stay Animal tissue In addition to special viscera, almost all tissues have the nature of this fermentation. Eukaryote microorganism Representative of lactic acid Fermentation is a fungus such as Rhizopus oryzae. Among bacteria lactic acid bacillus. stay lactic acid Bacillus is produced only from sugar during fermentation lactic acid It is called homogeneous lactic acid fermentation bacteria. Streptococcus, Diplococcus, Micrococcus, Lactobacillus, etc. and some lactic acid Bacillus belong to this class. except lactic acid Besides, it also produces ethanol, acetic acid, carbon dioxide and other by-products, which are called heterogeneous lactic acid fermentation bacteria. In addition to Leuconostoc, there are several species lactic acid Bacillus belongs to this class. stay microorganism Homogeneous lactic acid fermentation of Glycolysis pathway Pyruvic acid is generated from sugars lactate dehydrogenase Function to form lactic acid. Manufacturing L (+) in microbial streptococcus- lactic acid However, Lactobacillus can produce D (-) - lactic acid, and there are also two kinds of lactic acid that can be produced. In heterogeneity lactic acid Different from homogeneous lactic acid fermentation, fermentation is carried out according to the following reactions glucose Decomposition of. In the absence of oxygen, pyruvate will receive hydrogen carried by NADH from glyceraldehyde 3-phosphate and form lactic acid under the catalysis of lactate dehydrogenase (LDH).
Lactic acid fermentation is a strict anaerobic fermentation, which can be used in the production of cheese, yogurt, edible pickles, silage and other industries. Lactic acid fermentation includes homotypic lactic acid fermentation and heterotypic lactic acid fermentation [1] 。
glucose → Glucose-6- phosphoric acid → Gluconic acid -6-phosphoric acid → CO2 Ribulose -5-phosphoric acid → xylose -5-phosphoric acid → glycyl acetaldehyde -3-phosphoric acid+ Acetylphosphoric acid Glycyl acetaldehyde-3-phosphate Glycolysis pathway , from pyruvic acid formation lactic acid On the other hand, acetylphosphoric acid Acetyl CoA Acetaldehyde forms ethanol and acetic acid 。 In heterogeneity lactic acid Fermentation; Generate L (+) - lactic acid or D (-) - lactic acid, or both. lactic acid Bacteria can use glucose and other corresponding fermentable sugars to produce lactic acid, which is called lactic acid fermentation. Due to different strains, Metabolic pathway Different, different products are generated lactic acid Fermentation is divided into homotypic lactic acid fermentation, heterotypic lactic acid fermentation and bifidobacteria fermentation [1] 。 Homolactic acid fermentation
Via EMP. Homomorphic fermentation refers to the process in which Lactobacillus acidophilus, Lnc. delbriikii and other Lactobacillus produce lactic acid through glycolysis of glucose. Since most Lactobacillus do not have decarboxylase, pyruvate produced by glycolysis cannot generate acetaldehyde through decarboxylation. Only under the catalysis of lactate dehydrogenase (coenzyme I is required), pyruvate is used as hydrogen acceptor to generate lactic acid through reduction reaction. It can be concluded that the total reaction formula of glucose through homolactic acid fermentation is:
C six H twelve O six +2ADP+2Pi——+2CH three CH(OH)COOH+2ATP
1 molecule of glucose generates 2 molecules of lactic acid, and the theoretical conversion rate is 100% [1] 。
heterolactic fermentation
heterolactic fermentation After glucose is converted into 6-phosphogluconate, it is converted into ribulose 5-phosphate by 6-phosphogluconate dehydrogenase, and then generates xylulose 5-phosphate by the epimerization of ribulose 5-phosphate 3-epimerase, Xylose 5-phosphate can be decomposed into acetyl phosphate and glyceraldehyde 3-phosphate under the catalysis of phosphoketolase (phosphor01ysis ketonase). The former is converted into acetyl CoA by the action of phosphotransacetylase, and then ethanol is finally produced by the action of acetaldehyde dehydrogenase and alcohol dehydrogenase; The latter generates pyruvate via EMP pathway and converts to lactic acid under the catalysis of lactate dehydrogenase. Through the 6-phosphogluconic acid heterotypic lactic acid fermentation pathway, one molecule of glucose can finally be converted into one molecule of lactic acid and one molecule of ethanol, thus the theoretical conversion rate of lactic acid to sugar is 50% [1] 。
Bifidobacterium fermentation
Through HK pathway - hexyl phosphate ketolase pathway.
The reaction was carried out under anaerobic conditions, and no dehydrogenation reaction occurred in the reaction process. One molecule of glucose was finally converted into one molecule of lactic acid and 1.5 molecules of acetic acid through the bifidous reaction pathway, and the theoretical conversion rate of lactic acid to sugar was 50%; There are two phosphoketolase involved in the pathway, namely 6-phosphofructose ketolase and 5-phosphoxylose phosphoketolase [1] 。
lactobacillus , corn embryo, potato tuber, beet root tuber and skeletal muscle, etc. 
