冰核活性细菌Xanthomonas ampelinaTS206实验室水平发酵生产工艺条件优化的研究

优化冰核活性细菌XanthomonasampelinaTS206实验室水平发酵生产的工艺条件为将冰核活性细菌应用在工业化生产提供了重要的技术资料。本文对冰核活性细菌XanthomonasampelinaTS206实验室水平的发酵生产工艺条件进行了系统的研究,结果表明这种冰核活性细菌的最适培养条件为:培养温度18℃,装液量40ml/250ml,摇床转速180r/min,接种量3%,发酵液的初始pH8。实验还确定了冰核活性细菌在发酵48h时达到对数生长期。采用上述发酵条件培养XanthomonasampelinaTS206可以使细菌在冰核活性不降低的条件下发酵液的菌体浓度达到2.87×1010个/ml,菌体干重增加了37.7%。

卷曲霉素产生菌的改良

以卷曲霉素（ＣＰＭ）产生菌卷曲链霉菌Ｓ．ｃａｐｒｅｏｌｕｓ４００６（效价为６６４０ｕ／ｍＬ）为出发菌，经ＵＶ诱变／五氯酚浓缩，获得一株效价为７９５０ｕ／ｍＬ的营养缺陷型菌株４０６－３５，再经ＥＭＳ诱变，筛选到一株抗５０００ｕ／ｍＬＣＰＭ、效价为８５１３ｕ／ｍＬ的突变株５－４１，经原生质体ＮＴＧ诱变处理，获得一株效价为９０５０ｕ／ｍＬ的高产菌Ｎ１３菌株Ｎ１３连续传代１０代，卷曲霉素效价保持稳定通过单因子试验和多因子正交试验，确定了菌株Ｎ１３的最佳发酵条件菌株Ｎ１３在最佳发酵条件下卷曲霉素效价为９４８３ｕ／ｍＬ，比出发菌Ｓ．

Study on the Fermentation Conditions of a Mucopolysaccharide-producing Bacterium LV-1

bacterium LV-1 which isolated from soil sample were studied bacterium was isolated by serial dilution method, the effects of carbon source, nitrogen source, the initial pH and temperature on producing polysaccharide by it were discussed to confirm the optimum fermentation conditions. [ Result] The physicochemical properties showed that the polysaccharide was water-soluble, but insoluble in organic solvents including ethanol, butanol, and chloroform. It was neutral polysaccharide with negative charge and without reducing terminal. The pH of its solution was pH =7.5. There were no protein, fructose, uronic acid, sulphate and starch-like structure included in po/ysacchadde molecules. The optimum fermentation conditions for po/ysaccharide produc- tion were 3% mannitol as carbon source, 0.25% yeast extract as nitrogen source, culture temperature 28 ~（3 and pH =7.5. [Coadu^en] The re- search could provide basis for development and utilization of LV-1 and industrialized production of mucopolysaccharide.

Optimization of cultural conditions for thermostable β-1,3-1,4-glucanase production by Bacillus subtilis ZJF-1A5

The optimization of cultural conditions for β glucanase production by Bacillus subtilis ZJF 1A5 was investigated in flask trials. Temperature had great effect on β glucanase production which maximized at optimal temperature of 37℃ and decreased significantly when temperature was over 37℃.Charge quantity affected β glucanase production significantly. Adding oxygen vector N dodecane or acetic ether benefited β glucanase production, but it depended on the concentration and charge quantity. The results of fractional factorial design showed that age and size of inoculum and shaking speed were the key factors affecting β glucanase production and the cultivation time span to reach the highest β glucanase activity. The optimal cultural conditions for β glucanase production obtained with CCD were as follows: inoculum age and size (16 h, 3.82%(v/v)), shaking speed 210 r/min, charge quantity of 30 mL in 250 mL flask and initial pH 7.0, cultured at 37℃ for 50 h. Repeated experimental results accorded with those predicted by a second order polynomial model. The amount of β glucanase, α amylase and neutral protease produced by B subtilis ZJF 1A5 was associated partially with cell growth. Those three enzymes' activities increased following the cell growth and increased significantly when cells entered the stationary phase.

Optimization of fermentation conditions for 1,3-propanediol production by marine Klebsiella pneumonia HSL4 using response surface methodology

The industrially important organic compound 1,3-propanediol （1,3-PDO） is mainly used as a building block for the production of various polymers. In the present study, response surface methodology protocol was followed to determine and optimize fermentation conditions for the maximum production of 1,3-PDO using marine-derived Klebsiella pneumoniae HSL4. Four nutritional supplements together with three independent culture conditions were optimized as follows： 29.3 g/L glycerol, 8.0 g/L K2HPO4, 7.6 g/L （NH4）2SO4, 3.0 g/L KH2PO4, pH 7.1, cultivation at 35℃ for 12 h. Under the optimal conditions, a maximum 1,3-PDO concentration of 14.5 g/L, a productivity of 1.21 g/（L＇h） and a conversion of glycerol of 0.49 g/g were obtained. In comparison with the control conditions, fermentation under the optimized conditions achieved an increase of 38.8% in 1,3-PDO concentration, 39.0% in productivity and 25.7% in glycerol conversion in flask. This enhancement trend was further confirmed when the fermentation was conducted in a 5-L fermentor. The optimized fermentation conditions could be an important basis for developing low- cost, large-scale methods for industrial production of 1,3-PDO in the future.

Optimum Condition Selection of Xylitol Candida tropicalis Conversion Production

[Objective] The aim was to select the optimum conditions of xylitol Candida tropicalis conversion production. [Method] The effect of cell culture time,conversion time,conversion pH value,conversion initial sugar concentration,speed and inoculation rate were determined respectively.[Result] Optimum fermentation conditions were obtained as follows:cell culture 16 h,conversion time 10 h,conversion pH value 5.5,conversion initial sugar concentration 20 g/L,conversion shaking speed 150 r/min,inoculation rate 10% (volume ratio). The yield of xylitol has increased to 90%. [Conclusion] This study had provided basis for the further study on xylitol.

Biogenic Amines Profile of Serbian Traditional Sausage in Relation to Raw Material and Production Conditions

Petrovska klobasa is a traditional dry fermented sausage produced in the Autonomous Province of Vojvodina. Formation of nine hiogenic amines was determined in three sausage groups produced from hot deboned （A1） and cold meat （B1, B3） during drying and ripening in traditional room （A1, B1） and in industrial ripening chamber （B3）. Dansyl chloride derived amines were analysed by high-performance liquid chromatography with diode-array detector （HPLC-DAD） on Eclipse XDB-C18 column. Histamine, the most important amine from food safety point of view, was not found in any of the analyzed samples. Serotonin and spermidine were also not detected in any samples, while spermin was determined in all analyzed samples. At the end of drying, phenylethylamine was the predominant amine in A1 sausage group （51.6 mg/kg）, and tryptamine in B1 （38.1 mg/kg） and B3 （28.7 mg/kg） sausage groups. At the end of ripening, tryptamine was the predominant biogenic amine in all sausage groups （133, 121 and 39.8 mg/kg in A1, B1 and B3 groups, respectively）. Total level of biogenic amines in all investigated sausages did not exceed 174 mg/kg at the end of drying and 238 mg/kg at the end of ripening period. Tryptamine and cadaverine may be used as indicators of total biogenic amines for sausages produced in traditional and indusrial conditions from hot deboned and cold meat.