Boels Ingeborg C, Van Kranenburg Richard, Kanning Marja W, Chong Barrie Fong, De Vos Willem M, Kleerebezem Michiel
Wageningen Centre for Food Sciences, Wageningen. NIZO Food Research, Ede, The Netherlands.
Appl Environ Microbiol. 2003 Aug;69(8):5029-31. doi: 10.1128/AEM.69.8.5029-5031.2003.
Exopolysaccharides (EPS) play an important role in the rheology and texture of fermented food products. This is the first report demonstrating that homologous overexpression of a complete eps gene cluster in Lactococcus lactis leads to increased EPS production levels. A ninefold-elevated EPS plasmid copy number led to an almost threefold increase in the eps expression level, resulting in an almost fourfold increase in the NIZO B40 EPS production level. It was previously reported that increased EPS precursor levels did not influence NIZO B40 EPS production levels. However, the present results indicate that the maximal NIZO B40 EPS production level is limited by the activity level of the expression products of the eps gene cluster rather than by the level of EPS precursors.
胞外多糖（EPS）在发酵食品的流变学和质地方面发挥着重要作用。这是第一份证明乳酸乳球菌中完整的eps基因簇同源过表达导致EPS产量增加的报告。EPS质粒拷贝数增加九倍导致eps表达水平几乎增加了三倍，从而使NIZO B40 EPS产量水平几乎增加了四倍。此前有报道称，EPS前体水平的提高并不影响NIZO B40 EPS的产量水平。然而，目前的结果表明，NIZO B40 EPS的最大产量水平受eps基因簇表达产物的活性水平限制，而非受EPS前体水平的限制。
