Engineering in Life Sciences最新文献

Bioconversion of CO₂ into liquid fuels or chemicals, preferred medium chain carboxylic acids (caproic and caprylic acid), is an attractive CO₂ utilization technology. The present study aims to investigate the effects of different ratios of H₂/CO₂ on regulating the distribution of C2-C8 carboxylic acid products, while the headspace pressure of 1.5 bar was set to amplify the effect of different ratios. The H₂/CO₂ ratio of 4:1 was more suitable for preparing acetic acid, where the highest acetic acid yield was 17.5 g/L. And the H₂/CO₂ ratio of 2:1 showed excellent chain elongation ability with the highest n-caprylic yield of 2.4 g/L. Additionally, the actual H₂/CO₂ ratios of 4:1 reactors were higher than that in 2:1 may be course chain elongation often accompanied by H₂ production. The 16S rRNA genes analysis shows that the genus Terrisporobacter and Coriobacteriales may be related to acetic acid production enriched in H₂/CO₂ ratio 4:1 reactors, and the genus Clostridium and Paenibacillaceae may associate with the chain elongation pathway were enriched in H₂/CO₂ ratio 2:1 reactors.

An anaerobic granular sludge was enriched to utilize H₂/CO₂ in a continuous gas-fed up-flow anaerobic sludge reactor by applying operating conditions expected to produce acetic acid, butyric acid, and ethanol. Three stages of fermentation were found: Stage I with acetic acid accumulation with the highest concentration of 35 mM along with a pH decrease from initial 6 to 4.5. In Stage II, H₂/CO₂ was replaced by 100% H₂ to induce solventogenesis, whereas butyric acid was produced with the highest concentration of 2.5 mM. At stage III with 10 µM tungsten (W) addition, iso-valeric acid, valeric acid, and caproic acid were produced at pH 4.5–5.0. In the batch tests inoculated with the enriched sludge taken from the bioreactor (day 70), however, methane production occurred at pH 6. Exogenous 15 mM acetate addition enhanced both the H₂ and CO₂ consumption rate compared to exogenous 10, 30, and 45 mM acetate by the enriched sludge. Exogenous acetate was failed to be converted to ethanol using H₂ as electron donor by the enriched acetogens.

Retraction: ‘Comparative molecular docking and molecular-dynamic simulation of wild-type- and mutant carboxylesterase with BTA-hydrolase for enhanced binding to plastic’, by Fatana Lameh, Abdul Qadeer Baseer, and Abubakar Garba Ashiru, Eng Life Sci. 2021; 13-29: The above article, published online on 15 November 2021 in Wiley Online Library (https://doi.org/10.1002/elsc.202100083), has been retracted by agreement between the authors, the journal's Editors in Chief, Prof. Dr. Ralf Takors and Prof. Dr. An-Ping Zeng, and Wiley-VCH GmbH.

The retraction has been agreed because the copyright owner, Universiti Teknologi Malaysia, does not consent to publication of the research.

We present a transient large eddy simulation (LES) modeling approach for simulating the interlinked physics describing free surface hydrodynamics, multiphase mixing, reaction kinetics, and mass transport in bioreactor systems. Presented case-studies include non-reacting and reacting bioreactor systems, modeled through the inclusion of uniform reaction rates and more complex biochemical reactions described using Contois type kinetics. It is shown that the presence of reactions can result in a non-uniform spatially varying species concentration field, the magnitude and extent of which is directly related to the reaction rates and the underlying variations in the local volumetric mass transfer coefficient.