Augmented hydrolysis of acid pretreated sugarcane bagasse by PEG 6000 addition: a case study of Cellic CTec2 with recycling and reuse
In an integrated lignocellulosic biorefinery, the cost associated with the “cellulases” and “longer duration of cellulose hydrolysis” represents the two most important bottlenecks. Thus, to overcome these barriers, the present study aimed towards augmented hydrolysis of acid pretreated sugarcane bagasse within a short span of 16 h using Cellic CTec2 by addition of PEG 6000. Addition of this surfactant not only enhanced glucose release by twofold within stipulated time, but aided in recovery of Cellic CTec2 which was further recycled and reused for second round of saccharification. During first round of hydrolysis, when Cellic CTec2 was loaded at 25 mg protein/g cellulose content, it resulted in 76.24 ± 2.18% saccharification with a protein recovery of 58.4 ± 1.09%. Filtration through 50KDa PES membrane retained ~ 89% protein in 4.5-fold concentrated form and leads to simultaneous fractionation of ~ 70% glucose in the permeate. Later, the saccharification potential of recycled Cellic CTec2 was assessed for the second round of saccharification using two different approaches. Unfortified enzyme effectively hydrolysed 67% cellulose, whereas 72% glucose release was observed with Cellic CTec2 fortified with 25% fresh protein top-up. Incorporating the use of the recycled enzyme in two-stage hydrolysis could effectively reduce the Cellic CTec2 loading from 25 to 16.8 mg protein/g cellulose. Furthermore, 80% ethanol conversion efficiencies were achieved when glucose-rich permeate obtained after the first and second rounds of saccharification were evaluated using Saccharomyces cerevisiae MTCC 180.
KeywordsCellic CTec2 PEG 6000 PES membrane filter Recycling Saccharification
This work is financially supported by the Department of Biotechnology (DBT, India) under Indo-UK Industrial Waste Challenge 2017, with grant number being GAP 3513. The authors are thankful to Dr Anjan Ray, Director CSIR-Indian Institute of Petroleum for providing necessary facilities to complete this work and his constant motivation. Mrs. Lavika Jain is grateful to Council of Scientific and Industrial Research (CSIR) New Delhi, India, for awarding her Senior Research Fellowship.
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Conflict of interest
The authors declare that they have no conflict of interest.
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