02641naa a2200241 a 450000100080000000500110000800800410001910000200006024501400008026000090022052019480022965000170217765000190219465000090221365000140222265000090223665300180224565300190226370000160228270000190229870000170231777300650233417908692017-03-31       1990    bl ---       0--  u    #d1 aTHOMPSON, I. P.  aSurvival of two ecologically distinct bacteria (Flavobacterium and Arthrobacter) in unplanted and rhizosphere soilblaboratory studies.  c1990  aThe survival of two ecologically distinct bacteria was studied for up to 100 days in laboratory soil microcosms. A triple antibiotic resistant Flavobacterium (P25; km, sm, rif) was chosen as an example of "zymogenous" bacteria, defined as those which grow rapidly when simple nutrient sources are readily available. For comparison, a single antibiotic and methyl red resistant Arthrobacter strain (A 109; sm) was selected as an example of "autochthonous" bacteria which are defined as those members of the soil microflora which lend to be present in constant numbers and show low but consistent levels of activity. A 109 survived longer and in greater numbers than did P25 in both non-sterile unplanted (A109 t90=41.2 days, t99=&gt100 days; P25 t90 = 4.8 days, t99 = &gt 100 days; P25 t90 = 2.8 days) and rhizosphere soil (A109 t90 = 8.0 days, t99 = 78.2 days, t99 =&gt 100 days; P25 t90 = 2.8 days, t99 = 5.3 days, t99.9 = 9.0 days, BQL = 60.0 days); where t90, t99, t99.9 represents the real or extrapolated time for the population to decrease to 90%, 99% and 99,9% of the original inoculum density (4.0 x 10 g-1 soil) and BQL is below quantifiable limits (&lt1.0 x 10 g-1 soil). NUmbers of P25 fell BQL in non-sterile soil 12 days after introduction. Althrough P25 survived longer in the rhizosphere and rhizoplane than id did in unplanted soil, its numbers still fell to BQL within 60.0 and 41.3 days, respectively. Both organisms survived better in heat-sterilized than non-sterile soil, suggesting that inoculum death in non-sterile soil was due to competition from and predation by the indigenous community plus a lack of soluble nutrients. The presence of an estlablished inoculum reduced the survival of a second introduced bacterium, most noticeably when P25 was introduced 21 days after A109. Starving the culture or growing it under nutrient limiting conditions prior to introduction to soil affected survival of P25 but not A 109.  aArthrobacter  aFlavobacterium  asoil  aBactéria  aSolo  aMicroorganism  aMicroorganismo1 aCOOK, K. A.1 aLETHBRIDGE, G.1 aBURNS, R. G.  tSoil Biology and Biochemistrygv.22, n.8, p.1029-1037, 1990.