Studies on the relation between the agglutination of milk fat globule and the uneven distribution of bacteria in raw bovine milk

我们再次证实了牛奶中发酵剂细菌的凝集作用，并试图阐明这种凝集作用的机理。每种菌株的脱脂乳培养物（乳酸乳球菌乳酸亚种（Lactococcus lactis subsp. Cremoris）以1%的比例添加到新鲜原料乳中。在4 ° C下静置17小时后，测定上层（奶油层）、中间层和底层的细菌细胞数。11株供试菌株中，底层细菌数均高于中层.洗涤后的菌体与初乳乳清反应后，在菌体电泳图谱中发现了来源于IgM的条带，证实只有这条条带与抗牛IgM反应，同时也得到了IgG可能粘附在菌体上的一些结果.我们证实IgM的凝集能力在不同的菌株之间有很大的差异。牛血清IgM和IgG的最大稀释倍数相差约250倍。此外，5%乙醇或1 M-NaCl的存在对IgM的凝集能力没有任何影响。将PVDF膜转录的菌体多肽与牛初乳反应，证实膜上有与抗牛IgM抗体反应的条带，约52，000）特别高，该多肽被认为是IgM的受体。由于我们已经证实了新鲜生牛乳放置数小时后IgM在牛乳中的分布变得不均匀，本研究结果为IgM粘附于细菌细胞而促进牛乳中起始菌的不均匀分布提供了积极的证据。

We reconfirmed the agglutination of starter bacteria in cow's milk and tried to elucidate the mechanism of this agglutination.1. Skim milk culture of each strain (Lactococcus lactis subsp. cremoris) was added to fresh raw milk at the rate of 1 %. After the milk had stood still at 4flC for 17 hours, bacterial cell numbers of upper layr (cream layr), intermediate layr and bottom layr were determined. Bacterial cell number of bottom layr was higher than that of intermediate layr in all the test 11 strains.2. After washed bacterial cells were reacted with colostrum whey, we could find the band originated in IgM in the electrophoretic pattern of the bacterial cells and confirm that only this band reacted with anti-bovine IgM.We obtained some results that IgG was also suggested to adhere to bacterial cells.3. We confirmed that the agglutination abilities of IgM differed considerably among different strains. Moreover, about 250 times difference of maximum dilution rate was recognized between bovine serum IgM and IgG in case of certain strain. Additionally, there was not any effect of the existence of either 5% ethanol or 1 M-NaCl on the agglutination ability of the IgM.4. When the PVDF membrane transcribed polypeptides of bacterial cell was reacted with colostrum, we confirmed that some bands on the membrane reacted with anti-bovine IgM.As the reactivity of the band (M.W.= about 52,000) was especially high, this polypeptide was suggested to be a receptor of IgM.5. As we have confirmed the distribution of IgM in cow's milk became uneven a few hours after standing fresh raw milk, the present results gave positive evidence that uneven distribution of starter bacteria in cow's milk was promoted by the adhesion of IgM to bacteria cell.