Study On The Process Of Breeding And Fermentation Of High Naringinase-Producing Strains

China is the largest citrus producing country, ranking third in the world because of the citrus production of more than 10 million tons every year. Citrus fruits contain a variety of nutrients, so it's necessary to carry out processing and comprehensive utilization. During the juice processing,there is a bitter because of the naringin,and naringinase will be able to resolve the problem.Meanwhile, naringin's metabolite are important physiological active substances in medicine,food,daily chemical and oil fields. In this research, a high-yielding naringinase strain was breeding, and their culture was optimizd. Key findings are as follows:1 A strain named WP-108 was seperated from the soil of piled up rotting orange peel by using orange powder as inducer, its naringinase could reach 910.1U/mL when fermented in liquid medium,and its character was stable after subculturing for ten times. It was identified as a strain of Aspergillus niger by observing the strains's culture characteristics and cell morphology.2 UV mutagenesis protoplast of Aspergillus niger. The impacts on the protoplast preparation and regeneration of the mycelium incubation time, enzyme concentration, osmotic stabilizers, enzyme time and temperature were examined. It showed at 32℃,mycelia incubated for 72 hours, the mixture solution of 1% snailase,1% cellulose and 1% lysing enzyme,0.7 mol/L KCl as the osmotic stabilize, and enzyme for 3.5 hours were most suitable for protoplast release. A high-yield strain of naringinase named WP-108-45 with mutation breeding technology was obtained, its naringinase could reach 1470.1U/mL,it was 1.6 times than the staring strains when fermented in liquid medium, naringinase was increased significantly.3 The response surface method was used to optimizate the fermentation medium of a high-yield strain of Aspergillus niger, the different carbon sources, nitrogen sources, inorganic salts on the impact of naringinase production were tested, on the basis, Sucrose, peptone, KCl were determined as the most affecting factor through screen the main factor by Plackett-Burman design method. With the steepest ascent experiment close to the optimal level of the three factors above, and the best concentration of the major impact factor were determined by the central composite design and response surface analysis. In the culture conditions optimizationed, naringinase production increased 25.4% from 1470U to 1843U.4 Under the premise of cost savings, the solid-state fermentation medium was optimizated by single-factor test and response surface methodology. In the research brewer's grains was as the main carbon source, add the dried tangerine peel powder as inducing substrate, study the effects of different nitrogen sources, inorganic salts on the production of enzymes, screen the main factor to determine the optimum culture conditions as follows:brewer's grains is 3.202g, dried tangerine peel powder is 0.407 g, NaNO3 is 0.831 g, solid-liquid ratio is 2:7, (NH4) 2SO4 is 1.0 g, K2HPO4 is 0.5 g, NaCl is 0.3 g, enzyme activity can reach 110967.89U/g at this time.