Assessment of the Potential for Gene Transfer in the Phytosphere of Sugar Beet

Abstract

A comprehensive understanding of the microbial ecology of the phytosphere of sugar beet is required to make valid assessments concerning the fate of genetically modified microorganisms (GMOs) and their DNA in this habitat. Descriptions of resident populations are considered necessary as indigenous communities are potential mediators of in situ gene transfer events to and from introduced GMOs. In order to model impact analysis a survey, over an entire growing season, of the bacteria, yeast and filamentous fungi present on the aerial surface of field grown sugar beet (Beta vulgaris var. amethyst, Germians seeds, U.K), was undertaken. Bacteria were isolated on Tryptic Soy Agar (Difco) and identified to the species level by gas chromatography (Hewlett Packard 5096A) of component cellular fatty acid methyl esters using a commercially available database (MIDI-MIS, Delaware, USA). Figures 1 and 2 show the temporal and spatial distribution of the natural background bacterial populations. Members of the Pseudomonadaceae and Enterobacteriaceae were the most abundant colonizers isolated and within these groups, subtle fluctuations in the distribution of component species were recorded.