The Research On Using Mulberry Leaves Hydrolysate As Carbon And Nitrogen Source To Produce Bacterial Cellulose

In recent years,due to the unique advantages such as high purity,crystallinity and tensile strength,biocompatibility,and environmental friendly features,bacterial cellulose(BC)have been showing great application prospects in biological mask,artificial blood vessels and skin,food,textile,electrode materials,etc.However,the low production and high cost have greatly restricted its further development and research.In this paper,a method of simultaneously providing carbon and nitrogen sources in the fermentation medium by mulberry leaves acid hydrolysate was developed.First of all,the mulberry leaf protein hydrolysate was obtained with hydrochloric hydrolysis of mulberry leaf protein,and then the mulberry leaf residue was hydrolyzed by dilute sulfuric acid.In order to obtain the optimal reducing sugar yield,single factor and response surface optimization experiment of the hydrolysis of mulberry leaf residue were carried out.The results showed that the highest yield of reducing sugar could reach 20.17 g/L when the reaction was carried out with 7%volume fraction of sulfuric acid and 1:15 of solid-liquid ratio at 100℃ for 1.5 h.The yield of the fermented product(MH-BC)with mulberry leaf hydrolyzate as carbon and nitrogen source was determined.And then the molecular_structure and morphology was characterized by FT-IR,SEM.The water-holding and rehydration capacity,thermal stability,as well as antibacterial properties of MH-BC was also analyzed with BC prepared by the fermentation medium of this laboratory(LA-BC)as control.The yield of the MH-BC was 2.04 g/L which was lower than the yield of the LA-BC.The results of FT-IR indicated that MH-BC not only had the characteristic peaks of LA-BC,but also showed the characteristic peaks of flavonoids.The SEM results showed that fiber of MH-BC was slightly thicker than LA-BC fiber.Antibacterial test results showed that the MH-BC showed antibacterial properties while LA-BC did not have.Moreover,the water-holding and rehydration capacity as well as thermal stability had no significant difference between MH-BCand LA-BC.Finally,the optimization experiments of adding refined carbon and nitrogen sources to mulberry leaves hydrolyzate were carried out in order to obtain high yield of MH-BC.The results of FT-IR characterization and antibacterial performance of MH-BC before and after optimization were compared.The results revealed that the yield of MH-BC was similar to that the LA-BC be obtained when the added amount of glucose,sucrose,peptone and yeast extract were 1.80,2.20,0.60 and 0.45 g/100 mL respectively.And the peak shape of FT-IR results showed no difference before and after optimization,and the optimized MH-BC still remained good antibacterial properties.