A Novel Approach Using Conventional Methodologies to Scale up BNC Production Using Komagataeibacter medellinensis and Rotten Banana Waste as Alternative

Carlos Molina-Ramírez,Juan Álvarez,Robin Zuluaga,Piedad Gañán,Cristina Castro

doi:10.3390/pr8111469

Carlos Molina-Ramírez, Juan Álvarez + Show 3 more

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https://doi.org/10.3390/pr8111469

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Abstract

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.

Highlights

Bacterial nanocellulose (BNC) is a polymer of glucose units linked by β-1,4 glycosidic linkages, with specific properties such as high crystallinity, nanometric dimensions, and biological compatibility and lignin- and hemicellulose-free [1], making BNC a highly attractive material in industrial sectors such as food [2], paper [3], textile [4], medical devices [5] or composite materials [6]
Processes 2020, 8, 1469 different application fields of BNC, commercial exploitation has been developed in Southeast Asian to produce the dessert nata de coco, which is an good export of these countries [7,8]
In the design of the experiments (DoE), we evaluated five factors with a significant influence on the BNC yield based on previous findings [33,38,39]—glucose concentration (g/L), inoculum age (h), inoculum concentration (g/L), ethanol concentration (g/L) and volume/area ratio

Summary

Introduction

Bacterial nanocellulose (BNC) is a polymer of glucose units linked by β-1,4 glycosidic linkages, with specific properties such as high crystallinity, nanometric dimensions, and biological compatibility and lignin- and hemicellulose-free [1], making BNC a highly attractive material in industrial sectors such as food [2], paper [3], textile [4], medical devices [5] or composite materials [6]. Processes 2020, 8, 1469 different application fields of BNC, commercial exploitation has been developed in Southeast Asian to produce the dessert nata de coco (bacterial cellulose produced from coconut water as culture medium), which is an good export of these countries [7,8]. A different approach is to reduce the high cost of the feedstocks used in commercial culture media, such as Hestrin–Schramm (HS) medium [16]. In the last 20 years, the use of agro-industrial waste to produce BNC has been explored, from by-products in the corn industry such as corn steep liquor (CSL) [17] to banana fruit residues [18,19], to improve the production of BNC and reduce production costs [20], allowing the migration from culture broths commonly used to produce BNC, such as the Hestrin–Schramm (HS) medium [21]. Bananas have valuable nutritional components, including vitamins A, B1, B2 and C, minerals such as Na, Fe, Ca, and P, and a high K content [27,28,29,30,31] which can persist after sterilization process [32], supporting the major nutritional demand of the microbial cultures used to produce BNC and has better mechanical properties, as we previously demonstrated [18]

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