Evaluation of hydrolyzed cheese whey medium for enhanced bacterial cellulose production by Komagataeibacter rhaeticus MSCL 1463.

Industrial production of bacterial cellulose (BC) remains challenging due to significant production costs, including the choice of appropriate growth media. This research focuses on optimization of cheese whey (CW) based media for enhanced production of BC. Two modifications were made for CW medium for BC production with Komagataeibacter rhaeticus MSCL 1463. BC production in a medium of enzymatically hydrolyzed CW (final concentration of monosaccharides: glucose 0.13 g L-1, galactose 1.24 g L-1) was significantly enhanced, achieving a yield of 4.95 ± 0.25 g L-1, which markedly surpasses the yields obtained with the standard Hestrin-Schramm (HS) medium containing 20 g L-1 glucose and acid-hydrolyzed CW (final concentration of monosaccharides: glucose 1.15 g L-1, galactose 2.01 g L-1), which yielded 3.29 ± 0.12 g L-1 and 1.01 ± 0.14 g L-1, respectively. We explored the synergistic effects of combining CW with various agricultural by-products (corn steep liquor (CSL), apple juice, and sugar beet molasses). Notably, the supplementation with 15% corn steep liquor significantly enhanced BC productivity, achieving 6.97 ± 0.17 g L-1. A comprehensive analysis of the BC's physical and mechanical properties indicated significant alterations in fiber diameter (62-167 nm), crystallinity index (71.1-85.9%), and specific strength (35-82 MPa × cm3 g-1), as well as changes in the density (1.1-1.4 g cm-3). Hydrolyzed CW medium supplemented by CSL could be used for effective production of BC.

Bacterial cellulose production by Novacetimonas hansenii MSCL 1646 on apple juice.

Biomaterials and biopolymers, such as bacterial cellulose (BC), are becoming increasingly important as sustainable materials with a wide range of potential applications. However, BC industrial production is associated with several difficulties such as low BC production yields and high production costs; therefore, cheap alternative growth media, e.g. apple juice are being studied intensively. The aim of this study is to evaluate BC synthesis under static conditions on apple juice medium (AJM). The optimal concentration of apple juice in unsupplemented AJM for Novacetimonas hansenii MSCL 1646 was shown by its dilution 1:6 with water, which resulted in 0.89 ± 0.01 g/L of dry BC weight after 10 cultivation days. Low BC synthesis can be associated with insufficient N concentration in apple juice; therefore, different organic and inorganic N sources were evaluated in combination with AJM, and beef extract (5 g/L) was found to be the most suitable. Further, AJM optimisation experiment showed the optimal apple juice and beef extract concentrations as 1:2 and 15 g/L respectively, which resulted in 17.27 ± 0.07 g/L of dry BC weight, which is significantly higher than in standard Hestrin-Schramm (HS) medium (4.07 ± 0.02 g/L). Analysis of mechanical and physical properties showed that use of AJM results in changes in BC properties compared with the standard HS medium. Results of the study indicate that apple juice is an effective and cheap C source that in combination with appropriate N source leads to high BC synthesis and makes it suitable for industrial BC production. KEY POINTS: • Low quality apples can be used as raw material for BC production; • Beef extract improves BC synthesis in apple juice medium; • Use of apple juice and beef extract affect mechanical properties of BC.