ThiD encoded by thiD in Thermoanaerobacter tengcongensis is a key enzyme in the biosynthesis of thiamine. The structure and functions of thiD have been elucidated in fungi, yeasts, and plants, while the role of thiD in thermophiles remains unclear.[Objective] This study aims to explore the thermal adaptation mechanism of T. tengcongensis and reveal the role of thiD in the thermal adaptation of T. tengcongensis at different temperatures. [Methods] The thiD-deleted mutant (ΔthiD) of T. tengcongensis was constructed by homologous recombination. The growth trends of the wild type (WT) and ΔthiD at 50 ℃, 60 ℃, 75 ℃, and 80 ℃ were observed and compared. The differentially expressed genes (DEGs) between ΔthiD and WT cultured at 75 ℃ were determined by RNA-seq. The transcript levels of 13 genes and 3 sRNAs in WT and ΔthiD at 50 ℃, 60 ℃, 75 ℃, and 80 ℃ were compared and analyzed by real-time PCR. [Results] ΔthiD was successfully constructed, with the growth rate not significantly different from WT at 50 ℃. However, ΔthiD show cased slower growth than WT at 60 ℃ and 75 ℃ and did not grow at 80 ℃. The transcriptome results revealed 503 DEGs in ΔthiD compared with WT, including 278 DEGs with up regulated expression and 213 DEGs with down regulated expression. The Kyoto encyclopedia of genes and genomes (KEGG) analysis indicated the following pathways associated with thermophilic adaptation, involving thiamine metabolism, pyrimidine metabolism and purine metabolism, peptidoglycan biosynthesis, fatty acid metabolism, amino acid metabolism, two-component system, DNA replication, homologous recombination, mismatch repair, and phosphotransferase system. The transcript levels of 13 genes and 3 sRNAs related to thermal adaptation in WT and ΔthiD changed at specific temperatures. [Conclusion] thiD plays an important role in the thermal adaptation of T. tengcongensis. This study provides experimental data and a theoretical basis for revealing the role of thiD in the thermal adaptation of thermophiles at different temperatures.

[Objective] Over 7 million people die from bacterial infections every year due to the inappropriate or untimely use of antibiotics. Antimicrobial susceptibility test (AST) is a routine method guiding antibiotic therapy in clinical practice, while the existing methods have limitations as they require at least 16–20 h to get the results. We aimed to develop a novel rapid AST method based on bacterial morphology analysis, which can improve the diagnosis efficiency and provide timely treatment for the patients with bacterial infections, especially for urgent cases. [Methods] We developed an in-situ time-lapsed imaging (ISM-TLI) technique for microcolonies by combining bacterial incubation, in vitro antibiotic treatment, microscopic imaging, and image processing algorithm. The combination of the imaging device with the algorithm enabled the tracing of the morphological changes of colonies treated with different concentrations of antibiotics in-situ and the rapid obtainment of AST results. [Results] This technique worked effectively for both Gram-positive and Gram-negative bacteria and could determine the minimum inhibitory concentration (MIC) within 2 h, with the results in agreement with those obtained with the clinical gold standard method. [Conclusion] Our rapid AST technique significantly reduced the turn-around-time for obtaining the AST profile and had great potential for AST of a wide range of other strains.

[Objective] To investigate the fungal diversity and community dynamics in the roots and root zone soil of the invasive species Spathoglottis plicata at different development stages and mine potential fungal resources. [Methods] The developmental period of S. plicata was divided into the protocorm, pre-seedling, middle-seedling, late-seedling, adult, and flowering stages. Fungal community composition and diversity in the roots and root zone soil were analyzed by QIIME 2 and other software. Fungal strains were isolated by the tissue culture method from the protocorms and seedlings of S. plicata, and the phylogenetic relationship of the strains was analyzed. [Results] The dominant fungi in the roots and root zone soil of S. plicata were Tulasnellaceae and Onygenaceae, respectively. The fungal community composition of S. plicata varied across different developmental stages. Tulasnellaceae was the most prevalent from the protocorm to middle-seedling stage, while Nectriaceae and Trichocomaceae became dominant during the late-seedling stage and adult stage. At the flowering stage, Ceratobasidiaceae presented high relative abundance. A total of 101 fungal strains were isolated from the protocorms and seedling roots of S. plicata, belonging to 13 families, in which strains of Tulasnellaceae accounted for 35.65%, being dominant. [Conclusion] The present study elucidated the fungal community composition and diversity dynamics in the roots and root zone soil of S. plicata at different development stages. The findings offer a theoretical foundation for comprehensively understanding of the intricate relationship between orchids and symbiotic fungi and facilitating the selection of optimal habitats for the conservation of rare and endangered orchid species.

[Objective] This study explored the application potential of symbiotic fungi and bacteria of Odontotermes formosanus in the degradation of wheat (Triticum aestivum L.) straw resources, aiming to provide a theoretical basis and supplement strain resources for the industrialization of straw biodegradation. [Methods] The lignocellulose-degrading fungi and bacteria were isolated from O. formosanus and screened by Congo red staining and the agar plate supplemented with carboxymethyl cellulose sodium (CMC-Na), and the enzyme production of the strains screened out was examined. Liquid fermentation at room temperature was carried out to evaluate the degradation effects of different strains and strain combinations on wheat straw. Fourier transform infrared spectroscopy (FTIR), X-ray crystal diffraction (XRD), and scanning electron microscopy (SEM) were employed to analyze the physical and chemical properties of wheat straw before and after degradation. [Results] Five species of fungi and three species of bacteria were isolated from the termite combs, including two species of Penicillium, one species of Purpureocillium, one species of Aspergillus, one species of Eutypella, one species of Bacillus, one species of Escherichia, and one species of Stenotrophomonas. Four efficient degrading strains were screened out and identified as Penicillium citrinum, Aspergillus nomiae, Bacillus subtilis, and Escherichia coli. In the liquid fermentation at room temperature, the combination of the four strains had the strongest comprehensive degradation performance, with the degradation rates of 24.35%, 47.24%, 35.75%, and 32.72% for dry matter, cellulose, hemicellulose, and lignin, respectively, in 12 days. The degradation destroyed the chemical bonds, the intermolecular force, and the composite structure of lignocellulose in wheat straw, and decreased the crystallinity of cellulose from 37.40% to 32.97%. [Conclusion] The combination of P. citrinum, A. nomiae, B. subtilis, and E. coli isolated from the combs of O. formosanus had a good degradation effect on wheat straw, demonstrating the application potential in the industrialization of straw biodegradation.

[Objective] To explore the effects of CbrB from the carbon catabolite repression system on the biocontrol performance of Pseudomonas protegens Pf-5. [Methods] The mutant Pf5274 with the markerless deletion of the coding region of cbrB was constructed by a double-crossover recombination event based on pJQ200SK. Moreover, the complementary strain of cbrB and the control strains were constructed by the plasmid complementation method based on pBBR1Am. Lastly, the effects of CbrB on the growth, biofilm formation, motility, antifungal activity, and pyoluteorin synthesis of Pf-5 were analyzed by the measurement of OD₆₀₀, crystal violet staining, agar plate culture, plate confrontation method, and pltL'-'lacZ fusion report strains, respectively. [Results] CbrB greatly slowed the growth of Pf-5 in the natural medium LB, but greatly sped up the growth of Pf-5 in the basic medium M9-glucose. In addition, CbrB significantly promoted the motility but inhibited the biofilm formation, antifungal activity, and pyoluteorin synthesis of Pf-5. [Conclusion] CbrB plays a role in regulating the growth, biofilm formation, motility, antifungal activity, and pyoluteorin synthesis of P. protegens Pf-5, thus regulating the biocontrol performance of this strain. This study provides a theoretical basis for the biocontrol capabilities of strains by genetic engineering and lays a foundation for probing into the biosynthesis of pyoluteorin.

Depression is a prevalent affective disorder exerting negative impacts on an individual's emotional and cognitive functions and is commonly complicated with other diseases. As depression is affecting increasingly younger populations, it poses a serious challenge to the mental health initiatives in China. In recent years, the relationship between depressive symptoms and gut microbiota has garnered increasing attention, fueled by the deepening research on gut microbiota. Lactulose, a medication aimed at promoting gut health and known for its potential benefits on emotional and cognitive functions, has sparked interests regarding its clinical application in ameliorating depressive symptoms. This article reviews the clinical research findings on the efficacy of lactulose in alleviating depressive symptoms and outlines the potential mechanisms through which lactulose may mitigate these symptoms. Furthermore, this article offers a perspective on the mitigation of depressive symptoms through the gut-brain axis.

CRISPR-Cas is a defense system ubiquitous in bacteria and archaea. It has been successfully applied in genome editing in a variety of organisms. At present, CRISPR-Cas9 and CRISPR-Cas12a are the most widely used genome editing tools. However, the large protein sizes of Cas9 and Cas12a (more than 1 000 amino acids (aa)) hinder their delivery. TnpB and IscB (about 400 aa) encoded by the transposon family are considered ancestors of Cas12 and Cas9, respectively, whereas their functions are revealed just recently. They are named as obligate mobile element-guided activity (OMEGA), with the associated RNA named ωRNA. Since then, the OMEGA system has become one of the research hotspots in genome editing. OMEGA systems are diverse, with wide distribution in all the three domains of life. The in-depth research on the OMEGA system will aid in the development of new genome editing tools that are streamlined, efficient, and safe. Here, we reviewed the discovery history, structural characteristics, mechanisms of cleavage, and genome editing applications of OMEGA systems, aiming to lay a foundation for the development and optimization of genome editing tools.

Levilactobacillus brevis is a common species of lactic acid bacteria mainly detected on the surface of plant stems and leaves and in pickles, dairy products, and intestines. With excellent physiological functions, L. brevis is a potential probiotic species. With the rise of genomics, it is of great significance to reveal the genetic characteristics and functional gene properties of L. brevis at the gene level for application of this bacterium. This paper reviews the genetic background and major functional genes of L. brevis, aiming to lay a theoretical foundation for the application of L. brevis.

[Objective] To improve the culture medium components of Parvimonas micra, increase the number of live cells, and develop a demonstration method for culturing fastidious bacteria. [Methods] Biochemical analysis was conducted on a strain of P. micra to screen the potential substrates that could promote bacterial growth. A single-factor experiment was carried out for each substrate with three concentrations. The substrate with a significant bacterial enrichment effect was further optimized for concentration, and thus a new culture medium was obtained. [Results] The single-factor experiment results showed that the substrates with significant bacterial enrichment effects included L-serine, L-threonine, and glycyl-L-glutamine. In the medium with the addition of 4.8 g/L L-serine, the live cell count of P. micra reached 3.6×10⁸ CFU/mL, representing a 4.2-fold increase compared with that in the basic medium with tryptone soya broth (TSB) and fetal bovine serum (FBS). Furthermore, the improved culture medium was applied to the culture of another P. micra strain, demonstrating a significant growth-promoting effect. [Conclusion] This study proves that using biochemical identification plates to screen medium supplements is a fast and efficient method, providing a reference for the enlargement culture of fastidious bacteria.

Type 2 diabetes mellitus (T2DM) stands as a chronic metabolic disorder posing a challenge to global public health, owing to its widespread prevalence. The intricate interplay between gut microbiota and the onset and progression of T2DM, along with the potential therapeutic benefits of modulating gut microbiota, has emerged as a focal point in contemporary research. Recent studies have underscored the capacity of traditional Chinese medicine to ameliorate T2DM by inducing alterations in gut microbiota. Nevertheless, the precise mechanisms underlying the pharmacological actions of traditional Chinese medicine via gut microbiota regulation remain elusive. The diverse bioactive compounds in traditional Chinese medicine play pivotal roles in eliciting its pharmacological effects. This article systematically reviews the advancements in the research concerning the modulation of gut microbiota for T2DM intervention by a spectrum of bioactive components in traditional Chinese medicine, encompassing polysaccharides, alkaloids, flavonoids, saponins, and other compounds. The objective of this review is to furnish a comprehensive theoretical framework supporting the preventive and therapeutic potential of traditional Chinese medicine in T2DM management, thereby significantly contributing to the modernization of traditional Chinese medicine.