巨大芽孢杆菌25-B对普通生酮基古龙酸菌伴生作用机理的探究

Investigation of the mechanism for accompanying effects from Bacillus megaterium 25-B on Ketogulonigenium vulgare

为明确Vc混菌发酵中巨大芽孢杆菌25-B(俗称大菌)对普通生酮基古龙酸菌(俗称小菌)的伴生作用机理,通过摇瓶发酵实验考察大菌胞外组分上清液、胞内组分上清液、全组分超声上清液对小菌伴生活性的影响,并采用超滤分级分离技术,观察大菌胞外不同相对分子质量区间的组分对小菌生长和产酸的促进作用。结果表明,大菌培养12h(产芽孢前)的胞内组分上清液和大菌培养36h(大多数芽孢随母细胞裂解释放)的胞外组分上清液均能有效促进小菌生长和产酸,且二者能力相当,说明活性物质应该是在细胞内产生,并随着芽孢形成时母细胞裂解而释放,从而对小菌产生促进作用;大菌胞外组分上清液中大于30000的组分对小菌生长和产酸的促进作用最明显。

To reveal the mechanism of Bacillus megaterium 25-B＇s accompanying effects on Ketogulonigenium vulgare in mixed culture fermentation of Vc, the accompanying effect of different components of B. megaterium and different relative molecular weigh components obtained by ultra- filtrating supernatant of B. megaterium on Ketogulonigenium vulgare was analyzed by shaking-flask fermentation experiments in this study. The results showed that the cytosol of B. megaterium cultured 12 h and the extracellular supernatant of B. megaterium cultured 36 h could be effective in promoting the growth of Ketogulonigenium vulgare and enhancing the conversion of L-sorbose to 2-Keto-L-gulonic acid, and their ability were almost identical. It indicates that the active substance should be produced inside the cell and secreted, when parent cell was released with the spore-forming. The promoting effects of relative molecular weigh above 30000 in the extracellular supernatant of B. megaterium was more obvious.