Antibacterial Bioactivity Research Articles

Two new abietane diterpenoids from Caryopteris trichosphaera

Two new abietane diterpenoids, cartrisine A (1) and cartrisine B (2) were isolated from Caryopteris trichosphaera. Their structures were elucidated based on HR-ESI-MS and NMR spectral data. Compound 2 exhibited moderate antibacterial bioactivity against MRSA and VRE, and showed a strong synergistic effect with market antibiotics against MRSA and VRE.

Evaluating the bio-functionalities of Ti-6Al-7Nb alloy after surface modification using electrical discharge machining

The present work evaluates the influence of surface modification on the bio-functionalities of Ti-6Al-7Nb alloy in terms of apatite formation, metal ion release rate and anti-bacterial activities. The surface modification in the form of change in surface integrity, and increases in the exposed surface area, has been achieved using wire-electrical discharge machining (WEDM) and electrical discharge μ-drilling(EDD). Due to high discharge energies, molten material will deposit on the parent material (recast layer), which increases the surface roughness (parent surface 0.5 μm to 2.34 μm) and hardness (patent material 304VH to 385VH) after subsequent re-solidification and quenching. Surface roughness and hardness near the micro-drilled hole are observed to increase. After surface modification, the apatite formation is increased on Ti-6Al-7Nb alloy with increasing immersion time and the ion released rate was found lowest on the WEDMed surface as compared to micro drilled and polished surface. Field-emission electron scanning microscopy (FESEM) and energy dispersive x-ray spectroscopy (EDAX) observations confirmed the presence of phosphate and calcium ions on the WEDMed surface and nearby the micro-drilled surface. The variation in colour of the simulated body fluid (SBF) after the immersion of WEDMed, EDD, and polished samples indicates the variable effecton pH levels of the SBF solution for three types of samples.The anti-bacterial bioactivity of Ti-6Al-7Nb was found to be better on the WEDMed surface as compared to polished surfaces, which is due to the formation of a rutile-TiO2 layer on WEDMed surface.

Utilization of carbon catabolite repression for efficiently biotransformation of anthraquinone O-glucuronides by Streptomyces coeruleorubidus DM.

Carbon catabolite repression (CCR) is a highly conserved mechanism that regulates carbon source utilization in Streptomyces. CCR has a negative impact on secondary metabolite fermentation, both in industrial and research settings. In this study, CCR was observed in the daunorubicin (DNR)-producing strain Streptomyces coeruleorubidus DM, which was cultivated in high concentration of carbohydrates. Unexpectedly, DM exhibited a high ability for anthraquinone glucuronidation biotransformation under CCR conditions with a maximum bioconversion rate of 95% achieved at pH 6, 30°C for 24 h. The co-utilization of glucose and sucrose resulted in the highest biotransformation rate compared to other carbon source combinations. Three novel anthraquinone glucuronides were obtained, with purpurin-O-glucuronide showing significantly improved water solubility, antioxidant activity, and antibacterial bioactivity. Comparative transcript analysis revealed that glucose and sucrose utilization were significantly upregulated as DM cultivated under CCR condition, which strongly enhance the biosynthetic pathway of the precursors Uridine diphosphate glucuronic acid (UDPGA). Meanwhile, the carbon metabolic flux has significantly enhanced the fatty acid biosynthesis, the exhaust of acetyl coenzyme A may lead to the complete repression of the biosynthesis of DNR, Additionally, the efflux transporter genes were simultaneously downregulated, which may contribute to the anthraquinones intracellular glucuronidation. Overall, our findings demonstrate that utilizing CCR can be a valuable strategy for enhancing the biotransformation efficiency of anthraquinone O-glucuronides by DM. This approach has the potential to improve the bioavailability and therapeutic potential of these compounds, opening up new possibilities for their pharmaceutical applications.

Pathology‐Guided Cell Membrane‐Coated Polydopamine Nanoparticles for Efficient Multisynergistic Treatment of Periodontitis

AbstractNanodrug delivery systems (NDDSs) for the treatment of periodontitis remain a significant clinical challenge. The low biocompatibility, singular effect, and lack of disease specificity of conventional nanoparticles limit their biomedical application. Recent studies have highlighted the pivotal role of cell membrane‐coated nanotechnology in anti‐inflammatory strategies due to its improved biocompatibility and superior biointerface properties. Herein, combined with the pathological heterogeneity of periodontitis revealed by bioinformatics analysis, this study develops a novel cell membrane‐coated nanoparticle composed of two elements: minocycline‐loaded polydopamine nanoparticles (PM) and cRGD‐modified cell membrane (RCM). The in vitro results indicate that PM@RCM rescues impaired human periodontal ligament stem cells through antioxidant, anti‐ferroptosis, anti‐inflammatory, and pro‐osteogenic effects, and exhibits favorable antibacterial bioactivity. The in vivo studies further reveal that PM@RCM promotes periodontal tissue regeneration and remodeled periodontal homeostasis in periodontitis mice. Collectively, these findings highlight the unique pathological changes in periodontitis. Moreover, the novel NDDS developed in this study, which leverages the excellent natural properties of cell membrane‐coated nanotechnology and the versatility of nanoparticle cores, provides a promising strategy for the clinical treatment of periodontitis.

Cycloartobiloxanthone, a Flavonoid with Antidiabetic, Antibacterial and Anticancer Activities from Artocarpus kemando Miq.

In this present work, a cycloartobiloxanthone compound was isolated from the stem wood and root bark of the Pudau plant (Artocarpus kemando Miq.). The purity of the compound was determined using thin-layer chromatography with three eluent systems and melting point tests. The sample was then analyzed using UV-Vis, IR, and NMR spectroscopy, ensuring that the compound is cycloartobilox-anthone. The cycloartobiloxanthone compound was obtained in a yellow crystalline form with a melting point of 285.1-294°C. The compound was then investigated for antidiabetic, anticancer, and antibacterial properties, showing that the compound has an anti-diabetic effect by reducing the activity of the α-amylase enzyme, with the highest percentage of inhibition of 48.53 ± 1.84% achieved with the use of 1000 ppm of the compound. Cycloartobiloxanthone isolated has an IC50 value of 9.21 µg/mL for anticancer activity against MCF-7 cells, indicating that the compound shows active cytotoxic actions. Staphylococcus aureus was very strongly inhibited by the compound in the antibacterial test at all doses, whereas for Salmonellasp., the activity was categorized as moderate at concentrations of 0.4 and 0.3 mg/disc and strong at 0.5 mg/disc. The anti-diabetic, anti-cancer, and antibacterial bioactivity studies indicated that the cycloartobiloxanthone compound isolated has a broad spectrum of pharmacological actions, indicating that the compound has promising potential. Doi: 10.28991/ESJ-2024-08-01-04 Full Text: PDF

Antibacterial nanocomposite of chitosan/silver nanocrystals/graphene oxide (ChAgG) development for its potential use in bioactive wound dressings

An adequate wound dressing reduces time of healing, provides cost-effective care, thereby improving patients’ quality life. An antimicrobial bioactivity is always desired, for that reason, the objective of this work is to design an antimicrobial nanocomposite of chitosan/silver nanocrystals/graphene oxide (ChAgG). ChAgG nanostructured composite material is composed of chitosan from corn (Ch), and silver nanocrystals from garlic (Allium sativum). The nanocomposite obtained is the result of a series of experiments combining the graphene oxide (GrOx) with two members of the Amaryllidaceae family; garlic and onion (Allium cebae), which contain different sulfur materials. The characterization arrays confirmed the successful production of silver crystal, graphene oxidation and the blending of both components. The role of the chitosan as a binder between graphene and silver nanocrystals is proved. Moreover, the study discusses garlic as an optimal source that permits the synthesis of silver nanocrystals (AgNCs) (⁓ 2 to 10 nm) with better thermal and crystallinity properties. It was also confirmed the successful production of the ChAgG nanocomposite. Escherichia coli and Staphylococcus aureus were used to demonstrate the antibacterial bioactivity and L-929 fibroblast cells were utilized to visualize their biocompatibility. The proposed ChAgG nanomaterial will be useful for functionalizing specific fiber network that represents current challenging research in the fabrication of bioactive wound dressings.

Design, Synthesis, Antibacterial Evaluation, Three-Dimensional Quantitative Structure-Activity Relationship, and Mechanism of Novel Quinazolinone Derivatives.

Plant bacterial illnesses are common and cause dramatic damage to agricultural goods all over the world, yet there are few efficient bactericides to alleviate them at present. To discover novel antibacterial agents, two series of quinazolinone derivatives with novel structures were synthesized and their bioactivity against plant bacteria was tested. Combining CoMFA model search and the antibacterial bioactivity assay, D32 was identified as a potent antibacterial inhibitor against Xanthomonas oryzae pv. Oryzae (Xoo), with an EC50 value of 1.5 μg/mL, much better in inhibitory capacity compared to bismerthiazol (BT) and thiodiazole copper (TC) (31.9 and 74.2 μg/mL). The activities of compound D32 against rice bacterial leaf blight in vivo were 46.7% (protective activities) and 43.9% (curative activities), better than commercial drug thiodiazole copper (29.3% protective activities and 30.6% curative activities). Flow cytometry, proteomics, reactive oxygen species, and key defense enzymes were used to further investigate the relevant mechanisms of action of D32. The identification of D32 as an antibacterial inhibitor and revelation of its recognition mechanism not only open the possibility of developing new therapeutic strategies for treatment of Xoo but also provide clues for elucidation of the acting mechanism of quinazolinone derivative D32, which is a possible clinical candidate worth in-depth study.

Novel Gold(III), Palladium(II) and Copper(II) Schiff Base Complexes Derived from 1-Hydroxy-2-acetonaphthone and Phenylethyl Amine: Synthesis, Characterization and Biological Studies

In this work, a novel Schiff base from 1-hydroxy-2-acetonaphthone and phenyl ethylamine and its metal complexes were synthesized and characterized using UV-visible, FT-IR, 1H and 13C NMR, SC-XRD, LCMS, TGA-DSC and powder X-ray diffraction. The IR data indicated that the ligand was coordinated via bidentate bonding through the oxygen atom of naphthone and nitrogen atom of azomethine unit. The TGA-DSC analysis of Au(III), Pd(II), and Cu(II) revealed the presence of coordinated water molecules. According to powder X-ray diffraction data, the Schiff base ligand exhibits a tetragonal crystal structure, Au(III) complex has a cubic crystal structure, while Pd(II) and Cu(II) complexes have monoclinic crystal structures. The synthesized metal complexes were examined for their in vitro antibacterial bioactivity against the Gram-negative bacteria E. coli, P. aeruginosa and Gram-positive S. aureus, B. subtilis as well as their in vitro antifungal activity against the two fungus C. albicans and A. niger. According to the biological findings, the synthesized metal complexes exhibited better antimicrobial activities compared to the Schiff base ligand. Similar, outcomes were followed in the antioxidant activity analysis, where the synthesized Schiff base metal complexes had DPPH radical scavenging activity.

Self-assembled photosensitive carbon nanocrystals with broad-spectrum antibacterial bioactivity

Synthesis and antibacterial applications of self-assembled carbon nanocrystals.

Modified Media for Fungi Symbiont Sponge <I>Agelas</I> sp. (<I>Fusarium</I> sp.) Cultivation against Multidrug-Resistant Bacteria

Highlight Research Fusarium symbiont Agelas sponge has antibacterial activity against aureus and E. coli Multi Drug Resistant Fusarium can grow on modified media soursop juice (SJ) and ginger juice (GJ) and has different inhibitory abilities against bacteria test Fusarium bioactive compounds were analyzed and purified by HPLC Based on TLC visualization, one of the bioactive compounds contained in Fusarium is a steroid group Abstract Marine symbiont fungi, specifically, are likely to have antibacterial properties. The production of secondary metabolites in cultures is strongly influenced by nutrient availability. This study aimed to study the modified media for the cultivation of Fusarium sp. and its antibacterial bioactivity. Fusarium sp. was isolated from Agelas sp. sponge collected from Riung Sea, East South Nusa, Indonesia. In this study, the modified media was soursop juice (SJ), ginger juice (GJ), and sago (S). The fungal mycelium was cultured and scaled up for 7–14 days until the mycelium achieved maximum growth. A filtration funnel and HPLC were used to purify the bioactive compounds. The diffusion agar method was used to test antibacterial activity against the multi-drug resistant (MDR) Staphylococcus aureus and Escherichia coli. The results indicated that Fusarium sp. could grow on soursop juice and ginger juice but could not grow on sago media. The inhibition zone produced by the filtration fraction of Fusarium sp. from each media differed. The soursop juice media produced the largest inhibition zone against both S. aureus (11.56 mm ± 0.140) and E. coli (12.16 mm ± 0.094) at 100 μg/disc. The ginger juice (GJ) and soursop juice (SJ) media are promising as alternative culture media for Fusarium sp. The structure of the bioactive compound Fusarium sp. from GJ and MJ media culture can be further investigated using NMR.

Rationally Designed Minimal Bioactive Domains of AS-48 Bacteriocin Homologs Possess Potent Antileishmanial Properties.

Leishmaniasis, a category I neglected tropical disease, is a group of diseases caused by the protozoan parasite Leishmania species with a wide range of clinical manifestations. Current treatment options can be highly toxic and expensive, with drug relapse and the emergence of resistance. Bacteriocins, antimicrobial peptides ribosomally produced by bacteria, are a relatively new avenue for potential antiprotozoal drugs. Particular interest has been focused on enterocin AS-48, with previously proven efficacy against protozoan species, including Leishmania spp. Sequential characterization of enterocin AS-48 has illustrated that antibacterial bioactivity is preserved in linearized, truncated forms; however, minimal domains of AS-48 bacteriocins have not yet been explored against protozoans. Using rational design techniques to improve membrane penetration activity, we designed peptide libraries using the minimal bioactive domain of AS-48 homologs. Stepwise changes to the charge (z), hydrophobicity (H), and hydrophobic dipole moment (μH) were achieved through lysine and tryptophan substitutions and the inversion of residues within the helical wheel, respectively. A total of 480 synthetic peptide variants were assessed for antileishmanial activity against Leishmania donovani. One hundred seventy-two peptide variants exhibited 50% inhibitory concentration (IC50) values below 20 μM against axenic amastigotes, with 60 peptide variants in the nanomolar range. Nine peptide variants exhibited potent activity against intracellular amastigotes with observed IC50 values of <4 μM and limited in vitro host cell toxicity, making them worthy of further drug development. Our work demonstrates that minimal bioactive domains of naturally existing bacteriocins can be synthetically engineered to increase membrane penetration against Leishmania spp. with minimal host cytotoxicity, holding the promise of novel, potent antileishmanial therapies. IMPORTANCE Leishmaniasis is a neglected tropical disease caused by protozoan parasites of the genus Leishmania. There are three primary clinical forms, cutaneous, mucocutaneous, and visceral, with visceral leishmaniasis being fatal if left untreated. Current drug treatments are less than ideal, especially in resource-limited areas, due to the difficult administration and treatment regimens as well as the high cost and the emergence of drug resistance. Identifying potent antileishmanial agents is of the utmost importance. We utilized rational design techniques to synthesize enterocin AS-48 and AS-48-like bacteriocin-based peptides and screened these peptides against L. donovani using a fluorescence-based phenotypic assay. Our results suggest that bacteriocins, specifically these rationally designed AS-48-like peptides, are promising leads for further development as antileishmanial drugs.

Anti-Acne Activity of Turi Leaves (Sesbania grandiflora (L.) Poir.) against Propionibacterium acne

Turi (Sesbania grandiflora (L.) Poir.) is a native Indonesian plant with many benefits. One of the benefits of Turi leaves is that they can be used as antibacterial agents. Turi leaves contain several compounds with antibacterial bioactivity including tannins, flavonoids, and saponins. This study aimed to examine the activity of Turi leaf extracts against Propionibacterium acne, a bacterium that causes acne. Antibacterial activity testing was performed using the good diffusion method with three replicates. The test groups were X1, X2, and X3, which had extract concentrations of 5%, 7.5%, and 10%, respectively. The positive control group was treated with clindamycin disks. The results of measurements of the diameter of the inhibition zone showed that the mean for groups X1, X2, and X3 were 19.67 mm, 22 mm, and 23.67 mm, respectively. The positive control group was 37 mm. Based on the classifi cation of bacterial growth inhibition responses, the results of the inhibition zone diameter after deducting the good diameter × 10 mm were classifi ed as less eff ective for group X1 and weak for groups X2 and X3. The positive control group was classifi ed as strong. This study concluded that the antiacne activity of Turi leaf extracts at a concentration of less than 10% was weak when compared to the positive control.

Chitosan-Based Formulations Intended as Protective Spray for Mask Surfaces in Prevention of Coronavirus Dissemination.

The extraordinary occurrence of COVID-19 by the fast expansion of viral infections has propelled particular interest in developing novel antiviral and virucidal agents to guarantee personal security. The main objective of this work is to propose novel formulations able to optimize the use of personal protection elements. In recent years, chitosan (CH) has attracted attention for being an interesting multifunctional, biodegradable, non-antigenic, non-toxic, and biocompatible natural polymer with antimicrobial properties. In this work, formulations based on a CH matrix containing silver, and Copper based nanoparticles have been developed. The novelty of this proposal is that almost liquid formulations have been reached, possessing verified properties to inhibit evolved virus such as herpes simplex type 1 (HSV-1) and bovine betacoronavirus (BCoV), the latter belonging to the same family of the well-known the well-known SARS-CoV-2. Besides antibacterial bioactivity; as well as the ability of these formulations to be easily sprayed on various surfaces, including conventional face masks, have been verified and discussed. The results presented in this contribution provide strong evidence on CH films as an ideal biosafe surface-protective for several daily used materials including the conventional face masks.

Secretion of IFN-γ by Transgenic Mammary Epithelial Cells in vitro Reduced Mastitis Infection Risk in Goats.

Mastitis results in great economic loss to the dairy goat industry. Many approaches have attempted to decrease the morbidity associated with this disease, and among these, transgenic strategy have been recognized as a potential approach. A previous mammalian study reports that interferon-gamma (IFN-γ) has potential anti-bacterial bioactivity against infection in vitro; however, its capacity in vivo is ambiguous. In this study, we initially constructed targeting and homologous recombination vectors (containing the IFN-γ gene) and then transferred the vectors into goat mammary gland epithelial cells (GMECs). Enzyme digestion and sequencing analysis indicated that the vectors used in this study were built correctly. Subsequently, monoclonal cells were selected using puromycin and the polymerase chain reaction (PCR) test indicated that IFN-γ was correctly inserted downstream of the casein promoter. Monoclonal cells were then assessed for reducible expression, and reverse transcriptase-PCR (RT-PCR) and Western blot tests confirmed that monoclonal cells could express IFN-γ. Finally, anti-bacterial capacity was evaluated using bacterial counts and flow cytometry analysis. Decreased bacterial counts and cell apoptosis rates in transgenic GMECs demonstrated that the secretion of IFN-γ could inhibit bacterial proliferation. Therefore, IFN-γ gene transfection in goat mammary epithelial cells could inhibit bacterial proliferation and reduce the risk of mammary gland infection in goats.

Inhibition of bacterial growth of Leilem leaf extract (Clerodendrum minhassae Teijsm. &amp; Binn)

Leilem (Clerodendrum minhassae Teism. &amp; Binn.) is a plant endemic to Sulawesi. Leilem leaves are used as a typical food vegetable for the Minahasa tribe. However, leilem leaves were used as a medicinal plant for intestinal worms, abdominal pain and chest pain. There has been no research report on the use of leilem leaves as a source of antibacterial bioactivity. This study aims to obtain the best concentration of antibacterial Leilem leaf extract. Leilem leaves are obtained from North Minahasa. Extraction by maceration method using various solvents with a level of polarity. The test concentrations of the extract were 100 mg/L, 200 mg/L, 400 mg/L and 800 mg/L. As a positive control, clindamycin 400 mg/L was used. The results showed that the percentage of solvent yield was ethanol, which was 1.23% at 1:4 (w/v) maceration. The average diameter of bacterial growth is 12.6 mm. The results of the one way ANOVA analysis showed significant differences between test concentrations (p&gt;0.5). Tukey's test showed that the three extracts significantly inhibited the growth of gram-positive bacteria Staphylococcus aureus strain ATCC 25923. The n-hexane extract showed the best antibacterial activity, followed by ethanol extract and ethyl acetate extract. Leilem leaves are potential to be developed as a source of antibacterial bioactive.

Phytochemical and Antibacterial Constituents of Edible Globe Amaranth Flower against Pseudomonas aeruginosa.

Globe amaranth flower, the edible inflorescence of Gomphrena globose L., was used to treat dysentery and ulcer as well as other infectious diseases caused by microbes in Southwest China, but its function and bioactive components need experimental support. In this study, phytochemical constituents and antibacterial bioactivity of globe amaranth flower against P. aeruginosa were carried out. As a result, two new (1 and 2) and eleven known (3-11) compounds were isolated, in which compounds 4-7 displayed anti P. aeruginosa bioactivity with the minimum inhibitory concentration (MIC) from 0.008 to 0.256 mg/mL. Furthermore, with aid of the scanning electron microscope (SEM) and a superficial skin infection model in mice, the most potent compound 4 can significantly destroy the structure of bacteria in vitro and restore bacterial infection damage in vivo.

Phytochemical and anti-MRSA constituents of Zanthoxylum nitidum

Infectious diseases caused by multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus, pose a significant threat to humanity. Persistent and repeated invasive infection with MRSA led to higher morbidity and mortality, and required comprehensive measures in treatment and prevention. Zanthoxylum nitidum (Roxb.) DC. is used as detoxifying, analgesic, and hemostatic herbal medicine for thousands of years. Previously pharmacological studies showed that Z. nitidum had antibacterial bioactivity, but only the MIC of a few compounds, crude extracts, and fractions were reported. In our ongoing endeavor to explore bioactive compounds, two new coumarins, 6-(3-oxo-butyl)-limettin (1) and toddalin I (2), and 24 known compounds were isolated from the roots of Z. nitidum, in which two isoquinoline alkaloids, 6-acetonyl-dihydrofagaridine (16) and 6-acetonyl-dihydrochelerythrine (17) showed anti-MRSA bioactivity in vitro and in vivo. Both 16 and 17 showed synergistic action with ampicillin, which decreased the MIC significantly, and both compounds had a significant ability to destroy bacterial biofilm combined with ampicillin. The combined administration showed a strong scavenging effect on the planktonic bacteria in vitro and cleared skin infection effectively in the model of wound infection in vivo. Furthermore, compound 16 inhibited the efflux of the drug by combining with ampicillin or EtBr, resulting in the MIC decreased obviously. Our investigation supported the traditional use of Z. nitidum in treating infections caused by bacteria, and might provide new natural products to reduce the use of antibiotics and the treatment of drug-resistance bacteria.

Engineering Multifunctional Hydrogel-Integrated 3D Printed Bioactive Prosthetic Interfaces for Osteoporotic Osseointegration.

3D printed porous titanium alloy implants is an advanced orthopedic material for joint replacement. However, the high risk of aseptic loosening and periprosthetic infection is difficult to avoid, and the declined autophagy of osteoporosis-derived bone marrow mesenchymal stem cells (OP-BMSCs) further severely impairs the osseointegration under the osteoporotic circumstance. It is thus becoming urgently significant to develop orthopedic materials with autophagy regulation and antibacterial bioactivity. In this regard, a novel class of multifunctional hydrogel-integrated 3D printed bioactive prosthetic interfaces is engineered for in situ osseointegration in osteoporosis. The hydrogel is fabricated from the dynamic crosslinking of synthetic polymers, natural polymers, and silver nanowires to deliver autophagy-regulated rapamycin. Therefore, the resultant soft material exhibits antibacterial ability, biocompatibility, degradability, conductive, self-healing, and stimuli-responsive abilities. In vitro experiments demonstrate that the hydrogel-integrated 3D printed bioactive prosthetic interfaces can restore the declined cellular activities of OP-BMSCs by upregulating the autophagy level and show excellent antibacterial activity against S. aureus and MRSA. More remarkably, the multifunctional 3D printed bioactive prosthetic interfaces significantly improve osseointegration and inhibit infection in osteoporotic environment in vivo. This study provides an efficient strategy to develop novel prosthetic interfaces to reduce complications after arthroplasty for patients with osteoporosis.

Tabernaecorymine A, an 18-normonoterpenoid indole alkaloid with antibacterial activity from Tabernaemontana corymbosa

Tabernaecorymine A, an 18-normonoterpenoid indole alkaloid with conjugated (E)-3-aminoacrylaldehyde fragment was obtained from the stem bark of Tabernaemontana corymbosa. Its structure was elucidated by extensive spectroscopic data analyses, and further verified by ACD/structure elucidator, electronic circular dichroism (ECD) analyses and density functional theory (DFT) chemical shift predictions. The compound exhibited significant antibacterial bioactivity against Streptococcus dysgalactiae with an MIC value of 3.12 μg/mL, which is better than the plant drug berberine.

The regulation of BbLaeA on the production of beauvericin and bassiatin in Beauveria bassiana.

Beauvericin and bassiatin are two valuable compounds with various bioactivities biosynthesized by the supposedly same nonribosomal peptide synthetase BbBEAS in entomopathogenic fungus Beauveria bassiana. To evaluate the regulatory effect of global regulator LaeA on their production, we constructed BbLaeA gene deletion and overexpression mutants, respectively. Deletion of BbLaeA resulted in a decrease of the beauvericin titer, while overexpression of BbLaeA increased its production by 1-2.26 times. No bassiatin could be detected in ΔBbLaeA and wild type strain of B. bassiana, but 4.26-5.10µg/mL bassiatin was produced in OE::BbLaeA. Furthermore, additional metabolites with increased production in OE::BbLaeA were isolated and identified as primary metabolites. Among them, 4-hydroxyphenylacetic acid showed antibacterial bioactivity against Ralstonia solanacearum. These results indicated that BbLaeA positively regulates the production of beauvericin, bassiatin and various bioactive primary metabolites.