Effect of Bifidobacterium crudilactis and 3′-sialyllactose on the toddler microbiota using the SHIME® model

Efficient Production of 3'-Sialyllactose Using Escherichia coli

3'-Sialyllactose (3'-SL), a key component of human milk oligosaccharides, provides significant health benefits and immune modulation, and is increasingly used in infant formula and dietary supplements. This study presents a novel approach for the efficient biosynthesis of 3'-SL using Escherichia coli BL21star(DE3)ΔlacZ through genomic integration. We first addressed the issue of metabolic competition by deleting crucial genes, nanA, nanK, nanE, and nanT, that are involved in the degradation of N-acetylneuraminic acid. This strategic gene knockout minimized the flux through competing pathways. The engineered Escherichia coli strain was subsequently transformed with the exogenous genes neuBCA and nST, enabling the de novo synthesis of 3'-SL. A modular metabolic engineering strategy was utilized to optimize the expression of key enzymes within the MSU module, enhancing and balancing the carbon flux distribution. Additionally, a cofactor regeneration strategy was implemented to increase CTP availability, which improved cofactor recycling and fine-tuned the metabolic pathway for maximal 3'-SL production. Transport protein screening was incorporated to further increase the extracellular concentration of 3'-SL, resulting in an unprecedented yield of 56.8 g/L in a 5L bioreactor fermentation, setting a new benchmark in the field.

Antioxidant and anti-inflammatory properties of water kefir microbiota and its bioactive metabolites for health promoting bio-functional products and applications

Inflammation and oxidative stress are implicated in several chronic disorders, while healthy foods and especially fermented beverages and those containing probiotics can provide anti-inflammatory and antioxidant protection against such manifestations and the associated disorders. Water kefir is such a beverage that is rich in both probiotic microbiota and anti-inflammatory bioactives, with an increasing demand as an alternative to a fermented product based on non-dairy matrix with potential health properties. Within this study, the health-promoting properties of the most representative species and strains of microorganisms present in water kefir grains, as well as the health benefits attributed to the bioactive metabolites produced by each individual strain in a series of their cultures, were thoroughly reviewed. Emphasis was given to the antioxidant, antithrombotic, and anti-inflammatory bio-functionalities of both the cultured microorganisms and the bioactive metabolites produced in each case. Moreover, an extensive presentation of the antioxidant and anti-inflammatory health benefits observed from the overall water kefir cultures and classic water kefir beverages obtained were also conducted. Finally, the use of water kefir for the production of several other bio-functional products, including fermented functional foods, supplements, nutraceuticals, nutricosmetics, cosmeceuticals, and cosmetic applications with anti-inflammatory and antioxidant health promoting potential was also thoroughly discussed. Limitations and future perspectives on the use of water kefir, its microorganisms, and their bioactive metabolites are also outlined.

Preparation and synbiotic interaction mechanism of microcapsules of Bifidobacterium animalis F1-7 and human milk oligosaccharides (HMO)

Probiotics such as Bifidobacterium spp. generally possess important physiological functions. However, maintaining probiotic viability is a challenge during processing, storage, and digestive transit period. Microencapsulation is widely considered to be an attractive approach. In this study, B. animalis F1-7 microcapsules and B. animalis F1-7-HMO microcapsules were successfully prepared by emulsification/internal gelation with high encapsulation efficiency (90.67 % and 92.16 %, respectively). The current study revealed that HMO-supplemented microcapsules exhibited more stable lyophilized forms and thermal stability. Additionally, a significant improvement in probiotic cell viability was observed in such microcapsules during simulated gastrointestinal (GI) fluids or storage. We also showed that the individual HMO mixtures 6'-SL remarkably promoted the growth and acetate yield of B. animalis F1-7 for 48 h (p < 0.05). The synbiotic combination of 6'-SL with B. animalis F1-7 enhanced SCFAs production in vitro fecal fermentation, decreasing several harmful intestinal bacteria such as Dorea, Escherichia-Shigella, and Streptococcus while enriching the probiotic A. muciniphila. This study provides strong support for HMO or 6'-SL combined with B. animalis F1-7 as an innovative dietary ingredient to bring health benefits. The potential of the synbiotic microcapsules with this combination merits further exploration for future use in the food industry.

Sialyllactose Enhances the Short-Chain Fatty Acid Production and Barrier Function of Gut Epithelial Cells via Nonbifidogenic Modification of the Fecal Microbiome in Human Adults

Although various benefits of human milk oligosaccharides (HMOs) have been reported, such as promoting Bifidobacterium growth in the infant gut, their effects on adults have not been fully studied. This study investigated the effects of two types of sialyllactose, 3'-sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL), on the adult intestinal microbiome using the simulator of human intestinal microbial ecosystem (SHIME®), which can simulate human gastrointestinal conditions. HPLC metabolite analysis showed that sialyllactose (SL) supplementation increased the short-chain fatty acid content of SHIME culture broth. Moreover, 16S rRNA gene sequencing analysis revealed that SL promoted the growth of Phascolarctobacterium and Lachnospiraceae, short-chain fatty acid-producing bacteria, but not the growth of Bifidobacterium. Altogether, both types of SL stimulated an increase in short-chain fatty acids, including propionate and butyrate. Additionally, SHIME culture supernatant supplemented with SL improved the intestinal barrier function in Caco-2 cell monolayers. These results suggest that SL could act as a unique prebiotic among other HMOs with a nonbifidogenic effect, resulting in intestinal barrier protection.

Effects of tris (2-chloroethyl) phosphate exposure on gut microbiome using the simulator of the human intestinal microbial ecosystem (SHIME)

Tris (2-chloroethyl) phosphate (TCEP) has been widely used, and its health risk has received increasing attention. However, the rare research has been conducted on the effects of TCEP exposure on changes in the structure of the human gut microbiome and metabolic functions. In this experiment, Simulator of the human intestinal microbial ecosystem (SHIME) was applied to explore the influences of TCEP on the human gut bacteria community and structure. The results obtained from high-throughput sequencing of 16S rRNA gene have clearly revealed differences among control and exposure groups. High-dose TCEP exposure increased the Shannon and Simpson indexes in the results of α-diversity of the gut microbiome. At phylum level, Firmicutes occupied a higher proportion of gut microbiota, while the proportion of Bacteroidetes decreased. In the genus-level analysis, the relative abundance of Bacteroides descended with the TCEP exposure dose increased in the ascending colon, while the abundances of Roseburia, Lachnospira, Coprococcus and Lachnoclostridium were obviously correlated with exposure dose in each colon. The results of short chain fatty acids (SCFAs) showed a remarkable effect on the distribution after TCEP exposure. In the ascending colon, the control group had the highest acetate concentration (1.666 ± 0.085 mg⋅mL-1), while acetate concentrations in lose-dose medium-dose and high-doseTCEP exposure groups were 1.119 ± 0.084 mg⋅mL-1, 0.437 ± 0.053 mg⋅mL-1 and 0.548 ± 0.106 mg⋅mL-1, respectively. TCEP exposure resulted in a decrease in acetate and propionate concentrations, while increasing butyrate concentrations in each colon. Dorea, Fusicatenibacter, Kineothrix, Lachnospira, and Roseburia showed an increasing tendency in abundance under TCEP exposure, while they had a negatively correlation with acetate and propionate concentrations and positively related with butyrate concentrations. Overall, this study confirms that TCEP exposure alters both the composition and metabolic function of intestinal microbial communities, to arouse public concern about its negative health effects.

In Vitro Effect on Piglet Gut Microbiota and In Vivo Assessment of Newly Isolated Bacteriophages against F18 Enterotoxigenic Escherichia coli (ETEC)

Enterotoxigenic Escherichia coli (ETEC) causing post-weaning diarrhea (PWD) in piglets have a detrimental impact on animal health and economy in pig production. ETEC strains can adhere to the host's small intestinal epithelial cells using fimbriae such as F4 and F18. Phage therapy could represent an interesting alternative to antimicrobial resistance against ETEC infections. In this study, four bacteriophages, named vB_EcoS_ULIM2, vB_EcoM_ULIM3, vB_EcoM_ULIM8 and vB_EcoM_ULIM9, were isolated against an O8:F18 E. coli strain (A-I-210) and selected based on their host range. These phages were characterized in vitro, showing a lytic activity over a pH (4-10) and temperature (25-45 °C) range. According to genomic analysis, these bacteriophages belong to the Caudoviricetes class. No gene related to lysogeny was identified. The in vivo Galleria mellonella larvae model suggested the therapeutic potential of one selected phage, vB_EcoS_ULIM2, with a statistically significant increase in survival compared to non-treated larvae. To assess the effect of this phage on the piglet gut microbiota, vB_EcoS_ULIM2 was inoculated in a static model simulating the piglet intestinal microbial ecosystem for 72 h. This study shows that this phage replicates efficiently both in vitro and in vivo in a Galleria mellonella model and reveals the safety of the phage-based treatment on the piglet microbiota.

Impact Assessment of vB_KpnP_K1-ULIP33 Bacteriophage on the Human Gut Microbiota Using a Dynamic In Vitro Model

New control methods are needed to counter antimicrobial resistances and the use of bacteriophages as an alternative treatment seems promising. To that end, the effect of the phage vB_KpnP_K1-ULIP33, whose host is the hypervirulent Klebsiella pneumoniae SA12 (ST23 and capsular type K1), was assessed on intestinal microbiota, using an in vitro model: the SHIME® system (Simulator of the Human Intestinal Microbial Ecosystem). After stabilization of the system, the phage was inoculated for 7 days and its persistence in the different colons was studied until its disappearance from the system. The concentration of short chain fatty acids in the colons showed good colonization of the bioreactors by the microbiota and no significant effect related to the phage treatment. Diversity (α and β), the relative abundance of bacteria, and qPCR analysis targeting different genera of interest showed no significant variation following phage administration. Even if further in vitro studies are needed to assess the efficacy of this phage against its bacterial host within the human intestinal ecosystem, the phage ULIP33 exerted no significant change on the global colonic microbiota.

Recent progress on health effects and biosynthesis of two key sialylated human milk oligosaccharides, 3'-sialyllactose and 6'-sialyllactose

Human milk oligosaccharides (HMOs), the third major solid component in breast milk, are recognized as the first prebiotics for health benefits in infants. Sialylated HMOs are an important type of HMOs, accounting for approximately 13% of total HMOs. 3'-Sialyllactose (3'-SL) and 6'-sialyllactose (6'-SL) are two simplest sialylated HMOs. Both SLs display promising prebiotic effects, especially in promoting the proliferation of bifidobacteria and shaping the gut microbiota. SLs exhibit several health effects, including antiadhesive antimicrobial ability, antiviral activity, prevention of necrotizing enterocolitis, immunomodulatory activity, regulation of intestinal epithelial cell response, promotion of brain development, and cognition improvement. Both SLs have been approved as "Generally Recognized as Safe" by the American Food and Drug Administration and are commercially added to infant formula. The biosynthesis of SLs using enzymatic or microbial approaches has been widely studied. The enzymatic synthesis of SLs can be realized by two types of enzymes, sialidases with trans-sialidase activity and sialyltransferases. Microbial synthesis can be achieved by the multiple recombinant bacteria in one-pot reaction, which express the enzymes involved in SL synthesis pathways separately or in combination, or by metabolically engineered strains in a fermentation process. In this article, the physiological properties of 3'-SL and 6'-SL are summarized in detail and the biosynthesis of these SLs via enzymatic and microbial synthesis is comprehensively reviewed.

Explore and Analyze the Composition and Characteristics of Intestinal Microbiota between Gastric Cancer Patients and Healthy People

Gastric cancer is one of the most common malignant tumors in the world. As the intestine is downstream of the digestive tract, the occurrence of gastric cancer may have a certain significant impact on it. Therefore, it is particularly important to find out the intestinal bacteria closely related to gastric cancer, to identify the specific flora related to gastric cancer, and to maintain the stability of the core structure of intestinal microecology in patients with gastric cancer. Based on this, the fecal samples of gastric cancer patients and healthy people were collected, and the diversity and composition of intestinal flora in patients with gastric cancer were analyzed by 16S rRNA sequencing technology. We found that there was no significant difference in the diversity and abundance of intestinal flora between gastric cancer patients and healthy people. The relative abundance of Faecalibacterium, Bifidobacterium, and Subdoligranulum in the intestinal tract of patients with gastric cancer was significantly lower than that in healthy people, while the relative abundance of Enterococcus, Streptococcus, and Bacteroides was increased. This study found that there were six kinds of intestinal microflora closely related to the occurrence of gastric cancer, which provided a theoretical basis for further exploring the pathogenesis of gastric cancer.

Artificial Gastrointestinal Models for Nutraceuticals Research—Achievements and Challenges: A Practical Review

Imitating the human digestive system as closely as possible is the goal of modern science. The main reason is to find an alternative to expensive, risky and time-consuming clinical trials. Of particular interest are models that simulate the gut microbiome. This paper aims to characterize the human gut microbiome, highlight the importance of its contribution to disease, and present in vitro models that allow studying the microbiome outside the human body but under near-natural conditions. A review of studies using models SHIME, SIMGI, TIM-2, ECSIM, EnteroMix, and PolyfermS will provide an overview of the options available and the choice of a model that suits the researcher’s expectations with advantages and disadvantages.

The efficacy and effect on gut microbiota of an aflatoxin binder and a fumonisin esterase using an in vitro simulator of the human intestinal microbial ecosystem (SHIME®)

Mycotoxin intoxication is in general an acknowledged and tackled issue in animals. However, in several parts of the world, mycotoxicoses in humans still remain a relevant issue. The efficacy of two mycotoxin detoxifying animal feed additives, an aflatoxin bentonite clay binder and a fumonisin esterase, was investigated in a human child gut model, i.e. the in vitro Simulator of the Human Intestinal Microbial Ecosystem (SHIME®). Additionally, the effect of the detoxifiers on gut microbiota was examined in the SHIME. After an initial two weeks of system stabilisation, aflatoxin B1 (AFB1) and fumonisin B1 (FB1) were added to the SHIME diet during one week. Next, the two detoxifiers and mycotoxins were added to the system for an additional week. The AFB1, FB1, hydrolysed FB1 (HFB1), partially hydrolysed FB1a and FB1b concentrations were determined in SHIME samples using a validated ultra-performance liquid chromatography-tandem mass spectrometry method. The short-chain fatty acid (SCFA) concentrations were determined by a validated gas chromatography-mass spectrometry method. Colonic bacterial communities were analysed using metabarcoding, targeting the hypervariable V1-V3 regions of the 16S rRNA genes. The AFB1 and FB1 concentrations significantly decreased after the addition of the detoxifiers. Likewise, the concentration of HFB1 significantly increased. Concentrations of SCFAs remained generally stable throughout the experiment. No major changes in bacterial composition occurred during the experiment. The results demonstrate the promising effect of these detoxifiers in reducing AFB1 and FB1 concentrations in the human intestinal environment, without compromising the gastrointestinal microbiota.