Torres-Rodríguez Ingrid, Rodríguez-Alegría María Elena, Miranda-Molina Alfonso, Giles-Gómez Martha, Conca Morales Rodrigo, López-Munguía Agustín, Bolívar Francisco, Escalante Adelfo
Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México (UNAM), Av. Universidad 2001. Col. Chamilpa, Cuernavaca Morelos, 62210 México.
Departamento de Biología, Facultad de Química, UNAM. Ciudad Universitaria, México D. F, Coyoacán, 04510 México.
Springerplus. 2014 Oct 7;3:583. doi: 10.1186/2193-1801-3-583. eCollection 2014.
We report the screening and characterization of EPS produced by LAB identified as Leuconostoc kimchii isolated from pulque, a traditional Mexican fermented, non-distilled alcoholic beverage produced by the fermentation of the sap extracted from several (Agave) maguey species. EPS-producing LAB constitutes an abundant bacterial group relative to total LAB present in sap and during fermentation, however, only two EPS-producing colony phenotypes (EPSA and EPSB, respectively) were detected and isolated concluding that despite the high number of polymer-producing LAB their phenotypic diversity is low. Scanning electron microcopy analysis during EPS-producing conditions revealed that both types of EPS form a uniform porous structure surrounding the bacterial cells. The structural characterization of the soluble and cell-associated EPS fractions of each polymer by enzymatic and acid hydrolysis, as by 1D- and 2D-NMR, showed that polymers produced by the soluble and cell-associated fractions of EPSA strain are dextrans consisting of a linear backbone of linked α-(1→6) Glcp in the main chain with α-(1→2) and α-(1→3)-linked branches. The polymer produced by the soluble fraction of EPSB strain was identified as a class 1 dextran with a linear backbone containing consecutive α-(1→6)-linked D-glucopyranosyl units with few α-(1→3)-linked branches, whereas the cell-associated EPS is a polymer mixture consisting of a levan composed of linear chains of (2→6)-linked β-D-fructofuranosyl residues with β-(2→6) connections, and a class 1 dextran. According to our knowledge this is the first report of dextrans and a levan including their structural characterization produced by L. kimchii isolated from a traditional fermented source.
我们报告了从龙舌兰酒（一种由几种龙舌兰属植物提取的汁液发酵制成的传统墨西哥发酵非蒸馏酒精饮料）中分离出的被鉴定为金氏明串珠菌的乳酸菌所产生胞外多糖（EPS）的筛选和特性研究。相对于汁液中以及发酵过程中存在的总乳酸菌而言，产EPS的乳酸菌是一个丰富的细菌群体，然而，仅检测并分离出了两种产EPS的菌落表型（分别为EPSA和EPSB），得出的结论是，尽管产聚合物的乳酸菌数量众多，但其表型多样性较低。在产EPS条件下的扫描电子显微镜分析表明，两种类型的EPS均在细菌细胞周围形成均匀的多孔结构。通过酶解、酸解以及一维和二维核磁共振对每种聚合物的可溶性和细胞相关EPS组分进行结构表征，结果表明，EPSA菌株的可溶性和细胞相关组分产生的聚合物是葡聚糖，其主链由连接的α-(1→6)葡萄糖吡喃糖组成，带有α-(1→2)和α-(1→3)连接的分支。EPSB菌株可溶性组分产生的聚合物被鉴定为1类葡聚糖，其线性主链包含连续的α-(1→6)连接的D-葡萄糖吡喃糖基单元，带有少量α-(1→3)连接的分支，而细胞相关EPS是一种聚合物混合物，由由(2→6)连接的β-D-呋喃果糖基残基的线性链组成的左聚糖以及1类葡聚糖组成。据我们所知，这是首次报道从传统发酵源分离出的金氏明串珠菌产生的葡聚糖和左聚糖及其结构表征。
