|Hinz Sarah E,|
Submitted to: American Society for Microbiology
Publication Type: Abstract Only
Publication Acceptance Date: December 1, 1994
Publication Date: N/A
Technical Abstract: Third-instar larvae of the sugarbeet root maggot (SBRM) collected from four geographic regions were surface disinfested, homogenized and aerobic heterotrophs isolated on selective and non-selective media for identification of native microflora. Rhizoplane washings of field grown sugarbeet taproots were plated in dilution series for bacterial isolation. S. maltophilia was the only ubiquitously encountered aerobic heterotroph of the 53 eubacterial species identified. Following an assessment of antibiotic resistance, a highly selective medium was developed for isolation of S. maltophilia from complex samples. Rhizosphere- and SBRM- derived isolates were compared to the type strain, ATCC 13637, Serratia liquefaciens, Pseudomonas syringae 'aptata', and Escherichia coli JM109 for their abilities to provide for SBRM development when co-cultured with gnotobiotic larvae and axenic sugarbeet suspension culture cells. All bacterial species were capable of providing a 'moulting factor' for SBRM development, however, S. maltophilia isolates were superior in % moults obtained (i.e., > 45% of larvae reached final instar). A 0.2 um filtrate of S. maltophilia broth culture was also capable of providing for larval moulting. In the absence of added bacteria, SBRM gnotobiotics failed to grow or develop to the third instar. In co-cultures amended with bacteria, utilization of sugarbeet tissues was greatly enhanced compared to non-bacterial controls. None of the environmental or clinical isolates yielded a hypersensitive response or disease symptoms when inoculated into tobacco or sugarbeet leaves. Analysis of outer membrane proteins via SDS-PAGE indicated that isolates could be grouped in part by strain origin.