乳酸细菌转化甘蔗糖蜜为乳酸等有机酸的研究

Efficient Production of Lactic Acid and Other Organic Acids from Sugarcane Molasses by Lactic Acid Bacteria

乳酸是重要的工业原料,乳酸、乙酸等C2~C5短链脂肪酸是污水高效除磷脱氮所需的碳源。已有研究表明乳酸菌可把甘蔗糖蜜的发酵糖转化成乳酸或乳酸、乙酸等的混合物。为此,试验选用6株产酸优势乳酸细菌对5种不同配比的甘蔗糖蜜进行发酵,测定了发酵过程中的产酸量,乳酸、乙酸、甲酸的含量及糖分利用率等指标。结果表明:不同糖分配比发酵液中的酸产量达100 g/L;菌株MX4和SN2可高效转化甘蔗糖蜜与葡萄糖配比为3︰1培养基中的糖分;SN2菌株更适合于用甘蔗糖蜜生产乳酸, MX4菌株的甘蔗糖蜜发酵液更适于做污水处理的碳源补给,这两株菌具有工业化应用前景。

Sugarcane molasses contains a large amount of fermentable sugars and was an excellent carbon source for microbial fermentation. Most of lactic acid bacteria could convert the reduced sugar of sugarcane molasses into lactic acid or C2-C5 organic acids such as lactic acid, acetic acid, etc. Lactic acid was an important industrial raw material, and C2-C5 organic acids were important carbon sources needed for efficient phosphorus and nitrogen removal from sewage. Five different fermentation media were configured for this experiment. In order to screen out the highly fermentable sugarcane molasses culture medium and its corresponding specific strain, six strains of lactic acid bacteria were used to perform fermentation in these media. The amount of acid produced in the fermentation broth was determined by intermittent titration. The contents of lactic acid, acetic acid, and formic acid in the fermentation broth were determined by HPLC, respectively. The rate of sugar consumption performed by each strain was determined by DNS method. The results showed that the acid production of lactic acid bacteria reached above 100 g/L in different media. Among the consumption rations of sugars performed by the six strains in different media,the highest consumption ration was obtained by the strain MX4 followed by the strain SN2 in the fermentation medium composed by the 3︰1 ratio of sugarcane molasses to glucose. Based on the results from HPLC, strain SN2 was more suitable for the production of lactic acid from sugarcane molasses, and strain MX4 was more suitable for the production of d C2-C5 organic acids. These two strains could be selected as potential industrial strains.