Bioconversion and biotransformation of coir pith for economic production of Pleurotus florida: chemical and biochemical changes in coir pith during the mushroom growth and fructification

Coir pith represents ~50% of the waste
from the coir industries and was tested for its potential
in serving as a growth substrate for the production of
species of oyster mushroom, Pleurotus florida. Due to
its high lignin (~48%) content and amorphous powdery
nature, coir pith supported poor mushroom mycelial
growth and yields were considerably low (~25% bioconversion
efficiency). Pre-treating coir pith with hot
water did not prove economical to produce the mushroom
yields. Acid swelling and alkali delignification of
coir pith though served to change the structure of coir
pith; the mushroom yields were not improved.
Amendment of coir pith with rice (Oryza sativa) straw
and horse gram (Dolichos biflorus) plant residue tended
to greatly modify the physical characteristics of the
inoculated mushroom bed. Such a supplementation of
coir pith growth substrate resulted in production of
mushroom yields with 110–125% bioconversion effi-
ciency. Implications of supplementing coir pith with rice
straw/horse gram plant residue in terms of holocellulose:
lignin ratio are discussed. Sensorially, the mushrooms
so produced did not differ from that on rice straw,
the economic growth substrate recommended for production
of the mushroom yields on commercial scale.
Changes in cellulose, hemicellulose and lignin contents
of coir pith amended with rice straw were studied.
Cellulase, hemicellulase and protease enzyme activities
in the amended coir pith substrate showed a continuous
increase from inoculation till the end of fructification,
whereas laccase activity decreased during fructification,
in consonance with decreased lignin degradation during
fructification.