Retinoid acid-inducible gene-I-like receptor (RLR) signaling pathways, the immune signaling pathways in response to infections, play a regulatory role in the production of pro-inflammatory cytokines, chemokines, and type Ⅰ interferons. Ubiquitination as one of the post-translational modifications refers to the process of ubiquitin binding to different amino acid sites on the target proteins, which regulates the fates of proteins. For example, it initiates the proteasome pathway to degrade the target protein or activating the protein transport. The ubiquitination of RLR signaling pathways is a way of regulating multiple effectors and one of the classical pathways through which viruses induce major diseases in animals, autoimmune diseases, and chronic inflammation. This paper introduces the typical structural features and the ubiquitination types of key effectors in the RLR signaling pathways. Furthermore, it expounds the roles of ubiquitination in the regulation of key molecules in the RLR signaling pathways, aiming to provide a reference for the intervention or treatment of related diseases.

[Objective] To reveal the mechanisms ofPseudomonas putida Y-9 in actively regulating the extracellular and intracellular pH homeostasis during ammonia oxidation.[Methods] Y-9 was cultured in the nitrification media with initial pH 7.19 and 9.40, respectively, for 48 h. Metabolomics was employed to compare the differential metabolites and predict dissociation constant (pKa) during the ammonia oxidation. Transcriptomics was employed to compare the genes regulating.[Results] In the medium with initial pH 7.19, Y-9 produced maltitol to raise extracellular pH, and up-regulated the expression of the genes related to deaminase, deiminase, and cation transport to maintain intracellular pH stability. In the medium with initial pH 9.40, Y-9 produced acidic substances such as 5-aminovaleric acid 3 and oxamic acid to lower extracellular pH and regulated the expression of the genes associated with NADH dehydrogenase, cytochromes, ATP synthase, and amino acid transport to maintain intracellular acidity.[Conclusion] This study revealed the novel phenomenon of Y-9's extracellular pH stabilizing capacity and investigated its intracellular pH homeostasis mechanism. The findings enrich our knowledge about microorganism-environment interactions, and provide a theoretical basis for further understanding the pH stabilization mechanism in microbial denitrification processes.

The α-herpesviruses are a large class of enveloped double-stranded DNA viruses characterized by neurotropic infection and latent infection, posing a serious threat to human and animal health. The α-herpesvirus genome encodes a variety of proteins.UL24, a major virulence gene of α-herpesviruses, encodes a highly conserved protein and play a key role in regulating viral infection. This paper introduced the basic characteristics ofUL24 and the encoded protein and summarized the regulatory roles of UL24 in the virus assembly, replication, infection, pathogenicity, and inhibition of host innate immunity, aiming to provide a theoretical reference for understanding the functions of α-herpesvirus proteins and further preventing and controlling α-herpesvirus infection.

Inhibiting the synthesis of fungal cell wall is a safe and effective strategy for preventing and treating fungal infections. Chitin synthases are the key enzymes to catalyze the synthesis of chitin, an important structural component of fungal cell wall and septa. The roles of chitin synthases vary in regulating the synthesis of fungal chitin. This review outlines the roles of chitin synthases in regulating fungal cell proliferation, morphogenesis, interactions with hosts, and compensatory effect induced by cell wall damage in the three major pathogenic fungal species:Candida albicans,Aspergillus fumigatus, andCryptococcus neoformans, aiming to understand the importance of chitin synthases in fungal pathogenicity. Furthermore, this paper proposes a new antifungal strategy and the future research directions about the chitin synthases of fungi.

[Objective] Cyanophages, the viruses specifically infecting cyanobacteria, are ubiquitous in water environments. They play a role in regulating the population dynamics and density of cyanobacteria and promote the biogeochemical cycling of the aquatic ecosystem. This study aims to isolate and identify a cyanophage.[Methods] A novel cyanophage Yong-L2-223 was isolated from fresh water samples with marineSynechococcus sp. PCC 7002 as the indicator host. The host range, genome sequence, open reading frames (ORFs), and phylogenetic relationship of Yong-L2-223 were studied.[Results] The host range tests against 31 strains of cyanobacteria showed that Yong-L2-223 could infect the indicator host PCC 7002 (Synechococcales) and two freshwater strainsMicrocystis viridis FACHB-1342 (Chroococcales) andAphanizomenon flos-aquae FACHB-1209 (Nostocales) from the Dianchi Lake. The infection of the cyanobacterial strains from both the seawater and freshwater samples indicated that Yong-L2-223 was a euryhaline cyanophage. Yong-L2-223 was myovirus-like, consisting of an icosahedral head (about 60 nm in diameter) and a contractile tail (about 136 nm in length). The genome (double-stranded DNA) of Yong-L2-223 had a length of 65 725 bp, with the G+C content of 58.6% and 100 ORFs. It was predicted to carry theCas4 gene, gene transfer factor (GTA) gene, auxiliary metabolic genes (AMGs), and a gene cluster for the synthesis of pre-Q₀. These genes may contribute to the adaptation and infection of the cyanophage in cyanobacteria of three orders. The pairwise sequence comparison (PASC) illustrated that the highest similarity sharing by cyanophage Yong-L2-223 and all the viruses in the current genome databases was only 3.78%, far below the genus boundary cut-off of 70% defined by the International Committee on Taxonomy of Viruses. In the phylogenetic tree based on the whole proteomes, Yong-L2-223 formed an independent branch, with long evolutionary distances from other phages.[Conclusion] Yong-L2-223 is a new genus of theCaudoviricetes class. For the first time, we used a marine cyanobacterial strain as the indicator host to isolate and obtain a novel cyanophage from freshwater, which broadened the understanding of cyanophages, enriched cyanophage genome database, and laid a foundation for the development of cyanophage resources.

[Objective] This study aims to observe the changes of the fecal microbial communities in the dairy cows with subacute rumen acidosis (SARA) induced by a high-concentrate diet and modulated by the addition of vitamin E (VE). The potential effects on the metabolism of dairy cows were evaluated to provide data for exploring the physiological mechanisms of SARA.[Methods] Seven multiparous Holstein cows with rumen fistulas were selected for this trial which was carried out in three phases of 18 days each. The first phase was the control (CON) phase, with a concentrate-to-forage ratio of 50:50 in the diet (dry matter basis). The second phase was the induction (HG) phase, in which the forage was replaced with wheat flour at 15% of the diet (dry matter basis) to induce SARA. The third phase was the regulation (HGE) phase, in which VE was added at 12 000 IU/d/cow on the basis of the diet in the HG phase. The feces samples were collected on day 18 in each phase, and the microbial communities in the samples were examined.[Results] The fecal microbial community structure showed significant differences between three phases and the Shannon index in the HG phase was lower than that in the CON phase (P < 0.05). The HG phase had higher relative abundance ofProteobacteria andBlautia and lower relative abundance of unidentified_bacteria,Euryarchaeota,Desulfobacterota,Rikenellaceae_RC9_gut_group, andAlistipes than the CON phase (P < 0.05). The relative abundance ofBlautia in the HGE phase was higher than that in the HG phase (P < 0.05). The functional prediction results showed that SARA caused metabolic disorders in the dairy cows, while VE regulated the intestinal microbiota and health by improving the stability of microbial growth and promoting microbial reproduction.[Conclusion] The SARA induced by a high-concentrate diet led to reduced intestinal microbial diversity and metabolic disorders in dairy cows. VE can regulate intestinal health and maintain intestinal homeostasis by promoting the proliferation of beneficial intestinal microorganisms.

[Objective] To screen out a fungal strain that can efficiently assimilate ammonia nitrogen, reveal the metabolome differences of the strain in different media and the changes in the amino acid content of the feed fermented with the strain, and clarify the mechanism of its ammonia assimilation.[Methods] Seven strains ofTrichoderma, 7 strains ofAspergillus niger, and 9 strains ofAspergillus oryzae were cultured in the media with (NH₄)₂SO₄ as the only nitrogen source. The strains with high ammonia nitrogen use efficiency and glutamine synthetase (GS) activity were selected for comparison of the metabolic differences in potato dextrose agar (PDA) plates and inorganic nitrogen plates by non-targeted metabonomics. Furthermore, the crude protein and organic nitrogen content in the feed fermented with different strains was determined, and the changes in amino acid content in the fermented feed extract were measured by amino acid-targeted metabolomics.[Results] The utilization rate of ammonia nitrogen and the glutamine synthetase activity ofA. oryzae MQ28 were 54.46% and 0.61 μmol/(h·g), respectively, which were higher than those of other strains (P < 0.05). The comparative metabonomics analysis suggested that MQ28 was associated with the metabolism of multiple amino acids during ammonia assimilation. MQ28 fermentation increased the crude protein and organic nitrogen in the feed by 22.25% and 35.83% (P < 0.05), respectively. Furthermore, MQ28 fermentation increased the total amino acid content in feed extract from 31.86 mmol/100 g to 57.69 mmol/100 g (P < 0.05). Specifically, it increased the content of 14 amino acids such as threonine, lysine, and arginine, glutamic acid (by 3.46 folds), and glutamine (by 99 folds) (P < 0.05).[Conclusion] To sum up,A.oryzae MQ28 has high ammonia nitrogen utilization capacity. It may regulate the ammonia assimilation process through the synthesis of glutamine to regulate amino acid metabolism and can be used as an elite strain for the production of single-cell protein.

[Objective] To investigateBacillus velezensis XRD006 in terms of the inhibitory effects on diseases of postharvest green walnuts, the fresh-keeping effect on green walnuts, genetic characteristics, secondary metabolites, and antifungal mechanism.[Methods] The activities of XRD006 against pathogens of postharvest green walnuts were determined by the inhibition experiments.In vivo fungal inhibition and storage quality experiments were conducted to investigate the inhibitory effects of the strain on pathogens and the effect of the strain on the storage quality of postharvest green walnuts. The genomic characteristics and potential antifungal genes of XRD006 were investigated by whole genome sequencing. The secondary metabolites of XRD006 were predicted by antiSMASH, and the collinearity and differences of the secondary metabolite gene clusters between strains XRD006, FZB42, and SQR9 were analyzed by comparative genomics. The secondary metabolites of XRD006 were identified by high performance liquid chromatography (HPLC) and mass spectrometry. The antagonistic ability of the strain was tested by the oxford cup method.[Results] The inhibition rates of XRD006 againstColletotrichum aenigma,Colletotrichum siamense,Botryosphaeria dothidea, andFusarium fujikuroi of postharvest green walnuts were 49.22%, 50.61%, 53.83%, and 58.71%, respectively.In vivo antifungal experiments showed that XRD006 effectively inhibited the infection and growth of pathogenic fungi on the fruits. The fermentation supernatant of XRD006 significantly retarded the weight loss, inhibited the microbial growth, and reduced changes in peroxidase (POD) and polyphenol oxidase (PPO) activities while maintaining the kernel quality. The whole genome sequencing showed that the genome of XRD006 was 4 371 975 bp in length, containing 46.07% GC and 4 362 protein-coding genes (including antifungal and plant growth-promoting genes such as extracellular hydrolase and biofilm genes). The antiSMASH predicted that XRD006 had nine known and five unknown gene clusters of secondary metabolites. XRD006 was closely related to FZB42 and SQR9, and they shared eight secondary metabolite gene clusters, which showed varied location and coding genes. XRD006 produced two families of lipopeptides: iturin and fengycin. Compared with C13-iturin, C14-iturin, C15-iturin, and C17-fengycin C, C16-fengycin B of the fengycin family had the strongest inhibitory effect onC.siamense HT12.[Conclusion] B.velezensis XRD006 has good biocontrol effects on diseases of postharvest green walnuts and the potential for application in production.

[Objective] Bacillus velezensis SH-1471 (CCTCC No. M 2022923, Patent No. ZL 2022 1 1479280.X) is a strain that can control soil-borne diseases of crops and promote soil nutrient conversion and crop growth. This study aims to explore its potential biological activity and the optimum fermentation conditions, so as to promote the industrialization and commercial development of this strain.[Methods] A strain SH-1471 was identified based on the morphological, physiological, and biochemical characteristics and the 16S rRNA gene andgyrB-based phylogenetic trees. PCR was carried out to detect antibiotic synthesis genes in the strain. The inhibitory spectrum of the strain was measured by the plate confrontation assay and the fermentation liquid inhibition test. The abilities of the strain to produce enzymes, solubilize phosphorus and potassium, fix nitrogen, and secrete siderophoresin vitro were measured. The fermentation conditions were optimized by single factor tests and response surface methodology withOD₆₀₀ value and inhibition rate as indicators. The growth-promoting effect of the fermentation liquid on tomato plants and the control effect of the fermentation liquid on tomatoFusarium wilt before and after optimization were determined by indoor pot experiments.[Results] Strain SH-1471 was identified asB.velezensis, carrying the antibiotic synthesis genessrfA,fenB,ituA,ituD, andbymA. It had strong antagonistic effects on 8 pathogenic microorganisms such asFusarium oxysporum,Alternaria alternate, andExserohilum turcicum. Moreover, the strain was capable of producing protease and cellulase, solubilizing phosphorus, fixing nitrogen, and secreting siderophores. The optimal medium formula for the fermentation of SH-1471 was composed of 17.92 g/L sucrose, 16.95 g/L soybean powder, 2.88 g/L magnesium sulfate, and 5.0 g/L yeast extract. The optimum fermentation conditions were pH 7.5, 33 ℃, 220 r/min, and 20–24 h. After optimization, the inhibition rate,OD₆₀₀, and potted control efficiency of the fermentation liquid reached 94.08% (increasing by 15.6%), 3.28 (increasing by 36.7%), and 93.8%, respectively. Moreover, strain SH-1471 significantly improved plant height, stem circumference, root length, root weight, and fresh weight and dry weight of the aboveground part of tomato seedlings.[Conclusion] B.velezensis SH-1471 carries rich genes for antibiotic synthesis, has the abilities of producing protease and cellulase, solubilizing phosphorus, fixing nitrogen, and secreting siderophores, and demonstrates strong inhibitory effects on a variety of pathogens. It can significantly reduce the incidence of tomatoFusarium wilt and improve the agronomic traits of tomato seedlings. Therefore, the strain has broad application prospects in the biocontrol of plant diseases and the promotion of plant growth.

[Objective] To investigate the regulatory role of the transcription factor BldM in the morphological development and antibiotic synthesis ofStreptomyces pactum Act12, a biocontrol strain with multiple effects.[Methods] ThebldM-deleted mutant strain ∆bldM and thebldM-overexpressing mutant strain OE-bldM were constructed by genetic engineering. The scanning electron microscopy, antibacterial experiment, high performance liquid chromatography, and real-time quantitative PCR were employed to compare the morphological development, growth rate, oligomycin yield, and resistance to pathogens, respectively, between ∆bldM, OE-bldM, and the wild-type strain Act12.[Results] The sequencing results proved that ∆bldM and OE-bldM were successfully constructed. ∆bldM showed significantly reduced production of oligomycin D and was incapable of forming aerial hyphae. OE-bldM presented dense aerial hyphae and active sporulation. Compared with the wild type, OE-bldM showed an increase of 23% in the yield of oligomycin D and the up-regulation of 2–3 times in the transcriptional levels of the genes encoding oligomycin core synthetase. Moreover, the antimicrobial activity of OE-bldM remarkably enhanced.[Conclusion] The global transcriptional regulator BldM can not only affect the formation of aerial hyphae and sporulation but also participate in the positive regulation of oligomycin synthesis in Act12. The results of this study supplement the knowledge about the regulatory function of BldM and provide a reference for further research on the growth, metabolism, and regulation mechanism ofS.pactum Act12.