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: Copper contamination is common in paddy fields due to wastewater irrigation and application of sludge and Cu-containing fungicides, but it is concluded that the rhizosphere environment alleviated Cu2 + stress on methanogens and methanotrophs.
Abstract: Copper contamination is common in paddy fields due to wastewater irrigation and application of sludge and Cu-containing fungicides. We aimed to study the effects of copper (Cu2 +) application on methane emission, methanogens and methanotrophs in both the rhizosphere and bulk soil. The study was conducted in rhizobox in which flooded soil was applied with different Cu2 + concentrations. Methane emission was collected with static chamber method and determined by gas chromatography. The diversity and composition of methanogens and methanotrophs were studied using PCR–DGGE and sequencing analysis of methanogenic 16S rRNA and pmoA genes. The abundance of methanogens and methanotrophs was determined using quantitative real-time PCR of mcrA and pmoA genes, respectively. The results showed that Cu2 + application decreased methane emission along with the diversity and abundance of methanogens and methanotrophs, although the application of 200 mg kg− 1 Cu2 + did not significantly decrease the diversity of methanogens and methanotrophs in the rhizosphere. In addition, Cu2 + decreased methanotrophs diversity more profoundly than methanogens diversity. Methanogens in both the rhizosphere and bulk soil were closely related to Methanosaeta, Methanosarcina, Methanobacterium and Methanomicrobia archaeon. Methanotrophs in rhizosphere soil were clustered into four groups (type I methanotrophs, Methylobacter, Methylomonas and Methylosarcina) while those in bulk soil were much less diverse. The addition of 200 to 800 mg kg− 1 Cu2 + did not dramatically change the composition of methanogens; however, for methanotrophs, only one DGGE band belonging to Methylosarcina was present after the addition of 800 mg kg− 1 Cu2 +. We conclude that methanotrophs were more sensitive to Cu2 + addition than methanogens, and that the rhizosphere environment alleviated Cu2 + stress on methanogens and methanotrophs.
18 citations
TL;DR: An experimental framework based on the in situ pulse respirometry technique was developed to assess the impact of NAP addition on the methane biodegradation kinetics using Methylosinus sporium as a model methane-degrading microorganism.
18 citations
TL;DR: The novel isolation method developed in this study significantly shortened the time and efforts needed for isolation of methanotrophs from environmental samples and was capable of screening for the meethanotrophic strains with the fastest growth rates.
Abstract: Methanotrophs have recently gained interest as biocatalysts for mitigation of greenhouse gas emission and conversion of methane to value-added products; however, their slow growth has, at least partially, hindered their industrial application. A rapid isolation technique that specifically screens for the fastest-growing methanotrophs was developed using continuous cultivation with gradually increased dilution rates. Environmental samples collected from methane-rich environments were enriched in continuously stirred tank reactors with unrestricted supply of methane and air. The reactor was started at the dilution rate of 0.1 h−1, and the dilution rates were increased with an increment of 0.05 h−1 until the reactor was completely washed out. The shifts in the overall microbial population and methanotrophic community at each step of the isolation procedure were monitored with 16S rRNA amplicon sequencing. The predominant methanotrophic groups recovered after reactor operations were affiliated to the gammaproteobacterial genera Methylomonas and Methylosarcina. The methanotrophic strains isolated from the reactor samples collected at their respective highest dilution rates exhibited specific growth rates up to 0.40 h−1; the highest value reported for methanotrophs. The novel isolation method developed in this study significantly shortened the time and efforts needed for isolation of methanotrophs from environmental samples and was capable of screening for the methanotrophs with the fastest growth rates.
15 citations
TL;DR: It is indicated that CH4 oxidation biotechnologies applied at low NH4+ concentrations can support efficient abatement of CH4 and high diversity of methanotrophic consortia, whilst enriching type II methanosarcina and Methylobacter genera.
9 citations