Organic Acids Production After Industry Waste-algal Carcass Fermentation By Lactobacillus

The algae biodiesel as a renewable energy has the characteristic of low cost, small space, high oil content and so on. Having high oil content, algae are often applied to the production of biofuels and biodiesel. Compared with the crops, dozens of times higher than that of the yield of per unit area. But the residue after using becomes a waste. Algal carcass monosaccharide compositions are mainly glucose, fructose, galactose and so on. In addition, there are a lot of nutrients,that can help Lactobacillus grow better. We hope to use low value of the effective components in algal carcass, making the lactic acid bacteria fermentation the algal carcass material to produce valuable by-product, Lactic acid, and reduing production cost. At present, the domestic research on algal carcass concentration on the adsorption of metal ions and the modify of organic fertilizer, very little involves the lactic acid bacteria fermentation, and study on the lactic acid bacteria organic acid metabolism has almost no research. Therefore this experiment mainly research on the process of lactobacillus fermented algal carcass and metabolize organic acid.In this study, Lactobacillus bulgaricus 11842 and Lactobacillus plantarum 09004 two kinds of Lactobacillus were used as experimental object. 2%(w/v) the algal carcass(Acm), 2%(w/v) Acm + 1%(w/v) glucose(Glu), 10%(w/v) Acm and the control group MRS four solutions were used as fermentation substrates. Understanding the effect of the number of bacteria by coat-counting method. Using high performance liquid chromatography(HPLC) analyzed the change of organic acids(lactic acid, acetic acid), ATP and the acetyl coenzyme A. Measuring the activity of lactate dehydrogenase(LDH), acetate kinase(ACK), pyruvate kinase(PK), phosphofructokinase(PFK) by kit. And analysis the change by spectrophotometry and colorimetric method. Then rebuilding the metabolic pathways according to this changes.The research results showed that: after 16 hours growing in the algal carcass culture medium, the clump counts of Lactobacilli includes Lactobacillus bulgaricus 11842 and Lactobacillus plantarum 09004 were less than the control group in the MRS. The number in 2%(w/v) algal carcass(Acm) was the least. Lactobacillus bulgaricus 11842 was 12% lower than that of the control and Lactobacillus plantarum 09004 was 14.2% lower than that of the control. 2%(w/v)Acm+1%(w/v)glucose(Glu) closed to 10%(w/v)Acm. In these two fermentation substrates, Lactobacillus bulgaricus 11842 was 5.7% lower than that of the control and Lactobacillus plantarum 09004 was 6.9% lower than that of the control. While the three concentration of organic acids such as lactic acid, acetic acid produced in algal carcass culture medium was 90% lower than that of control group MRS. And in the algal carcass culture medium, the content of ATP in the cell also showed a significant downward trend. On the contrary, the content of Acetyl-Co A was much higher than the control group, and the highest level was 2%(w/v) Acm.Meanwhile,the study analyzed the activity of key enzymes involved in the organic acids, metabolic pathways.An obvious downward trend in the activity of both lactic dehydrogenase and pyruvate kinase has been shown in the three groups of algal carcass medium, among which 2%(w/v)Acm has the lowest activity.Besides the fructose phosphate kinase activity is slightly higher than the control group,while the activity of acetate kinase is significantly higher than the control group. These results illustrate that the lactobacillus-fermented algal carcass can affect the metabolic activity through regulating the relevant enzymatic activity in the metabolic pathway.According to the results, we have a conclusion as follows: algal carcass is suitable for the growth and survival of lactobacillus, in which either adding glucose or increasing the concentration of algal carcass will be more beneficial to the growth of lactobacillus as well as the acid-producing ability.Algal carcass promotes the production of lactobacillus intermediate metabolite, acetyl coenzyme A, which may lead to a severe reduction in the yield of lactic acid and acetic acid. Acetyl coenzyme A may promote the biosynthesis of cell membrance,making it more conductive to the growth of lactobacillus. Algal carcass can regulate the metabolic activity by controlling the relevant enzymatic activity in the metabolic process of lactobacillus.Based on our experimental data, we make a hypothesis on the organic acid metabolic process of lactobacillus-fermented algal carcass,which may provide the basis for the industrial production of algal carcass in the future.