Firmicutes-enriched IS1447 represents a group of IS3-family insertion sequences exhibiting unique + 1 transcriptional slippage

Targeting the chromatin structural changes of antitumor immunity

Epigenomic imbalance drives abnormal transcriptional processes, promoting the onset and progression of cancer. Although defective gene regulation generally affects carcinogenesis and tumor suppression networks, tumor immunogenicity and immune cells involved in antitumor responses may also be affected by epigenomic changes, which may have significant implications for the development and application of epigenetic therapy, cancer immunotherapy, and their combinations. Herein, we focus on the impact of epigenetic regulation on tumor immune cell function and the role of key abnormal epigenetic processes, DNA methylation, histone post-translational modification, and chromatin structure in tumor immunogenicity, and introduce these epigenetic research methods. We emphasize the value of small-molecule inhibitors of epigenetic modulators in enhancing antitumor immune responses and discuss the challenges of developing treatment plans that combine epigenetic therapy and immunotherapy through the complex interaction between cancer epigenetics and cancer immunology.

Antibiotic resistome associated with inhalable bioaerosols from wastewater to atmosphere: Mobility, bacterial hosts, source contributions and resistome risk

Antibiotic resistome can be carried by the bioaerosols and propagate from wastewater treatment plants (WWTPs) to the atmosphere, but questions remain regarding their mobility, bacterial hosts, source, and resistome risk. Here, fine particulate matter (PM2.5) was collected within and around a large WWTP and analyzed by the metagenomic assembly and binning. PM2.5 was discovered with increasing enrichment of total antibiotic resistance genes (ARGs), potentially mobile ARGs, and antibiotic-resistant bacteria (ARB) along the WWTP-downwind-upwind gradient. Some ARGs were found to be flanked by certain mobile genetic elements and generally mediated by plasmids in WWTP-PM2.5. Totally, 198 metagenome assembled genomes assigning to seven phyla were identified as the ARB, and a contig-based analysis indicated that 32 pathogens were revealed harboring at least two ARGs. Despite disparate aerosolization potentials of ARGs or ARB at different WWTP units, high resistome risks were found, along with the dominant contribution of wastewater for airborne ARGs (44.79-62.82%) and ARB (35.03-40.10%). Among the detected WWTP matrices, the sludge dewatering room was characterized by the highest resistome risk associated with PM2.5. This study underscores the dispersion of ARGs and ARB from WWTPs to the atmosphere and provides a reference for managing risks of antibiotic resistance.

Metagenomics analysis of probable transmission of determinants of antibiotic resistance from wastewater to the environment - A case study

During mechanical-biological treatment, wastewater droplets reach the air with bioaerosols and pose a health threat to wastewater treatment plant (WWTP) employees and nearby residents. Microbiological pollutants and antimicrobial resistance determinants are discharged to water bodies with treated wastewater (TWW), which poses a potential global epidemiological risk. In the present study, the taxonomic composition of microorganisms was analyzed, and the resistome profile and mobility of genes were determined by metagenomic next-generation sequencing in samples of untreated wastewater (UWW), wastewater collected from an activated sludge (AS) bioreactor, TWW, river water collected upstream and downstream from the wastewater discharge point, and in upper respiratory tract swabs collected from WWTP employees. Wastewater and the emitted bioaerosols near WWTP's facilities presumably contributed to the transmission of microorganisms, in particular bacteria of the phylum Actinobacteria and the associated antibiotic resistance genes (ARGs) (including ermB, ant(2″)-I, tetM, penA and cfxA2) to the upper respiratory tract of WWTP employees. The discharged wastewater increased the taxonomic diversity of microorganisms and the concentrations of various ARGs (including bacA, emrE, sul1, sul2 and tetQ) in river water. This study fills in the knowledge gap on the health risks faced by WWTP employees. The study has shown that microbiological pollutants and antimicrobial resistance determinants are also in huge quantities discharged to rivers with TWW, posing a potential global epidemiological threat.

Tailoring Genetic Elements of the Plasmid-Driven T7 System for Stable and Robust One-Step Cloning and Protein Expression in Broad Escherichia coli

The plasmid-driven T7 system (PDT7) is a flexible approach to trigger protein overexpression; however, most of the reported PDT7 rely on many auxiliary elements or inducible systems to attenuate the toxicity from the orthogonality of the T7 system, which limits its application as the one-step cloning and protein expression system. In this study, we developed a stable and robust PDT7 via tailoring the genetic elements. By error-prone mutagenesis, a mutated T7RNAP with TTTT insertion conferred a trace but enough amount of T7RNAP for stable and efficient PDT7, denoted as PDT7m. The replication origin was kept at the same level, while the ribosome binding site (RBS) of the T7 promoter was the most contributing factor, thus enhancing the protein expression twofold using PDT7m. For application as a host-independent screening platform, both constitutive and IPTG-inducible PDT7m were constructed. It was found that each strain harnessed different IPTG inducibilities for tailor-made strain selection. Constitutive PDT7m was successfully used to express the homologous protein (i.e., lysine decarboxylase) or heterologous protein (i.e., carbonic anhydrase, CA) as a one-step cloning and protein expression tool to select the best strain for cadaverine (DAP) or CA production, respectively. Additionally, PDT7m is compatible with the pET system for coproduction of DAP and CA simultaneously. Finally, PDT7m was used for in vivo high-end chemical production of aminolevulinic acid (ALA), in which addition of the T7 terminator successfully enhanced 340% ALA titer, thus paving the way to rapidly and effectively screening the superior strain as a cell factory.