Environmental Escherichia coli occur as natural plant growth-promoting soil bacterium.
Currently, it is presumed that Escherichia coli is not a normal inhabitant of the soil. Soilborne E. coli strains were isolated from broad range of 7 geoclimatic zones of India, indicating that E. coli can survive and thrive under different extreme soil conditions. Diversity among E. coli strains from widely separated geographic regions using enterobacterial repetitive intergenic consensus (ERIC)-PCR did not reveal any relationships between the genotypes and the source of isolation. Inoculation of maize (Zea mays cv. Arkil) seeds with E. coli NBRIAR3 (NBRIAR3) significantly enhanced (P < 0.05) plant growth and nutrient uptake, when compared with uninoculated control. Presence or absence of NBRIAR3 did not affect significantly (P < 0.05) diversity indexes, using substrate utilization patterns on the Biolog Eco plates. Clone libraries based on 16S rRNA gene from rhizosphere of maize plants demonstrated rather similar phylotype diversity from the uninoculated control and NBRIAR3-treated rhizosphere soil, which further indicated that NBRIAR3 did not exert a major influence on the overall bacterial diversity. The methodological approach described in this study supports the idea that E. coli should be treated as native soil bacterium instead of as an "indicator" of the possible presence of other fecal coliform bacteria.


BACKGROUND
The online version of this article (doi:10.1007/s00203-010-0544-1) contains supplementary material, which is available to authorized users.
Nautiyal
Chandra Shekhar
CS
Division of Plant Microbe Interactions, National Botanical Research Institute, Rana Pratap Marg, Lucknow 226 001, India. csn@nbri.res.in
Rehman
Ateequr
A
Chauhan
Puneet Singh
PS
D004926:Escherichia coli / Q000145:classification / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D063245:Plant Development; D010944:Plants / Q000382:microbiology*; D016133:Polymerase Chain Reaction; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D012639:Seeds / Q000254:growth & development / Q000382:microbiology; D012988:Soil Microbiology; D003313:Zea mays / Q000254:growth & development / Q000382:microbiology
D012336:RNA, Ribosomal, 16S