Salinization is a global soil problem. Plant growth-promoting rhizobacteria (PGPR) have unique advantages in remediating saline-alkali soils and promoting plant growth. Screening the rhizosphere microorganisms ofTamarix chinensis, a typical halophyte, and revealing the growth-promoting effect and mechanism of these microorganisms are of great significance for developing microbial fertilizers. [Objective] To screen out the microorganisms from the rhizosphere soil of saline-alkaline tolerantT.chinensis and measure their basic characteristics, salt and alkali tolerance, and plant growth-promoting effects.[Methods] A saline-alkali tolerant strain Bachu 26 was screened out from the rhizosphere soil of wildT.chinensis in Bachu, Xinjiang and identified based on the morphological, physiological, and biochemical characteristics and 16S rRNA gene sequence. We cultured the strain Bachu 26 in the media with different salt concentrations (0%–20%) and pH values (7.0–13.0) to evaluate its salt and alkali tolerance. We then used multiple functional media to examine the growth-promoting function of Bachu 26 and measured the production of indole-3-acetic acid (IAA). The petri dishes with two compartments were used to verify the ability of Bachu 26 to produce acidic volatile substances.Arabidopsis thaliana seedlings were co-cultured with strain Bachu 26 in common culture dishes, based on which the growth-promoting effect of Bachu 26 onA.thaliana seedlings was analyzed. Furthermore,A.thaliana seedlings and Bachu 26 were cultured dividually in the petri dishes with two compartments, based on which the growth-promoting effect of volatile acidic substances produced by Bachu 26 on the seedlings was analyzed. The growth-promoting effect of Bachu 26 on maize seedlings was analyzed by pot experiments.[Results] Strain Bachu 26 was identified as a species ofHalomonas and namedHalomonas sp. Bachu 26, with the maximum tolerance to 20% salt and pH 11.0.Halomonas sp. Bachu 26 could solubilize organic phosphorus, fix nitrogen, and produce ACC deaminase, IAA, and volatile acidic substances, with the IAA yield reaching 45.885 6 mg/L.Halomonas sp. Bachu 26 significantly increased the fresh weight, lateral roots, taproot length, and leaves ofA.thaliana seedlings under saline-alkali stress. In pot experiments,Halomonas sp. Bachu 26 significantly increased the fresh weight of aboveground part, fresh weight of underground part, and plant height of maize under saline-alkali stress.[Conclusion] The newly isolated PGPR strain Bachu 26 has a significant plant growth-promoting effect. The findings provide material and theoretical support for the remediation of saline-alkali soil and development of saline-alkali tolerant plant growth-promoting microbial fertilizers. Furthermore, the results will promote the applied and basic research onHalomonas.

[Objective] The cell wall structure characteristics make it a challenge to obtain the whole proteins ofPaenibacillus sp. as a Gram-positive bacterium. We employed three representative lysis methods: lysozyme combined with ultrasonic treatment (method 1), lysozyme combined with SDS heat treatment (method 2), and liquid nitrogen combined with ultrasonic treatment (method 3), to obtain the samples for mass spectrometry-based proteomics research onPaenibacillus sp.[Methods] We compared the protein extraction efficiency of the three methods based on protein yield and SDS-PAGE. Furthermore, we analyzed the obtained protein samples by mass spectrometry.[Results] The protein extraction efficiency of the three methods was similar. The number of proteins identified in the sample prepared with method 3 was the highest (2 638 proteins), followed by that with method 1 (2 452 proteins), and that with method 2 was the lowest (2 003 proteins). The Venn diagram was established to compare the protein identification flux of the samples prepared with different methods. Considering the protein extraction efficiency and the shortcomings of method 3, we finally chose method 1 as the most suitable method to extract the proteins for mass spectrometry-based proteomic analysis. Finally, the basic properties of proteins identified by mass spectrometry, including molecular weight, isoelectric point, and hydrophobicity, were analyzed. The proportion of each component of the proteins obtained by the three methods was the same as that of the predicted proteins of the model strainPaenibacillus polymyxa.[Conclusion] For the proteomics research on Gram-positivePaenibacillus sp. by mass spectrometry, lysozyme combined with ultrasonic treatment is the most suitable method for sample preparation.

Proper pH is crucial for the survival and functions of microorganisms, whether in the environment or within cells. Under acidic or alkaline stress, microorganisms have evolved diverse strategies, such as proton transport, production of acidic or alkaline substances, and cell membrane protection, to maintain intracellular pH homeostasis. Moreover, microorganisms have evolved the ability to actively change the extracellular pH. This article reviews the mechanisms by which microorganisms maintain intracellular pH homeostasis under acid or alkaline stress and alter extracellular pH. It aims to enhance our understanding of the interaction between microorganisms and the environment and provide a reference for further research on the synergistic mechanisms between microorganisms and the environment.

Fatty acids are not only the components of cell membrane but also the raw materials for the synthesis of bioactive molecules. Unsaturated fatty acids (UFAs) with low phase-transition temperatures are essential molecules for bacteria to regulate cell membrane fluidity. Therefore, the synthetic pathways of UFAs are key targets for the screening of antibacterial agents. Bacteria can adopt the anaerobic pathway to synthesize UFAs. For example,Escherichia coli, a model organism, synthesizes UFAsvia the classic FabA-FabB pathway. However, the anaerobic pathways for the synthesis of UFAs vary in different bacteria, and the catalytic enzymes are also different. Bacteria can synthesize UFAsvia aerobic pathways, in which fatty acid desaturase directly converts saturated fatty acids (SFAs) into UFAs. Different desaturases introduce double bond to form UFAs with different structures, which play roles in stress responses, pathogenicity and other aspects. Other enzymes involved in the synthesis of fatty acids can also participate in the synthesis of UFAs or regulation of different UFAs. Some bacteria can use monooxygenase to convert capryl-ACP (acyl carrier protein) in the fatty acid synthesis pathway intocis-3-decenyl ACP to synthesize UFAs. We comprehensively reviewed the research progress in the synthesis of UFAs in bacteria, aiming to provide theoretical support for deciphering the mechanism of bacterial synthesis of UFAs and developing the targeted antibacterial drugs.

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.

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.

With the evolution of bacteria and the overuse of certain antibiotics, drug-resistant bacterial infections have emerged as a major public health challenge in the 21st century.Klebsiella pneumoniae, in particular, has aroused wide concern due to its drug-resistant nature. Bacteriophages have demonstrated the potential and advantages in treating bacterial infections caused by drug-resistant strains, while there are no clinical guidelines for phage therapy. Notably, even though a few successful cases of bacteriophage therapy have been documented in the treatment ofK.pneumoniae infections, bacteriophages are used in combination with antibiotics in most cases and the role bacteriophages play remains unclear. This article provides an overview of bacteriophage therapies forK.pneumoniae infections, including their characteristics and the factors influencing their efficacy. We compiled and analyzed data from available studies, with the intention of offering valuable insights for the application of bacteriophage therapy in combatingK.pneumoniae and other drug-resistant bacteria.

The term "microorganism" refers to tiny organisms such as archaea, bacteria, protists, fungi, and viruses, and the term "microbiome" refers to a collection of microorganisms. Although they share the body space of the host, their roles as determinants in host health and diseases are ignored. As a collection of information, the microbiome includes the genomic data, structural elements, metabolites, and environmental conditions of microorganisms. Studies have demonstrated that the microbiome plays an essential role in maintaining host homeostasis and regulating host phenotypes. With the advent of new technologies, including next-generation sequencing (NGS) and sequencing-based microbiome profiling, researchers have probed into the relationship between the microbiome and host phenotypes. By an overview of microbiome, this paper elaborated on the microbiome-host genetics interactions based on genome-wide association analysis and made an outlook on the future of this field.

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] Bacillus thuringiensis (Bt), characterized by the massive production of insecticidal crystal proteins (ICPs) during sporulation, serves as the main strain resource for the commonly used and safe microbial insecticides. To further explore the mechanisms of sporulation and parasporal crystal formation and lay a theoretical foundation for the construction of efficient strains, we compared the transcriptomes of Bt at three important stages.[Methods] The transcriptomes of the hypervirulent strain Bt4.0718 at the middle vegetative growth stage (T1-10 h), the early sporulation stage (T2-20 h), and the late sporulation stage (T3-32 h) were compared. The representative differentially expressed genes (DEGs) were verified by real-time fluorescence quantitative PCR (qRT-PCR), and the phenotypes of the mutant strains with the knockout of specific functional genes were examined.[Results] The number of DEGs was 2 147 (T2/T1), 1 861 (T3/T1), and 1 708 (T3/T2), respectively. At T1, the medium was rich in nutrients, which served the sporulation and parasporal crystal formation. The high transcription levels ofkinA/D,spo0A/F, andsigE regulating sporulation played a role in the growth and development of the cells. The transcription of Cry1Ac, poly-hydroxybutyric acid (PHB), and hydroxybutanone (acetoin) were started at this time. The substantial formation of ICPs and spores occurred at T2 and T3, and the transcript levels of the regulatory genes were higher at T2 than those at T3. The genes associated with spore core/coat/cortex, germination protein, andspoII–spoVI began to be transcribed in large amounts at T2, with the highest levels among the three stages. The corresponding complex networks of carbohydrate, amino acid, and lipid metabolism, energy, nucleic acid, and peptide metabolism, secondary metabolite production, and environmental adaptation showed differences. In addition, as the physiological processes stimulated by nutrient signals, the two-component signal transduction system (TCS) and ABC transport system played an essential role in the process of sporulation and ICP transcription and expression, and their transcription levels were significantly different.[Conclusion] With the production of ICPs and sporulation, nutrients are gradually consumed, and the high expression ofsigB,sigW, andsigM contributed to the stability of cell wall and the resistance to environmental changes. Meanwhile, the small heat shock proteins Hsp20 and Hsp20B, as molecular chaperones, were also important for maintaining intracellular homeostasis and may facilitate the sporulation and ICP production.