The mechanism of environmental D-xylose perception by the bacterial membrane two-component complex XylFII-LytS

D-xylose,the main building block of plant biomass,is a pentose sugar that can be used by bacteria as a carbon source for bio-based fuel and chemical production through fermentation.In bacteria,the first step for D-xylose metabolism is signal perception at the membrane.Scientists previously identified a threecomponent system in Firmicutes bacteria comprising a membrane-associated sensor protein(XylFII)。

Bacterial outer membrane vesicles in the fight against cancer

Bacterial outer membrane vesicles(OMVs)are diminutive vesicles naturally released by Gram-negative bacteria.These vesicles possess distinctive characteristics that attract attention for their potential use in drug administration and immunotherapy in cancer treatment.Therapeutic medicines may be delivered via OMVs directly to the tumor sites,thereby minimizing exposure to healthy cells and lowering the risk of systemic toxicity.Furthermore,the activation of the immune system by OMVs has been demonstrated to facilitate the recognition and elimination of cancer cells,which makes them a desirable tool for immunotherapy.They can also be genetically modified to carry specific antigens,immunomodulatory compounds,and small interfering RNAs,enhancing the immune response to cancerous cells and silencing genes associated with disease progression.Combining OMVs with other cancer treatments like chemotherapy and radiation has shown promising synergistic effects.This review highlights the crucial role of bacterial OMVs in cancer,emphasizing their potential as vectors for novel cancer targeted therapies.As researchers delve deeper into the complexities of these vesicles and their interactions with tumors,there is a growing sense of optimism that this avenue of study will bring positive outcomes and renewed hope to cancer patients in the foreseeable future.

The Effect of Atmospheric Pressure Plasma Corona Discharge on pH, Lipid Content and DNA of Bacterial Cells

Effect of plasma corona discharges on the pH, whole cell lipids and DNA of bacteria is investigated. Results showed an increase in the acidity levels of water due to plasma reactive species which, however, were not responsible for bacterial cell death. No changes in the whole cell lipid contents were observed, while DNA after plasma treatment showed deterioration of the amplified sequences, indicating the possible occurrence of DNA degradation. In conclusion, reactive species produced by plasma discharges affects DNA, possibly contributing to cell death.

30 and 32 kDa outer membrane proteins of Bordetella pertussis as a modulator on promoting degranulation of mast cells

The correlation between the activities of the outer menbrane proteins （OMPs） of Bordetella pertussis and the lgE-mediated asthma was investigated in the present study, in which the OMPs of B. pertussis and their components were prepared by detergent treatment and chromatography, and the molecular weights of the OMPs components were determined by SDS-PAGE. The amounts of total as well as the ovalbumin （OVA）-specific IgE induced by dead B. pertussis whole bacterial vaccine on guinea pigs were detected by ELISA. Meanwhile, the effect of the OMPs and their components to promote the degranulation of guinea pig mast cells was observed by using the mast cell degranulation test, and ELISA assay was used to measure the histatmine levels in the supematants from the mast cell cultures. Histamine sensitive test was used to demonstrate the effects of the OMPs and their components to increase the histamine lethal sensitivity in mice. It was found that four components with molecular weights of 30, 32, 38 and 69 kDa could be obtained from the OMPs of B. pertussts, and the dead whole bacteria vaccine of B. pertussis had the ability to increase the levels of the total as well as the OVA-specific IgE in sera of guinea pigs. The OMPs and their 30 and 32 kDa components demonstrated significantly enhancing effect on the degranulation of guinea pig mast cells, and the histamine levels in the supematants from the mast cell culture treated with OMPs and their 30 and 32 kDa components were also significantly increased. It is evident that the strong adjuvant activity and the enhancing effect to degranulation of mast cells and the release of histamine of certain outer membrane components of B. pertussis could be demonstrated as revealed by the results of the present study, suggesting the possibility of a close relationship between the infection of vaccination with B. pertussis and the IgE-mediated asthma.

Bacterial outer membrane vesicles-based therapeutic platform eradicates triple-negative breast tumor by combinational photodynamic/chemo-/immunotherapy

Bacterial outer membrane vesicles(OMVs)are potent immuno-stimulating agents and have the potentials to be bioengineered as platforms for antitumor nanomedicine.In this study,OMVs are demonstrated as promising antitumor therapeutics.OMVs can lead to beneficial M2-to-M1 polarization of macrophages and induce pyroptosis to enhance antitumor immunity,but the therapeutic window of OMVs is narrow for its toxicity.We propose a bioengineering strategy to enhance the tumor-targeting ability of OMVs by macrophage-mediated delivery and improve the antitumor efficacy by co-loading of photosensitizer chlorin e6(Ce6)and chemotherapeutic drug doxorubicin(DOX)into OMVs as a therapeutic platform.We demonstrate that systemic injection of the DOX/Ce6-OMVs@M therapeutic platform,providing combinational photodynamic/chemo-/immunotherapy,eradicates triple-negative breast tumors in mice without side effects.Importantly,this strategy also effectively prevents tumor metastasis to the lung.This OMVs-based strategy with bioengineering may serve as a powerful therapeutic platform for a synergic antitumor therapy.

Biodegradable cationic e-poly-L-lysine-conjugated polymeric nanoparticles as a new effective antibacterial agent

Biocompatible and biodegradable ε-poly-L- lysine （EPL）/poly （ε-caprolactone） （PCL） copolymer was designed and synthesized. The amphiphilic EPL-PCL copolymer could easily self-assembled into monodispersed nanoparticles （NPs）, which showed a broad-spectrum antibacterial activity against Escherichia coli, Staphylococcus aureus and Bacillus subtilis. Interestingly, the antibacterial efficacy of the novel NPs is more potent than the cationic peptide EPL. To explore the underlying mechanism of the biodegradable cationic NPs, various possible antibacterial pathways have been validated. The NPs have been found that they can disrupt bacterial walls/ membranes and induce the increasing in reactive oxygen species and alkaline phosphatase levels. More importantly, the self-assembled NPs induced the changes in bacterial osmotic pressure, resulting in cell invagination to form holes and cause the leakage of cytoplasm. Taken together, our results suggest that the EPL-PCL NPs can be further developed to be a promising antimicrobial agent to treat infectious diseases as surfactants and emulsifiers to enhance drug encapsulation efficiency and antimicrobial activity.