Validation of microcosms for examining the survival of Pseudomonas aureofaciens (lacZY) in soil

• Published in: Applied and Environmental Microbiology 1995-08, Vol.61 (8), p.2835-2839
• Main Authors: Angle, J.S. (University of Maryland, College Park, MD.), Levin, M.A, Gagliardi, J.V, McIntosh, M.S
• Format: Article
• Language: English
• Subjects: ADN RECOMBINADO; ADN RECOMBINE; Animal, plant and microbial ecology; Bacteria; Biological and medical sciences; Biotechnology; Environment and pollution; ESPECE; ESPECIES; EXPRESION GENICA; EXPRESSION DES GENES; Fundamental and applied biological sciences. Psychology; GENE; GENES; Genetically engineered organisms behavior (microorganisms, plants, animals); GENIE GENETIQUE; Health risk assessment; Industrial applications and implications. Economical aspects; INGENIERIA GENETICA; Microbial ecology; PSEUDOMONAS; Pseudomonas aureofaciens; RHIZOSPHERE; RIZOSFERA; Soil; Soils; SUPERVIVENCIA; SURVIE; TIPOS TEXTURALES DE SUELOS; TRITICUM AESTIVUM; TYPE DE SOL TEXTURAL; VARIEDADES NATURALIZADAS; VARIETE INTRODUITE
• ISSN: 0099-2240; 1098-5336
• DOI: 10.1128/aem.61.8.2835-2839.1995

Evaluating the safety and efficacy of a recombinant bacterium prior to its release into the terrestrial environment requires that risk assessment data be collected in the laboratory. Much of this information is obtained with the use of microcosms. The design of the microcosm significantly affects the ability of the recombinant microorganism to survive in soil and, thus, complicates the risk assessment process. To standardize microcosms for future use, we evaluated the survival of Pseudomonas aureofaciens 3732 RN-L11 (lacZY Rifr Nalr) in intact soil cores (5.0 by 15 cm; polyvinyl chloride core) and disturbed soil microcosms (50 g of fresh, sieved soil). Survival data were compared with those obtained during a field release. The intact soil core microcosm was shown to closely simulate results obtained in the field. The intact soil core microcosm closely predicts survival in bulk soil and in the rhizosphere of wheat. Data obtained with the microcosm were also similar when evaluated in separate studies in two different years. In 1993, P. aureofaciens survived for approximately 63 days in bulk soil and 96 days in the rhizosphere. The disturbed soil microcosm exhibited a much more rapid decline in population size (34 days to zero) than the intact core microcosm. We speculate that drying and sieving of soil for the disturbed soil microcosm affected the ability of the soil to support the survival of P. aureofaciens. These results demonstrate that a small, inexpensive, and simple intact soil core microcosm may be appropriate for risk assessment