微生物胞外多糖具有多种有益特性,是潜在的益生元。胞外多糖BPS-2是从苏云金芽孢杆菌IX-01通过高密度发酵后提取出来的。BPS-2是一种由氨基半乳糖、阿拉伯糖、氨基葡萄糖、葡萄糖和甘露糖组成的杂多糖,摩尔比为5.53∶1.77∶4.74∶3.24∶1,其多糖分子质量为27.96 kDa。该研究通过四唑盐试验法对BPS-2的细胞毒性进行了评价,在验证了其多糖无细胞毒性的前提下,采集了10位健康人粪便微生物,探究BPS-2对人体粪便菌群组成及代谢产物的影响。在体外进行48 h的静态发酵时,与阴性对照相比,BPS-2明显增强了短链脂肪酸的产生(P＜0.05),乙酸、丙酸、丁酸和总短链脂肪酸的浓度分别达到(31.59±0.73)、(10.82±0.65)、(8.18±0.2)和(50.59±1.54)mmol/L。通过16S rRNA基因测序表明BPS-2可以显著增加有益菌属Parabacteroides的相对丰度,并减少有害微生物菌群Megamonas和Fusobacterium的相对丰度,进而参与改善宿主肠道微生物区系的结构。这是关于苏云金芽孢杆菌生产的BPS-2体外益生特性的首次报告,为其在食品工业中的应用提供了基础。
Microbial extracellular polysaccharides possess various beneficial properties and are potential prebiotic. The extracellular polysaccharide BPS-2 was extracted from Bacillus thuringiensis IX-01 by high-density cellular fermentation. BPS-2 is a heteropolysaccharide composed of aminogalactose, arabinose, glucosamine, glucose and mannose with a molar percentage of 5.53∶1.77∶4.74∶3.24∶1. It has a polysaccharide molecular mass of 27.96 kDa. MTT assay was used to evaluate the cytotoxicity of BPS-2, and microorganisms from 10 healthy human fecal were obtained to investigate the effect of BPS-2 on the composition and metabolites of human fecal flora under the premise that its polysaccharide was not cytotoxic. During 48 h of static fermentation in vitro, BPS-2 significantly enhanced the production of short-chain fatty acids compared to the negative control (P<0.05), with concentrations of acetic acid, propionic acid, butyric acid and total short-chain fatty acids reaching (31.59±0.73), (10.82±0.65), (8.18±0.2), (50.59±1.54) and (50.59±1.54) mmol/L, respectively. Sequencing of 16S rRNA gene showed that BPS-2 significantly increased the relative abundance of the beneficial genus Parabacteroides and reduced the relative abundance of the harmful microflora Megamonas and Fusobacterium, which in turn were involved in improving the structure of the host gut microbiota. This is the first report on in vitro probiotic properties of BPS-2 produced by B. thuringiensis, which can provide a basis for its application in the food industry.
[1] SUTHERLAND I W. Novel and established applications of microbial polysaccharides[J]. Trends Biotechnol, 1998, 16(1): 41-46.
[2] MALAKA R, ABUSTAM E, BACO S.Antitumor activity (in-vitro) of extracellular polysaccharide produced by ropy Lactobacillus delbrueckii ssp. bulgaicus isolated from traditional fermented milk[J].International Journal of Chemistry and Pharmaceutical Science, 2016, 4:246-249.
[3] SILVA L A, LOPES NETO J H P, CARDARELLI H R, et al.Exopolysaccharides produced by Lactobacillus plantarum:Technological properties, biological activity, and potential application in the food industry[J].Annals of Microbiology, 2019, 69(4):321-328.
[4] ZEIDAN A A, POULSEN V K, JANZEN T, et al.Polysaccharide production by lactic acid bacteria:From genes to industrial applications[J].FEMS Microbiology Reviews, 2017, 41(S1):S168-S200.
[5] CUTTING S M.Bacillus probiotics[J].Food Microbiology, 2011, 28(2):214-220.
[6] CRICKMORE N, ZEIGLER D R, FEITELSON J, et al.Revision of the nomenclature for the Bacillus thuringiensis pesticidal crystal proteins[J].Microbiology and Molecular Biology Reviews, 1998, 62(3):807-813.
[7] LIU W, LI X Q, ZHAO Z L, et al.Effect of chitooligosaccharides on human gut microbiota and antiglycation[J].Carbohydrate Polymers, 2020, 242:116413.
[8] DI T, CHEN G J, SUN Y, et al.In vitro digestion by saliva, simulated gastric and small intestinal juices and fermentation by human fecal microbiota of sulfated polysaccharides from gracilaria rubra[J].Journal of Functional Foods, 2018, 40:18-27.
[9] SCHROEDER B O, BÄCKHED F.Signals from the gut microbiota to distant organs in physiology and disease[J].Nature Medicine, 2016, 22(10):1 079-1 089.
[10] ZHU Y, MAO Y Q, CHEN H, et al.Apigenin promotes apoptosis, inhibits invasion and induces cell cycle arrest of T24 human bladder cancer cells[J].Cancer Cell International, 2013, 13(1):54.
[11] SCHULTHESS J, PANDEY S, CAPITANI M, et al.The short chain fatty acid butyrate imprints an antimicrobial program in macrophages[J].Immunity, 2019, 50(2):432-445.
[12] AL-LAHHAM S H, PEPPELENBOSCH M P, ROELOFSEN H, et al.Biological effects of propionic acid in humans;metabolism, potential applications and underlying mechanisms[J].Biochimica et Biophysica Acta, 2010, 1 801(11):1 175-1 183.
[13] CRESCI G A, GLUECK B, MCMULLEN M R, et al.Prophylactic tributyrin treatment mitigates chronic-binge ethanol-induced intestinal barrier and liver injury[J].Journal of Gastroenterology and Hepatology, 2017, 32(9):1 587-1 597.
[14] MORRIS D L.Quantitative determination of carbohydrates with dreywood′s anthrone reagent[J].Science (Washington), 1948, 107(2 775):254-255.
[15] BRADFORD M M.A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding[J].Analytical Biochemistry, 1976, 72(1-2):248-254.
[16] RAMAMOORTHY S, GNANAKAN A,LAKSHMANA S S, et al.Structural characterization and anticancer activity of extracellular polysaccharides from ascidian symbiotic bacterium Bacillus thuringiensis[J].Carbohydrate Polymers, 2018, 190:113-120.
[17] WANG M L, GENG L L, XUE B, et al.Structure characteristics and function of a novel extracellular polysaccharide from Bacillus thuringiensis strain 4D19[J].International Journal of Biological Macromolecules, 2021, 189:956-964.
[18] CARLSON J L, ERICKSON J M, HESS J M, et al.Prebiotic dietary fiber and gut health:Comparing the in vitro fermentations of beta-glucan, inulin and xylooligosaccharide[J].Nutrients, 2017, 9(12):1 361.
[19] KOH A, DE VADDER F, KOVATCHEVA-DATCHARY P, et al.From dietary fiber to host physiology:Short-chain fatty acids as key bacterial metabolites[J].Cell, 2016, 165(6):1 332-1 345.
[20] WANG R X, LEE J S, CAMPBELL E L, et al.Microbiota-derived butyrate dynamically regulates intestinal homeostasis through regulation of actin-associated protein synaptopodin[J].Proceedings of the National Academy of Sciences, 2020, 117(21):11 648-11 657.
[21] LAPARRA J M, SANZ Y.Interactions of gut microbiota with functional food components and nutraceuticals[J].Pharmacological Research, 2010, 61(3):219-225.
[22] LIU C, DU P, GUO Y H, et al.Extraction, characterization of aloe polysaccharides and the in-depth analysis of its prebiotic effects on mice gut microbiota[J].Carbohydrate Polymers, 2021, 261(11):117874.
[23] JOHNSON E L, HEAVER S L, WALTERS W A, et al.Microbiome and metabolic disease:Revisiting the bacterial phylum Bacteroidetes[J].Journal of Molecular Medicine, 2017, 95(1):1-8.
[24] YACHIDA S, MIZUTANI S, SHIROMA H, et al.Metagenomic and metabolomic analyses reveal distinct stage-specific phenotypes of the gut microbiota in colorectal cancer[J].Nature Medicine, 2019, 25(6):968-976.
[25] MULLISH B H, MCDONALD J A K, PECHLIVANIS A, et al.Microbial bile salt hydrolases mediate the efficacy of faecal microbiota transplant in the treatment of recurrent Clostridioides difficile infection[J].Gut, 2019, 68(10):1 791-1 800.
[26] LEI Y Y, TANG L, LIU S, et al.Parabacteroides produces acetate to alleviate heparanase-exacerbated acute pancreatitis through reducing neutrophil infiltration[J].Microbiome, 2021, 9(1):115.
