AMB Express最新文献

Probiotics show potential for preventing and mitigating inflammatory bowel disease (IBD), though their efficacy and mechanisms are strain-specific. This study aimed to elucidate the protective mechanism of Lactiplantibacillus (L.) plantarum P16 against dextran sulfate sodium (DSS)-induced ulcerative colitis (UC). The strain exhibited high gastrointestinal tolerance, with survival rates of approximately 86% in artificial gastric fluid (pH 3.0) and 94% in 0.3% bile salt after 3 h of incubation. Moreover, L. plantarum P16 showed stronger adhesion to Caco-2 cells, indicating a high potential for intestinal colonization. In a DSS-induced colitis model, L. plantarum P16 administration alleviated colitis by reducing the disease activity index (DAI), suppressing pro-inflammatory cytokines (TNF-α, IL-6, IL-1β), and mitigating colonic tissue damage while preserving epithelial barrier integrity. Additionally, L. plantarum P16 treatment increased short-chain fatty acid (SCFA) levels. 16 S rRNA amplicon sequencing of cecal content revealed that L. plantarum P16 supplementation restored gut microbial homeostasis by elevating the abundances of Firmicutes and Verrucomicrobiota, particularly Akkermansia, while reducing the proportions of Bacteroides and Helicobacter. These findings demonstrated that L. plantarum P16 could alleviate colitis by ameliorating intestinal inflammation and restoring gut microbiota dysbiosis, proposing a novel perspective of L. plantarum P16 for UC management.

Aspergillus niger serves as a cell factory for efficient enzyme production. The lipase derived from Thermomyces lanuginosus (TLL) is known for its remarkable thermal stability and is extensively utilized in various industrial fields. In this study, a heterologous expression strain, ΔAnTll-11, of TLL was successfully constructed in A. niger. Through fermentation optimization, the lipase activity was enhanced 8.7-fold to 4547.95 U/mL, compared with the initial value of 520 U/mL. Enzymatic characterization indicated that the recombinant lipase exhibited optimum activity at pH 9.5 and 45 °C, and its activity was positively influenced by Ca²⁺, Ag⁺, Mg²⁺, and Cu²⁺. The ΔAnTll-11 strain exhibited enhanced tolerance to high osmolarity, oxidative stress, and thermal shock. Furthermore, transcriptomic analysis of the ΔAnTll-11 strain revealed that half of the total annotated genes (7199 genes) were differentially expressed genes (DEGs). According to protein‒protein interaction network and weighted gene coexpression network analyses, genes involved in ribosome function, amino acid metabolism, glycosylation, energy metabolism, and the MAPK signalling pathway may affect the expression of lipase. The transcriptomic findings elucidated the regulatory mechanisms by which A. niger expresses foreign proteins and enzymes, establishing a groundwork for further enhancing A. niger as a cell factory for efficient enzyme and protein production.

Uricase, a key enzyme in purine metabolism, is widely used for uric acid detection and for treating gout and hyperuricemia. To obtain a uricase with both high activity and thermal stability, we cloned and heterologously expressed a novel uricase gene (tc1-uox2) from the Tengchong hot spring metagenome and combined enzymatic characterization with molecular dynamics simulations. TC1-Uox2 exhibited optimal catalytic activity at 35 °C and pH 8.0. It showed remarkable thermal stability, retaining over 40% residual activity after 16 h at 40 °C and maintaining over 80% activity for 14 h at physiological temperature (37 °C). In vitro uric acid-lowering assays demonstrated that 1 µg/mL TC1-Uox2 reduced serum uric acid to below 360 µM within 20 min in whole-blood samples from six hyperuricemic patients. Comparative molecular dynamics simulations with rasburicase indicated that, based on RMSF, radius of gyration (Rg), and hydrogen-bond counts, TC1-Uox2 adopts a more compact overall structure. Free energy landscape (FEL) analysis further revealed that TC1-Uox2 occupies deeper and narrower energy basins, consistent with greater conformational rigidity and thermodynamic stability. These findings elucidate the structural basis of its enhanced thermostability. In summary, TC1-Uox2 is a high-activity, high-stability uricase candidate that represents a promising enzyme target for biotherapeutic intervention in hyperuricemia and illustrates the translational potential of extreme-environment metagenomics for metabolic disease applications.

The development of rapid, sensitive, and user-friendly diagnostic methods for Chlamydia psittaci (C. psittaci) is critical for early diagnosis and effective control of infections. Current techniques, such as qPCR and next-generation sequencing, face limitations in accessibility and practicality for point-of-care testing (POCT). In this study, we present the WPTTS platform (one-step recombinase polymerase amplification (RPA)-CRISPR/Cas12b assay using weak protospacer adjacent motif (PAM) recognition with two-temperature shifting), which leverages the temperature-dependent PAM stringency of Alicyclobacillus acidophilus Cas12b (AapCas12b) to overcome the challenges of one-step CRISPR detection. By employing weak PAM sequences and a two-temperature protocol (37 °C for amplification, 60 °C for detection), WPTTS minimizes interference between RPA amplification and CRISPR cleavage, achieving a sensitivity of 10² copies/reaction-equivalent to two-step methods-while maintaining operational simplicity. The platform also demonstrates enhanced specificity, enabling single-base resolution at critical target positions. Clinical validation with 40 samples confirmed its superior performance, with 95% positive agreement and 100% negative agreement compared to qPCR. This study highlights the potential of WPTTS as a robust, rapid, and highly sensitive tool for POCT applications in C. psittaci detection and broader infectious disease diagnostics.