The aim of this work was to test the feasibility of introducing an ana
erobic microbial reductive dechlorination activity into non sterile so
il slurry microcosms by inoculation with the pure anaerobic bacterial
strain Desulfomonile tiedjei, which is capable of dechlorinating 3-chl
orobenzoate to benzoate. To show that the bacterium was established in
the microcosms we followed the expression of the reductive dechlorina
tion activity and a molecular probe based on PCR amplification of the
16S rDNA gene was developed. However, the success of PCR amplification
of the 16S rDNA gene depends on the DNA extraction and purification m
ethodologies applied, as shown through the use of several protocols. I
n this study we report a DNA extraction and purification method which
generates sufficient and very clean DNA suitable for PCR amplification
of the D. tiedjei 16S rDNA gene. The threshold of detection was about
5.10(3) bacteria per gram of soil slurry. Introduction of D. tiedjei
in soil slurry microcosms proved successful since 3-chlorobenzoate dec
hlorination activity was established with this bacterium in microcosms
normally devoid of this dechlorination capacity. Indeed, the addition
of D. tiedjei to microcosms supplemented with acetate plus formate as
cosubstrate, at their respective concentrations of 5 and 6 mM, led to
a total biotransformation of 2.5 mM of 3-chlorobenzoate within 12 day
s. After complete 3-chlorobenzoate dechlorination, the 16S rDNA gene o
f this bacterium was specifically detected only in the inoculated micr
ocosms as shown by PCR amplification followed by restriction mapping c
onfirmation.