Nattokinase enhances the preventive effects of Escherichia coli Nissle 1917 on dextran sulfate sodium-induced colitis in mice

Facile Labeling of Gram-Negative Bacteria with NIR-II Fluorescent Nanoprobes for Intestinal Bacteria Imaging

The gut bacteria not only play a crucial role in maintaining human health but also exhibit close associations with the occurrence of numerous diseases. Understanding the physiological and pathological functions of gut bacteria and enabling early diagnosis of gut diseases heavily relies on accurate knowledge about their in vivo distribution. Consequently, there is a significant demand for noninvasive imaging techniques capable of providing real-time localization information regarding gut bacteria. In this work, we developed a second near-infrared (NIR-II) fluorescent nanoprobe labeling-based visualization strategy for real-time tracking of the biodistribution of Gram-negative bacteria in the gastrointestinal tract of mice. By utilizing positively charged silver sulfide quantum dots (Ag2S QDs) as NIR-II nanoprobes and exploiting electrostatic interactions to efficiently label the Gram-negative probiotic Escherichia coli Nissle 1917 with negative surface charges, we have achieved rapid and effective labeling. Leveraging the exceptional NIR-II fluorescent performance of Ag2S QDs, our approach enables high spatiotemporal resolution visualization via NIR-II imaging in mouse gastrointestinal areas where Ag2S QD-labeled probiotics are present, facilitating real-time in vivo tracking capabilities for these labeled probiotics. This work not only establishes a powerful intestinal bacterial imaging strategy but also introduces novel concepts for constructing nanomaterial-bacteria hybrid systems.

From probiotic chassis to modification strategies, control and improvement of genetically engineered probiotics for inflammatory bowel disease

With the rising morbidity of inflammatory bowel disease (IBD) year by year, conventional therapeutic drugs with systemic side effects are no longer able to meet the requirements of patients. Probiotics can improve gut microbiota, enhance intestinal barrier function, and regulate mucosal immunity, making them a potential complementary or alternative therapy for IBD. To compensate for the low potency of probiotics, genetic engineering technology has been widely used to improve their therapeutic function. In this review, we systematically summarize the genetically engineered probiotics used for IBD treatment, including probiotic chassis, genetic modification strategies, methods for controlling probiotics, and means of improving efficacy. Finally, we provide prospects on how genetically engineered probiotics can be extended to clinical applications.

Evaluation of the Effect of Probiotic Supplementation on Intestinal Barrier Integrity and Epithelial Damage in Colitis Disease: A Systematic Review

CONTEXT

Previous reviews have focused on the effects of probiotics on colitis, but there is a need to understand their impact on barrier integrity and tight junction protein improvement in colitis.

OBJECTIVE

This study aimed to systematically examine the effects of probiotic use on barrier integrity in colitis disease. This study was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

DATA SOURCES

A systematic search in PubMed, Web of Science, Scopus, and Cochrane databases identified 2537 articles.

DATA EXTRACTION

As a result of the search, 2537 articles were accessed. Study results were summarized descriptively through discussions by intervention conditions, study population, measurement methods, and key findings. The included studies were independently reviewed and all authors reached consensus on the quality and major findings from the included articles. Forty-six studies that met the inclusion criteria were analyzed within the scope of the systematic review.

RESULTS

Although the study primarily utilized probiotics from the Lactobacillaceae family (notably, L casei, L reuteri, L rhamnosus, L plantarum, and L pentosus) and the Bifidobacteriaceae family (notably, B breve, B animalis, and B dentium), other probiotics also demonstrated positive effects on tight junction proteins. These effects are attributed to the production of bioactive and metabolic compounds, as well as short-chain fatty acids, which combat pathogens and reduce anti-inflammatory agents. However, it was observed that the effects of these probiotics on tight junction proteins varied depending on the strain and dose.

CONCLUSION

The beneficial effects of probiotics on remission in inflammatory bowel disease are well documented. Studies show that probiotics generally improve intestinal barrier function, but factors such as dose, duration, and bacterial species combinations need further clarification. Additionally, comprehensive studies are needed to understand how improved barrier function affects absorption in individuals.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO registration no. CRD42023452774.

Phenotypic and genomic insights into mutant with high nattokinase-producing activity induced by carbon ion beam irradiation of Bacillus subtilis

Nattokinase (NK) is found in fermented foods and has high fibrinolytic activity, which makes it promising for biological applications. In this study, a mutant strain (Bacillus subtilis ZT-S1, 5529.56 ± 183.59 U/mL) with high NK-producing activity was obtained using 12C6+ heavy ion beam mutagenesis for the first time. The surface morphology of B. subtilis is also altered by changes in functional groups caused by heavy ion beams. Furthermore, B. subtilis ZT-S1 required more carbon and nitrogen sources and reached stabilization phase later. Comparative genome analysis revealed that most of the mutant implicated genes (oppA, appA, kinA, spoIIP) were related to spore formation. And the affected rpoA is related to the synthesis of the NK-coding gene aprE. In addition, the B. subtilis ZT-S1 obtained by mutagenesis had good genetic stability. This study further explores the factors affecting NK activity and provides a promising microbial resource for NK production in commercial applications.

Constructing an Antibiotic-Free Protein Expression System for Ovalbumin Biosynthesis in Probiotic Escherichia coli Nissle 1917

Ovalbumin (OVA) is the principal protein constituent of eggs. As an alternative to eggs, cell-cultured OVA can reduce the environmental impact of global warming and land use. Escherichia coli Nissle 1917 (EcN), a probiotic with specific endogenous cryptic plasmids that stably exist in cells without the addition of antibiotics, was chosen as the host for the efficient heterologous expression of the OVA. OVA yield reached 20 mg·L-1 in shake flasks using the OVA expression cassette containing a tac promoter (Ptac) upstream of the OVA-coding sequences on the endogenous plasmid pMUT2. Subsequently, we improved the level of the expression of the OVA by employing a dual promoter (PP5 combined with Ptac via a sigma factor binding site 24) and ribosome binding site (RBS) substitution. These enhancements increased the level of production of OVA in shake flasks to 30 and 42 mg·L-1, respectively. OVA by EcNP-P28 harboring plasmid L28 equipped with both dual promoter and the strong RBS8 reached 3.70 g·L-1 in a 3 L bioreactor. Recombinant OVA and natural OVA showed similar biochemical characteristics, including secondary structure, isoelectric point, amino acid composition, and thermal stability. This is currently the highest OVA production reported among prokaryotes. We successfully constructed an antibiotic-free heterologous protein expression system for EcN.

Purification of fibrinolytic enzyme from Bacillus amyloliquefaciens GUTU06 and properties of the enzyme

A producing-fibrinolytic enzyme strain was isolated with high yield. The strain was identified as Bacillus amyloliquefaciens. B. amyloliquefaciens GUTU06 fibrinolytic enzyme was purified by acetone precipitation and reverse micelle. Acetone precipitation condition and reverse micelle condition were examined. Results showed that the total reverse micelle extraction efficiency was 64.49 % ± 1.6 %. The purification fold of the entire process reached 13.38. The optimum pH of purified enzyme is 5, and the optimum temperature is 45 °C. Fe3+ and K+ can enhance the fibrinolytic activity of the enzyme. Compared to commercial fibrinolytic enzymes such as urokinase and lumbrukinase, GUTU06 fibrinolytic enzymes have a lower pH optimal range and higher temperature stability. The molecular weight of the enzyme was approximately 28 kDa. Reverse micelle extraction with cetyl trimethylammonium bromide as a surfactant combined with acetone precipitation is suitable for separating and purifying fibrinolytic enzymes and a promising technique for obtaining active proteins.

Use of non-canonical amino acids in genetic code expansion-based therapeutics: Effects on mouse gut microbiota

Vaccines and cell therapeutics based on genetic code expansion are emerging. A crucial step in these therapeutic technologies is the oral administration of non-canonical amino acids (ncAAs) to control pathogen growth and therapeutic protein levels in vivo. Investigating the toxicity effects of ncAAs can help identify more suitable candidates for developing genetic code expansion-based vaccines and cell therapeutics. In this study, we determined the effects of three ncAAs, namely, 4-acetyl-phenylalanine (pAcF), 4-iodo-phenylalanine (pIoF), and 4-methoxy-phenylalanine (pMeoF), commonly used in genetic code expansion-based vaccines and cell therapeutics, on the main organs, serum biochemical parameters, and gut microbiota in mice. We observed that pIoF and pMeoF significantly altered serum biochemical parameters to some extent. Moreover, the alterations in the mouse gut microbial composition were considerably greater after the oral administration of pIoF and pMeoF than after that of pAcF, compared with that in the control mice. These findings suggest that pAcF is more suitable than pIoF and pMeoF for application in genetic code expansion-based vaccines and cell therapeutics as it disturbs the physiological and gut microecological balance in mice to a lesser extent.