Currently, cellulose nanostructures are among the most promising structures, and extensive work in materials and biotechnology industries is aimed at identifying an efficient process of production. Even when production at the laboratory scale is successful, crucial aspects of increased commercial applications for cellulose nanostructures are linked to large-scale production. Large-scale production requires a balance between the cost of the culture medium and product value. Therefore, in this work, for the optimization and scaling up of bacterial nanocellulose, a culture medium consisting of rotten banana unsuitable for human consumption was used for the first time as an inexpensive feedstock. Initially, the bacterial nanocellulose (BNC) culture medium conditions were optimized, and it was established that a glucose concentration of 26.4 g/L and a V/A ratio of 2.2 cm were the optimal conditions for production reaching a BNC yield of 5 g/L, which was 42.4% higher than the best result initially obtained. Finally, the scale-up process was performed, implementing a regime analysis methodology by comparing the characteristic times of the critical mechanisms involved in BNC production, namely, microbial growth, glucose consumption, BNC production, and glucose diffusion into the BNC membrane, as the first approach for this type of BNC production process. The mechanism underlying the BNC production process is glucose diffusion into the BNC membrane (characteristic time, 675.47 h). Thus, the V/A ratio was selected as the scale-up criterion most suitable for producing BNC under static culture conditions, allowing the production of 16 g of BNC after 12 d of fermentation in a plastic bioreactor, which was 3378% higher than that produced in glass vessels. The results obtained in this study may initiate further improvements in BNC commercial production by exploiting different feedstocks.
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Figure 5. A comparative images of BNC membranes obtained in (a) small and (b) large scale in this this research. research. 4. Conclusions 4. Conclusions The economic obstacle of producing BNC at low cost has been overcome, thus, industrial-scale The economic obstacle of producing BNC at low cost has been overcome, thus, industrial-scale production can be considered. In this way, the first approach for the scale-up of BNC production from the rotten banana (not suitable for human consumption) as a cheaper feedstock has been confirmed in this study. By applying response surface methodology (RSM), we established that the glucose concentration and V/A ratio are significant factors involved in the BNC optimization process while rotten banana is used as feedstock. The optimized glucose concentration of 26.4 g/L and V/A ratio of 2.2 cm allowed an increased BNC yield, up to 42.4%, compared with that obtained in the screening stage. Finally, the V/A ratio was chosen as the scale-up technical criterion to maintain the BNC yield in the plastic bioreactor, which was 20% less than that obtained in glass vessels. However, the quantity of the BNC obtained in the scale-up was 16 g, 3378% greater than that obtained in glass vessels under optimized conditions. The results obtained in this study showed that it is possible to scale-up the BNC production under static conditions using a technique that can be replicated by other researchers and with other types of feedstocks. Author Contributions: Conceptualization, C.M.-R. and P.G.; methodology, C.M.-R.; validation, P.G., J.Á. and Author Contributions: Conceptualization, C.M.-R. and P.G.; methodology, C.M.-R.; validation, P.G., J.Á . and R.Z.; formal analysis, C.M.-R.; investigation, C.M.-R.; resources, J.Á.; writing—original draft preparation, C.M.-R.; R.Z.; formal analysis, C.M.-R.; investigation, C.M.-R.; resources, J.Á .; writing—original draft preparation, C.M.-R.; writing—review and editing, R.Z and C.C.; supervision, P.G. All authors have read and agreed to the published version of the manuscript. Funding: This research was funded by The Science, Technology and Innovation Ministry of the Colombian Funding: This research was funded by The Science, Technology and Innovation Ministry of the Colombian Government (MINCIENCIAS) to support of Dr. Molina’s Postdoctoral Fellowship through grant # 848 of 2019, aAncdk nTohwe lAePdCgm weanst sfu: nTdheedaubtyh tohres Vacikcenrorweclteodrgíae dteecIhnnviceastlisguapcipóonr toffrUomnivtheersRideasdeadrcehl MCeangtdearlfeonraI.nvestigation and Development (CIDI) from the Universidad Pontificia Bolivariana. Acknowledgments: The authors acknowledge technical support from the Research Center for Investigation and Development (CIDI) from the Universidad Pontificia Bolivariana.
This research was funded by The Science, Technology and Innovation Ministry of the Colombian Government (MINCIENCIAS) to support of Dr. Molina?s Postdoctoral Fellowship through grant # 848 of 2019, and The APC was funded by the Vicerrector?a de Investigaci?n of Universidad del Magdalena.
© 2020 by the authors. Licensee MDPI, Basel, Switzerland.
- Agro-food waste
- BNC production optimization
- BNC scale-up strategy
- Rotten banana