To explore the flavonoids from Morus alba L. leaves (MLF), the process of extracting was optimized by a response surface methodology and the antimicrobial and antioxidant activities were evaluated in vitro. The yield of flavonoids reached 50.52 mg g⁻¹ under the optimized extraction conditions (i.e., extraction temperature, 70.85 °C; solvent concentration, 39.30%; extraction time, 120.18 min; and liquid/solid ratio, 34.60:1). The total flavonoids were extracted in organic solvents with various polarities, including petroleum ether (MLF_p), ethyl acetate (MLF_e), and n-butanol (MLF_b). In vitro, the four MLF samples exhibited good antioxidant activities for scavenging of 2, 2′-azinobis-(3-ethylbenz-thiazoline-6-sulphonate) radical, 1, 1-diphenyl-2-picrylhydrazyl radical, and total reducing power. Regarding antimicrobial efficacy, the MLF samples suppressed the development of Staphylococcus aureus, Bacillus subtilis, and Bacillus pumilus. The MLF samples inhibited α-amylase activity to a certain extent. The analytical hierarchy process (AHP) was used to evaluate comprehensively the bioactivities of the MLF samples. The AHP results revealed that the bioactivity comprehensive score (78.83 μg mL⁻¹) of MLF_e was optimal among the four MLF samples. Morus alba L. leaves also exhibited non-hemolytic properties. All bioactivities suggested the potential of MLF_e as a candidate resource in the food and drug industries.

Essential oil (Eo) from the Citrus reticulata peel has been widely used, and its adhesive effect on polystyrene (PS) was found accidentally. To analyze the essential oils of C. reticulata cv. Shatangju (CrspEos), the extraction of these oils by steam distillation was optimized using the response surface method. The chemical composition of CrspEos was analyzed by gas chromatography–mass spectrometry. Then, the adhesive effect of these essential oils on PS was evaluated. The adhesion area, the influence of adhesion on the thickness of the essential oil on the materials, the effect of adhesion on the transmittance of PS, the strength of adhesion point, and specificity of adhesion were determined. The optimum extraction conditions resulting in the extraction yield of 47.37 μL g^–1 were a ratio of liquid-to-solid of 8.94:1, a soaking time of 199.45 min, and an extraction time of 138.71 min. The major component in the essential oils was d-limonene (56.66%), followed by myrcene (6.62%). CrspEos presented a specific adherence effect on PS without influencing the thickness and transmittance of PS but with stronger tenacity than the parent material. CrspEos can be used as an environmentally friendly specific adhesive for PS.

During the life activities of microorganisms, a variety of secondary metabolites are produced, including antimicrobials and antitumor drugs, which are widely used in clinical practice. In addition to exploring new antibiotics, this makes it one of the research priorities of Actinomycetes to effectively increase the yield of antibiotics in production strains by various means. Most antibiotic-producing strains have a variety of functional regulatory factors that regulate their growth, development, and secondary metabolite biosynthesis processes. Through the study of precursor substances in antibiotic biosynthesis, researchers have revealed the precursor biosynthesis process and the mechanism by which precursor synthesis regulators affect the biosynthesis of secondary metabolites, which can be used to obtain engineered strains with high antibiotic production. This paper summarizes the supply of antibiotic biosynthesis precursors and the progress of research on the role of regulators in the process of precursors in biosynthesis. This lays the foundation for the establishment of effective breeding methods to improve antibiotic yields through the manipulation of precursor synthesis genes and related regulators.

The principal objectives of this study encompass three distinct aspects: firstly, to streamline the extraction process of Phragmites communis (Cav) Trin essential oil; secondly, to systematically analyze the essential oil’s chemical composition; and finally, to evaluate biological activity. Through the system optimization experiment, the optimal extraction process was determined: the crushing size was set to 10 mesh, the total solid-liquid ratio was 19:1 (mL/g), and the extraction time limit was 5 hours. Under this condition, the maximum yield of essential oil was 0.233% (mass fraction). In addition, the GC-MS (gas chromatography-mass spectrometry) composition of pure essential reed oil (PCT-Eos) was analysed, and 27 different compounds were detected. The major components included: 2-(2-ethylhexoxycarbonyl) benzoic acid (15.78%), 2,2'-methylenebis (6-tert-butyl- 4-methylphenol) (9.96%), pentacosane (4.97%), triacontane (4.96%), dibutyl phthalate (4.92%), dotriacontane (4.64%), and nonacosane (4.17%). The findings of the activity test demonstrated that this essential oil possessed a moderate antioxidant capacity, with IC50/EC50 values of 2.42 ± 0.311, 3.5 ± 0.306, 6.5 ± 0.395, and 9.8 ± 0.557 mg/mL. In both microdilution assessments, concurrently exhibiting significant inhibitory effects on various pathogenic bacteria, the respective minimum inhibitory concentrations (MICs) were determined to be 72.00, 72.00, 43.20, 9.33, and 120.00 mg/mL. These findings indicate that PCT-Eos possesses significant potential for applications in the food, pharmaceutical, and chemical sectors due to its notable antimicrobial and antioxidant properties.

In Streptomyces ahygroscopicus, the homologous PAS-LuxR regulators NysRIV and TtmRIV govern nystatin and tetramycin biosynthesis, respectively. To confirm their functional relationship within the same strain, gene deletion, complementation, domain swapping, electrophoretic mobility shift assays, transcriptomics, qRT-PCR, and CoA-derived metabolite measurements were combined to characterize their regulatory roles. Deletion of nysRIV abolished nystatin production, and native nysRIV complementation restored nystatin partially (about 17% of the parental level) in the ΔttmS₁ΔnysRIV background and not at all in ΔnysRIV, indicating that NysRIV is required for full nystatin production. TtmRIV and the two chimeric regulators failed to substitute for NysRIV, indicating limited regulatory interchangeability. Their DNA-binding preference regulators largely followed the origin of their HTH domains, supporting an important contribution of the C-terminal HTH region to differential promoter recognition in vitro. Their effects on polyene production also depended on genetic background. Transcriptomics of the nysRIV deletion mutant revealed changes in lipid, polyketide, pyruvate, and CoA-related metabolism, accompanied by altered acc-gene expression and intracellular CoA-derived metabolite pools. Together, these results indicate distinct but partially overlapping roles of NysRIV and TtmRIV in polyene biosynthesis and highlight the influence of regulator identity and host genetic background on PAS-LuxR regulatory outcomes.