植物乳杆菌在自制培养基中降解亚硝酸盐的研究

Effects of Simplified Defined Medium on Nitrite Degradation by Lactobacillus plantarum

观察植物乳杆菌LP-L134-1-P(简称LP)在自制培养基中生长及降解亚硝酸盐状况,结果发现:空白培养液中LP几乎不降解亚硝酸盐;在只添加3%碳源(葡萄糖、蔗糖、玉米淀粉)的培养液中LP不能正常生长、产酸,72 h后对亚硝酸盐的降解率只有6.70%左右;在添加3%葡萄糖和2%氮源的培养液中:酵母抽提物培养液、酶解的大豆分离蛋白培养液、未酶解的大豆分离蛋白培养液在72 h后pH分别为3.84、3.89、4.64,对亚硝酸盐的降解率为96.44%、96.27%、36.44%。而硝酸铵培养液pH仅为5.27,亚硝酸盐降解率为8.34%。调节乳酸溶液pH为5或以上时亚硝酸盐降解效果不明显,pH为4和3时降解率分别达到31.33%、87.30%。总之,LP在培养液中产酸达到pH为4或以下时酸降解作用才比较强烈,此时酶降解效果也能显著增强。LP在碳源和有机氮源的培养液中生长产酸较好,营养条件已足够供给LP达到清除亚硝酸盐的目的。

Lactobacillus plantarum L134-l-P （LP） was investigated in the simplified defined mediums to understand its nutritional requirements and trying to find out nitrite degradation mechanism,. It was found that nitrite was barely degraded by LP in blank control. Growth and nitrite reduction activity were restrained in mediums with 3% carbon source （glucose, sucrose and corn starch）, the final degradation rate was only 6.70% after 72 h. When adding 3% glucose and 2% nitrogen source, the pH of yeast extract medium, enzymatic and non-enzymatic hydrolysis isolated soy protein mediums were 3.84, 3.89 and 4.64 respectively, with nitrite degradation rate of 96.44%, 96.27% and 36.44 respectively, after 72 h. And the final pH and nitrite degradation rate of ammonium nitrate medium were only 5.27 and 8.34%. On that basis, pH of lactic acid solution was adjusted to 4 and 3, the degradation rates of nitrite were 31.33% and 81.30%, respectively. In short, the degradation course relied on enzymolysis and acid splitting when enough nutrition was offered. And acid splitting and enzymolysis could be reinforced when LP was afforded to ferment solution under pH of 4.