Analysis Of Major Organic Acids From Lactic Acid Bacteria Isolated From Yunnan Traditional Fermented Douchi And Study On Bacteriostasis

Douchi, a common food, which usually produced by black bean or soybean, is fermented by added specific microorganisms or from air. The douchi, taking the different microorganisms for fermentation into account, can be divided into several types, such as:Mucor, Rhizopus, Aspergillus and Bacteria type; judging by whether add salt or not during fermentation process, the product could be divided into salty douchi and semen sojae praeparatum. In addition, given the water in douchi, it divided into dry douchi, wet douchi and water douchi. China has majority amount of Mucor, with few Rhizopus and Bacteria type. Dan bei and natto are eminent in foreign countries. Rich resources of douchi are available in Yunnan Province, where provides varieties of environment climate, which contributes to an extraordinary status for microorganisms, of which the main type is the lactic acid bacteria. Lactic acid bacteria is a type of bacteria that could produce lactic acid from glucose or carbohydrate. This bacteria is used to called as lactic acid bacteria and it is not for microbial taxonomy. Bacteria, having hundreds of classification, is difficult to build classification standard according to whether to produce amount of lactic acid. The name of lactic acid bacteria, however, have been accepted by people. The live way of lactic acid bacteria is very complex, including saprophytic and parasitic. Lactic acid bacteria exist widely in body of people and animals. Some type of Lactic acid bacteria could make people and animals ill. But most of Lactic acid bacteria are important bacteria for food, health care, industry, agriculture, medicine and research.The ingredients of lactic acid bacteria fermentation fluid is very complex. Many of which matter have bacteriostasis, such as bacteriocins, organic acid and hydrogen peroxide. The study of organic acid is not much, it mainly focused on analysis and quantitate the type and content. It is usually use organic acid do experiment in vitro. And this method has some limitation. The interference of organic acids and other substance is not clear.This study use TLC method analysis the classification of organic acids in lactic acid bacteria fermente fluid and optimize it chromatographic conditions. And use ultraviolet spectrophotometry analysis the content of organic acids in bacteria. The study result that, the bacteriostatic effect is delcline when use starch for carbon sources, the content of citric acid is increased slightly. The content of tartaric acid content is rises much more, and lactic acid, oxalic acid, and malic acid are a small drop. When sucrose for carbon sources, the content of citric acid and lactic acid are decrease, and the content of oxalic acid, tartaric acid and malic acid are rise. It effect of bacteriostatic is declines. When lactose for carbon sources, the content of malic acid is decreases, and the content of other acids are rise. It effect of bacteriostatic is rise too. When fructose for carbon sources, the content of citric acid and lactic acid are decrease, and the content of oxalic acid, tartaric acid and malic acid are rise. It effect of bacteriostatic is declines. It is concluded that lactic acid is the main factor of bacteriostatic substance, the second is citric acid. The effect of malic acid, oxalic acid and.tartaric acid is very small. And the study showed that organic acid in lactic acid bacteria is the main factor of bacteriostatic substance but when organic acids and other substance cooperation each other it can cause fine effect of bacteriostasis. This result make data support for study on bacteriostasis mechanism in lacit acid bacteria and provides theory basis for it's application in areas of food preservation.