2株乳酸菌对亚硝酸盐的降解作用及其降解机理的初步分析

Experimental investigation and analysis on nitrite degradation by two strains of lactic acid bacteria

分别将植物乳杆菌LP-L134-1-P(LP)、肠膜明串珠菌LM-L134-1-P(LM)接种到含亚硝酸钠的MRS培养液中,测定发酵液在72 h内pH、总酸、活菌数及亚硝酸钠含量的变化,并分析其降解机理。结果表明,LP降解亚硝酸盐能力强于肠膜明串珠菌LM,培养72 h后LP、LM对亚硝酸钠的降解率分别为98.63%和38.77%。运用SPSS软件分析结果表明,亚硝酸盐降解率与pH值呈显著的负相关、与总酸度呈显著的正相关,与活菌数变化并无明显相关关系,溶液中的总酸值是影响乳酸菌降解亚硝酸盐的重要因素。在去离子水中直接添加不同浓度的乳酸后发现,当调节溶液初始pH值为3、总酸为1.04%时对亚硝酸盐的清除作用效果显著,进一步印证了乳酸菌降解作用主要依靠酸降解。

In order to study their nitrite reduction activity and find out thedegradation mechanism roughly, two strains of lactic acid bacteria, Lactobacillus plantarum-L134-1-P （LP） and Leuconostoc mesenteroides-L134-1-P （LM）, were investigated. It was found that LP had a better ability to degrade nitrite than LM on MRS broth with the addition of nitrite, the final nitrite degradation rate achieved 98.63% and 38.77% respectively. After 72 hours of fermentation, the pH value of LP broth fell to 3.87, the proportion of total acid reached 1.79%. Meanwhile, the pH value of LM broth only reached 5.35, and the proportion of total acid reached 0.34%. It was also shown in SPSS that there was a strong negative correlation between pH and degradation rate, and a positive correlation between total acid and nitrite degradation rate, but viable cell numbers did not have clear relation with nitrite degradation rate. On that basis, we also studied variation trend of nitrite content in deionized water after adding lactic acid. If pH value was adjusted to 3 and the proportion of total acid reached 1.04% in the deionized water, the degradation rate of nitrite would increase efficiently. It reinforces the view that nitrite degradation abilities of lactic acid bacteria mainly depends on acid degradation.