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Coenzyme Q10 (CoQ10) is the most consumed dietary supplement and mainly biosynthesized by aerobic fermentation of Rhodobacter sphaeroides (R. sphaeroides). Oxygen supply was identified as a bottleneck for improving CoQ10 yield in R. sphaeroides. In this study, a precise regulation strategy based on dielectric spectroscopy (DS) was applied to further improve CoQ10 biosynthesis by R. sphaeroide. First, a quantitative response model among viable cells, cell morphology, and oxygen uptake rate (OUR) was established. DS could be used to detect viable R. sphaeroides cells, and the relationship among cell morphology, CoQ10 biosynthesis, and OUR was found to be significant. Based on this model, the online specific oxygen consumption rate (QO2) control strategy was successfully applied to the CoQ10 fermentation process. QO2 controlled at 0.07 ± 0.01 × 10− 7mmol/cell/h was most favorable for CoQ10 biosynthesis, resulting in a 28.3% increase in CoQ10 production. Based on the multi-parameters analysis and online QO2 control, a precise online nutrient feeding strategy was established using conductivity detected by DS. CoQ10 production was improved by 35%, reaching 3384 mg/L in 50 L bioreactors. This online control strategy would be effectively applied for improving industrial CoQ10 production, and the precise fermentation control strategy could also be applied to other fermentation process. [ABSTRACT FROM AUTHOR]

Abstract The fermentation process is dynamically changing, and the metabolic status can be grasped through real-time monitoring of environmental parameters. In this study, a real-time and on-line monitoring experiment platform for substrates and products detection was developed based on non-contact type near-infrared (NIR) spectroscopy technology. The prediction models for monitoring the fermentation process of lactic acid, sophorolipids (SLs) and sodium gluconate (SG) were established based on partial least-squares regression and internal cross-validation methods. Through fermentation verification, the accuracy and precision of the NIR model for the complex fermentation environments, different rheological properties (uniform system and multi-phase inhomogeneous system) and different parameter types (substrate, product and nutrients) have good applicability, and R 2 was greater than 0.98, exhibiting a good linear relationship. The root mean square error of prediction shows that the model has high credibility. Through the control of appropriate glucose concentration in SG fermentation as well as glucose and oil concentrations SLs fermentation by NIR model, the titers of SG and SLs were increased to 11.8% and 26.8%, respectively. Although high cost of NIR spectrometer is a key issue for its wide application in an industrial scale. This work provides a basis for the application of NIR spectroscopy in complex fermentation systems.

Global pandemics caused by pathogenic viruses have highlighted the need to develop effective and sustainable materials to defend against these viruses. However, most commercial viral disinfection materials rely on precious metals, which are toxic. In this study, an engineered living material based on Bacillus subtilis biofilms is presented that can effectively remove Influenza A virus and SARS‐CoV‐2 from water. First, B. subtilis biofilm is used to display the H1N1 and H5N1 specific binding peptide C40 and SARS‐CoV‐2 specific binding peptide SBP1; thus, the biofilm materials has outstanding efficacy against H1N1, H5N1, and SARS‐CoV‐2 pseudovirus from water. In addition to capturing the virus, these biofilm materials can also inactivate the virus by secreting alkaline protease AprE, which effectively degrades the viral proteins at temperatures of 4, 16, 25, and 37 °C. Furthermore, to constrain bacterial growth and prevent the leakage of genetically modified organisms, a suicide genetic circuit using the quorum‐sensing system ComQXPA to control Lytc expression is constructed, leading to bacterial lysis. Overall, this study demonstrates a novel, effective, and sustainably engineered living material for preventing viral transmission. This material provides a safeguard for public health and promotes environmentally friendly governance. [ABSTRACT FROM AUTHOR]

While traveling through different zones in large‐scale bioreactors, microbes are most likely subjected to fluctuating dissolved oxygen (DO) conditions at the timescales of global circulation time. In this study, to mimic industrial‐scale spatial DO gradients, we present a scale‐down setup based on dynamic feast/famine regime (150 s) that leads to repetitive cycles with rapid changes in DO availability in glucose‐limited chemostat cultures of Penicillium chrysogenum. Such DO feast/famine regime induced a stable and repetitive pattern with a reproducible metabolic response in time, and the dynamic response of intracellular metabolites featured specific differences in terms of both coverage and magnitude in comparison to other dynamic conditions, for example, substrate feast/famine cycles. Remarkably, intracellular sugar polyols were considerably increased as the hallmark metabolites along with a dynamic and higher redox state (NADH/NAD+) of the cytosol. Despite the increased availability of NADPH for penicillin production under the oscillatory DO conditions, this positive effect may be counteracted by the decreased ATP supply. Moreover, it is interesting to note that not only the penicillin productivity was reduced under such oscillating DO conditions, but also that of the unrecyclable byproduct ortho‐hydroxyphenyl acetic acid and degeneration of penicillin productivity. Furthermore, dynamic flux profiles showed the most pronounced variations in central carbon metabolism, amino acid (AA) metabolism, energy metabolism and fatty acid metabolism upon the DO oscillation. Taken together, the metabolic responses of P. chrysogenum to DO gradients reported here are important for elucidating metabolic regulation mechanisms, improving bioreactor design and scale‐up procedures as well as for constructing robust cell strains to cope with heterogenous industrial culture conditions. [ABSTRACT FROM AUTHOR]