一株利用木糖产L-乳酸细菌的发酵特性研究

Fermentation Characteristics of a Novel Bacteria Strain Lt Producing L-Lactic Acid Using Xylose

对高效木糖乳酸菌Lt的发酵特性进行了研究,同时对其发酵玉米芯L-乳酸进行了初步探讨。Lt菌株生长需要氧气,延迟期约为6h,16h以后进入稳定期,可利用木糖、葡萄糖、D-甘露糖、L-阿拉伯糖产L-乳酸,转化率为88.0%-98.7%。最适发酵温度为46℃,从46-52℃产酸量均较高。用6%的纯木糖发酵48h,L-乳酸产量为57.35g/L,转化率约为95%;用含6%还原糖的玉米芯磷酸水解液发酵48h,L-乳酸产量为31.30g/L。该菌株具有发酵温度高、适温范围宽、发酵时间短、转化率高、L-乳酸纯度高等优点。

The growth of bacteria strain Lt takes oxygen,with the lag period of 6h and enters into the stationary growth phase at the 16th hour. Strain Lt can ferment xylose, glucose, D-mannose and L-arabinose into L-lactic acid with the conversion rate of 88.0% -98.7% , but failed with L-arabinose and lactose. The optimum fermentation medium was： xylose 60 g,peptone 5 g,yeast extract 3 g, beef paste 2 g,K2HPO4 2 g,MnSO4 · 4H2O 0.04 g,MgSO4 · 7H2O 0.20g,FeSO4 · 7H2O 0.05 g, CaCO3 72g in 1 000 mL water. The optimum fermentation conditions were： 150 mL medium in 250 mL bottle,inoculum size 10 % ,shaker rev 160 r/min, at 46℃ ,inaerobically. Using pure xylose （60 g/L） as substrate, the L-lactic acid yield reached 57.35 g/L; using the corncob hydrolysate（reduced sugar 60 g/L）, the L-lactic acid yield reached 31.30 g/L.