Biotechnology, University of Mysore. The bacterial cultures were
routinely cultivated on NA slants at 35 ± 2 C. Long term storage
was done in 40% glycerol at 80 C. All subsequent experiments
were conducted by raising fresh culture.
Bacterial inoculum was prepared as explained above. In order to
facilitate the bacterial adhesion on seed surface, carboxymethyl
cellulose (CMC) (100 mg) was added to 25 mL of bacterial inoculum.
Ten grams (400 ± 50) of brinjal seeds were soaked in bacterial
suspension for 2 h on a rotary shaker at 150 rpm. The bacterial suspension
was drained off and the treated seeds were dried overnight
aseptically in laminar air flow. Brinjal seeds soaked in
distilled water amended with CMC served as control (Hariprasad
et al., 2009).
In the laboratory, rhizosphere colonization bioassay was carried
out following standard procedure. Briefly, seedlings were raised
from bacterized seeds as described above. Twenty-day-old seedlings
were uprooted carefully without damaging the root system.
Loosely adhering soil on the root surface was removed by gentle
shaking and soil attached very close to the root was scraped off.
One gram of soil was dissolved in 10 mL of saline solution and serially
diluted up to 10–7. Bacteria present in each dilution were enumerated
by spread plate technique on NA medium.