Salicylic acid (SA) is an important phenolic compound that plays a key role in plant defenses and is widely used in pharmaceuticals, cosmetics, and personal care products due to its significant anti-inflammatory and antimicrobial activities. Currently, the production of SA mainly relies on plant extraction and chemical synthesis, which suffers from complex processes, severe environmental pollution, and high dependence on petrochemical resources. With the rapid development of synthetic biology, metabolic engineering, and artificial intelligence (AI) technologies, the green synthesis of SA through intelligently designed microbial cell factories, empowered by machine learning algorithms and automated platforms, has become an important research direction to replace conventional production methods. This review systematically summarizes the microbial biosynthetic pathways of SA. With a focus on the intelligent design theme, this paper highlights the application of AI and synthetic biology tools in the discovery and utilization of natural SA-producing microbial resources and the rational reconstruction and optimization of the SA biosynthetic pathway in model microorganisms via intelligent metabolic engineering strategies. Furthermore, it introduces the key intelligent technologies for enhancing yields and the challenges faced. Finally, it discusses the future trends in this field.

Neopestalotiopsis cubana Maharachch. is the primary pathogen responsible for leaf spot and fruit ring rot in guava (Psidium guajava L.). The ADP-ribosylation factor-like protein 8 (Arl8) belonging to the ADP-ribosylation factor (Arf) superfamily is associated with lysosomal processes including localization, trafficking, and fusion. The function of Arl8 in phytopathogenic fungi remains poorly understood. Objective To elucidate the function of Arl8 in N. cubana. Methods An Arl8 gene was identified from the genome of N. cubana and designated as NecArl8. A NecArl8 knockout mutant (ΔNecArl8) and a complemented strain (ΔNecArl8-C) were generated via clustered regularly interspaced short palindromic repeats (CRISPR)-associated 9, (CRISPR/Cas9)-mediated genome editing. These strains were subsequently analyzed through phenotypic experiments and RNA-seq. Results ΔNecArl8 showed a reduction of 34.93% in sporulation capacity and significant increases of 5.74% and 7.39% in inhibition rates by salt and osmotic stresses, respectively. In addition, this mutant exhibited weakened pathogenicity, as indicated by a reduction of 5.74 mm in the average spot diameter. In contrast, the mutant displayed significantly enhanced resistance to oxidative stress, which showed an inhibition rate of -19.22%. After long-term culture, a large number of vacuolated cells were observed in the mutant. RNA-seq analysis was performed on ΔNecArl8 and the wild-type strain to identify differentially expressed genes. Transcriptomic analysis showed that 2 330 genes were significantly down-regulated and 1 355 genes were significantly up-regulated. Gene set enrichment analysis further revealed that transmembrane transport proteins were broadly suppressed, and the expression levels of 16 fungal-type vacuolar-related proteins were significantly down-regulated, suggesting that the structure and functions of fungal-type vacuoles were seriously damaged. The reverse transcription quantitative PCR (RT-qPCR) results showed the expression patterns of 9 randomly selected transmembrane transport genes were consistent with those obtained by transcriptome sequencing, indicating that the transcriptome data were highly reliable. Conclusion NecArl8 may affect the pathogenicity of N. cubana on guava by regulating function of transmembrane transport. This study lays a theoretical foundation for exploring the pathogenic mechanism of N. cubana and developing new control strategies.

Objective To overcome the limitations such as high costs and restricted substrate utilization of mono-culture fermentation, bacterium-alga co-culture based on resource complementarity offers a promising new avenue for ectoine production. This study investigated the co-culture conditions of Dunaliella pseudosalina ZBY-1 and Halomonas campaniensis XH26 and the variations in ectoine yield, aiming to elucidate the metabolic regulation mechanism of ectoine biosynthesis in the co-culture system. Methods Strains XH26 and ZBY-1 were co-cultured at different inoculation ratios (1/0, 1/5, 1/10, 1/15, and 1/20) to screen the ratio yielding the highest ectoine production. Targeted metabolomics analysis was performed on the co-culture group [H group (H)], the bacterial control group [XH26 group (X)], and the algal control group [ZBY-1 group (D)] to identify significant differential metabolites. Results The highest ectoine yield was achieved at a bacterium-to-alga ratio of 1:15, while the pigment content of the algal strain was lower than that of the control group. Metabolomics analysis identified 15 (H vs. D), 16 (H vs. X), and 16 (X vs. D) significant differential metabolites, including L-alanine, L-asparagine, L-aspartic acid, L-phenylalanine, malic acid, and pyruvic acid. Kyoto encyclopedia of genes and genomes (KEGG) pathway enrichment analysis revealed that alanine, aspartate and glutamate metabolism, glyoxylate and dicarboxylate metabolism, and arginine biosynthesis were the significantly altered metabolic pathways. Conclusion The co-culture system exhibited an asymmetric pattern characterized by bacterial proliferation and algal inhibition. The co-culture system significantly activated the central carbon metabolic network of the bacteria. Notably, aspartic acid and glutamic acid were significantly accumulated in cells, serving as the direct carbon skeleton and amino donor, respectively, to directly promote the efficient synthesis of ectoine.

Objective To clarify the role and molecular mechanism of the host protein solute carrier family 25 member 6 (SLC25A6) during fowl adenovirus serotype-4 (FAdV-4) infection, thus providing a theoretical basis for elucidating the pathogenic mechanism of FAdV-4 and developing novel prevention and control strategies. Methods First, we confirmed that infection of LMH cells with FAdV-4 at different time points and multiplicities of infection (MOI) resulted in obvious cytopathic effects (CPE). Second, on the basis of the host protein SLC25A6 identified in previous screening, Western blotting was employed to examine the effect of FAdV-4 on the expression of endogenous SLC25A6 in cells. Subsequently, transfection experiments were performed to regulate the expression of SLC25A6 (overexpression or interference with endogenous expression). RT-qPCR and Western blotting were employed to analyze the effect of SLC25A6 on FAdV-4 replication from the aspects of mRNA level, protein level, and viral titer. Finally, co-immunoprecipitation (Co-IP) was employed to verify the interaction between SLC25A6 and the core capsid protein Hexon of FAdV-4. Results FAdV-4 significantly inhibited the expression of endogenous SLC25A6 in cells. The overexpression of SLC25A6 markedly inhibited FAdV-4 replication, while interference with endogenous SLC25A6 promoted viral replication. SLC25A6 could directly interact with the Hexon protein of FAdV-4. Conclusion The host protein SLC25A6 inhibits FAdV-4 replication through its interaction with the viral Hexon protein. The results provide a theoretical basis for further elucidating the pathogenic mechanism of FAdV-4 and developing novel prevention and control strategies.

Objective To address the limitations of current hair-loss treatments, we employed an in vitro human dermal papilla cell (HDPC) model and a telogen C57BL/6 mouse model to study the effects of Lactiplantibacillus plantarum CCFM1352 fermentation metabolites and bacterial preparations on the hair follicle cycle and decipher the associated molecular mechanisms. Methods HDPCs were treated with different concentrations of CCFM1352 fermentation metabolites or bacterial lysates in vitro, and cell viability as well as the expression of molecules related to Wnt/β-catenin signaling, anagen/catagen regulation, and apoptosis was assessed. Telogen C57BL/6 mice were administrated with the fermentation metabolites or heat-killed bacterial cells by gavage for 21 days, and changes in hair coverage, follicular structure, and associated signaling molecules were analyzed. Results CCFM1352 fermentation metabolites at a volume fraction of 10% increased the viability of HDPCs to 135.30%, up-regulated Wnt10b and FGF-7, down-regulated DKK1 and TGF-β1, and increased Bcl-2 and decreased Bax, inducing a favorable change pattern associated with the anagen phase. Continuous gavage of the fermentation metabolites promoted the transition of hair follicles from telogen to anagen, increased the hair coverage to 61.62%, and enhanced hair follicle density, dermal thickness, and β-catenin accumulation and nuclear translocation. However, the regulatory effects of bacterial lysate and heat-killed bacteria were weaker in both models and showed only limited improvements in some indices. Conclusion CCFM1352 fermentation metabolites could modulate Wnt/β-catenin-related molecules and the expression of key factors such as FGF-7, TGF-β1, Bcl-2, and Bax, which favors the transition of hair follicles from telogen to anagen and suggests an important role in promoting hair growth. This study provides experimental evidence for the application of bioactive metabolites from probiotics in the field of hair health.

Objective Planktonic bacteria are essential for marine ecosystem health, yet how mussel aquaculture influences planktonic microbial communities remains unclear. This study aims to clarify the effects of mussel aquaculture on the community structure, diversity, and assembly mechanisms of marine planktonic bacteria. Methods Sixty-eight water samples were collected from a mussel aquaculture area and surrounding areas in Shengsi, Zhejiang, during summer 2024. Integrated analyses of 16S rRNA gene amplicon sequencing data and environmental factors were performed. Results The alpha diversity of particle-attached bacteria (PAB) significantly reduced in the aquaculture area, whereas free-living bacteria (FLB) showed no significant change in alpha diversity but exhibited clear shifts in beta diversity and phylogenetic structure. Random forest analysis identified Pseudomonadales and Bdellovibrionaceae as indicator taxa within the aquaculture area, and their changes might be associated with organic matter inputs and altered nutrient conditions. Functional prediction indicated enhanced nitrogen cycling (especially nitrification and aerobic ammonia oxidation) and a shift toward reductive acetogenesis in carbon cycling, alongside suppressed methanogenesis in the aquaculture area. Microbial community assembly was governed mainly by deterministic processes (e.g., heterogeneous selection) in the aquaculture area but by stochastic processes in surrounding waters. Conclusion This study demonstrates that mussel aquaculture can reconfigure the structures, functions, and assembly mechanisms of planktonic bacterial communities, providing insights for ecological impact assessment of mariculture.

Objective Curcumin exhibits diverse pharmacological activities, yet its clinical and industrial applications are largely limited by its poor water solubility and low oral bioavailability. The present study was designed to evaluate the anti-fatigue efficacy of curcumin fermented by Lactobacillus delbrueckii subsp. bulgaricus CCFM1520 and to preliminarily elucidate the underlying mechanism responsible for its anti-fatigue effects. Methods The bioconversion efficiency of curcumin and its metabolites by CCFM1520 were quantified viain vitro bioconversion assays. A mouse model of fatigue was established by combining forced swimming with chronic restraint stress. Mice were randomized into six groups: blank control, model, curcumin, CCFM1520, CCFM1520-curcumin synbiotic, and CCFM1520-fermented curcumin. The anti-fatigue efficacy of fermented curcumin was comprehensively assessed from behavioral parameters, serum level of oxidative stress markers [superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), malondialdehyde (MDA)], and cerebral levels of neurotransmitters [dopamine (DA) and norepinephrine (NE)]. Real-time quantitative PCR was performed to examine the mRNA expression profiles of genes associated with the nuclear factor erythroid 2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling pathway in the skeletal muscle and the brain-derived neurotrophic factor/tyrosine kinase receptor B (BDNF/TrkB) signaling pathway in the brain tissue. Results CCFM1520 converted curcumin at an efficiency of 62.39%, efficiently converting it into tetrahydrocurcumin. Compared with unfermented curcumin, the fermented product significantly improved behavioral outcomes, including prolonged exhaustive swimming time, shortened escape latency in the water maze, and increased swimming distance. In addition, the fermented product significantly enhanced the activities of SOD and GSH-Px and reduced the content of MDA in the serum, and simultaneously elevated the levels of DA and NE in the mouse brain. Mechanism studies revealed that fermented curcumin up-regulated the mRNA levels of Nrf2 and HO-1 in the muscle tissue and BDNF and TrkB in the brain tissue. Conclusion L. delbrueckii subsp. bulgaricus CCFM1520efficiently converts curcumin into more bioactive metabolites. These metabolites exert a pronounced anti-fatigue effect by enhancing antioxidant capacity and modulating neurotransmitter balance. This study provides a novel strategy and a theoretical basis for developing high-efficacy anti-fatigue functional foods.

Objective To investigate the effects of Chlamydia trachomatis plasmid protein pORF5 on cellular mitophagy and mitochondrial fission and to elucidate whether its mechanism is related to Drp1 activation. Methods HeLa cells stably expressing pORF5 and control cells were constructed by lentiviral transfection. After serum starvation treatment, the expression levels of autophagy-related proteins—microtubule-associated protein 1 light chain 3 (LC3), Beclin-1, and p62—were determined by Western blotting. Co-localization of LC3 and translocase of outer mitochondrial membrane 20 (TOMM20) was assessed by indirect immunofluorescence. Mitochondria were stained with MitoTracker Red CMXRos, and mitochondrial morphology was observed and analyzed through confocal laser scanning microscopy. Dynamin-related protein 1 (Drp1) phosphorylation and its translocation to mitochondria were examined by Western blotting and indirect immunofluorescence. To explore the role of Drp1 in autophagy and mitochondrial fission, we pretreated cells with the Drp1-specific mitochondrial division inhibitor 1 (Mdivi-1). Changes in mitochondrial morphology and Drp1 translocation were evaluated by confocal microscopy and indirect immunofluorescence. Then, Western blotting was employed to determine the expression levels of autophagy-related proteins, and indirect immunofluorescence assay to analyze LC3 fluorescence intensity and its co-localization with TOMM20. Results Compared with the control group, pORF5 significantly upregulated the expression of LC3-Ⅱ and Beclin-1, downregulated the expression of p62, and enhanced the co-localization of LC3 and TOMM20. pORF5 expression led to the fragmentation of the mitochondrial network structure. It promoted Drp1 phosphorylation at Ser616 and enhanced Drp1 translocation to mitochondria. Inhibition of Drp1 with Mdivi-1 attenuated Drp1 phosphorylation and translocation, resulting in elongated mitochondrial morphology. In addition, the Mdivi-1 inhibitor group showed downregulated expression of LC3-Ⅱ and Beclin-1, upregulated the expression of p62, and attenuated co-localization of LC3 and TOMM20. Conclusion The C. trachomatis plasmid protein pORF5 may induce mitophagy and mitochondrial fission by promoting Drp1 phosphorylation and its mitochondrial translocation.

Objective To examine the anti-lung cancer activity of Cordyceps militaris and predict its potential quality markers. Methods We systematically reviewed the current studies on the anti-lung cancer effects of C. militaris and summarized its chemical components. Homo sapiens lung cancer microarray data were integrated with network pharmacology to build a “component-target-pathway” network, followed by molecular docking analysis. On this basis, the potential quality markers of C. militaris for lung cancer treatment were predicted. Results We predicted 11 potential quality markers, which were grouped into six categories: (1) cordycepin and its analog O^5′-acetylcordycepin; (2) adenosine and its analogs, including N⁶-[β-(acetylcarbamoyloxy)ethyl]-adenosine, N⁶-(2-hydroxyethyl)-adenosine, N⁶-(4-methylbutyrate)-adenosine, and 5′-(3″-deoxy-β-D-ribofuranosyl)-3′-deoxyadenosine; (3) ergosta-7,22-dien-3β,5α-dihydroxy-6-one; (4) cordycepisosalt A; (5) pentostatin; and (6) cordyrrole B. Conclusion This study integrates literature review and bioinformatics analysis to predict potential anti-lung cancer quality markers of C. militaris. The suggested mechanisms and candidate components are theoretical and need further experimental validation to confirm their effectiveness. This work offers a reference for developing a quality standard system of C. militaris for anti-lung cancer applications.

Heyndrickxia coagulans, formerly known as Bacillus coagulans, exhibits pronounced intraspecific heterogeneity and represents an important probiotic candidate for animal feed. Objective To isolate high-quality H. coagulans strains and evaluate their potential for feed applications. Methods H. coagulans strains were isolated from spoiled fruits, soil, and feces through the plate streaking method. The isolates were identified by 16S rRNA gene sequencing. Functional assays were conducted to comprehensively evaluate their feed potential, including acid production, gastrointestinal tolerance, biosurfactant production, antimicrobial activity, protease activity, and utilization of different carbohydrates and feed raw materials. Results A total of 133 strains were isolated, among which 23 strains were identified as H. coagulans. Nine strains with strong acid-producing ability were further selected. Among them, strain N9 isolated from rotten Artocarpus heterophyllus exhibited the highest acid production, decreasing the pH to 3.89±0.05 after 24 h of incubation at 37 °C and achieving a lactic acid yield of (3 370.00±87.36) μg/mL. Following treatment with simulated gastric and intestinal fluids and bile salts, the survival rates of N9 were (73.50±1.54)% and (83.20±1.66)%, respectively. Furthermore, strain N9 showed the strongest biosurfactant production, with an oil displacement diameter of (43.00±0.46) mm. Antimicrobial assays revealed that N9 effectively inhibited three intestinal pathogens: Salmonella enterica subsp. enterica, Escherichia coli, and Staphylococcus aureus. In addition, strain N9 exhibited notable protease activity, with enzymatic characteristics well adapted to the animal intestinal environment. It was capable of utilizing carbohydrates such as xylo-oligosaccharides, as well as feed ingredients including palm kernel meal, cottonseed meal, sunflower meal, soybean meal, and wheat bran for acid production. Conclusion H. coagulans N9, isolated from rotten A. heterophyllus, demonstrates good potential for feed additive, serving as a new candidate strain for the research on probiotic application.