The production of high-value bioproducts using cellobiose and glucose is crucial for cellulose utilization. Cellobiose as a glycosyl precursor for biosynthesizing uridine diphosphate glucose (UDP-glucose) has been used for the glycosylation of flavonoids. Hyperoside is the key pharmacological component in Hypericum monogynum L and has unique pharmacological activities. In this study, a recombinant strain was constructed by introducing glycosyltransferase from Petunia hybrida (PhUGT), UDP-glucose epimerase (GalE), and the cellobiose phosphinylation route to produce hyperoside. By optimizing the fermentation conditions, the maximal hyperoside production reached 3274 mg/L. Subsequently, microcrystalline cellulose was pretreated with organic electrolyte solution (OES) to produce cellobiose and glucose, which was used as the carbon source and glycosyl precursor for hyperoside production. The hydrolysis yield of cellulose was increased from 30.1 to 91.7%, and the yield of cellobiose was increased by 298% with OES pretreatment. The highest yield of hyperoside in the recombinant strain reached 2013.2 mg/L when the optimal cellulose enzymatic solution was used as the glycosyl precursor. Finally, 100 g of cellulose could yield 60.25 g of glucose and 39.5 g of cellobiose, which served as the glycosyl precursor to produce 20.13 g of hyperoside. This study provides a novel method for the production of hyperoside by using enzymatic hydrolysis of microcrystalline cellulose.
Membrane biofouling is a challenge to be solved for the stable operation of the seawater reverse osmosis (SWRO) membrane. This study explored the regulation mechanism of quorum sensing (QS) inhibition on microbial community composition and population-level behaviors in seawater desalination membrane biofouling. A novel antibiofouling SWRO membrane (MA_m) by incorporating one of quorum sensing inhibitors (QSIs), methyl anthranilate (MA) was prepared. It exhibited enhanced anti-biofouling performance than the exogenous addition of QSIs, showing long-term stability and alleviating 22 % decrease in membrane flux compared with the virgin membrane. The results observed that dominant bacteria Epsilon- and Gamma-proteobacteria ( Shewanella, Olleya, Colwellia, and Arcobacter ), which are significantly related to ( P ≤ 0.01) the metabolic products (i.e., polysaccharides, proteins and eDNA), are reduced by over 80 % on the MA_m membrane. Additionally, the introduction of MA has a more significant impact on the QS signal-sensing pathway through binding to the active site of the transmembrane sensor receptor. It effectively reduces the abundance of genes encoding QS and extracellular polymeric substance (EPS) (exopolysaccharides (i.e., galE and nagB ) and amino acids (i.e., ilvE, metH, phhA , and serB )) by up to 50 % and 30 %, respectively, resulting in a reduction of EPS by more than 50 %, thereby limiting the biofilm formation on the QSI-modified membrane. This study provides novel insights into the potential of QSIs to control consortial biofilm formation in practical SWRO applications.
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