肠膜明串珠菌BD3749亚种水平的鉴定及其生长特性研究

对肠膜明串珠菌BD3749进行亚种水平的鉴定,探索其在食品工业中的应用前景。利用分子生物学及生化鉴定的手段对高产胞外多糖的肠膜明串珠菌BD3749进行了亚种水平上的鉴定；通过测定其在番茄汁培养基中生长过程的OD₅₉₅、pH值动态变化以及对其中蔗糖的利用来评价其生长状况；通过对其生长过程中的胞外多糖产量的分析评价其发酵产物作为膳食补充剂的潜力；使用不同装液量培养模拟不同的氧压力强度,研究氧胁迫强度对胞外多糖产量的影响,并据此对其产胞外多糖的条件进行了优化。经鉴定BD3749为肠膜明串珠菌肠膜亚种,属于食品中可以使用的菌株。在此基础上研究了该菌株在番茄汁中的发酵及产胞外多糖性能,BD3749在番茄汁培养基中生长旺盛,其合成的胞外多糖主要为不溶性多糖。通过不同装液量发酵实验考察了通氧量对BD3749不溶性多糖产量的影响,并对BD3749在番茄汁培养基中的产多糖量进行了初步优化,在优化条件下,不溶性多糖的产量可达14.5g/L。BD3749属于食品中可以使用的肠膜明串珠菌肠膜亚种,其能以番茄汁为基质生长并合成大量胞外多糖,在食品工业中具有重要应用价值。

Subspecies Determination of Leuconostoc mesenteroides BD3749 and Its Growth Characteristics

To identify Leuconostoc mesenteroides BD3749 at the subspecies level and to explore the application prospect of this strain in food industry, BD3749 was identified at the subspecies level by molecular biology and biochemistry techniques. The growth of BD3749 in tomato juice supplemented with sucrose was investigated through dynamic monitoring of OD₅₉₅ and pH as well as the remnant amount of sucrose. The productivity of exopolysaccharide (EPS) was determined to evaluate the potential of BD3749 to serve as dietary supplement. The effect of oxygen stress on the amount of EPS was analyzed and the growth condition was optimized accordingly for EPS production. BD3749 was assigned to be L. mesenteroides subsp. mesenteroides based on these studies. Furthermore, BD3749 grew well in tomato juice supplemented with sucrose, and EPS produced was mainly insoluble EPS (iEPS). Subsequently, the effect of oxygen on EPS production was analyzed and the condition was optimized accordingly for EPS production. In the optimized content of oxygen, 14.5g/L iEPS was achieved after 48h fermentation. BD3749 is a strain of L. mesenteroides subsp. mesenteroides, which is generally regarded as safe and can be applied in food industry. With the excellent fermentation performance, BD3749 is a strain of high potential in food industry.