Bacterial Cellulose Cultivations Containing Gelatin Form Tunable, Highly Ordered, Laminae Structures with Fourfold Enhanced Productivity

Abstract

Manipulation of bacterial cellulose (BC) morphology is important to tune BC properties to meet specific application requirements. In this study, gelatin was added to cultivation media at 0.1–7.5 wt %. After cultivations, gelatin was removed from the BC matrix, and its effects on BC matrix characteristics and fermentation production efficiency were determined. Higher contents of gelatin in cultivation media (up to 5%) resulted in BC that, from scanning electron microscopy observations, had larger pore sizes and formation of a lamina morphology that was highly unidirectional. Crystallinity remained unchanged between 0.1 and 5 wt % gelatin concentrations (92–95%); however, it decreased to 86% at a gelatin concentration of 7.5 wt %. Mechanical properties showed a positive trend as both the specific modulus and specific strength values increased as the gelatin concentration increased to 5 wt %. A breakdown in the ordered structure of the BC matrix occurs at 7.5 wt % gelatin, with corresponding decreases in the specific modulus and specific strength of the BC. The productivity increased by almost 4-fold relative to the control, reaching 1.64 g·L–1h–1 at the 2.5 wt % gelatin content. Also, the water holding capacity increased by 3-fold relative to the control, reaching 306.6 g of water per g BC at the 5.0 wt % gelatin content. The changes observed in these BC metrics can be explained based on literature findings associated with the formation of gelatin aggregates in the cultivation media and an increase in gel stiffness seen at higher media gelatin concentrations. Overall, this work provides a roadmap for manipulating BC properties while creating highly organized lamina morphologies.

Bacterial cellulose: A comprehensive review

“…30,99,[134][135][136][137] Other additives include ethanol, polymers such as polyethylene glycol (PEG), agar, agarose, pectin, gelatin and many others. [138][139][140][141][142] Among culture medium formulations, the Hestrin and Schramm (HS) medium has been widely recognized as favorable for BC production, providing optimal conditions for fermentation. 143,144 HS medium has been extensively studied and demonstrated to promote BC production.…”

“…Other additives include ethanol, polymers such as polyethylene glycol (PEG), agar, agarose, pectin, gelatin and many others 138‐142 …”

Free-Standing Bacterial Cellulose/Polypyrrole Composites for Eco-Friendly Remediation of Hexavalent Chromium Ions

“…The most productive BC production strain is considered Komagataeibacter xylinus (previously known as Gluconacetobacter xylinus or Acetobacter xylinum). The BC production yields depend on the strain, culture medium, and growing conditions . BC is a nontoxic and biocompatible material formed by cellulose ribbon-like nanofibrils resembling nonwoven textile structures.…”