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.
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