Survival and naphthalene-degrading activity of Rhodococcus sp. strain 1BN in soil microcosms.
OBJECTIVE
The survival and activity of Rhodococcus sp. strain 1BN, inoculated into naphthalene-contaminated sandy-loam soil microcosms, were studied using classical and molecular methods.


RESULTS
The naphthalene-degrading activity of 1BN in microcosms was examined through viable counts, CO2 production and naphthalene consumption, while its survival after inoculation was monitored by detecting the contemporary presence of alkane and naphthalene degradative genes and by analysing the 16S rDNA specific restriction profile. The inoculation of 1BN did not significantly enhance naphthalene degradation in the naphthalene-contaminated native soil, where 1BN maintained its catabolic activity also when in the presence of indigenous microflora. Instead the rate of naphthalene degradation by the inoculated 1BN was greater in sterile naphthalene-contaminated soil. The level of 1BN was only slightly higher after inoculation regardless of whether indigenous naphthalene-degrading bacteria were present or not and 1BN remained viable even when the substrate was depleted.


CONCLUSIONS
This study documents the colonization and growth of 1BN in a non-sterile, naphthalene-added, sandy-loam soil having an active indigenous naphthalene-degrading population.


CONCLUSIONS
An active and well-established naphthalene-degrading bacterial population in the native soil did not hamper the survival of the introduced 1BN that, through its activity, enhanced the mineralization rate of naphthalene.
Cavalca
L
L
Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, Università degli Studi di Milano-Bicocca, Milano, Italy.
Colombo
M
M
Larcher
S
S
Gigliotti
C
C
Collina
E
E
Andreoni
V
V
D042926:Cytochrome P-450 CYP4A; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics; D049308:Dioxygenases; D008903:Minerals; D006899:Mixed Function Oxygenases / Q000235:genetics; D009097:Multienzyme Complexes / Q000235:genetics; D009281:Naphthalenes / Q000378:metabolism*; D010105:Oxygenases / Q000235:genetics; D012240:Rhodococcus / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D012822:Silicon Dioxide; D012988:Soil Microbiology; D012989:Soil Pollutants / Q000378:metabolism
D008903:Minerals; D009097:Multienzyme Complexes; D009281:Naphthalenes; D012989:Soil Pollutants; C031721:naphthalene; D012822:Silicon Dioxide; D003577:Cytochrome P-450 Enzyme System; D006899:Mixed Function Oxygenases; D010105:Oxygenases; D049308:Dioxygenases; C038703:naphthalene dioxygenase; D042926:Cytochrome P-450 CYP4A