【作者】 张耀中；

【导师】 戴良英； 刘绍；

【作者基本信息】 湖南农业大学 ， 微生物学， 2012， 硕士

【摘要】 如今,由微生物发酵所得到的天然色素,因其自身具有来源丰富、安全且对环境无污染和可持续发展等诸多优点,被广泛使用。本论文以从土壤中分离得到的供试菌株为研究对象,对该菌株进行了鉴定并对其发酵条件和产物稳定性进行了研究,所得结果如下：1、采用形态学和分子生物学鉴定的方法,对一株产酸碱指示剂的真菌进行了鉴定。结果表明,该菌株的无性态为串珠镰孢(Fusarium Moniliforme),接种后12小时左右,产孢细胞开始萌生,呈乳头状或角锥形,其形状上细下粗。小型分生饱子链状着生或假头状着生。通过该菌株rDNA ITS的PCR扩增和序列测定,与NCBI网站进行同源性比对分析,结果表明待测菌株与藤仓赤霉菌(Gibberella fujikuroi)同源性为100%,确定该菌株为藤仓赤霉菌。2、为了进一步提高色素产量,对A-01菌株的培养条件进行了优化。以色素在紫外分光光度下OD485nm值为指标,筛选出的最佳培养条件为固体培养基是PDA,液体培养基是马铃薯葡萄糖培养基,最佳碳源为蔗糖,最佳氮源为鱼粉,最佳培养温度为28℃,最佳的pH值为6.5,最佳发酵时间为120h,最佳发酵转速为180r/min,最佳装液量为75mL/250mL,为了达到最佳配比,对碳源浓度、氮源浓度、温度、pH值四个因素进行了正交试验,其中温度对产色素的影响最大,其次依次是：碳源,pH值和氮源。正交试验的结果显示最佳配比是：发酵温度28℃,初始pH值6.5,2.5%蔗糖,2.5%鱼粉。3、A-01菌株发酵产物的稳定性实验结果表明,该发酵产物的热稳定性较好,但随着温度的升高,色素的稳定性减弱。在偏中性条件下,色素稳定性较强,色素在强酸强碱条件下都不稳定。紫外线对色素的稳定性几乎没有影响,说明色素不会被紫外线分解。日光的照射不会对色素的稳定性造成影响。Na+、Fe3+对色素的稳定性有一定的破坏作用,其中K+、Mg2+对色素的稳定性具有较大的破坏作用,但不因时间的延长而产生进一步的破坏。而Ca2+对色素的稳定性没有影响,能起到一定的稳定色素的作用。柠檬酸对色素的稳定性无影响,苯甲酸钠对色素的稳定性有一定的破坏作用,但随着时间的延长并不会产生更大的破坏；而蔗糖、葡萄糖不但不会破坏色素的稳定性,相反,还有一定的增色作用,并且不随时间的延长而受影响。更多还原

【Abstract】 Nowadays, the natural pigment obtained by microbial fermentation, for its rich resource, safety,no pollution to the environment and sustainable development are widely used. The tested strains were isolated from soil which have been identified, its fermentation conditions and the stability of product were studied,the results are as follows:1.An identification of morphological and molecular biology methods, to produce an acid-base indicator fungus were identified. The results showed that the strain asexual state Fusarium is Fusarium Moniliforme, about12hours after inoculation, the spore cell begin to initiate, were papillary or pyramidal, its shape fine and coarse. Small conidia sub-chain with raw or slimy heads.Homology analysis by PCR amplification and sequencing of the rDNA ITS of the strains, with the NCBI website, the results show that the homology of the test strains and Fujikura Fusarium, is100%,determine the strain is Fujikura Fusarium.2.In order to improve the production of pigment, the A-01strain culture conditions are optimized. OD485nm value indicators pigment under ultraviolet spectrophotometry, filter out the best culture conditions for the solid culture is PDA, the best liquid medium is potato dextrose medium, the best carbon source is sucrose, the best nitrogen source is fishmeal, the optimum temperature is28℃, the optimum pH value is6.5, the optimum fermentation time is120h, the optimum fermentation speed is180r/min, the optimum liquid volume is75mL/250mL.In order to obtain the best ratio,the four factors of carbon source concentration, nitrogen source concentration, temperature, pH value of the orthogonal experiment, in which the greatest impact on the production of pigment is temperature, followed in turn:carbon source, pH and nitrogen source.The orthogonal experiment results show that the best ratio is:fermentation temperature28°C, initial pH6.5,2.5%sucrose,2.5%fishmeal.3.A-01fermentation product stability experiment results show that the thermal stability of fermentation product is stable, however, as the temperature rises, the stability of pigment is weaker. In neutral pH conditions, the stability of the pigment is more stable, the pigment is not stable in acid and alkali conditions. The stability of the pigment under UV has almost no effect, indicating the pigment does not decompose by UV. Sunlight radiation does not affect the stability of the pigment. Na+and Fe3+damage the stability of pigment,K+and Mg+greatly damage the stability of pigment, but not produce more damage with the extension of time. Ca2+has no effect on the stability of pigment, can play a role of the stability of pigment. Citric acid has no effect on the stability of pigment, sodium benzoate has effect on the stability of pigment, but not produce more damage with the extension of time; sucrose and glucose do not damage the stability of pigment, On the contrary, there is a certain hyperchromic effect and is not affected with the extension of time.更多还原