Genetic diversity through the looking glass: Effect of enrichment bias

Journal Article · Tue Apr 01 04:00:00 EST 1997 · Applied and Environmental Microbiology

OSTI ID:535266

Dunbar, J; Forney, L ^[1]; White, S ^[2]

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1. Michigan State Univ., East Lansing, MI (United States)
2. Los Alamos National Lab., NM (United States)

The effect of enrichment bias on the diversity of 2,4-dichlorophenoxyacetate (2,4-D)-degrading (2,4-D{sup +}) bacteria recovered from soil was evaluated by comparing the diversity of isolates obtained by direct plating to the diversity of isolates obtained from 85 liquid batch cultures. By the two methods, a total of 159 isolates were purified from 1 g of soil and divided into populations based on repeated extragenic palindromic sequence PCR (rep-PCR) genomic fingerprints. Approximately 42% of the direct-plating isolates hybridized with the tfdA and tfdB genes from Alcaligenes eutrophus JMP134(pJP4), 27% hybridized with the tfdA and tfdB genes from Burk holderia sp. strain RASC, and 30% hybridized with none of the probes. In contrast, the enrichment isolates not only represented fewer populations than the isolates obtained by direct plating but also exhibited, almost exclusively, a single hybridization pattern with 2,4-D catabolic gene probes. Approximately 98% of the enrichment isolates possessed pJP4-type tfd4 and tfdB genes, whereas isolates containing RASC-type tfdA and tfdB genes were obtained from only 2 of the 85 enrichment cultures. The skewed occurrence of the pJP4-type genes among the isolates obtained by enrichment suggests that the competitive fitness of 2,4-D{sup +} populations during growth with 2,4-D may be influenced either by specific tfd alleles or by genetic factors linked to these alleles. Moreover, the results indicate that evaluation of the diversity and distribution of catabolic pathways in nature can be highly distorted by the use of enrichment culture techniques. 34 refs., 4 figs., 1 tab.

• OSTI ID: 535266
• Journal Information: Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 4 Vol. 63; ISSN AEMIDF; ISSN 0099-2240
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
55 BIOLOGY AND MEDICINE
BASIC STUDIES
BACTERIA
BIODEGRADATION
CULTURE MEDIA
ENRICHMENT
EVALUATION
GENETIC VARIABILITY
ORGANIC CHLORINE COMPOUNDS