Optimization of Fermentation Conditions for Xylanase Production by Aspergillus niger NS-1

In this study, a xylanase-produeing Aspergillus niger strain, NS-1, was screened and isolated from agricultural and forestry wastes. Based on single-fac- tor experiments, the effects of different carbon sources, composite carbon sources, nitrogen sources, calcium carbonate concentrations, initial pH and surfactants on xylanase production by A. niger NS-1 were investigated. The results indicated that the most appropriate carbon source was corncobs ; the best composite carbon source was corncobs ＋ xylan, which was conducive to xylanase secretion; the most suitable nitrogen source was ammonium sulfate. Xylanase activity reached the highest in the medium added with 1.5% calcium carbonate and SDS as a surfactant with an initial pH of 5.0. This study provided the basis for the production of high-activity xylanase.

DES Mutagenesis of Antagonistic Streptomyces of Botryosphaeria dothidea and Optimization of Its Fermentation Conditions

[ Objective] The paper wag to improve the antimicrobial effect of antagonistic Streptomyces on Botryosphaeria dothidea. [ Method ] Different concentrations of DES were adopted for mutagenic treatment of antagonistic Streptomyces F-58. After fermentation, the mutant strain numbered F-58-06 with genetic stability and good antimicrobial effect was selected among 200 mutant strains; the biological activity of the strain was determined with B. dothidea as the indicator fungus, and the best concentration of DES wag 2%. The fermentation conditions of antagonistic substances of Streptomyces strain F-58-06 produced in shake flasks were opti- mized using the method of single factor and orthogonal experimental design. [ Result] The optimal fermentation conditions were carbon source corn flour, nitrogen source KNO3, initial pH 7, loading volume 30 mL in 250 mL shake flask, inoculation volume 3%, incubation time 132 h. Based on orthogonal experiments, the best cultured medium ratio was corn flour 4%, KNO3 0.5%, CaCO3 0.2%, NaCI 0.35%, MgSO4 · 7H2O 0. 15%. [ Conclusion ] After mutation and optimization of culture medium, the antimicrobial activity of Streptomyces F-58 was greatly improved, and the average inhibition zone diameter was 1.35 times of that of the original strain.

Study on Brewing Technology of Pear Wine

[Objectives]The quality of pear wine is directly affected by parameter control in the production process, especially in the fermentation stage. The fermentation parameters of pear wine were controlled by studying the effects of fermentation parameters on the product, in order to optimize the fermentation parameters. [Methods]The fermentation conditions of pear wine were optimized by single factor experiments and an orthogonal experiment. [Results] The optimum fermentation conditions of pear wine were nitrogen source 1.0 g/L, fermentation temperature 20 ℃, and pH of fermentation liquid 4.3. The pear wine brewed was full, mellow and harmonious, and had a unique style. The ethanol content of the pear wine was 12.33 through physical and chemical analysis. [Conclusions] This study provides theoretical basis and technical support for the industrial production and promotion of pear wine.

Production of Protein Feedstuff by Mixed Fermentation of Waste Lees

[ Objective] To produce protein feedstuff by mix fermentation of waste lees. [ Method] Waste lees was fermented by mixture of Aspergillus niger, Trichoderma vinde and Candida tropicalis to produce protein feedstuff. The fermentation conditions were optimized by single factor test and orthogonal test. [ Result] The optimum fermentation conditions of waste lees are as following： raw materials with fineness of 20 meshes composed of waste lees of 750 g/kg, com meal of 50 g/kg and wheat bran of 200 g/kg; pH value of inoculum culture, 5.0; Aspergillus niger： Trichoderma viHde： Candida tropicalis, 1 ： 1 ： 1 ; inoculum size, 12% （V/V） ; fermentation temperature, 30 ℃; and fermentation time, 6 d. After fermentation, the crude protein content, pure protein content, and crude fiber content were increased by 78.97%, 56.29% and 31.60%, respectively. In addition, the fermented waste lees was rich in beneficial live microorganisms and bioactive substances such as enzymes and vitamins. [ Conclusion] Waste lees can be well fermented to produce protein feedstuff by mix fermentation.