Strain Tracking Reveals the Determinants of Bacterial Engraftment in the Human Gut Following Fecal Microbiota Transplantation

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微生物-肠-脑轴与神经系统疾病的研究进展

肠道微生物对神经系统疾病 (如帕金森病、抑郁症和阿尔兹海默症等) 的治疗具有辅助治疗的作用。其主要通过神经通路、免疫通路以及微生物代谢物等途径在肠-脑轴的作用下影响大脑功能和宿主行为。因此,文中结合国内外的研究进展,就微生物-肠-脑轴在神经系统疾病中的主要作用进行探讨,以期为神经退行性疾病的治疗提供新思路。     

The Benefit of a Roseobacter Species on the Survival of Scallop Larvae

A marine strain (BS107), identified as a Roseobacter species, was antagonistic to Vibrio species on agar plates. Results suggested that the inhibitory effect was displayed only in the presence of another bacterium. Quantification of the antibacterial activity showed that 48-hour-coculture supernatants from BS107 and another bacterial strain (V. anguillarum 408) reached the highest titers of bacterial inhibition. The antibacterial substance was also liberated when supernatants from V. anguillarum 408 were added to pure cultures of the inhibition-productive bacterium. The presence of a proteinaceous molecule may induce BS107 to display the inhibitory effect. The antibacterial substance was sensitive to trypsin (8000 U/ml) and stable at 100°C. Cell extracts of the isolate BS107 (10⁶ cells/ml) significantly enhanced scallop larval survival, thus being beneficial to the rearing process. Received December 8, 1997; accepted July 15, 1998.     

Survival and retention of the probiotic Lactobacillus casei LAFTI L26 in the gastrointestinal tract of the mouse

AIMS: This study aimed to develop methods for the detection of the probiotic Lactobacillus casei LAFTI L26 (L26) from mouse faeces, and to determine the survival and retention time of L26 in the mouse gastrointestinal tract. METHODS AND RESULTS: A selective medium, de Man Rogosa Sharpe (MRS) + bromocresol green + vancomycin (MGV), was designed for the isolation and enumeration of L26 from faecal samples of mice. PCR primers were designed to confirm the identity of L26-like colonies on MGV. These primers did not produce PCR products from related organisms that grew on MGV. Following the administration of L26 to BALB/c mice, faecal samples were collected and analysed using the designed methods. Survival studies showed viable L26 cells to be present in the faeces of mice for >48 h. CONCLUSIONS: Our results suggest that L26 is able to survive and be retained within the digestive tract of mice for at least 48 h following oral administration. SIGNIFICANCE AND IMPACT OF THE STUDY: MGV allows effective recovery of L26 from the background microbiota, including lactobacilli of mice. PCR was used to confirm that L26-like colonies were correctly identified as L26. Given the long retention time of L26 in the gastrointestinal tract of mice, it would appear that this probiotic strain may survive in the human gastrointestinal tract.     

Generation of species-specific antihemoglobin antibodies by immunization with synthetic peptides of human hemoglobin

Four peptides (7–16 residues) representing nonconserved regions of human hemoglobin (Hb) were selected for synthesis by comparison of the amino acid sequence of human Hb with those of the most common domesticated animals. Mouse antisera resulting from immunization with the synthetic peptides were investigated for binding to a panel of animal Hbs using solid-phase radioimmunoassay (RIA). One of the peptides elicited antibodies which bound specifically to human Hb, but not to any Hb of the nonprimate animals tested. The results show that the peptide immunogen chosen on the basis of dissimilarity between regions of different species is useful for the generation of species-specific antibodies. Such antibodies could serve as valuable tools for clinical screening of fecal occult blood trait and for forensic identification of bloodstains of human origin.     

内蒙古草原布氏田鼠与绵羊的营养生态位研究

放牧活动对小型啮齿动物种群数量的影响是草原生态系统研究中的热点问题,确定绵羊和小型啮齿动物的营养生态位关系对于草原生态系统的管理具有重要的作用。运用粪便显微分析法分析了内蒙古草原动物生态研究站大型野外围栏内布氏田鼠和绵羊在6—9月份的食谱组成,确定两种草食动物食性选择和营养生态位的变化,从食物利用途径揭示放牧活动对布氏田鼠种群数量的影响方式及二者之间的竞争与共存关系。研究结果表明：围栏中共有23种植物,其中糙隐子草、克氏针茅、羊草和刺藜是围栏中的优势植物;布氏田鼠共取食10种植物,绵羊共取食8种植物,禾本植物为两种动物的主要采食植物。布氏田鼠和绵羊的喜食植物种类都存在季节性变化;除7月外,两种动物的食物多样性与围栏植物多样性有显著的正相关关系,表明动物的食性选择受植物资源变化的影响。布氏田鼠和绵羊具有很高的营养生态位重叠度,除8月(0.691)外,6、7、9月份的营养生态位重叠度均高于0.9,表明二者之间存在激烈的食物竞争;放牧活动极显著地降低了禾本科植物的地上生物量,导致布氏田鼠的食物数量减少;放牧处理下布氏田鼠的喜食植物的物种数和营养生态位宽度(除9月)增加,导致布氏田鼠的食物质量...     

Relevance of microbial coculture fermentations in biotechnology

The purpose of this article is to review coculture fermentations in industrial biotechnology. Examples for the advantageous utilization of cocultures instead of single cultivations include the production of bulk chemicals, enzymes, food additives, antimicrobial substances and microbial fuel cells. Coculture fermentations may result in increased yield, improved control of product qualities and the possibility of utilizing cheaper substrates. Cocultivation of different micro‐organisms may also help to identify and develop new biotechnological substances. The relevance of coculture fermentations and the potential of improving existing processes as well as the production of new chemical compounds in industrial biotechnology are pointed out here by means of more than 35 examples.     

Prebiotics enhance survival and prolong the retention period of specific probiotic inocula in an in vivo murine model

AIM: To identify novel prebiotics that could be used to maintain persistence of three representative probiotic strains in vivo. METHODS AND RESULTS: Test mice were treated with prebiotics soybean oligosaccharide (SOS), fructooligosaccharide (FOS) or inulin, followed by probiotics Lactobacillus acidophilus LAFTI L10 (L10), Bifidobacterium lactis LAFTI B94 (B94) or Lactobacillus casei L26 LAFTI (L26). Faecal samples were then collected and analysed using selective medium and PCR analysis to determine the presence of the probiotic strains. In contrast to the control groups, in mice fed prebiotics, the survival and retention time of the test probiotics was increased extensively. SOS and FOS prolonged the retention period of L10 from 24 to 30 h. Of the three prebiotics, FOS gave the best result with B94, prolonging the retention period from 3 to > or =10 days. Of the three prebiotics, inulin gave the best result for L26, prolonging the retention period from 2 to > or =6 days. CONCLUSIONS: The prebiotics SOS, FOS and inulin significantly enhance survival and prolong the retention period of L10, B94 and L26 in vivo. SIGNIFICANCE AND IMPACT OF THE STUDY: Our results demonstrate the potential use of FOS, inulin and SOS as prebiotics in conjunction with the probiotic strains L10, B94 and L26 for new synbiotic products.     

高效递送趋化因子CXCL12工程益生菌的构建及其在糖尿病慢性创面愈合中的应用

糖尿病慢性创面具有难愈性、反复进展性和较高的致残/死亡率等特点,其临床治疗是亟待解决的医学难题之一。因其复杂的局部微环境,如高蛋白酶活性和持续的炎症反应等,使外源性因子(如趋化因子CXCL12)在局部慢性创面的生物利用率非常低,限制了外源性因子在慢性创面的局部应用。本研究利用合成生物学技术原理,以植物乳杆菌WCFS1为底盘菌,旨在开发一种高效的CXCL12递送系统,并评估其在糖尿病慢性创面修复中的作用。采用分子克隆技术将植物乳杆菌内源性分泌信号肽lp_3050和乳酸菌常用分泌信号肽usp45分别与gusA报告基因融合,插入pTRK892-P_32(pgm)质粒中,制备相应的工程菌,并通过GusA酶活分析表征了该菌株的蛋白分泌表达效率。结果表明,与usp45信号肽相比,lp_3050信号肽在植物乳杆菌WCFS1中能高效驱动GusA的分泌表达,其发酵上清中GusA酶活力提高了近5倍。基于此,将lp_3050分泌信号肽与密码子优化后的CXCL12基因进行融合表达,构建了高效分泌表达CXCL12的工程益生菌Lpw-CXCL12,其发酵上清中CXCL12的含量高达(13.40±0.20) μg/mL。随后,在慢性创面小鼠模型中发现Lpw-CXCL12工程益生菌可加速糖尿病慢性创面愈合。本研究构建了一株高效分泌表达趋化因子CXCL12的工程益生菌,并揭示了其在糖尿病慢性创面小鼠模型中的促创面愈合功效,为未来糖尿病慢性创面的治疗提供了新的思路和技术支撑。     

Orally supplemented Lactobacillus acidophilus strain L‐92 inhibits passive and active cutaneous anaphylaxis as well as 2,4‐dinitroflurobenzene and mite fecal antigen induced atopic dermatitis‐like skin lesions in mice

Oral supplementation of lactic acid bacteria is a potential approach to the prevention and manipulation of allergic diseases such as atopic dermatitis. Our previous report showed that heat‐killed Lactobacillus acidophilus strain L‐92 (L‐92) possessed anti‐allergic properties, although its physiological function in atopic dermatitis has largely remained undefined. To evaluate the anti‐allergic efficacy of L‐92, we used four experimental animal models with the major features of atopic dermatitis and compared the results to those of clinically active drugs. ICR mice were passively sensitized by anti‐dinitrophenyl mouse monoclonal IgE for passive cutaneous anaphylaxis (PCA), and BALB/c mice were actively sensitized by ovalbumin for active cutaneous anaphylaxis (ACA). Allergic reaction was induced by repeated exposure to 2,4‐dinitroflurobenzene (DNFB) and mite (Dermatophagoides farinae) fecal allergen, in BALB/c and NC/Nga mice, respectively. Orally administrated L‐92 significantly inhibited the vascular permeability increase in both PCA and ACA, and the elevation of ovalbumin‐specific IgE titer in ACA. Moreover, repeated applications of DNFB and mite fecal antigen onto the BALB/c and NC/Nga mouse ear, respectively, caused clinical symptoms similar to atopic dermatitis such as ear swelling, scratching behavior and elevation of total serum IgE levels that were also moderately suppressed by L‐92. In addition, L‐92 treated mice exhibited lower levels of mast cells, eosinophil infiltration and Th1/Th2 cytokine expression. Our results, therefore, suggest that oral administration of L‐92 might be useful for alleviating allergic symptoms.