ABSTRACT
Hyaluronic acid (HA) is widely used in many fields, such as medicine, cosmetics and food. The bioactivity of HA depends on its molecular weight (Mw). Owing to the important physiological activities and special physiological functions, HA oligosaccharides have important application prospects in medicine fields. Streptococcus zooepidemicus has wide applications in commercial production of HA, due to its short fermentation cycle and strong production intensity. In order to efficiently synthesize HA oligosaccharides and solve the dissolved oxygen in the fermentation process, in this study, we overexpressed HA synthase (HasA) and introduced and optimized the leech hyaluronidase LHAase in Streptococcus zooepidemicus WSH-24. As a result, HA oligosaccharides were efficiently produced with improved dissolved oxygen. After 24 h, HA oligosaccharides production intensity reached to 294.2 mg/(L·h), and the concentration accumulated to 0.97 g/L in flask cultures, which was 1.82 times of the wild strain. Impressively, HA oligosaccharides were increased to 7.06 g/L in 3 L fermentor. The constructed Streptococcus zooepidemicus strain for producing HA oligosaccharides would have broad application prospects.