Identification Of Microorganism In Soy Sauce Mash And Optimization Of Fermentation Conditions For Bacillus Subtilis

In this paper,the microorganisms in soy sauce mash were isolated and identified,and 56 strains were isolated and purified according to the colony morphology of microorganisms.According to the colony morphology and physiological and biochemical characteristics,they were identified as lactic acid bacteria,yeast and Bacillus.Further morphological analysis of the strains,refer to the Berger’s bacterial identification manual,and through physiological and biochemical experiments,the isolated Bacillus were identified as Bacillus subtilis,Bacillus megaterium,Bacillus polymyxa,Clostridium,Bacillus licheniformis and Bacillus fastidious.Bacillus subtilis was identified as Bacillus amyloliquefaciens by molecular biology.According to the classification,identification and experimental methods of lactic acid bacteria,the isolated lactic acid bacteria contained Lactobacillus plantarum,Pediococcus halophilus,Lactobacillus and Brevibacterium.According to the morphological observation and sugar fermentation experiment of yeasts,and referring to the manual of fungal classification,the isolated yeasts were identified to contain Zygosaccharomyces rouxii,Hansenula,Saccharomyces parvum and Candida utilis.Therefore,lactic acid bacteria,yeast and bacillus are the main microorganisms in soy sauce fermentation.Because Bacillus subtilis can give soy sauce special flavor,the enzymology characteristics of Bacillus subtilis isolated were studied.It can produce extracellular protease,amylase and cellulase,and has the ability to ferment soy sauce.The culture conditions were optimized and orthogonal experiments were carried out.The optimal culture conditions were determined as follows: glucose concentration 3%,peptone concentration 0.8%,inoculum volume 8%,liquid volume 16%,pH 7.0.