A selective medium for enumeration and recovery of Pseudomonas cepacia biotypes from soil

Abstract

TB-T medium provides a high degree of selectivity for and detection of Pseudomonas cepacia biotypes upon initial plating from soil. TB-T medium consists of a basal medium with glucose as the sole carbon source and asparagine as the sole nitrogen source. The selectivity of TB-T medium is based on the combination of trypan blue (TB) and tetracycline (T) (pH 5.5). On TB-T medium, 216 of 300 isolates (72%) from five different soil types were identified as P. cepacia. The remaining 28% were facultative organisms that could be separated readily from P. cepacia by anaerobic glucose fermentation and by their inability to grow at 41°C. Molds were controlled on low soil dilutions by adding crystal violet, nystatin, or both. Elimination of either ingredient or elevation of the pH to 7.5 resulted in a pronounced loss of selectivity. The efficiency of recovery varied considerably among P. cepacia strains but was high enough for some strains (76 to 86%) to permit quantitative studies. TB-T medium combines a defined formulation with high selectivity and allows recovery of P. cepacia biotypes from low soil dilutions (10' to 103).

Ocurrence of the antibiotic producing bacteriumBurkholderiasp. in colonies of the leaf-cutting antAtta sexdens rubropilosa

“…This fieldwork was carried out to recover the main bacterium identified (Burkholderia sp. ), using the selective medium Trypan Blue + Tetracycline [15]. Pseudomonas Agar Base (Oxoid CM559) was also used with the selective supplement CFC (Oxoid SR103E).…”

Distribution of Burkholderia cepacia phenotypes by niche, method of isolaiton and pathogenicity of onion

“…The nutritionally stringent medium of Lumsden and Sasser (US Patent No. 4 588 584) was judged better for the collection of a phenotypically broad sample of B. cepacia than those of Hagedorn, Gould, Bardinelli & Gustavson (1987) and Wu & Thompson (1984), which are based on antibiotic insensitivity. Pectolytic activity and pathogenicity to onion were shown to be highly correlated characters.…”

“…While others (Ballard et al, 1970; Gonzalez & Vidaver, 1979; Bevivino et al, 1994) report differences among strains isolated from several ecological niches, their studies have been limited in inferential power by small sample sizes. The use of semi-selective media (Wu & Thomson, 1984; Lumsden & Sasser, 1986; Hagedorn et al, 1987) or of baits (Kawamoto, 1966) in assembling a collection relies on the differential behaviour of the target organisms relative to their biotic milieus; variation in stringencies and efficiencies among different methods may introduce an unintended bias into the structure of the study population. Hence, a primary objective of the present study was to assemble an ecologically diverse collection of B. ccJpaciu strains and to find if biases were imposed on our collection by our methods.…”

Polymorphisms within the prnD and pltC genes from pyrrolnitrin and pyoluteorin-producing Pseudomonas and Burkholderia spp.

“…Fragments of the appropriate size were cloned into the T/A vector pCR2.1 (Invitrogen, Carlsbad, CA, USA), and transformed into Escherichia coli strain INVKFP. Transformants were selected on LB agar amended with kanamycin (75 Wg ml 31 ) and X-Gal (20 Wg ml 31 ). Plasmid DNA was isolated from transformants using the S.N.A.P.…”