Angiotensin-Converting Enzyme 2 (ACE2) As a Novel Biorecognition Element in A Cell-Based Biosensor for the Ultra-Rapid, Ultra-Sensitive Detection of the SARS-CoV-2 S1 Spike Protein Antigen

Antigen screening for the SARS-CoV-2 S1 spike protein is among the most promising tools for the mass monitoring of asymptomatic carriers of the virus, especially in limited resource environments. Herewith, we report on the possible use of the angiotensin-converting enzyme 2 (ACE2), the natural receptor and entry point of the virus, as a biorecognition element for the detection of the S1 antigen combined with an established bioelectric biosensor based on membrane-engineered cells. The working principle of our approach is based on the measurable change of the electric potential of membrane-engineered mammalian cells bearing ACE2 after attachment of the respective viral protein. We demonstrate that sensitive and selective detection of the S1 antigen is feasible in just three min, with a limit of detection of 20 fg/mL. In a preliminary clinical application, positive patient-derived samples were identified with a 87.9% score compared to RT-PCR. No cross-reactivity was observed against a wide range of nucleocapsid protein concentrations. The novel biosensor is embedded in a commercially ready-to-use testing platform, complete with the consumable immobilized cell–electrode interface and a portable read-out device operable through smartphone or tablet. In addition, the possible application of the system for the high throughput screening of potential pharmacological inhibitors of the ACE2 receptor-S1 RBD interaction is discussed.

Study on the effect of headspace on biohydrogen production using palm oil mill effluent (POME) via immobilized and suspended growth

The world has been using fossil fuels to generate energy for centuries and has had adverse effects on the environment; hence renewable energy needs to be discovered and developed. Biohydrogen production is renewable energy since it emits no greenhouse gases and may provide clean energy. Therefore, this study aimed to investigate the optimum headspace ratio and biohydrogen production for suspended and immobilized cells using Palm Oil Mill Effluent (POME) as the fermentation substrate, while its anaerobic sludge acted as the inoculum. Five different ratios were investigated, which are 0.2, 0.3, 0.4, 0.5, and 0.6. These are equivalent to working volume (WV) of 80 mL, 70 mL, 60 mL, 50 mL, and 40 mL, respectively. The solution contained 10 % of inoculum and 90 % (v/v) of the feedstock. For immobilized cells, additional of glass beads as carrier material was added into the solution, using the ratio of 1:1 for anaerobic sludge (mL) to support carrier (g). The kinetic study was investigated using a modified Gompertz equation whereby for suspended cells, the best ratio was 0.3, with the highest biohydrogen concentration of 357.6 ppm. Meanwhile, the optimum ratio for the immobilized cell was 0.2, with the highest biohydrogen concentration of 479.3 ppm. Based on the kinetic studies, the kinetic parameters for suspended cells were: Hm = 89.8 mL, Rm = 6.8 mL/h, and λ = 0.1 hr. Meanwhile for immobilized cell, the kinetic parameters were: Hm = 73.6 mL, Rm = 6.9 mL/h and X λ 0 hr. In conclusion, selecting the suitable headspace ratio could affect the biohydrogen quality and improve the effectiveness of the production rate.

Bioethanol Production Through Syngas Fermentation by a Novel Immobilized Bioreactor Using Clostridium Ragsdalei

Global energy demand has been escalating creating ever increasing pressure on climate crisis caused by fossil-based fuels. Humankind is now desperately in need of alternative and sustainable energy sources. Therefore, biofuels provide promising solution. Amongst the various biofuels, bioethanol from syngas, which is a mixture of, mostly, CO, CO2, N2, H2, and CH4 gases has been drawing increasing attention recently. Regarding this, the conversion of syngas to bioethanol, an alternative biofuel to fossil fuels, is considered a promising approach to reduce the negative effects of global warming by reducing greenhouse gas emissions. In this study, a novel immobilized cell bioreactor, where Clostridium ragsdalei was grown, was designed and used to achieve an efficient production of ethanol regarding volumetric production. For this purpose, a 300 mL immobilized reactor filled with ceramic balls as immobilization material was set and operated at 30oC throughout the study where CO gas as the main substrate was fed at rate of 6 ml/min continuously. Results showed ethanol and acetic acid concentrations reaching up to 1.4 g/L and 0.2 g/L, respectively, after 600h with a volumetric production rate of 0,0023g ethanol/L/h. We believe, the ceramic ball was used for bioethanol production for syngas for the first time.

Treatment of Slaughterhouse Wastewater by Integrated Anaerobic/Aerobic Bioreactors Loaded with Immobilized Nanoporous Activated Carbon

Slaughterhouse wastewater consists of moderate to high strength complex wastewater comprising about 45% soluble and 55% coarse suspended organics exhibiting high COD and BOD levels. Conventional wastewater treatment methods cannot effectively treat slaughterhouse wastewater. Thus, a four-stage sequential anaerobic/aerobic immobilized bio reactor system comprising a two stage Fluidized Anaerobic immobilized Reactor (FAIR – I and FAIR – II), a Fluidized Immobilized Cell Carbon Oxidation (FICCO) reactor and a Chemo Autotrophic Activated Carbon Oxidation (CAACO) reactor was tested in a slaughterhouse treating wastewater between 3 m3 /day to 17 m3 /day. Nanoporous activated carbon (NPAC) was used for the immobilization of microorganisms in all of the reactors. The NPAC BET surface area was found to be 291 m2/g with the average pore diameter of 28 Å. Spin density (free electrons) in the NPAC, was calculated to be 16 x 1018 spins/g using ESR spectroscopy. The overall NH3-N, TKN, COD and BOD removal efficiency was 64%, 71%, 82% and 85% respectively. Multivariate analysis (PCA and cluster analysis) found that the COD removal by the FICCO and CAACO reactors is more efficient than the FAIR reactors. The treatment was confirmed through UV-visible and UV-fluorescence spectroscopic analysis.