title: Capsular and slime-polysaccharide production by Lactobacillus rhamnosus JAAS8 isolated from Chinese sauerkraut: potential application in fermented milk products.
abstract: Exopolysaccharides (EPSs) produced by lactic acid bacteria (LAB) play an important role in the improvement of the physical properties of fermented dairy products. To find EPS-producing LAB strains with potential industrial applications, a Lactobacillus rhamnosus strain, L. rhamnosus JAAS8, that is capable of producing two forms of EPS when grown in MRS broth or semi-defined medium with glucose as a carbon source was isolated and identified from Chinese sauerkraut. The capsular-polysaccharide (CPS) present surrounding the bacterial surface of L. rhamnosus JAAS8 was observed by both optical microscopy and transmission electron microscopy. The slime-polysaccharide (SPS) present in the growth medium was produced mainly during the exponential growth phase, while the CPS was produced only in fermentation. Monosaccharide analysis of the purified polysaccharide samples showed that the CPS was composed of galactose and N-acetylglucosamine in a molar ratio of 5:1, and the SPS was composed of galactose, glucose and N-acetylglucosamine in a molar ratio of 4:1:1. The use of L. rhamnosus JAAS8 could be considered for potential applications in the dairy industry to improve the rheological properties of fermented milk products by increasing their water-holding capacity and viscosity.
authors.affiliation: Center of Agro-food Technology, Northeast Agricultural Research Center of China, No. 1363 Cai-Yu Street, Changchun, Jilin Province, 130033, PR China. zyang@cjaas.com
authors.forename: Zhennai
authors.initials: Z
authors.lastname: Yang
authors.forename: Shengyu
authors.initials: S
authors.lastname: Li
authors.forename: Xue
authors.initials: X
authors.lastname: Zhang
authors.forename: Xianpeng
authors.initials: X
authors.lastname: Zeng
authors.forename: Da
authors.initials: D
authors.lastname: Li
authors.forename: Yujuan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Jian
authors.initials: J
authors.lastname: Zhang
mesh_terms: D000117:Acetylglucosamine / Q000032:analysis; D016667:Bacterial Capsules / Q000737:chemistry / Q000648:ultrastructure; D002681:China; D003470:Culture Media; D043302:Cultured Milk Products / Q000382:microbiology*; D005285:Fermentation / Q000502:physiology; D005516:Food Microbiology; D005690:Galactose / Q000032:analysis; D005947:Glucose / Q000378:metabolism; D052201:Lacticaseibacillus rhamnosus / Q000254:growth & development / Q000302:isolation & purification / Q000378:metabolism*; D009005:Monosaccharides / Q000032:analysis; D011135:Polysaccharides, Bacterial / Q000096:biosynthesis* / Q000302:isolation & purification / Q000378:metabolism
chemical_list: D003470:Culture Media; D009005:Monosaccharides; D011135:Polysaccharides, Bacterial; D005947:Glucose; D000117:Acetylglucosamine; D005690:Galactose