Production, statistical optimization and application of endoglucanase from Rhizopus stolonifer utilizing coffee husk

Coffee cherry husk (CH) is one of the major
by-products obtained from coffee processing industry and
accounts to 43 ± 5.9 % of cellulose. Screening of fungal
organism for cellulase production was carried out and the
potential organism was identified as Rhizopus stolonifer by
internal transcribed spacer’s (ITS)—5.8S rDNA analysis.
A systematic study with response surface methodology
(RSM) based on CCRD was used to study the interactions
among the variables such as pH (3–7), moisture (40–80 %)
and progression duration (72–168 h) of the fermentation
process to maximize the enzyme production. Under the
optimized cultivation condition, R. stolonifer synthesized
22,109 U/gds. Model validations at optimum operating
conditions showed excellent agreement between the
experimental results and the predicted responses with a
confidence level of 95 %. Endoglucanase thus produced
was utilized for ethanol production by simultaneous saccharification
and fermentation and maximum of 65.5 g/L
of ethanol was obtained. This fungal cellulase has also
reported to be efficient detergent additives and promising
for commercial use. The present study demonstrates coffee
husk as a significant bioprocess substrate. Statistical optimization
with major parameters for cellulase production
can be highly applicable for industrial scale. Furthermore,
value addition to coffee husk with sustainable waste
management leading to environment conservation can be
achieved.