Biodiversity of exopolysaccharide-producing lactic acid bacteria from Iranian traditional Kishk and optimization of EPS yield by Enterococcus spp.  

作　　者：Paria Rahnama Vosough Mohammad Reza Edalatian Dovom Mohammad Bagher Habibi Najafi Ali Javadmanesh Baltasar Mayo 

机构地区：[1]Food Science and Technology Department,Agriculture Faculty,Ferdowsi University of Mashhad(FUM),P.O.Box:91775-1163,Mashhad,Iran [2]Department of Animal Science,Faculty of Agriculture,Ferdowsi University of Mashhad(FUM),Mashhad,Iran [3]Departamento de Microbiología y Bioquímica,Instituto de Productos Lacteos de Asturias(IPLA-CSIC),Paseo Río Linares,s/n,33300,Villaviciosa,Asturias,Spain

出　　处：《Food Bioscience》2022年第5期543-555,共13页食品生物科学（英文）

基　　金：supported by a grant(No.3/47333)from the Ferdowsi University of Mashhad(Research Affairs),Iran.

摘　　要：The production of polysaccharides derived from lactic acid bacteria(LAB)can be a valuable alternative to current polysaccharides.In this study,eight samples of Kishk(traditional dairy product)were collected in sterile conditions and directly cultured on MRS agar medium.Following purification and examination of microscopic,macroscopic characteristics and doing biochemical tests,143 isolates were selected,and the production of exopolysaccharide(EPS)was investigated by the ruthenium red and disc methods.The EPS production of 79 isolates was confirmed.Total carbohydrate of EPS was determined by the phenol sulfuric acid method.Finally,Enterococcus durans K48,Enterococcus faecium R114,and Enterococcus faecium T52 strains were selected as the best EPS producers.The optimization of EPS production was then performed using Central Composite Design(CCD)and Response Surface Methodology(RSM)approaches.Optimization plots showed the highest EPS yield for E.durans K48,E.faecium R114,and E.faecium T52 occurred at 38.4,37.4 and 36.7℃and pH of 5.9,5.6 and 5.8,respectively,cultured in a Sucrose-MRS medium.Under optimal conditions,the maximum predicted and actual production of EPSs for the examined isolates were 3.18,3.21,2.99 and 3.02,3.15,3.15,g L1,respectively.As determined by Gel Permeation Chromatography,the EPSs molecular weights were in the range of 2.93×10^(5)to 3.52×10^(5)Da.Analysis of the component monosaccharides by HPLC showed that all three tested EPSs were heteropolysaccharides.After appropriate evaluation,the EPSs produced by native species of LAB isolated from Iranian Kishk could be of interest for industrial applications or as functional food ingredients.

关 键 词：EXOPOLYSACCHARIDE Lactic acid bacteria Diversity Optimization RSM 

分 类 号：TS201.3[轻工技术与工程—食品科学]