Rios-Covián D, Sánchez B, Cuesta I, Cueto-Díaz S, Hernández-Barranco A M, Gueimonde M, De los Reyes-Gavilán C G
1 Probiotics and Prebiotics Group, Department of Microbiology and Biochemistry of Dairy Products, Instituto de Productos Lácteos de Asturias, Consejo Superior de Investigaciones Científicas (IPLA-CSIC), Paseo Rio Linares s/n, 33300 Villaviciosa, Asturias, Spain.
2 Scientific and Technical Facilities, IPLA-CSIC, Paseo Rio Linares s/n, 33300 Villaviciosa, Asturias, Spain.
Benef Microbes. 2016;7(2):265-73. doi: 10.3920/BM2015.0129. Epub 2016 Feb 3.
Microorganisms of the genus Bifidobacterium are inhabitants of diverse niches including the digestive tract of humans and animals. The species Bifidobacterium adolescentis, Bifidobacterium animalis, Bifidobacterium bifidum, Bifidobacterium breve and Bifidobacterium longum have qualified presumption of safety status granted by EFSA and several strains are considered probiotic, and are being included in functional dairy fermented products. In the present work we carried out a preliminary exploration of general metabolic characteristics and organic acid production profiles of a reduced number of strains selected from these and other species of the genus Bifidobacterium. The use of resting cells allowed obtaining metabolic fingerprints without interference of metabolites accumulated during growth in culture media. Acetic acid was the most abundant organic acid formed per mol of glucose consumed (from 1.07 ± 0.03 to 1.71 ± 0.22 mol) followed by lactic acid (from 0.34 ± 0.06 to 0.90 ± 0.12 mol), with moderate differences in production among strains; pyruvic, succinic and formic acids were also produced at considerably lower proportions, with variability among strains. The acetic to lactic acid ratio showed lower values in stationary phase as regard to the exponential phase for most, but not all, the microorganisms; this was due to a decrease in acetic acid molar proportions together with increases of lactic acid proportions in stationary phase. A linear discriminant analysis allowed to cluster strains into species with 51-100% probability, evidencing different metabolic profiles, according to the relative production of organic acids from glucose by resting cells, of microorganisms collected at the exponential phase of growth. Looking for a single metabolic marker that could adequately discriminate metabolic groups, we found that groups established by the acetic to lactic acid ratio fit well with differences previously evidenced by the discriminant analysis. The proper establishment of metabolic groups within the genus Bifidobacterium could help to select the best suited probiotic strains for specific applications.
双歧杆菌属的微生物存在于包括人类和动物消化道在内的多种生态位中。青春双歧杆菌、动物双歧杆菌、两歧双歧杆菌、短双歧杆菌和长双歧杆菌已获得欧洲食品安全局（EFSA）授予的合格安全推定地位，并且有几种菌株被认为是益生菌，已被纳入功能性乳制品发酵产品中。在本研究中，我们对从双歧杆菌属的这些及其他物种中挑选出的数量较少的菌株的一般代谢特征和有机酸产生概况进行了初步探索。使用静止细胞能够获得代谢指纹图谱，而不受培养基中生长过程中积累的代谢物的干扰。每消耗1摩尔葡萄糖形成的最丰富的有机酸是乙酸（从1.07±0.03到1.71±0.22摩尔），其次是乳酸（从0.34±0.06到0.90±0.12摩尔），菌株之间的产量存在适度差异；丙酮酸、琥珀酸和甲酸的产量也相当低，且菌株之间存在差异。对于大多数（但不是全部）微生物而言，乙酸与乳酸的比率在稳定期相对于指数期显示出较低的值；这是由于稳定期乙酸摩尔比例的降低以及乳酸比例的增加。线性判别分析能够以51 - 100%的概率将菌株聚类为不同的物种，根据生长指数期收集的微生物通过静止细胞从葡萄糖中产生有机酸的相对产量，证明了不同的代谢谱。在寻找能够充分区分代谢组的单一代谢标志物时，我们发现由乙酸与乳酸比率建立的组与先前判别分析所证明的差异非常吻合。在双歧杆菌属内正确建立代谢组有助于为特定应用选择最适合的益生菌菌株。
