Methoxychlor is an organochlorine pesticide
used worldwide against several insect pests, resulting in
human exposure. This pesticide mimics endocrine hormone
functions, interfering with normal endocrine activity in
humans and wildlife. For this reason, it is imperative to
develop methods to remove this pesticide from the environment,
and though, bioremediation using microorganisms
results as an excellent strategy. Five
Streptomyces
spp. strains previously isolated from organochlorine-polluted
sites and capable to grow and remove methoxychlor
were combined as different mixed cultures to increase
methoxychlor removal. From the 39 consortia tested, one
consortium (
Streptomyces spp. A6, A12, A14, M7) was
selected because of its high pesticide removal and specific
dechlorinase activity to be assayed on slurry and soil systems.
This consortium showed higher biomass values
(8.3 9 10
6 ± 5.7 9 10
5 CFU mL
-1) and methoxychlor
removal (56.2 ± 2.3 %) on enriched slurry than in nonenriched
slurry (7.3 9 10
5 ± 1.2 9 10
5 CFU mL
-1 and
45.6 ± 7.4 % of pesticide removal). In soil systems,
Streptomyces consortium showed higher growth
(1.0 9 10
11 ± 5.0 9 10
10 CFU g
-1) than in enriched
slurry, although differences in methoxychlor removal
between both culture conditions were not statistically significant.
Therefore, the selected
Streptomyces consortium
may be suitable for the development of in situ (soil) and ex
situ (slurry bioreactor) bioremediation methods because of
their potential to remove methoxychlor from different
systems.
