Ermann Lundberg Ludwig, Mata Forsberg Manuel, Lemanczyk James, Sverremark-Ekström Eva, Sandström Corine, Roos Stefan, Håkansson Sebastian
Department of Molecular Sciences, Uppsala BioCenter, Swedish University of Agricultural Sciences, 750 07 Uppsala, Sweden.
BioGaia AB, 112 27 Stockholm, Sweden.
Microorganisms. 2024 Oct 12;12(10):2058. doi: 10.3390/microorganisms12102058.
Improved efficacy of probiotics can be achieved by using different strategies, including the optimization of production parameters. The impact of fermentation parameters on bacterial physiology is a frequently investigated topic, but what happens during the formulation, i.e., the step where the lyoprotectants are added prior to freeze-drying, is less studied. In addition to this, the focus of process optimization has often been yield and stability, while effects on bioactivity have received less attention. In this work, we investigated different metabolic activities of the probiotic strain DSM 17938 during formulation with the freeze-drying protectant sucrose. We discovered that the strain consumed large quantities of the added sucrose and produced an exopolysaccharide (EPS). Using NMR, we discovered that the produced EPS was a glucan with α-1,4 and α-1,6 glycosidic bonds, but also that other metabolites were produced. The conversion of the lyoprotectant is hereafter designated lyoconversion. By also analyzing the samples with GCMS, additional potential bioactive compounds could be detected. Among these were tryptamine, a ligand for the aryl hydrocarbon receptor, and glycerol, a precursor for the antimicrobial compound reuterin (3-hydroxypropionaldehyde). To exemplify the bioactivity potential of lyoconversion, lyoconverted samples as well as purified EPS were tested in a model for immunomodulation. Both lyoconverted samples and purified EPS induced higher expression levels of IL-10 (2 times) and IL-6 (4-6 times) in peripheral blood mononuclear cells than non-converted control samples. We further found that the initial cultivation of DSM 17938 with sucrose as a sugar substrate, instead of glucose, improved the ability to convert sucrose in the lyoprotectant into EPS and other metabolites. Lyoconversion did not affect the viability of the bacteria but was detrimental to freeze-drying survival, an issue that needs to be addressed in the future. In conclusion, we show that the metabolic activities of the bacteria during the formulation step can be used as a tool to alter the activity of the bacteria and thereby potentially improve probiotic efficacy.
通过采用不同策略，包括优化生产参数，可以提高益生菌的功效。发酵参数对细菌生理的影响是一个经常被研究的课题，但在制剂过程中，即在冷冻干燥前添加冻干保护剂的步骤中会发生什么，却较少被研究。除此之外，工艺优化的重点往往是产量和稳定性，而对生物活性的影响则较少受到关注。在这项工作中，我们研究了益生菌菌株DSM 17938在与冻干保护剂蔗糖制剂过程中的不同代谢活性。我们发现该菌株消耗了大量添加的蔗糖并产生了一种胞外多糖（EPS）。通过核磁共振（NMR），我们发现产生的EPS是一种具有α-1,4和α-1,6糖苷键的葡聚糖，而且还产生了其他代谢物。冻干保护剂的这种转化在此后被称为冻干转化。通过用气相色谱-质谱联用仪（GCMS）分析样品，还可以检测到其他潜在的生物活性化合物。其中包括色胺，一种芳烃受体的配体，以及甘油，抗菌化合物罗伊氏菌素（3-羟基丙醛）的前体。为了举例说明冻干转化的生物活性潜力，在免疫调节模型中测试了冻干转化样品以及纯化的EPS。与未转化的对照样品相比，冻干转化样品和纯化的EPS在外周血单核细胞中均诱导了更高水平的白细胞介素-10（2倍）和白细胞介素-6（4-6倍）的表达。我们进一步发现，用蔗糖作为糖底物对DSM 17938进行初始培养，而不是葡萄糖，提高了将冻干保护剂中的蔗糖转化为EPS和其他代谢物的能力。冻干转化不影响细菌的活力，但对冷冻干燥存活不利，这是一个未来需要解决的问题。总之，我们表明细菌在制剂步骤中的代谢活性可以用作改变细菌活性的工具，从而有可能提高益生菌的功效。
