Investigation On Characteristics Of Anti-mold Lactobacillus And Optimization Of Fermentation Conditions

Some strains of Lactobacillus isolated from traditional fermented dairy food in Inner Mongolia were used in the test.The strains being of strong anti-mold abilities were screened as the experimental strains.The characteristic of the strains and active substance were studied.The conditions and culture medium of producing active substance were determined too.The results were showed as follows:(1)The anti-mold activity of five strains isolated from Inner Mongolia traditional fermented food were tested.Among them,ALAC-1 and ALAC-4 were of good anti-mold activity and used as tested strains.(2)Determination of OD value of Lactobacillus in different temperature,pH value,and salt concentrations.The result showed that the strain ALAC-1 and ALAC-’4 grew vigorously at 37℃ with pH 6.0,and they are moderately salinity tolerant.(3)The single-factor experiment and orthogonal test were applied to optimize fermentation conditions.The optimal condition of ALAC-1 was fermentation for 30h at 35 ℃ with inoculum size 2%and initial media pH 6.5.The optimal condition of ALAC-4 was fermentation for 28h at 34℃ with inoculum size 4%and initial media pH 7.0.(4)The components of fermentation medium were optimized to improve the production of anti-mold substance by single-factor experiment and orthogona test.The result showed that the optimized medium of ALAC-1 were glucose 15g/L,beef extract 10g/L,peptone lOg/L,yeast extract 5g/L,magnesium sulfate 0.4g/L,manganese sulfate 0.2g/L,potassium chloride 0.2g/L,sodium chloride 0.2g/L,Tween-80 1.5mL/L.The optimized medium of ALAC-4 were sucrose 20g/L,beef extract 12g/L,peptone 12g/L,yeast extract 6g/L,magnesium sulfate 0.6g/L,manganese sulfate 0.3g/L,potassium chloride 0.3g/L,Tween-80 1.0mL/L.(5)The metabolites of ALAC-1 and ALAC-4 were still of anti-mold activity after acid neutralization and catalase treatment.But they were sensitive to protease.It indicated that there were protide in anti-mold substances.The anti-mold substances were also thermal stability and had a broad spectrum of antifungal activity to a variety of yeasts and molds.The MIC of the antifungal activities to Aspergillus flavus were 62.50mg/mL and 31.25mg/mL respectively.