| The natural biopreservative replace chemical preservation was played an essential role for improving the security and demand of consumer.Most bacteriocin from lactic acid bacteria is food-grade microbial metabolites,which is the natural biopreservative.So in this study,Lactobacillus plantarum 1.557 was studied which separated from sauerkraut fermentation broth.The plantaricin1.557 produced from L.plantarum have physical and chemical characteristics of widely inhibitory spectrum,tolerance of pH wide range,thermal stability and tolerance of the organic solvent had been found.The plantaricin1.557 has a good application prospect.The adsorption characteristics was studied which plantaricin1.557 acted indicator bacteria in a different condition.And the impact on indicator bacteria cell permeability with plantaricin1.557 was studied.It provides a theoretical basis for understanding the structure and elements of plantaricin1.557's inhibitory mechanism.The fermentation conditions of L.plantarum 1.557 were optimized.It is quantity of inoculum size 5%,medium initial pH 7.0 and culture temperature is 40?,and fermentation supernatant after optimization to improve efficiency value to 102.74AU/mL,optimizing production of plantaricin1.557 1.14 times.Plantaricin1.557 was purified mainly by Yang method,DEAE-52 ion-exchange column chromatography,Sephadex G-50 gel filtration chromatography.After purified specific activity of plantaricin1.557 is 6.02x104 AU/mg,the sample purification is 46.67 times and extraction rate is 4.81%;the relative molecular mass of plantaricin1.557 is about 8kDa which detected by Tricine-SDS-PAGE.The results which to determiner adsorption characteristics indicator bacteria with plantaricin1.557 showed that:adsorption rate was unchanged at-20??60?,at 100? appearing a slight decrease;when acting time is 5,15,25,30,40 min respectiveiy,the adsorption rate was unchanged;When the salt concentration increased from 5mmol/L?400mmol/L,the adsorption rate was decreased;The adsorption rate was increased first the pH of solution in from 2.0 to 12.0,reached the maximum at 6.0,then it was falled;the adsorption rate of E.coli with Plantaricin 1.55 7 was increased after treatment.It confirmed solution pH and salt concentration have the larger on the adsorption of indicator bacteria and Plantaricin 1.557.The result of the influence of bacterial cell membrane permeability showed:adding MIC concentration plantaricin 1.557 in the culture medium of indicator bacteria,K+,inorganic phosphorus,ATP,having an ultraviolet absorbing material which existing extracellular potassium were significantly increased within 0.5h.The acting time of plantaricin 1.557 with indicator bacteria increasing,the activity of extracellular dehydrogenase was increased.By scanning electron microscopy,it can be observed which cell morphology of indicator bacteria changed after plantaricin 1.557 functioning 3h,even holes in cells membrane can be observed.It confirmed the bacterial cell membrane permeability was increased and the cells were damaged.Indicator bacteria growth were subduedad after plantaricin1.557 functioning,justments of S.aureus was delayed,but E.coli was not appear the phenomenon.The results showed that:after Plantaricin1.557 effecting indicator bacteria,membrane permeability increasing,cells are death autolysis because of the leakage of intracellular material. |
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