Acknowledgments

43

for the hydrolysis of sugarcane bagasse [36]. Obtained hydrolysates were used for

the production of ethanol [36].

Mesoporous silica nanoflowers grafted with amino groups were used for the

immobilization of lipase from C. antarctica [37]. This immobilized lipase was used

for the selective production of ethyl levulinate (a biofuel) from biomass-derived

levulinic acid [37]. A novel one-pot synthesis method was developed for making

functional oil having diacyl glycerols, α-linolenic acid, and phytosterol esters. In

this method, Fe3O4 nanoparticles co-immobilized with C. rugosa lipase and Ther-

momyces lanuginosus lipase were used as nanobiocatalysts [38]. Lipase from Bacillus

atrophaeus was immobilized onto graphene oxide nanosheets modified with amine

groups and coated with maleic copolymer. This immobilized enzyme showed

(96.3%) better esterification of valeric acid compared to free enzyme (34.5%) [39].

3.6

Challenges and Opportunities

Circular economy-based ecological development has attained a significant role

globally. The idea of circular economy is based on several factors such as valoriza-

tion, waste minimization, resource efficiency, recycling, etc. Food industry waste

can be generally considered as a key-focused area in circular economy which can be

converted into several useful products [30]. Though immobilized enzymes became

unique technological instruments for addressing economical, environmental,

and waste problems, several challenges remain as such with their large-scale

applicability. Pilot-scale research studies are required to overcome these obstacles.

The cost is another impeding future while accepting immobilized catalystic system

in the waste valorization. Almost, 47% of the cost is related to the immobilization

support system or matrix. Yet another issue is change in the behavior of different

enzymes upon their immobilization.

The usage of purified enzymes instead of whole cells or crude extract can also

raise the cost of biocatalysis. Hence, economical carriers or carrier-free immobi-

lization systems like cross-linked enzyme aggregates or systems utilizing whole

cells or crude extracts have to be explored. Compared to single enzymatic systems,

multi-enzymatic biocatalytic systems are more promising for higher conversion

efficiencies and effective catalysis of waste into value-added products. Certainly,

interdisciplinary approaches in terms of molecular biology, enzyme engineering,

biochemistry, agricultural economics, biotechnology, food technology, waste man-

agement, regulations and laws, etc., are required to facilitate the enzyme-assisted

applications to the commercial-scale valorization of water stream [3].

Acknowledgments

The authors thank Sri Sharada Peetham, Sringeri, Karnataka, India, and Jyothy

Charitable Trust, Bengaluru, Karnataka, India, for their support and facilities