Bacterial Lighthouses—Real-Time Detection of Yersinia enterocolitica by Quorum Sensing

Foodborne zoonotic pathogens have a severe impact on food safety. The demand for animal-based food products (meat, milk, and eggs) is increasing, and therefore faster methods are necessary to detect infected animals or contaminated food before products enter the market. However, conventional detection is based on time-consuming microbial cultivation methods. Here, the establishment of a quorum sensing-based method for detection of foodborne pathogens as Yersinia enterocolitica in a co-cultivation approach using a bacterial biosensor carrying a special sensor plasmid is described. We combined selective enrichment with the simultaneous detection of pathogens by recording autoinducer-1-induced bioluminescent response of the biosensor. This new approach enables real-time detection with a calculated sensitivity of one initial cell in a sample after 15.3 h of co-cultivation, while higher levels of initial contamination can be detected within less than half of the time. Our new method is substantially faster than conventional microbial cultivation and should be transferrable to other zoonotic foodborne pathogens. As we could demonstrate, quorum sensing is a promising platform for the development of sensitive assays in the area of food quality, safety, and hygiene.

Screening of Potential Inhibitors of Covid-19 with Repurposing Approach Via Molecular Docking

Background: 2019-nCoV (COVID-19) is a pandemic disease with a high infectivity and mortality. The prevention and treatment of COVID-19 have become urgent matters for consideration. It often takes several years to develop new drugs, or vaccines, based on the usual clinical trial process. This dwell-time can be shortened by repurposing previously approved drugs.Methods: We have designed and evaluated a bacterial biosensor expressing a luciferase We aimed to assess several available small-molecule; Abl kinase inhibitors, Janus kinase inhibitor, Dipeptidyl peptidase 4 inhibitors, RNA-dependent RNA polymerase inhibitors, and Papin-like Protease inhibitors, using binding simulation with proteins that might prove to be effective in inhibiting COVID-19 infection. The efficiency of inhibitors was evaluated based on docking scores using auto dock vina software.Results: Strong ligand-protein interactions were predicted among some of these drugs, such as Imatinib, Remdesivir, and Telaprevir, and this may render these compounds promising candidates. Some candidate drugs might be efficient in disease control (directly and indirectly) or in viral proteins attenuation. It is worth to highlight the powerful immunomodulatory role of Abivertinib that inhibits pro-inflammatory cytokine production that are associated with cytokine release syndrome (CRS) or cytokine storm and progression of COVID-19 infection.Conclusions: COVID-19 is similar to SARS-CoV, the potential role of Abl kinase inhibitors such as Imatinib in reducing SARS-CoV and MERS-CoV viral titers, immune regulatory function and the development of acute respiratory distress syndrome (ARDS) may indicate that these drugs may be useful for COVID-19. Moreover, Remdesivir, and Telaprevir have the most efficiency with their docked proteins in-silico as well although clinical trials are needed to confirm the effect of these drugs.

Construction of a sensitive and specific lead biosensor using a genetically engineered bacterial system with a luciferase gene reporter controlled by pbr and cadA promoters

Background A bacterial biosensor refers to genetically engineered bacteria that produce an assessable signal in the presence of a physical or chemical agent in the environment. Methods We have designed and evaluated a bacterial biosensor expressing a luciferase reporter gene controlled by pbr and cadA promoters in Cupriavidus metallidurans (previously termed Ralstonia metallidurans) containing the CH34 and pI258 plasmids of Staphylococcus aureus, respectively, and that can be used for the detection of heavy metals. In the present study, we have produced and evaluated biosensor plasmids designated pGL3-luc/pbr biosensor and pGL3-luc/cad biosensor, that were based on the expression of luc+ and under the control of the cad promoter and the cadC gene of S. aureus plasmid pI258 and pbr promoter and pbrR gene from plasmid pMOL30 of Cupriavidus metallidurans. Results We found that the pGL3-luc/pbr biosensor may be used to measure lead concentrations between 1–100 μM in the presence of other metals, including zinc, cadmium, tin and nickel. The latter metals did not result in any significant signal. The pGL3-luc/cad biosensor could detect lead concentrations between 10 nM to 10 μM. Conclusions This biosensor was found to be specific for measuring lead ions in both environmental and biological samples.

Construction of a sensitive and specific lead biosensor using a genetically engineered bacterial system with a luciferase gene reporter controlled by pbr and cadA promoters

Background: A bacterial biosensor refers to genetically engineered bacteria that produce an assessable signal in the presence of a physical or chemical agent in the environment.Methods: We have designed and evaluated a bacterial biosensor expressing a luciferase-reporter gene controlled by pbr and cadA promoters in Cupriavidus metallidurans (previously termed Ralstonia metallidurans ) containing the CH34 and pI258 plasmids of Staphylococcus aureus , respectively, and that can be used for the detection of heavy metals. In the present study, we have produced and evaluated biosensor plasmids designated pGL3-luc/pbr -biosensor and pGL3-luc/cad -biosensor, that were based on the expression of luc+ under the control of the cad promoter and the cadC gene of S. aureus plasmid pI258 and pbr promoter and pbrR gene from plasmid pMOL30 of Cupriavidus metallidurans.Results: We found that the pGL3-luc/pbr -biosensor may be used to measure lead concentrations between 1-100 μM in the presence of other metals, including: zinc, cadmium, tin and nickel. The latter metals did not result in any significant signal gene expression of the reporter . The pGL3-luc/cad -biosensor could detect lead concentrations between 10 nM to 10 μM.Conclusions: This biosensor was found to be a specific for measuring lead ions in both environmental and biological samples.

Construction of a sensitive and specific lead biosensor using a genetically engineered bacterial system with a luciferase gene reporter controlled by pbr and cadA promoters

Background: A bacterial biosensor refers to genetically engineered bacteria that produce an assessable signal in the presence of a physical or chemical agent in the environment. Methods: We have designed and evaluated a bacterial biosensor expressing a luciferase-reporter gene controlled by pbr and cadA promoters in Cupriavidus metallidurans (previously termed Ralstonia metallidurans) containing the CH34 and pI258 plasmids of Staphylococcus aureus, respectively, and that can be used for the detection of heavy metals. In the present study, we have produced and evaluated biosensor plasmids designated pGL3-luc/pbr-biosensor and pGL3-luc/cad-biosensor, that were based on the expression of luc+ and under the control of the cad promoter and the cadC gene of S. aureus plasmid pI258 and pbr promoter and pbrR gene from plasmid pMOL30 of Cupriavidus metallidurans. Results: We found that the pGL3-luc/pbr-biosensor may be used to measure lead concentrations between 1-100 μM in the presence of other metals, including: zinc, cadmium, tin and nickel. The latter metals did not result in any significant signal. The pGL3-luc/cad-biosensor could detect lead concentrations between 10 nM to 10 μM. Conclusions: This biosensor was found to be a specific for measuring lead ions in both environmental and biological samples.