2.3. Isolation, acclimation and maintenance of microbial
consortium
The microbial consortium capable of degrading DDT
was developed by shake flask enrichment of DDTcontaminated
soil. An aqueous suspension of the soil
sample was inoculated to M4 medium containing 5 ppm
DDT as a sole carbon source. The culture was regularly
transferred, at weekly intervals, to fresh medium. After
10/15 transfers, a mixed microbial population was
established, as evidenced by an increase in turbidity
and the ability to degrade 5 ppm of DDT. This
consortium was maintained on minimal agar containing
5 ppm DDT and 1/50 nutrient broth. This consortium
was gradually acclimated to increasing concentrations of
DDT, 5 through 25 ppm. The cells harvested from the
previous batch were used as inoculum to start a fresh
batch with or without increasing the substrate concentration.
At each step, complete degradation of DDT in
terms of 100% Cl release and absence of residual
substrate, was assured before going to the next higher
concentration. The microbial consortium thus developed
was maintained on M4-agar plates/slopes containing
5 ppm DDT.
2.3. Isolation, acclimation and maintenance of microbial
consortium
The microbial consortium capable of degrading DDT
was developed by shake flask enrichment of DDTcontaminated
soil. An aqueous suspension of the soil
sample was inoculated to M4 medium containing 5 ppm
DDT as a sole carbon source. The culture was regularly
transferred, at weekly intervals, to fresh medium. After
10/15 transfers, a mixed microbial population was
established, as evidenced by an increase in turbidity
and the ability to degrade 5 ppm of DDT. This
consortium was maintained on minimal agar containing
5 ppm DDT and 1/50 nutrient broth. This consortium
was gradually acclimated to increasing concentrations of
DDT, 5 through 25 ppm. The cells harvested from the
previous batch were used as inoculum to start a fresh
batch with or without increasing the substrate concentration.
At each step, complete degradation of DDT in
terms of 100% Cl release and absence of residual
substrate, was assured before going to the next higher
concentration. The microbial consortium thus developed
was maintained on M4-agar plates/slopes containing
5 ppm DDT.
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