Bob T G, Barabanshchikova G V, Raĭgorodskaia V Ia, Etingov E D, Fradkova T A
Antibiotiki. 1978 Oct;23(10):882-5.
It was shown on model experiments that the microbiological method was not applicable for determination of levorin content in industrial intermediate products containing in addition levoristatin, since the presence of the latter made higher the results of the microbiological assay. Because of this till to the present date the quantitative content of levorin in the industrial intermediate products was determined photometrically using alcohol (pure solvent) as the reference solution. Still, this method also made higher the results of the assay, especially when the content of levorin was determined in the fermentation broth. In the solid phase levorin is contained in the mycelium which occupies only 1 to 2 per cent of the fermentation broth, while the liquid phase or the fermentation broth filtrate occupies 98 to 99 per cent. It was found that the fermentation broth filtrate contained protein admixtures which coagulated on addition of alcohol to the fermentation broth and formed fine colloid solutions. As a result the absorption values became higher. In the present study not the pure solvent but an extract of the fermentation broth filtrate containing neither levorin, nor levoristatin was used as the reference solution. Such a differential method provided elimination of all errors due to the presence of various metabolites in the fermentation broth filtrate which varied both qualitatively and quantitatively.
模型实验表明，微生物学方法不适用于测定除左菌素外还含有左抑素的工业中间产品中的左菌素含量，因为后者的存在会使微生物学测定结果偏高。因此，直到目前，工业中间产品中左菌素的定量含量是使用酒精（纯溶剂）作为参比溶液通过光度法测定的。然而，这种方法也会使测定结果偏高，尤其是在测定发酵液中的左菌素含量时。在固相中，左菌素存在于仅占发酵液1%至2%的菌丝体中，而液相或发酵液滤液则占98%至99%。研究发现，发酵液滤液中含有蛋白质杂质，在向发酵液中加入酒精时会凝结并形成细胶体溶液。结果，吸光度值升高。在本研究中，不是使用纯溶剂，而是使用既不含左菌素也不含左抑素的发酵液滤液提取物作为参比溶液。这种差分法消除了由于发酵液滤液中各种代谢物的存在而产生的所有误差，这些代谢物在质量和数量上都有所不同。
