Sucrose-modified iron nanoparticles for highly efficient microbial production of hyaluronic acid by Streptococcus zooepidemicus.

Nanoparticles (NPs) were hypothesized to enhance fermentation processes and assist microorganisms in producing valuable biopolymers. Donors of trace iron, i.e., FeSO·7HO, zero-valence iron nanoparticles (Fe NPs), and ferric oxide nanoparticles (α-FeO NPs), were tested to study the impact on hyaluronic acid (HA) production. The bioprocess with the addition of 30 mg/L Fe NPs produced higher HA than the other groups. However, Fe NPs were limited by the synergistic effect of geomagnetism and high surface energy, resulting in obvious agglomeration behavior. To address this, we developed novel sucrose-modified iron nanoparticles (SM-Fe NPs), which showed effective improvement of dispersion and agglomeration. Concerning the SM-Fe NP additives, an adequate supply of nutrients and trace elements provided sufficient substrates and energy for the reproduction of Streptococcus zooepidemicus. Furthermore, the highest HA production with the addition of 30 mg/L SM-Fe NPs was 0.226 g/L, and the dry weight of the produced HA increased 3.28 times compared with the control group (0.069 g/L). This work significantly improved HA production and presented promising opportunities for industrial production.