Deltamethrin is one of the most commonly
used pyrethroid in agricultural practice in different geographic
regions of the world. It is detected in many environments,
especially in soil and water, and can exhibit
toxic effect to human and other organisms. In this study,
we describe two bacterial strains DeI-1 and DeI-2, isolated
from soil, and both identified as
Serratia marcescens
based
on profile of the fatty acid methyl esters, biochemical test,
and 16S RNA gene analysis, which were shown to efficiently
degrade deltamethrin. Degradation of deltamethrin
in mineral salt medium (50 mg l
-1) proceeded by strains
DeI-1 or DeI-2 reached the values of 88.3 or 82.8 % after
10 days, and DT50 was 2.8 or 4.0 days, respectively.
Bioaugmentation of deltamethrin-contaminated non-sterile
soils (100 mg kg
-1) with strains DeI-1 or DeI-2 (3 × 10
6
cells g
-1 of soil) enhanced the disappearance rate of
pyrethroid, and its DT50 was reduced by 44.9, 33.1, 44.4,
and 58.2 days or 39.1, 25.8, 35.6, and 46.0 days in sandy,
sandy loam, silty loam, and silty soils, respectively, in
comparison with non-sterile soils with only indigenous
microflora. The three-way ANOVA indicated that DT50
of deltamethrin was significantly (
P < 0.01) affected by
soil type, microflora presence, and inoculum, and the
interaction between these factors. Generally, the lower
content of clay and organic carbon in soil, the higher
degradation rate of deltamethrin was observed. Obtained
results show that both strains of
S. marcescens may possess
potential to be used in bioremediation of deltamethrincontaminated
soils.
