Micrococcus luteus - 宮崎大学

with isotonic sodium chloride solution until the pH of the wash solution was in neutral
range around 7, and then used for subsequent experiments. The yield was 763 mg dry
weight. (3) CHCl3-MeOH-treated cells. Two grams (dry weight basis) of fresh
Micrococcus cells were treated with 100 ml of 96% (w/v) methanol at 65 o C under reflux
for 10 min. A 200 ml of chloroform were added to the suspension, the mixture was stirred
for 20 min, and the cells were then collected by centrifugation (18,000×g). The cells
were suspended again in 100 ml CHCl3-MeOH (2:1) solution, and the suspension was
stirred for 20 min. The cells were again collected by centrifugation (18,000×g), and used
for subsequent experiments. The yield was 1516 mg dry weight basis. (4) CHCl3-
MeOH/concentrated potassium hydroxide (KOH)-treated cells. Half of the chloroform-
methanol-treated cells (758 mg dry weight basis) were suspended in 100 ml of 24 % (w/v)
KOH solution, and the suspension was left to stand for 2 h under N2 flow, being stirred
occaisionally. The cells were collected by centrifugation (18,000×g), and suspended in
10 ml of 24 % (w/v) KOH solution again for 2 h. The cells were collected by
centrifugation (18,000×g), washed thoroughly with isotonic sodium chloride solution
until the pH of the wash solution was in neutral range around 7, and then used for
subsequent experiments. The yield was 169 mg dry weight.
Copper biosorption experiments
The copper adsorption experiments were conducted as follows: precultured fresh cells or
chemically treated cells (20 mg dry weight basis) were suspended in 40 ml of a solution
containing the desired amounts of copper. Copper was supplied as copper(II) nitrate. The
solution pH was adjusted to desired values with 0.1 N HCl and 0.1 N NaOH solutions.
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