Preparation of Komagataeibacter xylinus Inoculum for Bacterial Cellulose Biosynthesis Using Magnetically Assisted External-Loop Airlift Bioreactor

Abstract

The aim of this study was to demonstrate the applicability of a novel magnetically assisted external-loop airlift bioreactor (EL-ALB), equipped with rotating magnetic field (RMF) generators for the preparation of Komagataeibacterxylinus inoculum during three-cycle repeated fed-batch cultures, further used for bacterial cellulose (BC) production. The fermentation carried out in the RMF-assisted EL-ALB allowed to obtain an inoculum of more than 200× higher cellular density compared to classical methods of inoculum preparation. The inoculum obtained in the RMF-assisted EL-ALB was characterized by a high and stable metabolic activity during repeated batch fermentation process. The application of the RMF-assisted EL-ALB for K. xylinus inoculum production did not induce the formation of cellulose-deficient mutants. It was also confirmed that the ability of K. xylinus to produce BC was at the same level (7.26 g/L of dry mass), regardless of inoculum age. Additionally, the BC obtained from the inoculum produced in the RMF-assisted EL-ALB was characterized by reproducible water-related properties, mechanical strength, nano-fibrillar structure and total crystallinity index. The lack of any negative impact of inoculum preparation method using RMF-assisted EL-ALB on BC properties is of paramount value for its future applications, including use as a biomaterial in tissue engineering, wound healing, and drug delivery, where especially BC liquid capacity, nanostructure, crystallinity, and mechanical properties play essential roles.

Bacterial cellulose: A comprehensive review

“…For instance, one research group developed an external-loop airlift bioreactor in which they were able to achieve 200x higher cellular density than that of classical inoculum preparations. 174 In another modified version of the airlift reactor, the authors inserted porous plates inside a tubular reactor to diffuse an enriched oxygen supply. The research group found that the BC produced with this method had improved water-retention capabilities and enhanced Young's modulus.…”

“…While the base design of the airlift may provide some advantage towards BC synthesis, specific requirements towards BC production necessitates some modifications of the reactor. For instance, one research group developed an external‐loop airlift bioreactor in which they were able to achieve 200x higher cellular density than that of classical inoculum preparations 174 . In another modified version of the airlift reactor, the authors inserted porous plates inside a tubular reactor to diffuse an enriched oxygen supply.…”

Integrated biophysical matching of bacterial nanocellulose coronary artery bypass grafts towards bioinspired artery typical functions

“…Additionally, we found that our fundamental preparative work on high cell density K. xylinus cultivation strategies, which we started and proceeded in 2020, also crosses very recent and meaningful industrial progress. In this context, Zywicka et al 2021 presented a strategy to prepare high cell density K. xylinus culture broth for standardized inoculation of BNC producing processes under constant gassing and magnetic field stimulation in repeated fed batch airlift cultivation 49 . There, the authors report a drop of the dissolved oxygen to a final value of 2–3%.…”

Bacterial Nanocellulose Produced by Cost-Effective and Sustainable Methods and Its Applications: A Review

“…The utilization of RMF has been shown to enhance the growth and metabolic activity of K. xylinus [118]. Furthermore, employing RMF-assisted bioreactors has led to an increase in BC yield compared to conventional static methods because they enhance both the quantity and quality of K. xylinus inoculum, consequently leading to a higher yield of the resulting BC [115]. However, the RMF application does not result in a higher incidence of cellulose non-producing mutants within the 72 h exposure period [119].…”