2.1. Fiber sample, enzyme and natural phenol
Coconut fibers were collected from the local market (H.P.) India.
Fibers were washed withmild detergentfollowed by distilled water
to remove the water soluble impurities. Clean fibers were then
Soxhlet extracted with acetone for 24 h for further purification. Lac-
case from Trametes versicolor) and p-coumaric acid were purchased
from Sigma–Aldrich. Citric acid (Himedia), sodium citrate (Hime-
dia), nutrient broth (Himedia) and nutrient agar (Himedia) were
used as received.
2.2. Laccase-mediated biografting
Optimumincubationconditions were determined for enzymatic
biografting by using an experimental design with three parameters,
i.e. laccase concentration, PCA concentration and incubation time.
Biografting process was carried out in a 250 mL Erlenmeyer flask
containing 200 mg of coconut fibers, 40 mM citrate buffer (pH 4),
3.5% (w/w) p-coumaric acid (relative to dry fiber weight), and 40 U
laccase/g fiber. The reaction mixture was incubated with 30 rpm
shaking at 50 ◦C for 24 h. Control reaction was also carried out
under identical conditions in the absence of PCA. After biograft-
ing,treated fibers were washed thoroughly with distilled water and
then Soxhlet extracted with acetone for 12 h to remove the fraction
of unreacted PCA. Fiber samples were then dried in a vacuum oven
to a constant weight