This article explores the dynamic regulation of fluid shear stress on the biofilm formation of Streptococcus mutans, aiming to elucidate the pathogenic mechanism of this bacterium and provide references for the prevention of dental caries. S. mutans is a major cariogenic bacterium in the oral cavity, and it destroys the tooth tissue by forming biofilms and producing acids by metabolism. Studies have shown that fluid shear stress can regulate the physical structure, secretion of extracellular polymeric substances, adhesion, and quorum sensing of biofilms, thereby affecting the pathogenicity. This study provides a theoretical basis for deeply understanding the ecological adaptability of pathogens in fluid environments and the development of new intervention measures in clinical practice.

Currently, the drugs available for treating fungal infections show limited number and off-target effects. Thus, there is an urgent need to develop new antifungal drugs. Fungal apoptosis-like cell death (ALCD) is a cell death phenomenon that occurs during the normal development stage of organisms. This article summarizes the characteristics, signaling pathways, and key factors involved in fungal ALCD and introduces the natural and synthetic drugs that can induce fungal apoptosis. The natural drugs include lipid peptides, farnesol, statins, and alkaloids from microorganisms, organic acids and essential oils from plants, and melittins from insects. Furthermore, this article establishes the basic molecular landscape of drug-induced fungal ALCD. This article provides a theoretical basis for formulating a new strategy for resisting pathogenic fungi and developing targeted antifungal drugs.

Brucellosis is a zoonotic disease caused by Brucella. Brucella can replicate within various host cells and evade the host immune system, which underpins its pathogenicity. Rough Brucella strains, characterized by the absence or inadequacy of the O-antigen chain, exhibit incomplete lipopolysaccharide structures, precluding the production of anti-lipopolysaccharide antibodies. This distinguishing feature facilitates differential diagnosis and has attracted considerable attention. Rough Brucella can invade and manipulate the host immune system via low endotoxin activity, lysosomal escape, and resistance to complement attacks. Nevertheless, comprehensive investigations into the host immune responses, rough Brucella-host interaction mechanisms, and virulence gene functions of rough Brucella remain scarce. This article elucidates the intracellular parasitism process of rough Brucella and the molecular mechanisms underlying their interactions with hosts, with the aim of offering insights for the development of effective vaccines against rough Brucella.

Hydroxylamine, as an important intermediate product in the nitrogen cycle, connects ammonia oxidation and nitrite oxidation, influencing the velocities and directions of processes like ammonia oxidation, nitrite oxidation, and denitrification. Because of the close associations with the generation of N₂O through enzymatic reactions and self-decomposition or reactions with other substances, hydroxylamine has become a focus and hotspot of research. This paper summarized the generation and transformation of hydroxylamine in autotrophic and heterotrophic ammonia oxidation, the key role of hydroxylamine in the nitrogen cycle, and the promoting effect of hydroxylamine on N₂O emissions. It analyzed the processes of autotrophic and heterotrophic ammonia oxidation and their enzymatic differences, aiming to provide a theoretical reference for in-depth research on the role of hydroxylamine in the microbial nitrogen cycle and for the research and development of measures to reduce N₂O emissions and protect the atmospheric environment.

Saccharomyces cerevisiae is a classic model organism for studying the biochemical mechanisms of eukaryotic cells. Eukaryotes have three main types of RNA polymerases: RNA polymerase I (RNAPI), RNA polymerase II (RNAPII), and RNA polymerase III (RNAPIII). Among them, RNAPIII has the most complex structure, consisting of 17 subunits, and it is primarily responsible for the synthesis of transfer RNA (tRNA). Compared with RNAPII consisting of 12 subunits, RNAPIII contains a unique heterotrimer Rpc82/31/34 and a heterodimer Rpc53/37 which is homologous to the counterpart of RNAPI. This paper reviews the structures and functions of the specific heterotrimer and heterodimer in RNAPIII, aiming to lay a theoretical foundation for further studies on the modification mechanisms and assembly processes of specific subunits of RNAPIII in S. cerevisiae.

Transcription factors are essential for the survival of bacteria, and revealing their functions is conducive to the development of antimicrobials, industrial applications, and environmental protection. At present, there are many methods and strategies for the research on transcription factors, which have been developed rapidly in the fields of bioinformatics and molecular biology. This paper summarizes the methods for identifying unknown transcription factors, unveiling the regulatory functions of transcription factors, constructing regulatory networks of transcription factors, and validating the regulatory genes of transcription factors. This review aims to provide new strategies and new ideas for the analysis and verification of the regulatory functions of bacterial transcription factors.

The aggravating soil-borne diseases threaten the production of a variety of crops and undermine the sustainable development of agriculture. Streptomyces-based bio-agents have been widely explored as an environmentally safe and economically durable biocontrol resource. However, the biocontrol efficacy and influencing factors require further optimization. [Objective] Here we conducted a meta-analysis to evaluate the efficacy of Streptomyces-based bio-agents in controlling the two common soil-borne diseases and identify the key influencing factors. [Methods] The relevant articles were retrieved from Web of Science and CNKI with the keywords “Streptomyces” and “Fusarium wilt”, “Streptomyces” and “bacterial wilt”, “Streptomyces” and “Fusarium oxysporum”, and “Streptomyces” and “Ralstonia solanacearum (or Pseudomonas solanacearum)”. The articles containing comparable treatment groups (with Streptomyces application) and control groups (without Streptomyces application), disease incidence, sample sizes, and mean values were systematically selected. Finally, 76 articles (113 groups) on Streptomyces-based bio-agents for Fusarium wilt control and 19 articles (28 groups) on those for bacterial wilt control were obtained. [Results] After the application of Streptomyces-based bio-agents, the disease incidence of Fusarium wilt decreased from 75.58% to 24.49% (average control efficacy of 67.60%), and that of bacterial wilt decreased from 73.75% to 19.83% (average control efficacy of 73.11%). The soil density of Streptomyces, the final concentration ratio of Streptomyces to pathogen in soil, and climate types were vital for the biocontrol performance of Streptomyces-based bio-agents. Moreover, Streptomyces at the final concentration of 10⁷ CFU/g demonstrated the best biocontrol performance on both diseases. The biocontrol effect of Streptomyces on Fusarium wilt was better when the final concentration ratio of Streptomyces to pathogen was 1:1, whereas the biocontrol effect on bacterial wilt disease was better when the ratio was 10:1 or 100:1. Notably, Streptomyces demonstrated enhanced biocontrol effects on the both diseases in tropical monsoon climate regions. [Conclusion] The application dose of Streptomyces-based bio-agents in soil-borne disease management should be adjusted according to the species and concentration of the pathogen. In addition, it may be better to apply Streptomyces-based bio-agents in tropical monsoon climate regions.

[Objective] Listeria monocytogenes (Lm) is a Gram-positive foodborne pathogen causing human and animal listeriosis with high case fatality rates (20%-30%). Lm can grow at low temperatures, which brings great risks to food safety and human health. Exploring the mechanism of Lm growth at low temperatures will provide a theoretical basis for the formulation of measures to control Lm growth at low temperatures and the development of low-temperature growth inhibitors. Studies have shown that LisK/R, a two-component signal transduction system (TCS) in Lm, plays a role in regulating the growth of Lm at low temperatures, while the specific mechanism remains unclear. This study aims to reveal the mechanism of LisK/R in regulating the growth of Lm at low temperatures. [Methods] With the Lm strain LM201 isolated from foodstuff as the parental strain, we constructed three strains: ΔlisR (RR-deleted mutant of LisK/R), ΔlisRc (complementary strain of ΔlisR), and ΔlisKc (complementary strain of ΔlisK, which was constructed before this study in our laboratory). The growth curves of these strains were determined at 4 ℃. RNA-Seq was performed for ΔlisK and the parental strain growing at 4 ℃, and the obtained data were analyzed. We assayed the swarming area diameter on soft agar plate, flagellar biosynthesis by transmission electron microscopy, and transcriptional levels of flagellar genes by RT-qPCR for all the strains at 4 ℃. [Results] The growth of deletion mutants was slower than that of the parental strain (P<0.05), and the growth of complementary strains was consistent with that of the parental strain at 4 ℃. The RNA-Seq data showed that compared with that in the parental strain, the expression of flagellar genes in ΔlisK was up-regulated (P<0.05). At 4 ℃, the swarming area diameters of deletion mutants on soft agar plates were bigger than those of the parental strain and complementary strains (P<0.05); the deletion mutants had more flagella, while the parental and complementary strains had fewer flagella; the expression of flagellar genes in the deletion mutants was higher than that in the parental and complementary strains (P<0.05). [Conclusion] At 4 ℃, the LisK/R mutants with slow growth had more flagella, while the parental strain with rapid growth had fewer flagella. The results indicate that LisK/R inhibits the expression of flagellar genes in Lm to reduce flagellar production, and the energy is used to promote Lm growth at low temperatures. The specific molecular regulatory mechanism of LisK/R needs further study. This study provides new information for elucidating the mechanism of Lm growth at low temperatures.

Allergic asthma is a prevalent chronic inflammatory disease characterized by airway hyperresponsiveness and airway inflammation, often triggered by inhalant allergens such as pet dander and pollen. [Objective] Studies have revealed that helper T cells (Th cells) play a crucial role in the immune regulation of allergic asthma. Particularly, Th2 cells exacerbate airway inflammation by secreting cytokines such as interleukin (IL)-4 and IL-5, which promote the proliferation of eosinophils and mast cells. Additionally, the activation of Th17 cells is closely related to the inflammatory response in allergic asthma. Therefore, modulating the balance of Th1/Th2 and Th17/Treg cells has become an effective strategy for treating allergic asthma. This study explores the pathogenesis of allergic asthma and novel therapeutic approaches. [Methods] We constructed an engineered bacterium EcN ^canf-1 specifically expressing the dog allergen Canf-1. Using the pBAD promoter, we controlled the expression of Canf-1 in the lungs of mice. [Results] EcN ^canf-1 exerted immunomodulatory effects by regulating pulmonary cytokine expression profiles, specifically downregulating the expression of pro-inflammatory cytokines including IL-6, IL-5, and IL-13, while upregulating the expression of anti-inflammatory mediators such as interferon-γ (IFN-γ), transforming growth factor-β (TGF-β), and IL-10, thus alleviating allergic symptoms in the lungs. EcN ^canf-1 demonstrated remarkable efficacy in suppressing the pathological overexpression of Th2 and Th17 lymphocyte subsets under allergic conditions, while enhancing the functions of Th1 and regulatory T cells. Furthermore, EcN ^canf-1 significantly reduced pulmonary mast cell infiltration, attenuated vascular permeability, and mitigated allergen-induced hypothermia and airway constriction. These findings demonstrated that EcN ^canf-1 played a pivotal role in immune homeostasis regulation and represented a promising therapeutic candidate for allergic pulmonary inflammation through its multifaceted modulation of immunological pathways. [Conclusion] EcN ^canf-1 provides a new therapeutic avenue for allergic asthma by modulating the expression of immune cells and cytokines. This not only offers new insights into the immune mechanisms of allergic asthma but also provides a scientific basis for the development of new targeted biological treatment strategies.

[Objective] To isolate and screen the salt-tolerant strains with good plant growth-promoting effect from the saline-alkali soil of the Yellow River Delta, thus providing strain resources for the efficient cultivation of crops in saline-alkali soil. [Methods] Bacillus strains were isolated by the dilution coating method, and the strains with good plant growth-promoting effects were further selected by the seed soaking test. The growth-promoting characteristics of the selected strains were measured, and the growth-promoting effects of the strains on Sesbania cannabina under salt stress was evaluated by pot experiments. The strain with the strongest plant growth-promoting effect was identified based on morphological characteristics, physiological and biochemical characteristics, and molecular biological evidence. Through the whole genome sequence analysis, the genes related to the plant growth-promoting function were discovered. [Results] A total of 60 Bacillus strains were isolated, from which strains M4, M5, B5, L3, and Q17 were screened out by the seed soaking test. These strains showed robust plant growth-promoting properties, being capable of solubilizing inorganic phosphorus, solubilizing potassium, and producing inole-3-acetic acid. The pot experiment results showed that under normal culture conditions and under low salt stress (NaCl concentration of 100 mmol/L), inoculation with Bacillus increased the plant height, maximum leaf area, stem dry weight, and root dry weight of S. cannabina seedlings (P<0.05). Under high salt stress (NaCl concentration of 200 mmol/L), the fresh and dry weights of stem and leaves of S. cannabina seedlings were increased by inoculation with five strains of Bacillus (P<0.05). In addition, inoculation with Bacillus enhanced the activities of catalase, superoxide dismutase, and peroxidase while reducing the content of malondialdehyde in the leaves of S. cannabina seedlings (P<0.05). Strain M4 with the strongest plant growth-promoting effect was identified as Bacillus thuringiensis. [Conclusion] All the five isolates have various plant growth-promoting properties, being capable of promoting the growth of S. cannabina seedlings under salt stress and alleviating the inhibitory effect of salt on the seedlings. Strain M4 with the robust plant growth-promoting effect is identified as B. thuringiensis, and it has the potential to be developed as plant growth-promoting bacterial fertilizer for saline-alkali soil.