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United States Department of Agriculture

Agricultural Research Service


item Tanprasert, Tanprasert
item Reed, Barbara

Submitted to: In Vitro Plant
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/1996
Publication Date: N/A
Citation: N/A

Interpretive Summary: Bacteria and fungi can be found inside normal healthy plants. These small organisms can cause difficulty when starting plant tissue cultures. Plant tissue cultures need the same nutrients as bacteria and fungi. Our experiments looked for bacteria and fungi from newly surfaced sterilized plants to prevent contamination. Strawberry runners were partly submerged in a liquid with nutrients for one week. This liquid detected most of the contaminating bacteria and fungi from the new cultures. The bacteria were isolated, purified and identified using standard tests. Most bacteria were soil and plant associated species.

Technical Abstract: Microbial contaminants of surface sterilized explants were successfully detected in strawberry runners partially submerged in one-half strength liquid Murashige & Skoog medium. About ten percent more contaminants were observed from June to August, 1994 than in 1995. Bacterial out numbered fungal contaminants. Bacterial contaminants from 22 contaminated strawberry genotypes were isolated, purified, and identified to genus using standard biochemical tests such as Gram's stain, motility, oxidase, & gelatinase; and carbon source utilization (Biolog). Among the isolates, 16 different strains were identified, the majority being fluorescent pseudomonads including Pseudomonas fluorescens types A, F, and G. P. corrugata, P. tolaasii, & P. paucimobilis. X. campestris, Xanthomonas spp, & Enterobacter cloacae were also identified. Five Gram-negative & two Gram-positive contaminants could not be identified by the Biolog test. Biochemical test were useful to characterize the bacteria & to confirm Biolog test results. Bacteria found in this study were soil, water, & plant related, indicating that efforts to reduce explant contaminant levels should be centered on the care of stock plants or the sterility of the watering system.

Last Modified: 08/21/2017
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