Cooper-Bribiesca Barbara, Navarro-Ocaña Arturo, Díaz-Ruiz Gloria, Aguilar-Osorio Guillermo, Rodríguez-Sanoja Romina, Wacher Carmen
Departamento de Alimentos y Biotecnología, Facultad de Química, Universidad Nacional Autónoma de México, Mexico City, Mexico.
Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Mexico City, Mexico.
Front Microbiol. 2018 Dec 18;9:3061. doi: 10.3389/fmicb.2018.03061. eCollection 2018.
ssp. 25124 (25124) is a lactic acid bacterium (LAB) isolated from , a refreshing beverage prepared by suspending fermented (a thermal and alkali-treated maize dough) in water. Although s are the predominant strains in fermented doughs, such as sourdoughs, and non-nixtamalized fermented maize foods, the microbiota is markedly different. This may be the result of the nixtamalization process, which could act as a selective force of some strains. 25124 has been reported as the main amylolytic LAB in pozol; starch is the primary carbon source on since monosaccharides and disaccharides are lost during nixtamalization; however, non-amylolytic LAB counts are higher than amylolytic LAB in after 24-h fermentation suggesting that another carbon source is being used by the former bacteria. Hemicellulose (arabinoxylan in maize) becomes available via nixtamalization and is subsequently metabolized by LAB. The aim of this work was to determine whether this bacterium is able to use arabinoxylan as the only carbon source in a defined medium containing arabinoxylan extracted from either (wash water produced during preparation), or beechwood xylan. Xylanase activity in the presence of arabinoxylan (135.8 ± 48.7 IU/mg protein) was higher than that of beechwood (62.5 ± 19.8 IU/mg protein). Other enzymatic activities, such as arabinofuranosidase and acetyl esterase, were also detected, suggesting the adaptation of the bacterium studied to dough. It was concluded that 25124 isolated from was able to use arabinoxylans, which are present in nixtamal dough, so fermentation does not depend exclusively on free sugars and starch.
菌株25124（25124）是一种从一种清爽饮料中分离出的乳酸菌（LAB），该饮料是通过将发酵后的“nixtamal”（经过热处理和碱处理的玉米面团）悬浮在水中制成的。尽管LAB是发酵面团（如酸面团）和未经过碱处理的发酵玉米食品中的优势菌株，但“nixtamal”的微生物群却明显不同。这可能是碱处理过程的结果，该过程可能对某些菌株起到了选择作用。据报道，25124是“pozol”中主要的淀粉分解LAB；由于在碱处理过程中单糖和二糖会流失，淀粉是“nixtamal”上的主要碳源；然而，在24小时发酵后，“nixtamal”中非淀粉分解LAB的数量高于淀粉分解LAB，这表明前者细菌正在利用另一种碳源。半纤维素（玉米中的阿拉伯木聚糖）通过碱处理变得可用，随后被LAB代谢。这项工作的目的是确定这种细菌是否能够在含有从“nixtamal”（制作“nixtamal”过程中产生的洗涤水）或山毛榉木聚糖中提取的阿拉伯木聚糖的限定培养基中，将阿拉伯木聚糖作为唯一碳源使用。在存在“nixtamal”阿拉伯木聚糖的情况下，木聚糖酶活性（135.8±48.7 IU/mg蛋白质）高于山毛榉木聚糖（62.5±19.8 IU/mg蛋白质）。还检测到了其他酶活性，如阿拉伯呋喃糖苷酶和乙酰酯酶，这表明所研究的细菌适应了“nixtamal”面团。得出的结论是，从“nixtamal”中分离出的菌株25124能够利用“nixtamal”面团中存在的阿拉伯木聚糖，因此发酵并不完全依赖于游离糖和淀粉。
