Comparing the genome expression profiles of Verrucomicrobium sp. strain TAV2 cells grown under two different oxygen concentrations.

摘要

Termites are significantly different in their lifestyles and organization but most are linked by the common trait in degrading plant material, whether it is leaf litter, wood, soil or animal waste. They consume the cellulose, hemicelluloses and lignin that make up the plant material but rely on a food web consisting of about 270 different phylotypes of microorganisms to break down the biomass into usable nutrients. Isolated from the hindgut of the termite Reticulitermis flavipes, one such organism is Verrucomicrobium sp. strain TAV2. Members of this relatively new bacterium phylum have rigid peptidoglycan with some possessing prosthecae. They have been detected in soils, aquatic habitats, as well as symbionts in termites. Within the interior of the termite's hindgut, oxygen concentrations range from 2% oxygen near the interior lumen, to an anoxic environment at the core of the hindgut. TAV2 is thought to be found in the 2% oxygen range although little else is known about the organism. Determining the bacteria's genomic expression profile when grown under two different oxygen concentrations provides information into the organisms ability to survive and thrive within the termite as well as elicit information concerning TAV2's activated genes when in differing oxygen concentrations. TAV2 was grown under 2% oxygen, its presumed natural environment, and 20% oxygen concentration, near atmospheric oxygen concentration, and had its RNA extracted while growing at exponential growth to use for microarray analysis. Growth curves provide evidence that genomic regulation is affected by the oxygen concentrations in that TAV2 has a doubling time approximately eight hours faster when grown under 2% oxygen verses 20% oxygen. Microarray results convey that 75 genes are up and down regulated when comparing the two oxygen conditions. Examples of affected genes include malate/L-lactate dehydrogenase genes as well as hypothetical genes within the genome. Using TAV2 as a model organism, information gathered can be applied to the other TAV strains within the hindgut illuminating how oxygen concentrations affect the ability to breakdown plant material effectively.