The response of microbial populations from oil-brine contaminated soil to gradients of NaCl and sodium p-toluate in a diffusion gradient chamber

• Published in: FEMS microbiology ecology Vol. 23; no. 4; pp. 285 - 300
• Main Authors: Emerson, David, Breznak, John A
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-08-1997
• Subjects: halophilic microorganisms; Marinobacter hydrocarbonoclasticus; NaCl gradient; Oil-brine contamination; Pseudomonas; Pseudomonas nautica; salt tolerance; Sodium p-toluate; Pseudomonas nautica; Sodium p-toluate; NaCl gradient; Oil-brine contamination
• ISSN: 0168-6496; 1574-6941
• DOI: 10.1016/S0168-6496(97)00034-2

Microbial populations from soil contaminated with oil-brine were examined for their response to two-dimensional gradients of NaCl (10–25%) and sodium
p-toluate (0–10 mM) in a diffusion gradient chamber (DGC). In the DGC, growth of cells in the mixed population began at the lowest concentrations of NaCl and toluate and then spread slowly towards higher concentrations of these compounds, indicating that NaCl and toluate were mutually antagonistic to cell growth. Nevertheless, a number of halophilic, toluate-utilizing bacteria could be isolated from such enrichments. In pure culture, none of the strains grew above 10% NaCl in the presence of toluate, nor did they grow well at toluate concentrations above 3 mM at any NaCl concentration; however, most of the strains could grow in a glucose minimal medium containing up to 20% NaCl. Two numerically dominant strains, H1102 and I1101, each identified as
Pseudomonas nautica by the Biolog® system and closely related to each other on the basis of cellular fatty acid composition and repetitive extragenic palindromic sequences, responded to gradients of toluate and NaCl in a manner similar to that of the whole community. However, they could be distinguished from each other by distinctive differences in their growth patterns in the DGC. These results reveal the usefulness of diffusion gradient systems for enriching and isolating microorganisms while gaining important information about their behavior and physiology.