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

Abstract

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.

Sustainable Production of Stiff and Crystalline Bacterial Cellulose from Orange Peel Extract

“…At 1 Hz, an increase in the G′ of 44% from 32.84 kPa to 47.18 kPa for BC and BC_Orange, respectively, was observed. This can be ascribed to both a higher number of fiber entanglements in the bacterial cellulose hydrogel, as reported by Li et al [41], and to the higher crystallinity content and thickness of the cellulose fibers of BC_Orange samples, as demonstrated by the XRD and SEM results. The higher number of fiber entanglements might be attributed to the citric acid content in the BC_Orange medium, which may act as a carbohydrate cross-linker on BC to cross-link nanofibers thus reinforcing and stiffening the BC network [42].…”

Better under stress: Improving bacterial cellulose production by Komagataeibacter xylinus K2G30 (UMCC 2756) using adaptive laboratory evolution

“…At cycle 1, comparing the diameter of the fibers among the conditions, no differences were observed among them by using the three carbon sources, except when the adapted strain was tested back in glucose, showing thinnest fibers among all. The slight change in the fiber diameter could be due to changes in culture condition, which interfere with the formation of microfibers, resulting in smaller diameters, as observed by Li et al (2021b) . At cycle 30, a general increase in width of fiber dimension in all the conditions was detected, ranging from 34–54, 28–52, and 26–44 nm in 30MA, 30MG, and 30MF, respectively.…”

“…Formation of organic acids is a peculiar trait of AAB during the oxidative fermentation (Gullo et al, 2018). A massive Fructose utilization as carbon source for BC production: production of organic acids leads to a reduction of environmental pH, representing a stressor for the bacterial culture and affecting the BC production (Li et al, 2021b). By using mannitol (condition MA and MC), no production of gluconic acid was detected.…”

Bacterial cellulose produced by Medusomyces gisevii on glucose and sucrose: biosynthesis and structural properties

“…All these factors strongly restrict the commercial e cacy of BC production. Optimization of culture medium composition, pH, carbon course, and ionic strength thus remain actual tasks since many BC production technologies are critically hindered by the slow production rate and a signi cant batch-to-batch variability of the yield (Li et al 2021, Semjonovs et al 2017).…”