumption. Growth rates and lag times for single carbon sources have been determined, allowing us to develop an expanded carbon source hierarchy for S. meliloti. Carbon source pairs have also been investigated, allowing us to quantitate the magnitude of succinate-mediated catabolite repression, and observe systems where no repression occurs.