[Objective] Riemerella anatipestifer (RA) is a Gram-negative bacterium that mainly infects domesticated birds such as ducks and geese. The clinical isolates of RA are multi-drug resistant and increasing year by year. However, the transmission ways of antibiotic resistance genes in RA have not been identified. This study aims to identify the transmission ways and distribution of antibiotic resistance genes in the clinical isolates of RA. [Methods] The drug resistance phenotypes of the reference strain RA ATCC 11845 and the clinical isolates RA CH-1 and RA CH-2 to 28 antibiotics belonging to 10 categories were determined. The antibiotic resistance genes were identified by genome analysis and construction of gene deletion strains. The transmission ways of antibiotic resistance genes were identified by natural transformation. The distribution of these resistance genes in different clinical isolates was detected by PCR. [Results] RA CH-1 and RA CH-2 were resistant to β-lactams, tetracyclines, macrolides, lincosamides, and amide alcohols, while RA ATCC 11845 was sensitive to the above antibiotics. The resistant strains became sensitive to the corresponding antibiotics after the deletion of 13 resistance genes, respectively, indicating that these genes were involved in antibiotic resistance. All the resistant genes can be transferred to the sensitive strain RA ATCC 11845 by natural transformation. The detection rates of resistance genes in 100 clinical isolates from 2017 to 2023 varied within the range of 3% to 89%. [Conclusion] Antibiotic resistance genes can be transmitted in RA through natural transformation, and different antibiotic resistance genes presented varied distribution in clinical isolates, among which tetX (B739_0030) and bla_OXA (G148_1768) were carried by the most and fewest strains, respectively.

Lignin, the most abundant aromatic biopolymer resource in the nature, is difficult to be degraded by common microorganisms due to its complexity and highly aggregated aromatic structure. Lignin-degrading microorganisms from extreme environments are considered as suitable candidates for lignin bioprocessing. This review summarizes several types of extremophiles capable of degrading lignin and the extremozymes produced by them and elucidates the properties, catalytic mechanisms, and metabolic pathways of the extremozymes. Furthermore, this article discusses the prospects for the identification of novel extremophiles and extremozymes by multi-omics and makes an outlook on the development and utilization methods of extremophiles, with a view to providing a reference for the subsequent screening and development of more efficient lignin-degrading strains.

[Objective] To develop probiotics for gynecological inflammation, we isolated and screened out Lactobacillus with antimicrobial and probiotic properties from the vagina of healthy women. [Methods] The plate streaking method was employed to isolate the Lactobacillus strains from vaginal samples, and the isolates were then identified based on morphological and 16S rRNA gene sequencing evidence. The growth and adhesion of the five strains were characterized. The Oxford cup method with Escherichia coli and Staphylococcus aureus as indicator strains was employed to assess the antimicrobial activities of the strains. The microtiter plate method was used to measure the inhibitory effects of the strains on Candida albicans. The antimicrobial components were explored by organic acid elimination and hydrogen peroxide elimination methods. [Results] Five strains of Lactobacillus were isolated, including three strains (Q2.1, BHC04, and Q8.5) of Lactobacillus crispatus and two strains (Q6.3 and BHG05) of Lactobacillus gasseri. All the five strains of Lactobacillus had strong growth and high acid production. Strains Q2.1, BHC04, and BHG05 had a short delay period and reached a plateau growth stage after 20 h, and strains BHG05, Q6.3, and Q8.5 had high acid production, with the culture medium finally reaching pH 3.80–4.03. The adhesion capacity (hydrophobicity, self-agglutination rate, and co-agglutination rate with pathogens) of L. crispatus Q2.1, BHC04, and Q8.5 was significantly higher than that of the positive control strain, L. delbrueckii DM8909. The inhibitory effects of the five strains on E. coli, S. aureus, and C. albicans were stronger than those of the positive control (nisin). Strains BHC04, BHG05, and Q8.5 showcased stronger inhibitory effects on E. coli than DM8909. The inhibitory effect of BHG05 on C. albicans was significantly stronger than that of DM8909, with the inhibition rate reaching up to (73.14±0.14)%. The inhibitory effects of BHC04 and Q8.5 on C. albicans were not significantly different from that of DM8909, with the inhibition rates reaching up to (72.80±0.30)% and (72.93±0.10)%, respectively. According to the results above, we selected BHC04 and BHG05 as high quality strains with antimicrobial potential. The five strains produced organic acids and hydrogen peroxide to exert antimicrobial effects. [Conclusion] Two strains of Lactobacillus with antimicrobial effects and excellent probiotic properties were screened out. They can be used as candidate strains of antimicrobial probiotics for the prevention and treatment of gynecological inflammation caused by E. coli, S. aureus, and C. albicans.

Probiotics refer to live microorganisms that are beneficial to the health of the host when ingested in sufficient quantities, and their beneficial effects have been widely recognized. However, the probiotic function of probiotics is strain-specific. As more and more emerging technologies are introduced into the research on probiotics, the screening of probiotics with specific functions according to individual needs has become a research hotspot. Conventional probiotic screening methods have limitations and cannot meet the current demand for precision medicine. Therefore, a bottom-up precision screening strategy for probiotics based on phenotyping, genotyping, and target is of great practical significance. This article discusses the theoretical basis, methods, and technologies of accurate screening of probiotics from phenotype, genotyping, and target, and the application and safety evaluation of probiotics, aiming to provide reference for the accurate screening of probiotics.

[Objective] To realize the de novo biosynthesis of caffeic acid from glucose by reconstruction of its biosynthetic pathway in Escherichia coli. Fine-tuning gene expression allows us to improve caffeic acid production, which paves a way for the high production of caffeic acid and its derivatives in E. coli. [Methods] The biosynthetic pathway of caffeic acid was reconstructed based on FjTAL and EchpaBC, which encoded the tyrosine ammonia lyase in Flavobacterium johnsoniaeu and the 4-hydroxyphenylacetate 3-hydroxylase complex in E. coli, respectively. The reconstructed pathway was then introduced into commonly used E. coli strains. We improved the expression levels of FjTAL and EchpaBC by screening constitutive promoters, utilizing an intermediate-based biosensor, and increasing the copy number of the key gene. Thus, a total of fourteen recombinant strains were obtained, and the production of caffeic acid and the intermediate p-coumaric acid in these strains was quantified by HPLC. Moreover, the effects of different nitrogen sources and substrate concentrations on the production of caffeic acid were investigated. [Results] We realized de novo biosynthesis of caffeic acid from glucose in E. coli. The use of constitutive promoters other than the commonly used T7 promoter contributed to the yield increase of caffeic acid. When glucose was used as the substrate, the yield of caffeic acid was increased from 1.40 mg/L to 96.40 mg/L. When tyrosine was used as the substrate, the yield of caffeic acid was increased from 1.78 mg/L to 123.31 mg/L. Furthermore, the yield of caffeic acid reached 162.73 mg/L when a p-coumaric acid biosensor instead of a constitutive promoter was used to drive the expression of EchpaBC. Moreover, the yield of caffeic acid was improved to 185.15 mg/L in the case of introducing an extra copy of EchpaBC. [Conclusion] We constructed the strains with high production of caffeic acid by promoter engineering, using an intermediate-base biosensor, and increasing copy number of the key gene. Our study laid a solid foundation for the high production of caffeic acid.

With the increasing emphasis on health, probiotics have garnered increasing attention due to their safe and beneficial features for intestinal health and have become a hot spot in the fields of food and medicine. In terms of oral drug delivery, it is difficult to select a safe, convenient, and stable carrier. Probiotics can be used as carriers to deliver drugs through the complex in vivo environment without damage and have excellent safety and stability. This review describes the structures, advantages, and disadvantages of five common probiotic-based oral drug delivery approaches: display on spore surface, yeast microcapsules, recombinant probiotic expression, bacterium-like particles, and bacterial ghost, aiming to provide options for the application of oral delivery carriers.

[Objective] To investigate the effects of hydrogen sulfide (H₂S) on the structures of phyllosphere and rhizosphere microbial communities of soybean plants under drought stress. [Methods] High-throughput sequencing of the 16S rRNA gene was combined with bioinformatics analyses (α and β diversity, species composition, co-occurrence networks analysis, etc.) to study the phyllosphere and rhizosphere microbial communities of soybean plants before and after NaHS treatment. [Results] For the soybean plants under normal moisture conditions, the addition of NaHS decreased the diversity and increased the endemic species of phyllosphere microbial community. The addition of NaHS increased the diversity of rhizosphere microbial community of soybean plants under normal moisture conditions but not under severe drought. In addition, exogenous addition of NaHS altered the bacterial co-occurrence network, and the microbial communities in both phyllosphere and rhizosphere were so aggregated that neither rhizobium inoculation nor NaHS addition had significant influences on them. The addition of NaHS mildly affected the relative abundance of operational taxonomic unit (OTU) in the phyllosphere and decreased the relative abundance of OTU in the rhizosphere, which was particularly pronounced under severe drought. Rhizobium inoculation and NaHS addition enriched different microbial taxa in both phyllosphere and rhizosphere. [Conclusion] Under drought stress, H₂S had an insignificant modulating effect on the microbial community structure in the phyllosphere but a pronounced effect on the microbial community structure in the rhizosphere of soybean plants. H₂S reduced the relative abundance of total OTU in the rhizosphere and altered the bacterial co-occurrence network, thus influencing soybean adaptation to drought stress.

Innate immunity constitutes the first line of immune defense. As a part of the body's innate immunity, the antimicrobial peptide LL-37 plays a crucial role in maintaining homeostasis, with two primary functions: direct antimicrobial activity and immunomodulation. Currently, research on LL-37 mainly focuses on its function, while its induced expression in vivo has rarely been studied. However, understanding the induced expression of LL-37 is essential for delving into the body's immune defense mechanisms. Therefore, this paper briefly reviewed the research progress on the synthesis and functions of LL-37, the factors inducing its secretion, and the regulatory pathways involved in its induced expression. The aim is to offer new insights into the regulatory pathways and immune defense functions of LL-37 in the human body.

Parkinson's disease is a common neurodegenerative disorder that seriously threatens the health of middle-aged and elderly individuals. However, the pathogenesis of Parkinson's disease is not fully understood. Recent studies have shown that gut microbiota plays an important role in the occurrence and development of Parkinson's disease. Gut microbiota and its metabolites influence the intestinal mucosal barrier, neuroinflammation, endocrine system, and other aspects through the microbiota-gut-brain axis, thereby participating in the occurrence and development of Parkinson's disease. Gut microbiota can be regulated by various methods such as probiotic supplementation, fecal microbiota transplantation, dietary adjustments, and traditional Chinese medicine interventions, being an important target for the prevention and treatment of Parkinson's disease. This article reviews the possible mechanisms of gut microbiota being involved in the occurrence of Parkinson's disease and further discusses the current status of prevention and treatment of gut microbiota dysbiosis.

[Objective] Bovine bones contain a large amount of beneficial nutrients such as proteins, mineral salts, and vitamins for human health. With the calcium-to-phosphorus ratio meeting the optimal absorption ratio for the human body, bovine bones serve as a valuable nutrient source. [Methods] Lactic acid bacteria with high yields of L-lactic acid were screened by the calcium-dissolving ring method and the performance of strains in L-lactic acid production was then determined via fermentation of bovine bone meal. Metabolomics was employed to explore the differential metabolites and main pathways during the fermentation. [Results] One strain LP15, identified as Lactobacillus plantarum, was isolated from the liquid sample in the production of sour bamboo shoots for its strong ability to produce L-lactic acid. After fermentation of bone meal for 96 h, the strain produced 3.89 g/L L-lactic acid and 69.82 mg/100 mL free calcium, which represented a 32.6-fold increase compared with that in the control group. The metabolomic analysis revealed ABC transporters, metabolic pathway, and biosynthesis of secondary metabolites as the most important differential metabolic pathways during the fermentation of bovine bone meal. Meanwhile, a huge number of physiological active substances, such as cyclocreatine and 2-hydroxy-2-methylbutyric acid, were detected in the fermented bone meal. [Conclusion] Fermentation of bovine bone meal by L. plantarum LP15 is an effective strategy to promote calcium dissolution and produce beneficial active substances. This study lays a practical foundation for developing health food products by microbial fermentation of bovine bone meal.