Kinetics and Stoichiometry of an Efficient Methanotroph Methylosarcina sp. LC-4 Isolated from a Municipal Solid Waste Dumpsite
01 May 2021-Journal of Environmental Engineering (American Society of Civil Engineers)-Vol. 147, Iss: 5, pp 04021011
TL;DR: In recent times methanotrophs have gained immense interest due to their ability to sequester and utilize methane, which is an inexpensive carbon source as well as a very potent greenhouse gas.
Abstract: In recent times methanotrophs have gained immense interest due to their ability to sequester and utilize methane, which is an inexpensive carbon source as well as a very potent greenhouse g...
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TL;DR: In this paper , an efficient methanotroph, Methylosarcina sp. LC-4, was studied as a prospective organism for biodiesel production using methane, and the methane uptake rate by the organism was enhanced 1.6 times and 2.35 times by supplementing it with micronutrients such as copper and tungstate, respectively.
Abstract: The conversion of methane into liquid biofuels using methane-consuming bacteria, known as methanotrophs, contributes to sustainable development, as it mitigates the problem of climate change caused by greenhouse gases and aids in producing cleaner and renewable energy. In the present research, an efficient methanotroph, Methylosarcina sp. LC-4, was studied as a prospective organism for biodiesel production using methane. The methane uptake rate by the organism was enhanced 1.6 times and 2.35 times by supplementing LC-4 with micronutrients, such as copper and tungstate, respectively. This unique ability of the isolated organism enables the deployment of methanotrophs-based processes in various industrial applications. A Plackett–Burman statistical (PBD) design was used to quantify the role of the micronutrients and other media components present in the nitrate minimal salt media (NMS) in biomass and fatty acid methyl esters (FAME) yields. Nitrate, phosphate, and tungstate had a positive effect, whereas copper, magnesium, and salinity had a negative effect. The modified NMS media, formulated according to the results from the PBD analysis, increased the FAME yield (mg/L) by 85.7%, with the FAME content of 13 ± 1% (w/w) among the highest reported in methanotrophs. The obtained FAME consisted majorly (~90%) of C14–C18 saturated and monounsaturated fatty acids, making it suitable for use as biodiesel.
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TL;DR: In this paper , the authors present the current state of research in the last five years on contaminants in soils, especially in leachates from solid waste landfills, with emphasis on biological remediation.
Abstract: This systematic review presents the current state of research in the last five years on contaminants in soils, especially in leachates from solid waste landfills, with emphasis on biological remediation. In this work, the pollutants that can be treated by microorganisms and the results obtained worldwide were studied. All the data obtained were compiled, integrated, and analyzed by soil type, pollutant type, bacterial type, and the countries where these studies were carried out. This review provides reliable data on the contamination of soils worldwide, especially soils contaminated by leachate from municipal landfills. The extent of contamination, treatment objectives, site characteristics, cost, type of microorganisms to be used, and time must be considered when selecting a viable remediation strategy. The results of this study can help develop innovative and applicable methods for evaluating the overall contamination of soil with different contaminants and soil types. These findings can help develop innovative, applicable, and economically feasible methods for the sustainable management of contaminated soils, whether from landfill leachate or other soil types, to reduce or eliminate risk to the environment and human health, and to achieve greater greenery and functionality on the planet.
TL;DR: In this article , a sequential electrochemical oxidation (EO) and algal bubble column photobioreactor (BPBR) system was proposed to treat distillery wastewater (DWW), and the optimal treatment conditions for the growth of A. quadricellulare were 27 A for 26 h and a post-treatment dilution of 8.7%.
Abstract: A sequential electrochemical oxidation (EO) and algal bubble column photobioreactor (BPBR) system was proposed to treat distillery wastewater (DWW). EO was carried out in a 2 L reactor with Ti-RuO2 anodes. Electrochemically oxidised DWW (EO-DWW) was then supplied to the microalgae Asterarcys quadricellulare. The EO operating current, treatment time and post-treatment dilution were optimised with a central composite design (CCD) with algal specific growth rate, lipid accumulation and photosynthetic quantum yield (Fv/Fm) as dependent variables. The optimal treatment conditions for the growth of A. quadricellulare were 27 A for 26 h and a post-treatment dilution of 8. Under optimal conditions, A. quadricellulare grew at a specific growth rate of 1.06 d-1 with a lipid accumulation of 12.7% and an Fv/Fm of 0.7. The optimal conditions were validated, and a 1.6 L bubble column photobioreactor was designed to treat the EO-DWW sequentially. The sequential EO-BPBR system removed 92% COD, 76% TOC and 82% TN from DWW. The algal biomass productivity was 0.96 g/L/d with a carbon sequestration of 550-700 mg/L/d and an aqueous carbon capture of 240-280 mg C/L/d. Additionally, the flue gas evolved from the EO reactor was analysed and contained 68% H2, 18% O2 and 12.5% CO2. The H2 in the flue gas can compensate for 26.5% of the energy spent for the EO process. The algal biomass produced in the sequential process can compensate for 6% of the total energy consumed for EO. Therefore, 32% of the energy spent on EO can be reclaimed by sequential EO-BPBR treatment.
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TL;DR: In this review, a number of abiotic factors including temperature, pH, water content, packing material, empty-bed residence time, inlet gas flow rate, CH4 concentration, as well biotic factors, such as biomass development, are reviewed based on empirical findings on CH4 biofiltration studies that have been performed in the last decades.
36 citations
01 Jan 2016
TL;DR: This review highlights some of the most recent discoveries in microbial utilization of methane and describes unique properties of well-established microbial catalysts side by side with their less explored comrades.
Abstract: Methane utilization has been demonstrated for a number of microbial species. Some of them, such as Methylococcus capsulatus Bath, Methylomonas spp., and Methylosinus trichosporium OB3b, became the catalytic platforms of choice for biotechnological explorations. These strains have been used for the production of single-cell protein, polysaccharides, polyhydroxyalkanoates, lipids, and carotenoids. Emerging biotechnologies for conversion of the abundant C1 alcane into next-generation chemicals/biofuels add extra requirements to the catalyst leading to a new quest for fast, efficient, and genetically tractable systems. Over the past few decades, a number of novel biochemical pathways for microbial methane utilization have been discovered. As a result, new methane-utilizing microbes have been brought into laboratory cultures. Today a wide spectrum of such microbes is available, including thermophilic and psychrophilic, alkaliphilic and acidophilic, and oligotrophic and halophilic variants. Methanotrophs have been isolated from landfills and garden soils, animal dung and rumen, groundwater and oil-drilling sites, thermal vents, and permafrost. These microbes are becoming new sources of chemicals and enzymes and offer new strategies for metabolic engineering of C1 metabolism. This review highlights some of the most recent discoveries in microbial utilization of methane and describes unique properties of well-established microbial catalysts side by side with their less explored comrades.
32 citations
TL;DR: A methane‐utilizing mixed culture isolated from activated sludge by selective enrichment at 45°C was found to consist of three interacting species: a methaneutilizing bacterium, a citrate‐utilize bacterium and a methanol‐utilized bacterium.
Abstract: A methane-utilizing mixed culture isolated from activated sludge by selective enrichment at 45°C was found to consist of three interacting species: a methaneutilizing bacterium, a citrate-utilizing bacterium, and a methanol-utilizing bacterium. All three species grew well at 45°C. Three different stable mixed cultures were reconstituted by various combinations of these pure cultures. The nutritional requirements and substrate ranges for each pure culture were determined. The nutritional requirements and substrate ranges for each pure culture were determined. The saturation constant for the methane-utilizing bacterium on methane (K CH 4) and for the methanol-utilizing bacterium on methanol (K CH 3OH) were 1.73 × 10-6 M and 4.51 × 10-7 M, respectively. The volumetric mass transfer coefficient for methane (KL a) was determined to be 65.6 hr-1 .
29 citations
TL;DR: The obtained kinetic parameters confirm the prominence of utilizing type I methanotrophs mixed cultures in resources recovery processes from waste streams.
21 citations
TL;DR: This work characterized the oxidation of CH4 in two biotrickling filters packed with polyethylene rings and inoculated with two methanotrophic bacteria, Methylomicrobium album and Methylocystis sp.
Abstract: The oxidation of methane (CH4) using biofilters has been proposed as an alternative to mitigate anthropogenic greenhouse gas emissions with a low concentration of CH4 that cannot be used as a source of energy. However, conventional biofilters utilize organic packing materials that have a short lifespan, clogging problems, and are commonly inoculated with non-specific microorganisms leading to unpredictable CH4 elimination capacities (EC) and removal efficiencies (RE). The main objective of this work was to characterize the oxidation of CH4 in two biotrickling filters (BTFs) packed with polyethylene rings and inoculated with two methanotrophic bacteria, Methylomicrobium album and Methylocystis sp., in order to determine EC and CO2 production (pCO2) when using a specific inoculum. The repeatability of the results in both BTFs was determined when they operated at the same inlet load of CH4. A dynamic mathematical model that describes the CH4 abatement in the BTFs was developed and validated using mass transfer and kinetic parameters estimated independently. The results showed that EC and pCO2 of the BTFs are not identical but very similar for all the conditions tested. The use of specific inoculum has shown a faster startup and higher EC per unit area (0.019 gCH4 m-2 h-1) in comparison to most of the previous studies at the same CH4 load rate (23.2 gCH4 m-3 h-1). Global mass balance showed that the maximum reduction of CO2 equivalents was 98.5 gCO2eq m-3 h-1. The developed model satisfactorily described CH4 abatement in BTFs for a wide range of conditions.
21 citations