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Propanediol Production from Glycerol
Published in Ozcan Konur, Biodiesel Fuels, 2021
Biebl (1991) studies the fermentation of glycerol to 1,3-PD, acetate, and butyrate by Clostridium butyricum with respect to growth inhibition by the accumulating products in a paper with 118 citations. He grew the clostridia in a pH-auxostat culture at low cell density and product concentration and near the maximum growth rate. He then added the products individually to the medium in increasing concentrations and used the resulting depression of the growth rate as a quantitative estimate of product inhibition. Under these conditions, he observed that growth was totally inhibited at concentrations of 60 g/L for 1,3-PD, 27 g/L for acetic acid, and 19 g/L for butyric acid at pH 6.5. He found an appreciable inhibition by glycerol only above a concentration of 80 g/L. In a pH-auxostat without added products but with high cell density as well as in batch cultures, the product proportions were different. The 1,3-PD concentration may approach the value of complete inhibition while the concentrations of acetic and butyric acids remained below these values by at least one order of magnitude. He concludes that 1,3-PD was the first range inhibitor in this fermentation.
High rate biological sulphate reduction in a lactate fed inverse fluidized bed reactor at a hydraulic retention time of 3 h
Published in Luis Carlos Reyes-Alvarado, Optimization of the electron donor supply to sulphate reducing bioreactors treating inorganic wastewater, 2018
Furthermore, the electron donor (mg CODLactate.L−1d−1) and sulphate (mg SO42-.L−1d−1) loading rate did positively influence the Xrate, this is observed in the positive slopes indicating the generation of new VSS on the sulphate and COD consumption, respectively, 2.52 mg VSS.mg [SO42-]−1 (Figure 4-3B) and 1.05 mg VSS.mg COD−1 (Figure 4-3C). This VSS yield on sulphate was 15 times smaller in comparison to that reported for a membrane bioreactor performing sulphate reduction at pH 6 (38 mg VSS. mg [SO42-]−1) using formate as electron donor in a pH auxostat system [36].
A critical process variable-regulated, parameter-balancing auxostat, performed using disposed COVID-19 personal protective equipment-based substrate mixture, yields sustained and improved endoglucanase titers
Published in Preparative Biochemistry & Biotechnology, 2023
Navnit Kumar Ramamoorthy, Revanth Babu Pallam, Kabilan Subash Chandrabose, Renganathan Sahadevan, Venkateswara Sarma Vemuri
Manabe and coworkers performed a pH-static, prolonged NH3-pH auxostat using a genome-manipulated strain of Bacillus subtilis MGB874 (strain 874ΔrocG), and recorded titers close to 5.5 g/L of alkaline cellulase Egl-237.[64] Gelain et al. reported 1048 ± 16 U/mol h of beta-glucosidase production while performing a carbon-limited chemostat using glucose, and a constant dilution rate of 0.05 h−1.[65] Wheeler and coworkers reported a 4-fold increase in exo-β-glucosidases activity while employing Penicillium spinulosum in a chemostat operation using galactose-containing standard growth medium.[66]