Growth Analysis of Methylotuvimicrobium buryatense 5GB1C and Its Utilization for Treating Low Methane Concentrations in a Packed-Bed Column Reactor

Biodegradation of high concentration phenol using sugarcane bagasse immobilized Candida tropicalis PHB5 in a packed-bed column reactor

The online version contains supplementary material available at 10.1007/s13205-021-02932-3.

Investigation of the Combined Effects of External Mass Transfer and Biodegradation Rates on Phenol Removal Using Immobilized P. putida in a Packed-Bed Column Reactor

The CO2 absorption performance of hollow-fiber membranes and conventional packed-bed column reactors under similar operating conditions was evaluated. Two-scale, nonisothermal, steady-state models were used to simulate the reactors behavior. The membrane reactor model accounts for CO2 diffusion in gas-filled membrane pores, CO2 and amine diffusion accompanied by chemical reaction in liquid-filled membrane pores, and CO2 and amine diffusion accompanied by chemical reaction in the liquid film zone surrounding the inside membrane wall. The packed-bed column reactor model interconnects a two-fluid 2D hydrodynamic platform with 2D mass and energy transport equations in the gas and liquid phases and nonlinear differential equations governing diffusion and reaction in the liquid film. In the absence of membrane wetting, the hollow-fiber membrane reactor outperforms the packed-bed column reactor with similar volume and specific surface area. This is not the case under membrane wetting conditions, when at low spec...

The role of water on the continous synthesis of geranyl esters by immobilized lipase fromHumicola lanuginosa No. 3 was studied in a packed-bed column reactor (PBR) installed with a molecular sieve column for water extraction. The conversion degress by PBR were highly influenced by the water concentration throughout the reaction which acted as a determinant on the reaction equilibrium. Almost 100% conversion of geranyl laurate could be achieved under the optimum water-controlled conditions. The stability of the PBR system was for 35 days with the half-life of 38 days.

Integration of purification with immobilization of Candida rugosa lipase for kinetic resolution of racemic ketoprofen

The novel carboxylesterase gene (est741) was cloned from Geobacillus uzenensis. The optimal pH and temperature of Est741 were 8.0 and 50 °C. Through site-directed mutation, the optimum temperature of the mutant M160K(EstM160K) was increased from 50 to 60 °C, and showed enhanced T1/2 of 2.5 h at 70 °C in comparison to the wild type (1.3 h). EstM160K was successfully expressed Pichia pastoris and EstM160K fermentation broth was directly immobilized on epoxy-functionalized supports via a one-pot strategy to obtain the immobilized enzyme lx-EstM160K. Additionally, lx-EstM160K showed enhanced T1/2 of 36.8 h at 70 °C in comparison to free enzyme. lx-EstM160K could degrade various pyrethroid pesticides. After 40 min reaction with 50 U of the lx-EstM160K, the malathion removal was 95.8% with a malathion concentration of 20 mg/L. When 2.5 g lx-EstM160K was added to the 10 mL column reactor with the concentration of bifenthrin was 500 mg/L and the transfer rate of the pump was 0.7 mL/min, the degradation rate of lx-EstM160K to bifenthrin was 90.4%. lx-EstM160K exhibited high operational stability and maintained 72% initial activity after ten batches of continuous reaction for bifenthrin pesticide biodegradation.

The present work aims at employment of cucumber peel for adsorption of cadmium in packed-bed column reactor in an attempt to testify the efficiency of this sorbent for treating huge volume of wastewater needed for practical purpose. The study was performed with dried and powdered cucumber peel packed in a glass column reactor with influent metal solution being pumped in upflow mode using peristaltic pump at pH 5.0. Different design parameters of adsorption in continuous mode were evaluated, and experiments were performed at varied flow rates (15, 18 and 20 mL min−1), bed heights (5.0, 6.5 and 8.0 cm) and influent concentrations (50 and 100 mg L−1). Results illustrated delayed breakthrough, and higher percentage removal of cadmium were associated with lowest flow rate, highest bed height and lower influent concentration. Experimental outcome further revealed percentage removal of 78.03% at saturation with adsorption capacity of 107.76 mg g−1 at 50 mg L−1 influent concentration, 20 mL min−1 flow rate and 8.0 cm bed height. Evaluation of experimental data with different kinetic models established pertinence of Thomas model and Yoon–Nelson model in defining adsorption pattern in continuous mode. Elution of adsorbed cadmium from packed bed was executed using 0.1 M HCl which efficiently recovered more than 94% of the loaded metal in three consecutive cycles. The work has conveniently established the prospect of cucumber peel as a cheap biological sorbent for treating large volume of cadmium contaminated water.

Enzymatic CO2 capture in countercurrent packed-bed column reactors with high performance random packings

A growing body of literature has identified methane mitigation as a key component of limiting the rate and extent of global warming. However, little is known about how methane mitigation can benefit other critical aspects of the climate system. This study explores the value of early methane mitigation in addition to carbon dioxide mitigation in helping avert an approaching and concerning climate event: the near-complete loss of Arctic summer sea ice. While drastic cuts in carbon dioxide emissions will ultimately control the fate of Arctic summer sea ice, we show that simultaneous early deployment of feasible methane mitigation measures is essential to avoiding the loss of Arctic summer sea ice this century. In fact, the benefit of combined methane and carbon dioxide mitigation on reducing the likelihood of a seasonally ice-free Arctic can be greater than the simple sum of benefits from two independent greenhouse gas policies. The extent to which methane mitigation can help preserve Arctic summer sea ice depends on the implementation timeline. The benefit of methane mitigation is maximized when all technically feasible measures are implemented within this decade, and it decreases with each decade of delay in implementation due to its influence on end-of-century temperature. A key insight is that methane mitigation substantially lowers the risk of losing Arctic summer sea ice across varying levels of concomitant carbon dioxide mitigation. This analysis provides further evidence of the value of early methane mitigation and the need to consider its benefits beyond reduced global temperature and improved air quality.

Due to their fast growth rate and robustness, some haloalkalitolerant methanotrophs from the genus Methylotuvimicrobium have recently become not only promising biocatalysts for methane conversion but also favorable materials for obtaining fundamental knowledge on methanotrophs. Here, to realize unmarked genome modification in Methylotuvimicrobium bacteria, a counterselectable marker (CSM) was developed based on pheS, which encodes the α-subunit of phenylalanyl-tRNA synthetase. Two-point mutations (T252A and A306G) were introduced into PheS in Methylotuvimicrobium buryatense 5GB1C, generating PheSAG, which can recognize p-chloro-phenylalanine (p-Cl-Phe) as a substrate. Theoretically, the expression of PheSAG in a cell will result in the incorporation of p-Cl-Phe into proteins, leading to cell death. The Ptac promoter and the ribosome-binding site region of mmoX were employed to control pheSAG, producing the pheSAG-3 CSM. M. buryatense 5GB1C harboring pheSAG-3 was extremely sensitive to 0.5 mM p-Cl-Phe. Then, a positive and counterselection cassette, PZ (only 1.5 kb in length), was constructed by combining pheSAG-3 and the zeocin resistance gene. A PZ- and PCR-based strategy was used to create the unmarked deletion of glgA1 or the whole smmo operon in M. buryatense 5GB1C and Methylotuvimicrobium alcaliphilum 20Z. The positive rates were over 92%, and the process could be accomplished in as few as eight days.

New kinetic models for predicting the removal of oil and grease from food-processing industry wastewater

The ability of dried bacterial strain Bacillus sp. S14 to adsorb Malathion in a packed bed column reactor was studied. The effects of important design parameters such as bed height, flow rate and influent Malathion concentration on Malathion removal from an aqueous solution was studied using a packed bed column reactor. The optimised conditions for maximum Malathion removal were found to be: flow rate: 5 mL min-1, bed height: 6.0 cm and influent Malathion concentration: 25 mg L-1. The Adams-Bohart model, Wolborska model, Thomas model, Yoon and Nelson Model were employed to determine characteristic parameters such as N0 (saturation concentration, mg L-1), βo (external mass transfer coefficient, min-1), k Th(Thomas rate constant, mL min-1mg-1), q0 (maximum solid phase concentration of the solute, mg L-1), kYN (rate constant, min-1) and τ (time required for 50 % adsorbate breakthrough time, min) which are useful for process design. Data were fitted with Adams-Bohart model at lower region of (C/C0) values but more accurately fitted with Wolborska and Thomas model.

Methanotrophic bacteria are a group of prokaryotes capable of using methane as their sole carbon and energy source. Although efforts have been made to simulate and elucidate their metabolism via computational approaches or 13C tracer analysis, major gaps still exist in our understanding of methanotrophic metabolism at the systems level. Particularly, direct measurements of system-wide fluxes are required to understand metabolic network function. Here, we quantified the central metabolic fluxes of a type I methanotroph, "Methylotuvimicrobium buryatense" 5GB1C, formerly Methylomicrobium buryatense 5GB1C, via 13C isotopically nonstationary metabolic flux analysis (INST-MFA). We performed labeling experiments on chemostat cultures by switching substrates from 12C to 13C input. Following the switch, we measured dynamic changes of labeling patterns and intracellular pool sizes of several intermediates, which were later used for data fitting and flux calculations. Through computational optimizations, we quantified methane and methanol metabolism at two growth rates (0.1 h-1 and 0.05 h-1). The resulting flux maps reveal a core consensus central metabolic flux phenotype across different growth conditions: a strong ribulose monophosphate cycle, a preference for the Embden-Meyerhof-Parnas pathway as the primary glycolytic pathway, and a tricarboxylic acid cycle showing small yet significant fluxes. This central metabolic consistency is further supported by a good linear correlation between fluxes at the two growth rates. Specific differences between methane and methanol growth observed previously are maintained under substrate limitation, albeit with smaller changes. The substrate oxidation and glycolysis pathways together contribute over 80% of total energy production, while other pathways play less important roles.IMPORTANCE Methanotrophic metabolism has been under investigation for decades using biochemical and genetic approaches. Recently, a further step has been taken toward understanding methanotrophic metabolism in a quantitative manner by means of flux balance analysis (FBA), a mathematical approach that predicts fluxes constrained by mass balance and a few experimental measurements. However, no study has previously been undertaken to experimentally quantitate the complete methanotrophic central metabolism. The significance of this study is to fill such a gap by performing 13C INST-MFA on a fast-growing methanotroph. Our quantitative insights into the methanotrophic carbon and energy metabolism will pave the way for future FBA studies and set the stage for rational design of methanotrophic strains for industrial applications. Further, the experimental strategies can be applied to other methane or methanol utilizers, and the results will offer a unique and quantitative perspective of diverse methylotrophic metabolism.

Biofilm reactors are particularly suitable for the treatment of large amounts of diluted effluent, such as groundwater contaminated with scarcely soluble pollutants. A packed-bed column reactor was tested for the degradation of acenaphthene, phenanthrene and pyrene provided at their aqueous solubility concentrations. Acenapthene and phenanthrene were removed to more than 99% efficiency from this reactor whilst pyrene was removed to 90%. Pollutant disappearance was also recorded in the control reactor and was probably caused by the adsorption of pollutants into the reactor. The measurement of oxygen consumption in both reactors confirmed that microbial degradation of the pollutants was indeed occurring in the inoculated reactor. Physical adsorption is not however unwanted, as it could help with the formation of a biofilm at an early stage of the treatment.