Isolation and Characterization of Endophytic Colonizing Bacteria from Agronomic Crops and Prairie Plants

Authors

Denise K. Zinniel, University of Nebraska - LincolnFollow
Patricia A. Lambrecht, University of Nebraska - LincolnFollow
N. Beth Harris, University of Nebraska - Lincoln
Zhengyu Feng, University of Nebraska - Lincoln
Daniel Kuczmarski, University of Nebraska - Lincoln
Phyllis Higley, University of Nebraska - Lincoln
Carol A. Ishimaru, University of Nebraska - Lincoln
Alahari Arunakumari, University of Nebraska - Lincoln
Raul G. Barletta, University of Nebraska - LincolnFollow
Anne K. Vidaver, University of Nebraska-LincolnFollow

Document Type

Article

Date of this Version

5-1-2002

Comments

Published in APPLIED AND ENVIRONMENTAL MICROBIOLOGY, May 2002, p. 2198–2208. Copyright © 2002, American Society for Microbiology. Used by permission.

Abstract

Endophytic bacteria reside within plant hosts without causing disease symptoms. In this study, 853 endophytic strains were isolated from aerial tissues of four agronomic crop species and 27 prairie plant species. We determined several phenotypic properties and found approximately equal numbers of gram-negative and gram-positive isolates. In a greenhouse study, 28 of 86 prairie plant endophytes were found to colonize their original hosts at 42 days postinoculation at levels of 3.5 to 7.7 log₁₀ CFU/g (fresh weight). More comprehensive colonization studies were conducted with 373 corn and sorghum endophytes. In growth room studies, none of the isolates displayed pathogenicity, and 69 of the strains were recovered from corn or sorghum seedlings at levels of 8.3 log₁₀ CFU/plant or higher. Host range greenhouse studies demonstrated that 26 of 29 endophytes were recoverable from at least one host other than corn and sorghum at levels of up to 5.8 log₁₀ CFU/g (fresh weight). Long-range dent corn greenhouse studies and field trials with 17 wild-type strains and 14 antibioticresistant mutants demonstrated bacterial persistence at significant average colonization levels ranging between 3.4 and 6.1 log₁₀ CFU/g (fresh weight) up to 78 days postinoculation. Three prairie and three agronomic endophytes exhibiting the most promising levels of colonization and an ability to persist were identified as Cellulomonas, Clavibacter, Curtobacterium, and Microbacterium isolates by 16S rRNA gene sequence, fatty acid, and carbon source utilization analyses. This study defines for the first time the endophytic nature of Microbacterium testaceum. These microorganisms may be useful for biocontrol and other applications.