Chitin valorization through microbial bioprocessing relies on efficient utilization of its monomeric units as fermentation substrates. In this study, the effects of salt concentration and the mixing ratio of N-acetylglucosamine (GlcNAc) to glucosamine hydrochloride (GlcN·HCl) on the specific growth rate of our previously isolated V. natriegens N5.3 was investigated in the shake-flask. Batch and fed-batch fermentations using chitin-derived amino sugars were further performed to assess high-cell-density cultivation potential.
Although the maximum specific growth rate ( \({\mu }_{max}\) ) at 60 g/L NaCl was nearly two-fold lower than that at the optimal concentration of 15 g/L, strain N5.3 retained robust growth with \({\mu }_{max}\) values of 0.37 h−1 on GlcN·HCl and 0.66 h−1 on GlcNAc. Fed-batch cultivation yielded a maximum cell dry weight (CDW) of 42.3 g/L within 9 h on GlcNAc, with \({\mu }_{max}\) of 0.53 h−1, but with a low biomass yield ( \({Y}_{X/S}\) = 0.16 g/g). In contrast, a substrate mixture containing 5% (w/w) GlcNAc and 95% (w/w) GlcN·HCl maintained a high \({\mu }_{max}\) (0.49 h−1) while substantially improving \({Y}_{X/S}\) (0.29 g/g), resulting in a CDW of 35.5 g/L after 9 h. Due to low solubility of both amino sugars, exponential feeding with non-sterilized powders was successfully applied. The absence of contamination demonstrate the feasibility of this approach. These results demonstrate that the mixture of GlcNAc:GlcN·HCl (1:19 ratio) is effective substrate for cultivation of V. natriegens N5.3. This provides a promising foundation for the microbial conversion of chitin-derived feedstocks into high-value products.
