Effect of Atomized Delivery of Nutrients on the Growth Characteristics and Microstructure Morphology of Bacterial Cellulose

Abstract

This work demonstrates a general strategy for introducing remarkable changes in matrix organization and, consequently, functional properties of bacterial cellulose (BC). BC-producing cells were induced, using a well-defined atomized droplet nutrient delivery (ADND) system, to form pellicles with a regular layered morphology that persists throughout the mat depth. In contrast, the morphology of mats formed by conventional static medium nutrient delivery (SMND) is irregular with no distinguishable pattern. ADND also resulted in larger meso-scale average pore sizes but did not alter the fibril diameter (∼70 nm) and crystallinity index (92−95%). The specific modulus and specific tensile strength of ADND mats are higher than those of SMND mats. This is due to the regularity of dense layers that are present in ADND mats that are able to sustain tensile loads, when applied parallel to these layers. The density of BC films prepared by ADND is 1.63-fold lower than that of the SMND BC film. Consequently, the water contents (g/g) of ADND-and SMND-prepared BC mats are 263 ± 8.85 and 99.6 ± 2.04, respectively. A model that rationalizes differences in mat morphology resulting from these nutrient delivery methods based on nutrient and oxygen concentration gradients is proposed. This work raises questions as to the extent that ADND can be used to fine-tune the matrix morphology and how the resulting lower density mats will alter the diffusion of actives from the films to wound sites and increase the ability of cells to infiltrate the matrix during tissue engineering.

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

“…The sample orientation ensured that the tensile load was applied parallel to the BC laminae direction. Stress–strain curves similar to those reported in Amason et al were obtained from load–displacement data. The heterogeneity of the pellicle in terms of microstructure was addressed by comparing the specific strength and specific modulus of the samples.…”

“…The method used follows that described in the literature . In summary, a seed culture of Komagataeibacter xylinus ATCC 700178 was prepared by inoculating 2 mL of a bacterial glycerol stock in 50 mL of Hestrin–Schramm (HS) medium and performing the cultivation in 250 mL Erlenmeyer flasks for 5 days at 30 °C.…”

“…The method used for scanning electron microscopy (SEM) analyses followed a literature protocol . Mat cross-sectional images were recorded on a Supra 55 scanning electron microscope at 5–8 kV.…”

“…The films were cut using a tungsten carbide roller cutter such that five rectangular samples were obtained from each BC pellicle. The samples were prepared and tested following the same protocol as outlined elsewhere . A piezoelectric load cell (Kistler 9256C1, Switzerland), with a sampling frequency of 100 Hz, was used to collect the force data during this process.…”

“…The method used follows that described in the literature. 43 In summary, a seed culture of Komagataeibacter xylinus ATCC 700178 was prepared by inoculating 2 mL of a bacterial glycerol stock in 50 mL of Hestrin–Schramm (HS) medium and performing the cultivation in 250 mL Erlenmeyer flasks for 5 days at 30 °C. The Hestrin–Schramm (HS) medium consisting of 5 g/L yeast extract, 5 g/L peptone, 2.7 g/L sodium phosphate dibasic, 1.05 g/L citric acid, and 40 g/L mannitol was purchased from Millipore Sigma.…”