Design and production of a novel antimicrobial fusion protein in Escherichia coli

Novel Genetically Engineered Probiotics for Targeted Elimination of Pseudomonas aeruginosa in Intestinal Colonization

The intestinal carriage rates of Pseudomonas aeruginosa are notably elevated in immunosuppressed individuals and hospitalized patients, increasing the risk of infection and antibiotic-associated diarrhea. A potential solution to this issue lies in autonomous antibacterial therapy, remaining inactive until a pathogen is detected, and releasing antibacterial compounds on demand to eliminate the pathogen. This study focuses on the development of genetically engineered probiotics capable of detecting and eradicating P. aeruginosa by producing and secreting PA2-GNU7, a P. aeruginosa-selective antimicrobial peptide (AMP), triggered by the presence of P. aeruginosa quorum-sensing molecule N-(3-oxododecanoyl)-L-homoserine lactone (3OC12HSL). To achieve this goal, plasmid-based systems were constructed to produce AMPs in response to 3OC12HSL and secrete them into the extracellular medium using either the microcin V secretion system or YebF as a carrier protein. Following the transfer of these plasmid-based systems to Escherichia coli Nissle 1917 (EcN), we successfully demonstrated the ability of the engineered EcN to express and secrete PA2-GNU7, leading to the inhibition of P. aeruginosa growth in vitro. In addition, in a mouse model of intestinal P. aeruginosa colonization, the administration of engineered EcN resulted in reduced levels of P. aeruginosa in both the feces and the colon. These findings suggest that engineered EcN holds promise as a potential option for combating intestinal P. aeruginosa colonization, thus mitigating the risk of future endogenous infections in vulnerable patients.

Highly efficient low-temperature biodegradation of polyethylene microplastics by using cold-active laccase cell-surface display system

To eliminate efficiency restriction of polyethylene microplastics low-temperature biodegradation, a novel InaKN-mediated Escherichia coli surface display platform for cold-active degrading laccase PsLAC production was developed. Display efficiency of 88.0% for engineering bacteria BL21/pET-InaKN-PsLAC was verified via subcellular extraction and protease accessibility, exhibiting an activity load of 29.6 U/mg. Cell growth and membrane integrity revealed BL21/pET-InaKN-PsLAC maintained stable growth and intact membrane structure during the display process. The favorable applicability was confirmed, with 50.0% activity remaining in 4 days at 15 °C, and 39.0% activity recovery retention after 15 batches of activity substrate oxidation reactions. Moreover, BL21/pET-InaKN-PsLAC possessed high polyethylene low-temperature depolymerizing capacity. Bioremediation experiments proved that the degradation rate was 48.0% within 48 h at 15 °C, and reached 66.0% after 144 h. Collectively, cold-active PsLAC functional surface display technology and its significant contributions to polyethylene microplastics low-temperature degradation constitute an effective improvement strategy for biomanufacturing and microplastics cold remediation.

The future of recombinant host defense peptides

The antimicrobial resistance crisis calls for the discovery and production of new antimicrobials. Host defense peptides (HDPs) are small proteins with potent antibacterial and immunomodulatory activities that are attractive for translational applications, with several already under clinical trials. Traditionally, antimicrobial peptides have been produced by chemical synthesis, which is expensive and requires the use of toxic reagents, hindering the large-scale development of HDPs. Alternatively, HDPs can be produced recombinantly to overcome these limitations. Their antimicrobial nature, however, can make them toxic to the hosts of recombinant production. In this review we explore the different strategies that are used to fine-tune their activities, bioengineer them, and optimize the recombinant production of HDPs in various cell factories.

Novel tissue-engineered skin equivalent from recombinant human collagen hydrogel and fibroblasts facilitated full-thickness skin defect repair in a mouse model

Tissue-engineered skin equivalent (TESE) is an optimized alternative for the treatment of skin defects. Designing and fabricating biomaterials with desired properties to load cells is critical for the approach. In this study, we aim to develop a novel TESE with recombinant human collagen (rHC) hydrogel and fibroblasts to improve full-thickness skin defect repair. First, the bioactive effect of rHC on fibroblast proliferation, migration and phenotype was assayed. The results showed that rHC had good biocompatibility and could stimulate fibroblasts migration and secrete various growth factors. Then, rHC was cross-linked with transglutaminase (TG) to prepare rHC hydrogel. Rheometer tests indicated that 10% rHC/TG hydrogel could reach a oscillate stress of 251 Pa and remained stable. Fibroblasts were seeded into rHC/TG hydrogel to prepare TESE. Confocal microscope and scanning electronic microscope observation showed that seeded fibroblasts survived well in the hydrogel. Finally, the therapeutic effect of the newly prepared TESE was tested in a mouse full-thickness skin defect model. The results demonstrated that TESE could significantly improve skin defect repair in vivo. Conclusively, TESE prepared from rHC and fibroblasts in this study exhibits great potential for clinical application in the future.

In Vivo Bactericidal Efficacy of GWH1 Antimicrobial Peptide Displayed on Protein Nanoparticles, a Potential Alternative to Antibiotics

Oligomerization of antimicrobial peptides into nanosized supramolecular complexes produced in biological systems (inclusion bodies and self-assembling nanoparticles) seems an appealing alternative to conventional antibiotics. In this work, the antimicrobial peptide, GWH1, was N-terminally fused to two different scaffold proteins, namely, GFP and IFN-γ for its bacterial production in the form of such recombinant protein complexes. Protein self-assembling as regular soluble protein nanoparticles was achieved in the case of GWH1-GFP, while oligomerization into bacterial inclusion bodies was reached in both constructions. Among all these types of therapeutic proteins, protein nanoparticles of GWH1-GFP showed the highest bactericidal effect in an in vitro assay against Escherichia coli, whereas non-oligomerized GWH1-GFP and GWH1-IFN-γ only displayed a moderate bactericidal activity. These results indicate that the biological activity of GWH1 is specifically enhanced in the form of regular multi-display configurations. Those in vitro observations were fully validated against a bacterial infection using a mouse mastitis model, in which the GWH1-GFP soluble nanoparticles were able to effectively reduce bacterial loads.

Strategies for recombinant production of antimicrobial peptides with pharmacological potential

INTRODUCTION

The need to develop new drugs for the control of pathogenic microorganisms has redoubled efforts to prospect for antimicrobial peptides (AMPs) from natural sources and to characterize its structure and function. These molecules present a broad spectrum of action against different microorganisms and frequently present promiscuous action, with anticancer and immunomodulatory activities. Furthermore, AMPs can be used as biopharmaceuticals in the treatment of hospital-acquired infections and other serious diseases with relevant social and economic impacts.Areas covered: The low yield and the therefore difficult extraction and purification process in AMPs are problems that limit their industrial application and scientific research. Thus, optimized heterologous expression systems were developed to significantly boost AMP yields, allow high efficiency in purification and structural optimization for the increase of therapeutic activity.Expert opinion: This review provides an update on recent developments in the recombinant production of ribosomal and non-ribosomal synthesis of AMPs and on strategies to increase the expression of genes encoding AMPs at the transcriptional and translational levels and regulation of the post-translational modifications. Moreover, there are detailed reports of AMPs that have already reached marketable status or are in the pipeline under advanced stages of preclinical testing.

Evaluation of baiting fipronil-loaded silica nanocapsules against termite colonies in fields

Various pesticide nanocarriers have been developed. However, their pest-control applications remain limited in laboratories. Herein, we developed silica nanocapsules encapsulating fipronil (SNC) and their engineered form, poly(ethyleneimine)-coated SNC (SNC-PEI), based on recombinant catalytic modular protein D4S2 and used them against termite colonies Coptotermes lacteus in fields. To achieve this, an integrated biomolecular bioprocess was developed to produce D4S2 for manufacturing SNC containing fipronil with high encapsulation efficiency of approximately 97% at benign reaction conditions and at scales sufficient for the field applications. PEI coating was achieved via electrostatic interactions to yield SNC-PEI with a slower release of fipronil than SNC without coating. As a proof-of-concept, bait toxicants containing varied fipronil concentrations were formulated and exposed to nine termite mounds, aiming to prolong fipronil release hence allowing sufficient time for termites to relocate the baits into and distribute throughout the colony, and to eliminate that colony. Some baits were relocated into the mounds, but colonies were not eliminated due to several reasons. We caution others interested in producing bait toxicants to be aware of the multilevel resistance mechanisms of the Coptotermes spp. "superorganism".