L-lysine Producing Nitrogen And Growth Factor Replacement And Optimization Of Fermentation Conditions

Lysine is a kind of aliphatic basic amino acid, chemical name is2.62amino acid, is eight kinds of essential amino acids (also called essentialamino acids, lysine, threonine, leucine, isoleucine, methionine, valine,phenylalanine and tryptophan). Exists widely in protein, such as casein,egg protein hydrolysate, people and animals can’t own synthesis, must befrom food intake, it to adjust the body metabolic balance with animals,improve the people and animals on the absorption of cereal protein,improve human dietary nutrition and animal nutrition, promote thegrowth and development have important role. Now is widely used inmedicine, food and feed additives, and other fields. L-lysine at home andabroad main production by fermentation method, i.e., according to thestarch glucose as raw material, by microorganisms under the condition ofhigh concentration suitable after fermentation.At home and abroad generally with hair pink hair (amino acid) as anitrogen source, and corn syrup, molasses as nitrogen source and growthfactors. But hair powder in the process of continual production, feeding,let a person produce discomfort, and generate odor, and somemanufacturers may lead to heavy metal exceeds bid, in production, theuse of cost-effective integrated less than corn starch, glucose from cornstarch milk, and corn starch by soaking liquid of corn processing cornstarch milk, easy to use. To sum up, as far as possible in the process oflysine fermentation as far as possible to reduce or do not use hair powderas a medium, has become the important content of fermentation mediumoptimization direction.. Betaine as a new medium, has a large number of used in amino acidfermentation cultivation, from beet betaine is a kind of alkaloid, found inits molecular formula for C5H11NO2. Mainly to maintain cell osmoticpressure, the protection of enzyme action effect, salt resistance, durability,etc. Betaine is contained in a large number of growth factors, because ofthe extracted from beet, and refined, so add the effect is superior to thesugar beet molasses, biochemical reaction process of betaine as a methyldonor activity, the process of homocysteine to methionine, reduce the addmethionine, is helpful to reduce the production cost. Betaine can protectmicroorganisms from the effects of osmotic pressure in order to improvethe survival rate, and betaine and many enzymes have very goodcompatibility, betaine has also become the amino acid fermentationacidification promoter, become the latest hot topic in the field offermentation industry, has aroused high attention. Specific studies are asfollows:1. Seed pot culture medium optimizationWith lysine fungus a bacterium or virus (yellow) as the growth of bacteria,study to determine the lysine strains in the seed jar of rapid growth,shorten the training time, keeping strains. In the seed jar of medium toreduce or don’t add hair powder, because of the decrease in the number ofnitrogen source, according to the production need to appropriatelyincrease proportion of corn starch to supplement the reduction. Do notuse hair powders, through experiment to determine seed can increase thecorn syrup ingredients ratio to9%, can make the seed jar of OD value ofrapid growth, and reduce the training time.2. Fermentation medium optimizationIncrease in the production of fermentation tank culture do not use hairpowder, corn starch in the culture medium ratio to3.1%, do not use sugarbeet molasses, improve betaine in medium ratio to0.32%, reduce the proportion of methionine in culture, reduced to0.013%, adjust andoptimize the culture medium, to improve produce acid fermentation rateis18.5g/dl-19.2g/dl, sugar acid conversion rate reached68-70%,respectively compared with the original medium: fermentationacidification rate increased by0.04g/dl, conversion rate increased by2%,shorten the training time4hr, to reduce energy consumption, lowerproduction cost.