INTERGENERIC TRANSFER OF CONJUGATIVE AND MOBILIZABLE PLASMIDS HARBORED BY ESCHERICHIA-COLI IN THE GUT OF THE SOIL MICROARTHROPOD FOLSOMIA-CANDIDA (COLLEMBOLA)
A. Hoffmann et al., INTERGENERIC TRANSFER OF CONJUGATIVE AND MOBILIZABLE PLASMIDS HARBORED BY ESCHERICHIA-COLI IN THE GUT OF THE SOIL MICROARTHROPOD FOLSOMIA-CANDIDA (COLLEMBOLA), Applied and environmental microbiology, 64(7), 1998, pp. 2652-2659
The gut of the soil microarthropod Folsomia candida provides a habitat
for a high density of bacterial cells (T. Thimm, A. Hoffmann, H. Bork
ott, J. C. Munch, and C. C. Tebbe, Appl. Environ. Microbiol. 64:2660-2
669, 1998), We investigated whether these gut bacteria act as recipien
ts for plasmids from Escherichia coli, Filter mating with E. coli dono
r cells and collected feces of F. candida revealed that the broad-host
-range conjugative plasmid pRP4-luc (pRP4 with a luciferase marker gen
e) transferred to fecal bacteria at estimated frequencies of 5.4 x 10(
-1) transconjugants per donor. The mobilizable plasmid pSUP104-luc was
transferred from the IncQ mobilizing strain E, coli S17-1 and less ef
ficiently from the IncF1 mobilizing strain NM522 but not from the nonm
obilizing strain HB101, When S17-1 donor strains were fed to F. candid
a, transconjugants of pRP4-luc and pSUP104-luc were isolated from fece
s. Additionally, the narrow-host-range plasmid pSUP202-luc was transfe
rred to indigenous bacteria, which, however, could not maintain this p
lasmid, Inhibition experiments with nalidixic acid indicated that pRP4
-luc plasmid transfer took place in the gut rather than in the feces.
A remarkable diversity of transconjugants was isolated in this study:
from a total of 264 transconjugants, 15 strains belonging to the alpha
, beta, or gamma subclass of the class Proteobacteria were identified
by DNA sequencing of the PCR-amplified 16S rRNA genes and substrate ut
ilization assays (Biolog). Except for Alcaligenes faecalis, which was
identified by the Biolog assay, none of the isolates was identical to
reference strains from data banks. This study indicates the importance
of the microarthropod gut for enhanced conjugative gene transfer in s
oil microbial communities.