Abstract
Waste paper holds great potential as a substrate for the microbial production of bioplastic (Poly-3-hydroxybutyrate (PHB)). This study aimed to produce PHB by utilizing office paper as a substrate using Cupriavidus necator through batch and fed-batch simultaneous saccharification and fermentation (SSF) approach. For the batch experiment, different loadings of shredded office paper (3, 5 and 10%) with two different pretreatments H2O2 (OPH) and H2O2 and Triton X-100 (OPTH) were carried out. For the fed-batch experiment, paper loading started with 3% and two more additions were made at 36 and 84 h. Both experiments were conducted at 30 °C, 200 rpm and pH 7 using 55.5 FPU/g of cellulase and 37.5 CBU/g of β-glucosidase with a fixed amount of nitrogen source. High PHB yield was observed with OPH in all loadings, though the OPHT showed a better hydrolysis. Maximum PHB yield (4.27 g/L) was achieved with 10% OP on the sixth day of fermentation in batch SSF. Whereas, maximum PHB yield (4.19 g/L) was obtained within a shorter time (66 h)with OPH in the fed-batch experiment. The extracted PHB showed well-matched characteristic features to the standard PHB. Finally, this study proves the feasibility of employing the SSF process for PHB production using waste paper as an alternative approach to overcome the shortcoming of the separate hydrolysis and fermentation (SHF) process.
Highlights
Waste paper can be utilized as a cheap alternative substrate of noble sugars for poly-3-hydroxybutyrate (PHB) production [1–4]
This study focused on PHB production using waste paper through simultaneous saccharification and fermentation (SSF) by C. necator, where both enzymatic hydrolysis and sugar fermentation coincide
OPH showed better PHB yield compared to OPTH in all loadings
Summary
Waste paper can be utilized as a cheap alternative substrate of noble sugars for poly-3-hydroxybutyrate (PHB) production [1–4]. The major components of waste paper are cellulose, hemicellulose, and lignin. It has filling materials such as calcium carbonate, clay, and other chemical additives, for instance, rosin, alum, and starch were added in various proportions depending upon the paper type. Residuals of talc or sodium silicate used during paper processing remain in the paper materials [5–8, 2]. The presence of these chemicals reduces the efficiency of the enzymatic hydrolysis of the cellulose present in the waste paper. Waste paper pretreatment is a critical step to remove these chemicals and expose more cellulose in the paper to the enzymatic hydrolysis
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