Lactic Acid Fermentation From Cassava By Bacillus Coagulans LA204

Lactic acid is a chemical product that can be produced by fermentation and widely used in food and industry.Cassava has become one of the most important biomass energy crops because it has the advantages of easy cultivation,rapid growth,and high yield per mu.Dried cassava contains approximately 73.9% starch and 11.8% cellulose,and can be hydrolyzed to glucose for fermentation.Therefore,the use of cassava fermentation to produce biofuels and chemical products is one of the important goals of improving the industrialization level of cassava.Bacillus coagulans has the advantages of high temperature resistance and fast lactic acid production.This article focused on the physiological metabolic characteristics of Bacillus coagulans LA204,combined with the lactic acid fermentation process to study the process of producing lactic acid in cassava fermentation.The relevant results are as follows:1.The results of starch ability analysis showed that B.coagulans LA204 could use starch as the only carbon source,which showed that the bacteria had the ability to produce lactic acid by amylase without adding amylase.2.B.coagulans LA204 secreted more extracellular proteins than starch as the sole carbon source under starch induction.The results of mass spectrometry showed that starch specific induced proteins were mainly involved in transport and regulation of gene expression,but there was no detection of extracellular amylase,indicating that the bacteria could hydrolyze starch using the amylase anchored by cell membrane.3.With cassava as the raw material in the 5-L fermentor,the results of optimizing the production of lactic acid by nitrogen source show that B.coagulans LA204 can produce amylase using cassava as the carbon source to ferment lactic acid,and the nitrogen source has an important influence on the growth of B.coagulans LA204 and the production of lactic acid.The final yield of lactic acid was increased by 83% the yeast extract compared with the corn steep liquor used as the nitrogen source.4.In the 5L fermenter,8% cassava was used as the substrate and 1% corn steep liquor was used as the nitrogen source in the fermentation medium.The final concentration was 12 U/g of ?-amylase and 180 U/g of glucoamylase or 20 U/g of cellulase.The experimental group without gelatinization or enzymolysis could not produce lactic acid;not gelatinized but the amylase was added,the lactic acid reached 36.03 g/L for 96 h,and the lactic acid concentration was 44.24 g/L at 96 h after gelatinization and the addition of amylase.The groups added cellulase with or without gelatinization could get lactic acid 47.29 g/L and 33.90 g/L,respectively,in 120 hours.The above results show that the final yield of lactic acid can be increased by optimizing the enzymatic hydrolysis process.The above results indicate that B.coagulans LA204 can convert cassava into lactic acid by secreting amylase itself.The final lactic acid yield and production rate can be increased via optimizing nitrogen source and enzymatic hydrolysis process.By adding amylase and cellulase,a more efficient lactic acid fermentation can be achieved,laying a solid foundation for the efficient utilization of cassava.