FIG 3 - available via license: Creative Commons Attribution 4.0 International
Content may be subject to copyright.
M. album BG8 reactors during substrate limitation and recovery. (A) 2.8-day RT reactor response during CH 4 limitation; (B) 2.8-day RT reactor genome and pmoA mRNA amounts during CH 4 limitation; (C) 2.8-day RT reactor pmoA mRNA copies per cell during CH 4 limitation; (D) 4.3-day RT reactor response during O 2 limitation; (E) 4.3-day RT reactor genome and pmoA mRNA amounts during O 2 limitation; (F) 4.3-day RT reactor pmoA mRNA copies per cell during O 2 limitation. Data are means 6 standard deviations from triplicate reactors. Asterisks indicate samples selected for RNA-seq. Data following RT switch are not shown.
Source publication
Methanotrophs are naturally occurring microorganisms capable of oxidizing methane, having an impact on global net methane emissions. Additionally, they have also gained interest for their biotechnological applications in single-cell protein production, biofuels, and bioplastics.
Contexts in source publication
Context 1
... activities. For the three aerobic methanotroph cultures in Fig. 2, a strong positive correlation (Pearson's R 2 = 0.91) between per-cell pmoA transcript levels and per-cell methane oxidation rates was observed across several orders of magnitude. Strong correlations were maintained when pure methanotroph cultures were examined individually (Fig. S3). Cell amounts alone and methanotrophic activity have been shown to be poorly correlated previously in methanotrophs (37,50). Identical populations in terms of cell abundances can display vastly different activities, which could explain the stronger relationship when looking at cell amounts in conjunction with transcript amounts. The ...
Context 2
... demonstrated under controlled lab conditions using pure cultures and requires more robust testing in complex microbial bioreactors and ecosystems. effects of a 24-h methane and oxygen limitation on M. album BG8 cultures were explored. The limitation period was followed by a 24-h recovery period in which membrane pressures were turned back on ( Fig. 3 and Fig. S2A and B). Methane limitation caused reactor oxygen levels to increase from 5.5 to 9.0 mg L 21 due to the lack of incoming methane, while biomass levels decreased by about half (Fig. 3A). The decrease in biomass was reflected in both cell genome and pmoA mRNA amounts (Fig. 3B). Within 2 h of methane limitation, genome copies ...
Context 3
... on M. album BG8 cultures were explored. The limitation period was followed by a 24-h recovery period in which membrane pressures were turned back on ( Fig. 3 and Fig. S2A and B). Methane limitation caused reactor oxygen levels to increase from 5.5 to 9.0 mg L 21 due to the lack of incoming methane, while biomass levels decreased by about half (Fig. 3A). The decrease in biomass was reflected in both cell genome and pmoA mRNA amounts (Fig. 3B). Within 2 h of methane limitation, genome copies were about a third of steady-state amounts, while pmoA mRNA amounts decreased by about 3 orders of magnitude. During steady state, per-cell pmoA transcript levels ranged from 9.02 to 11.60 ...
Context 4
... period in which membrane pressures were turned back on ( Fig. 3 and Fig. S2A and B). Methane limitation caused reactor oxygen levels to increase from 5.5 to 9.0 mg L 21 due to the lack of incoming methane, while biomass levels decreased by about half (Fig. 3A). The decrease in biomass was reflected in both cell genome and pmoA mRNA amounts (Fig. 3B). Within 2 h of methane limitation, genome copies were about a third of steady-state amounts, while pmoA mRNA amounts decreased by about 3 orders of magnitude. During steady state, per-cell pmoA transcript levels ranged from 9.02 to 11.60 transcripts per cell. A sharp decrease in the pmoA transcriptional activity 0.5 h after the onset ...
Context 5
... per-cell pmoA transcript levels ranged from 9.02 to 11.60 transcripts per cell. A sharp decrease in the pmoA transcriptional activity 0.5 h after the onset of methane limitation was observed, reaching its minimum 8 h postlimitation, with a log 2 fold decrease of 8.2 in per-cell pmoA transcript levels compared to average steady-state levels ( Fig. 3C and Table S3). Per-cell pmoA transcript levels stayed significantly depleted through the 24 h following the onset of methane limitation. Resumption of methane saw sharp increases in pmoA transcript amounts, with per-cell pmoA transcript levels approaching steady-state levels 24 h after recovery, while biomass (as both genome copies and ...
Context 6
... oxygen-limited reactors, a sharp decrease in biomass levels was also observed, which continued into the recovery period (Fig. 3D). Steady-state pmoA transcript levels for the 4.3-day reactors ranged between 24.19 and 47.52 for the days preceding oxygen limitation. During oxygen limitation, oxygen levels decreased from 4 to 2 mg L 21 and methane levels increased from 1 to 3 mg L 21 . Genome copies dropped slowly throughout both the limitation and recovery ...
Context 7
... levels decreased from 4 to 2 mg L 21 and methane levels increased from 1 to 3 mg L 21 . Genome copies dropped slowly throughout both the limitation and recovery periods, while pmoA mRNA amounts decreased by 2 orders of magnitude 0.5 h after oxygen limitation, with a more gradual decline observed in the subsequent hours during oxygen limitation (Fig. 3E). The decrease pattern in pmoA transcript amounts was reflected in per-cell pmoA transcript levels, with a log 2 fold decrease of 4.3 in compared to average steady-state levels ( Fig. 3F and Table S3). The oxygen recovery period also saw increases in pmoA transcript amounts which led to per-cell pmoA transcript levels comparable to ...
Context 8
... amounts decreased by 2 orders of magnitude 0.5 h after oxygen limitation, with a more gradual decline observed in the subsequent hours during oxygen limitation (Fig. 3E). The decrease pattern in pmoA transcript amounts was reflected in per-cell pmoA transcript levels, with a log 2 fold decrease of 4.3 in compared to average steady-state levels ( Fig. 3F and Table S3). The oxygen recovery period also saw increases in pmoA transcript amounts which led to per-cell pmoA transcript levels comparable to steady-state levels after 24 h following oxygen repletion ( Fig. 3B and C and Table ...
Context 9
... was reflected in per-cell pmoA transcript levels, with a log 2 fold decrease of 4.3 in compared to average steady-state levels ( Fig. 3F and Table S3). The oxygen recovery period also saw increases in pmoA transcript amounts which led to per-cell pmoA transcript levels comparable to steady-state levels after 24 h following oxygen repletion ( Fig. 3B and C and Table ...
Context 10
... to that in steady state. Genome copies in the methane-limited reactors exhibited a sharp decrease within the first hour, with no further change observed through 24 h until recovery, when a small increase in genome copies was observed, while oxygen- limited reactors exhibited a steady decrease throughout both the limitation and recovery periods ( Fig. 3B and E). Both methane and oxygen limitation had the largest decrease of pmoA transcript levels in the first hour, with a larger overall decrease observed with methane limited. Differences between per-cell pmoA transcript levels during both methane and oxygen limitation and their preceding steady-state levels were statistically significant (P , ...
Context 11
... than in the study by Rodríguez the first hours of methane limitation suggest a fast pmoA regulation in response to methane levels. This is also supported by the increase observed in per-cell pmoA transcripts when methane was available during the recovery period, where a response occurred in the first 8 h and reached steady-state levels after 24 h (Fig. 3C). The observed rapid response of methanotrophs to changing methane and oxygen conditions suggests that they can quickly adapt to changes in local environmental conditions. In addition to cell amounts decreasing, the observed changes in biomass could be due to decreases in protein mass, as starvation under aerobic conditions has been ...
Citations
... Cytochrome c L , in turn, is oxidized by a typical class I cytochrome c (cytochrome c H ), which is also specific for methanol oxidation (Kang-Yun et al. 2022). Importantly, all three components-MDH, cytochrome c L , and cytochrome c H -are soluble and reside within the periplasm of gramnegative methylotrophs (Tentori et al. 2022). In contrast, gram-positive methylotrophs employ an NAD-linked MDH for methanol oxidation, while methanol-oxidizing yeast species use a methanol oxidase system for the same purpose. ...
... The extensive dataset of pMMO gene sequences from various methanotrophs offers the opportunity to utilize pmo as a "functional gene probe" in molecular ecology studies, enabling investigations into the diversity of methanotrophs within natural environments. This utilization has been recently explored and reviewed in publications such as Tentori et al. (2022) and Tyne et al. (2023). ...
The potential consequences for mankind could be disastrous due to global warming, which arises from an increase in the average temperature on Earth. The elevation in temperature primarily stems from the escalation in the concentration of greenhouse gases (GHG) such as CO2, CH4, and N2O within the atmosphere. Among these gases, methane (CH4) is particularly significant in driving alterations to the worldwide climate. Methanotrophic bacteria possess the distinctive ability to employ methane as both as source of carbon and energy. These bacteria show great potential as exceptional biocatalysts in advancing C1 bioconversion technology. The present review describes recent findings in methanotrophs including aerobic and anaerobic methanotroph bacteria, phenotypic characteristics, biotechnological potential, their physiology, ecology, and native multi-carbon utilizing pathways, and their molecular biology. The existing understanding of methanogenesis and methanotrophy in soil, as well as anaerobic methane oxidation and methanotrophy in temperate and extreme environments, is also covered in this discussion. New types of methanogens and communities of methanotrophic bacteria have been identified from various ecosystems and thoroughly examined for a range of biotechnological uses. Grasping the processes of methanogenesis and methanotrophy holds significant importance in the development of innovative agricultural techniques and industrial procedures that contribute to a more favorable equilibrium of GHG. This current review centers on the diversity of emerging methanogen and methanotroph species and their effects on the environment. By amalgamating advanced genetic analysis with ecological insights, this study pioneers a holistic approach to unraveling the biopotential of methanotrophs, offering unprecedented avenues for biotechnological applications.
Key points
• The physiology of methanotrophic bacteria is fundamentally determined.
• Native multi-carbon utilizing pathways in methanotrophic bacteria are summarized.
• The genes responsible for encoding methane monooxygenase are discussed.
... Methane. In some bacteria, strong transcriptional responses accompany growth under nutrient limitation and at low growth rates: Bacteria often decrease expression of the translation and transcription apparatus, up-regulate functions involved in motility and chemotaxis, and up-regulate amino acid synthesis pathways (25,(29)(30)(31). To understand how M. buryatense 5GB1C responds to low methane at the transcriptional level, we quantified holistic gene expression of cultures grown at 500 ppm and 1,000 ppm at methane-limited steady-state in the bioreactor, with growth rates of 0.009 h −1 and 0.02 h −1 , respectively. ...
... These changes also reflect decreased need at the low growth rates. By contrast, many genes related to flagellar protein synthesis and chemotaxis are up-regulated (Fig. 3F), as bacteria tend to be more active in searching for nutrients and more favorable environments under stress (29). ...
The rapid increase of the potent greenhouse gas methane in the atmosphere creates great urgency to develop and deploy technologies for methane mitigation. One approach to removing methane is to use bacteria for which methane is their carbon and energy source (methanotrophs). Such bacteria naturally convert methane to CO2 and biomass, a value-added product and a cobenefit of methane removal. Typically, methanotrophs grow best at around 5,000 to 10,000 ppm methane, but methane in the atmosphere is 1.9 ppm. Air above emission sites such as landfills, anaerobic digestor effluents, rice paddy effluents, and oil and gas wells contains elevated methane in the 500 ppm range. If such sites are targeted for methane removal, technology harnessing aerobic methanotroph metabolism has the potential to become economically and environmentally viable. The first step in developing such methane removal technology is to identify methanotrophs with enhanced ability to grow and consume methane at 500 ppm and lower. We report here that some existing methanotrophic strains grow well at 500 ppm methane, and one of them, Methylotuvimicrobium buryatense 5GB1C, consumes such low methane at enhanced rates compared to previously published values. Analyses of bioreactor-based performance and RNAseq-based transcriptomics suggest that this ability to utilize low methane is based at least in part on extremely low non-growth-associated maintenance energy and on high methane specific affinity. This bacterium is a candidate to develop technology for methane removal at emission sites. If appropriately scaled, such technology has the potential to slow global warming by 2050.
From the view of a circular economy, the bioconversion of methane into cell protein and carbohydrates could provide alternative food resources while cutting greenhouse gases, considering renewable gases from anaerobic...
The remediation of volatile chlorinated hydrocarbons in the quasi-vadose zone has become a significant challenge. We applied an integrated approach to assess the biodegradability of trichloroethylene to identify the biotransformation mechanism. The formation of the functional zone biochemical layer was assessed by analyzing the distribution of landfill gas, physical and chemical properties of cover soil, spatial-temporal variations of micro-ecology, biodegradability of landfill cover soil and distributional difference metabolic pathway. Real-time online monitoring showed that trichloroethylene continuously undergoes anaerobic dichlorination and simultaneous aerobic/anaerobic conversion-aerobic co-metabolic degradation on the vertical gradient of the landfill cover system and reduction in trans-1,2-dichloroethylene in the anoxic zone but not 1,1-dichloroethylene. PCR and diversity sequencing revealed the abundance and spatial distribution of known dichlorination-related genes within the landfill cover, with 6.61 ± 0.25 × 104-6.78 ± 0.09 × 106 and 1.17 ± 0.78 × 103-7.82 ± 0.07 × 105 copies per g/soil of pmoA and tceA, respectively. In addition, dominant bacteria and diversity were significantly linked with physicochemical factors, and Mesorhizobium, Pseudoxanthomonas and Gemmatimonas were responsible for biodegradation in the aerobic, anoxic and anaerobic zones. Metagenome sequencing identified 6 degradation pathways of trichloroethylene that may occur in the landfill cover; the main pathway was incomplete dechlorination accompanied by cometabolic degradation. These results indicate that the anoxic zone is important for trichloroethylene degradation.
