Effect of pH Buffer and Carbon Metabolism on the Yield and Mechanical Properties of Bacterial Cellulose Produced by Komagataeibacter hansenii ATCC 53582

Bacterial cellulose (BC) is widely used in the food industry for products such as nata de coco. The mechanical properties of BC hydrogels, including stiffness and viscoelasticity, are determined by the hydrated fibril network. Generally, Komagataeibacter bacteria produce gluconic acids in a glucose medium, which may affect the pH, structure and mechanical properties of BC. In this work, the effect of pH buffer on the yields of Komagataeibacter hansenii strain ATCC 53582 was studied. The bacterium in a phosphate and phthalate buffer with low ionic strength produced a good BC yield (5.16 and 4.63 g/l respectively), but there was a substantial reduction in pH due to the accumulation of gluconic acid. However, the addition of gluconic acid enhanced the polymer density and mechanical properties of BC hydrogels. The effect was similar to that of the bacteria using glycerol in another carbon metabolism circuit, which provided good pH stability and a higher conversion rate of carbon. This study may broaden the understanding of how carbon sources affect BC biosynthesis. Bacterial cellulose (BC) is a naturally occurring nanomaterial produced by some bacteria, such as those from the genus Komagataeibacter, consisting of a network of cellulose nanofibers connected by ?-1-4-glycosidic bonds [1, 2]. Compared to other genera, Komagataeibacter is usually the genus of choice for research and food applications, due to its higher BC yield and purity [3, 4]. These attributes allow it good liquid absorption capacity, Bacterial cellulose (BC) is widely used in the food industry for products such as nata de coco. The mechanical properties of BC hydrogels, including stiffness and viscoelasticity, are determined by the hydrated fibril network. Generally, Komagataeibacter bacteria produce gluconic acids in a glucose medium, which may affect the pH, structure and mechanical properties of BC. In this work, the effect of pH buffer on the yields of Komagataeibacter hansenii strain ATCC 53582 was studied. The bacterium in a phosphate and phthalate buffer with low ionic strength produced a good BC yield (5.16 and 4.63 g/l respectively), but there was a substantial reduction in pH due to the accumulation of gluconic acid. However, the addition of gluconic acid enhanced the polymer density and mechanical properties of BC hydrogels. The effect was similar to that of the bacteria using glycerol in another carbon metabolism circuit, which provided good pH stability and a higher conversion rate of carbon. This study may broaden the understanding of how carbon sources affect BC biosynthesis. Keywords: Bacterial cellulose, pH buffer, mechanics, gluconic acid, glycerol, rheology

Automated summary

This study investigates the effect of pH buffer on the yield of Komagataeibacter hansenii strain ATCC 53582, finding that phosphate and phthalate buffers with low ionic strength can increase BC production, although leading to a significant decrease in pH due to gluconic acid accumulation. However, the addition of gluconic acid enhances the mechanical properties of BC hydrogels and increases its polymer density.