Sugarcane smut caused by Sporisorium scitamineum is one of the major diseases affecting the development of China's sugar industry, and biocontrol is currently the most efficient and safe means, which necessitates the screening of antagonists with strong environmental adaptability and inhibitory effects. [Objective] To isolate and identify the strains with good antagonistic effects against S. scitamineum from soil and provide high-quality biocontrol strain resources for the efficient prevention and control of sugarcane smut. [Methods] The antagonists were isolated by the plate confrontation assay, and their taxonomic status was determined by morphological observation, physiological and biochemical tests, and 16S rRNA gene sequencing. The pot and field experiments were conducted to study the inhibition effects of the antagonists on sugarcane smut. [Results] Three strains of bacteria with significant antagonistic effects were obtained. Strains GB-3 and GH16-3 were identified as Bacillus velezensis and GH16-8 as B. amyloliquefaciens, with the inhibition zone diameters of (30.00±1.07), (44.00±1.21), and (18.00±0.89) mm and the inhibition rates of 16.12%, 31.92%, and 5.91%, respectively. The inhibition effects of the three strains against sugarcane smut were 74.33%, 76.57%, and 69.07% in pots and 20.08%, 55.59%, and 50.08% in fields, respectively. All the three strains had phosphorus-solubilizing ability, tolerance to extreme salt-alkaline environments, and inhibitory effects on a variety of phytopathogenic bacteria and fungi, with the indole-3-acetic acid (IAA) yields of 2.12, 1.30, and 1.22 mg/L, respectively. The application of the three strains increased the sugarcane plant height by 28.25%, 17.09%, and 23.31%, respectively. [Conclusion] Strain GH16-3 has strong environmental adaptability, growth-promoting effect, and prevention effect against sugarcane smut, demonstrating a promising application prospect.

[Objective] Soft rot is one of the major diseases affecting the yield and quality of konjac. This study screened a strain with antagonistic effect on Pectinobacterium aroidearum from the rhizosphere soil of konjac, aiming to provide germplasm resources for the biocontrol of soft rot in konjac. [Methods] An antagonistic strain was screened by the plate confrontation method, and its antagonistic effects on pathogenic fungi were measured. The control effect of GZA12 on soft rot in konjac was examined by the inoculation in konjac corm tissue, pot experiment, and root irrigation. The growth-promoting effect of this strain was tested indoors and preliminarily verified by tomato pot experiments. [Results] A strain GZA12 with antagonistic effect was screened out and identified as Bacillus velezensis. This strain showed the inhibition zone diameter of 21.33 mm against P. aroidearum and the inhibition rates of 58.16%, 47.30%, and 54.53% against Botryosphaeria dothidea, Fusarium oxysporum, and F. solani, respectively. Inoculation of GZA12 in konjac corm tissue decreased the disease index by 26.67%, 33.33%, and 40.00%, respectively, compared with the inoculation of B. dothidea alone. In the pot experiment, the treatment with GZA12 suspension decreased the disease index by 22.85% compared with the control group and reached the control effect of 53.31%. The results from the root irrigation experiment showed that compared with water irrigation, irrigation with GZA12 fermentation broth reduced the disease index by 4.89% and reached the control effect of 21.57%. Strain GZA12 had the ability to fix nitrogen, solubilize phosphorus, and produce siderophores and indole-3-acetic acid (IAA). Inoculation with GZA12 suspension promoted the growth of tomato seedlings in a concentration-dependent manner. [Conclusion] Strain GZA12 can inhibit the pathogen causing soft rot and promote the growth of konjac, demonstrating the potential for further development and utilization.

[Objective] To investigate the effects of a metabolite cocktail composed of indole-3-propionic acid (IPA), sodium butyrate (SB), and valeric acid (VA) of gut microbiota on the proliferation of hepatocellular carcinoma cells. [Methods] The human hepatocellular carcinoma HepG2 cells were cultured in vitro and treated with the cocktail at different concentrations (1×, 2×, 3×, 4×, and 5×). The total cholesterol (TC) and triglyceride (TG) levels in the cells were determined by the total cholesterol and triglyceride assay kits. The Cell Counting Kit-8 (CCK-8) and colony formation assays were employed to examine the cell proliferation. Twelve BALB/c athymic nude mice were randomized into a control (Ctrl) group and a treatment (Treat) group and then subjected to subcutaneous injections of HepG2 cells. The tumor size was measured every three days, and the tumor volume and tumor inhibition rate were calculated. When the tumor volume reached 100 mm³, the mice in the Ctrl group were administered with sterile water by gavage daily, while those in the Treat group received the cocktail via gavage until euthanized under anesthesia. After 27 days of treatment, the body weights of mice in both groups were measured, and tumors were excised and weighed, with the tumor weight/body weight ratio calculated. The content of Ki-67 protein in the tumors was determined by immunohistochemical (IHC) staining, and the lipid accumulation within tumor cells was assessed by Oil Red O staining. [Results] The cocktail of IPA, SB, and VA lowered the levels of TC and TG in hepatocellular carcinoma HepG2 cells and exerted an inhibitory effect on the proliferation of HepG2 cells. Both CCK-8 and colony formation assays indicated that the cocktail inhibited the proliferation of HepG2 cells in a dose-dependent manner. The oral administration of the cocktail inhibited the growth of hepatocellular carcinoma cells, as evidenced by smaller and lighter tumors and lower tumor weight/body weight ratios in the Treat group than in the Ctrl group (Ctrl: 723 mm³, 0.47 g, 22.23%; Treat: 526 mm³, 0.32 g, 16.65%). IHC and Oil Red O staining further demonstrated reductions in Ki-67 expression and lipid accumulation in the mice administered with the cocktail via gavage. [Conclusion] The cocktail of IPA, SB, and VA can inhibit the proliferation and suppress the lipid synthesis of hepatocellular carcinoma cells.

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.

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.

[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.

[Objective] Outer membrane vesicles (OMVs) are spherical bilayer membrane structures secreted by Gram-negative and some Gram-positive bacteria. OMVs contain abundant surface antigens and are of great research significance in vaccine development. However, the presence of lipopolysaccharides (LPS), which is the primary component of OMVs, arouses safety concern. Therefore, genetically modifying bacterial LPS to produce safe and efficient OMVs is a viable approach to enhance the production and application of OMVs. [Methods] We modified Salmonella minnesota Re595 with O antigen and most core antigen deletions by deleting the acyl chain coding gene msbB and inserting the phosphatase coding gene lpxE from Francisella novicida to reduce acyl chains and phosphate groups on lipid A, thus obtaining less toxic LPS. LPS and OMVs were extracted from the starting strain and modified strain, and their pro-inflammatory activities were compared between the two strains. In addition, inactivated foot-and-mouth disease virus vaccines were prepared with OMVs to assess the immune adjuvant activity of OMVs. [Results] The modification of LPS reduced the endotoxin activity and pro-inflammatory responses while significantly increasing the immune adjuvant activity of OMVs. [Conclusion] This study demonstrates that the modification of LPS can attenuate the toxicity and enhance the immune adjuvant activity of bacterial OMVs. These findings provide a theoretical foundation for utilizing OMVs as immune adjuvants in the future.

Isoquercetin is a flavonoid with antioxidant, anti-inflammatory, and immunomodulatory activities. However, the low content in plants poses a challenge to the large-scale production of isoquercetin by the extraction method.[Objective] α-L-rhamnosidase can specifically hydrolyze the terminal L-rhamnose residues of natural glycosides. In this study, we screened the strains capable of efficiently and specifically transforming rutin to produce isoquercetin with rutin as the sole carbon source and applied the α-L-rhamnosidase to the production of isoquercetin, aiming to provide new elements for the large-scale production of isoquercetin. [Methods] The selective culture medium with rutin as the sole carbon source was used to screen and identify the strains that can specifically hydrolyze rutin into isoquercetin. The transcriptome analysis was carried out to obtain highly efficient and specific α-L-rhamnosidase, the domain composition of which was determined by structural simulation. The enzymatic properties and substrate specificity of the α-L-rhamnosidase were studied. Furthermore, the hydrolysis effect of the enzyme heterologously expressed in Pichia pastoris in a 5 L fermenter was determined. [Results] AfRhase had five domains, including one α-domain (domain A) and four β-domains (domains N, E, F, and C). With rutin as the substrate, the recombinant enzyme AfRhase showcased the best performance at 55 ℃ and pH 4.5. AfRhase had a wide range of substrates including rutin, hesperidin, naringin, and epimedin C. In a 5 L fermenter for scaled-up production of isoquercetin, P. pastoris expressing AfRhase generated 61 g isoquercetin by hydrolyzing 120 g crude rutin (purity of 70%), with the molar conversion rate of 95.4% and production efficiency of 2.0 mmol/(L·h). [Conclusion] This study for the first time discovered a highly efficient and specific α-L-rhamnosidase from Aspergillus sp. XT-1 for the production of isoquercetin from rutin and heterologously expressed this enzyme in P. pastoris. The domain composition, enzymatic properties, substrate specificity, and hydrolysis efficiency in a 5 L fermenter of this enzyme were determined. In conclusion, this study broadened the function of a fungus-derived α-L-rhamnosidase for the transformation of rutin and laid a foundation for the industrial production of isoquercetin.

Beneficial bacteria in the gut affect human health, and it is generally believed that the assemblage of healthy gut flora is achieved through vertical transmission of by breastfeeding in early infancy. There is limited evidence for the difference in the composition of beneficial bacteria across different mother-infant cohorts and the presence of population-specific microbial taxa. [Objective] To investigate Lactobacillus spp. and the vertical transmission and genetic differences of the dominant species Lacticaseibacillus paracasei among mother-infant cohorts of different ethnic groups, providing a theoretical basis for developing personalized probiotic regimens. [Methods] Lactobacillus strains were isolated from 39 mother-infant pairs of three ethnic groups without mixed marriage in China and identified by repetitive extragenic palindromic PCR (rep-PCR) and groEL sequences. The genetic differences of 83 strains of L. paracasei, a representative species, were analyzed by multilocus sequence typing (MLST). [Results] The species and abundance of Lactobacillus varied among the mother-infant pairs of different ethnic groups. A total of 945 Lactobacillus strains were isolated, belonging to 15 species of 4 genera. L. rhamnosus (20.07%), L. paracasei (16.54%), and L. casei (11.90%) were dominant species in the Han ethnic group, while L. casei (13.55%), L. paracasei (12.69%), and Ligilactobacillus salivarius (11.47%) were dominant bacteria in Uighur ethnic group in Hotan. The dominant species in the Li ethnic group in Hainan were Limosilactobacillus oris (24.55%), L. paracasei (15.85%), and Lactobacillus gasseri (10.87%). The 83 strains of L. paracasei were classified into 11 phylogenetic groups by rep-PCR and 31 sequence types (STs) by MLST, demonstrating ethnic specificity. L. paracasei isolates from the same mother-infant pair had the same STs, and isolates from the mother-infant pairs of the same ethnic group had higher genetic similarity. [Conclusion] Lactobacillus species varied in the mother-infant pairs of different ethnic groups, and L. paracasei strains from the same origin displayed higher genetic similarity, which supported vertical transmission at strain level and ethnic specificity.