• Journal of Microbiology and Biotechnology
• /
• v.32 no.3
• /
• pp.269-277
• /
• 2022

Human activities account for approximately two-thirds of global methane emissions, wherein the livestock sector is the single massive methane emitter. Methane is a potent greenhouse gas of over 21 times the warming effect of carbon dioxide. In the rumen, methanogens produce methane as a by-product of anaerobic fermentation. Methane released from ruminants is considered as a loss of feed energy that could otherwise be used for productivity. Economic progress and growing population will inflate meat and milk product demands, causing elevated methane emissions from this sector. In this review, diverse approaches from feed manipulation to the supplementation of organic and inorganic feed additives and direct-fed microbial in mitigating enteric methane emissions from ruminant livestock are summarized. These approaches directly or indirectly alter the rumen microbial structure thereby reducing rumen methanogenesis. Though many inorganic feed additives have remarkably reduced methane emissions from ruminants, their usage as feed additives remains unappealing because of health and safety concerns. Hence, feed additives sourced from biological materials such as direct-fed microbials have emerged as a promising technique in mitigating enteric methane emissions.

• Plant Breeding and Biotechnology
• /
• v.6 no.4
• /
• pp.381-390
• /
• 2018

Percentage of aerenchyma area has been closely linked with amounts of methane emitted by rice. A diversity panel of 39 global rice varieties were examined to determine genetic variation for root transverse section (RTS), aerenchyma area, and % aerenchyma. RTS and aerenchyma area showed a strong positive correlation while there existed no significant correlation between RTS area and % aerenchyma. Five varieties previously shown to differ in methane emissions under field conditions were found to encompass the variation found in the diversity panel for RTS and aerenchyma area. These five varieties were evaluated in a greenhouse study to determine the relationship of RTS, aerenchyma area, and % aerenchyma with methane emissions. Methane emissions at physiological maturity were the highest for 'Rondo', followed by 'Jupiter', while 'Sabine', 'Francis' and 'CLXL745' emitted the least. The same varietal rank, 'Rondo' being the largest and 'CLXL745' the smallest, was observed with RTS and aerenchyma areas. RTS and aerenchyma area were significantly correlated with methane emissions, r = 0.61 and r = 0.57, respectively (P < 0.001); however, there was no relationship with % aerenchyma. Our results demonstrated that varieties with a larger root area also developed a larger aerenchyma area, which serves as a gas conduit, and as a result, methane emissions were increased. This study suggests that root transverse section area could be used as a means of selecting germplasm with reduced $CH_4$ emissions.

• Asian-Australasian Journal of Animal Sciences
• /
• v.21 no.1
• /
• pp.144-154
• /
• 2008

The rumen microbial ecosystem produces methane as a result of anaerobic fermentation. Methanogenesis in the rumen is thought to represent a 2-12% loss of energy intake and is estimated to be about 15% of total atmospheric methane emissions. While methanogenesis in the rumen is conducted by methanogens, PCR-based techniques have recently detected many uncultured methanogens which have a broader phylogenetic range than cultured strains isolated from the rumen. Strategies for reduction of methane emissions from the rumen have been proposed. These include 1) control of components in feed, 2) application of feed additives and 3) biological control of rumen fermentation. In any case, although it could be possible that repression of hydrogen-producing reactions leads to abatement of methane production, repression of hydrogen-producing reactions means repression of the activity of rumen fermentation and leads to restrained digestibility of carbohydrates and suppression of microbial growth. Thus, in order to reduce the flow of hydrogen into methane production, hydrogen should be diverted into propionate production via lactate or fumarate.

• Korean Journal of Agricultural Science
• /
• v.45 no.3
• /
• pp.463-473
• /
• 2018

The objective of this study was to investigate the effects of dietary hydrolysable tannin on growth performance and methane emissions of Hanwoo beef cows. Fifteen cows participated in a seven-week experiment. The cows were stratified by initial methane emissions and assigned to one of two treatments: Control and tannin supplementation. Commercial hydrolysable tannin was top-dressed to a concentrate mix at 3 g/kg based on the dry matter. Enteric methane production was measured for 4 consecutive days at 1 week before and 1, 3 and 7 weeks after the initiation of the experiment using a laser methane detector. The feed intake was measured daily during the methane measurement periods and an additional two days prior to each measurement. The body weight of the cows was measured every 4 weeks. Hydrolysable tannin had no effect (p > 0.05) on body weight, average daily gain, dry matter intake (DMI) and feed conversion ratio. After one week, the methane emission of the tannin supplementation group was 3.66 ppm-m / kg DMI, which was about 3.4% lower (p = 0.078) than that of the control group; however, this tendency disappeared at 3 weeks after the start of the experiment (p > 0.05). The results of this study show that hydrolysable tannin supplementation can reduce enteric methane emissions for a limited period in Hanwoo beef cows. More research, however, is needed to determine the optimal level of hydrolysable tannin supplementation to reduce enteric methane emissions for a longer period without adversely affecting the animal performance of Hanwoo beef cattle.

• Journal of Korean Society for Atmospheric Environment
• /
• v.21 no.6
• /
• pp.649-655
• /
• 2005

Automotive exhaust is suspected to be one of the main reasons of the rapid increase in greenhouse effect gases in ambient air. Although methane emissions are generally orders of magnitude lower than emissions of $CO_{2}$, the global warming potential (GWP) of methane is greater than that of $CO_{2}$. The environmental impact of methane emissions from vehicles is negligible and is likely to remain so for the foreseeable future. In this study, in order to investigate greenhouse gas emission characteristics from gasoline passenger cars, 20 vehicles were tested on the chassis dynamometer and methane emissions were measured. The emission characteristics by model year, mileage, vehicle speed were discussed. Test mode is CVS-15 mode that have been used to regulate for light-duty vehicle in Korea. It was found that $CH_{4}$ emissions showed higher for cold start, old model year and long mileage than hot start, new model year and short mileage, respectively. These results were compared with IPCC emission factors and the overall our results were anticipated to contribute for domestic greenhouse gas emissions calculation.

• Asian Journal of Atmospheric Environment
• /
• v.9 no.3
• /
• pp.187-193
• /
• 2015

Livestock is one of the major contributors of greenhouse gases (GHGs). It accounts for 14.5% of the global GHGs emissions like methane ($CH_4$) from enteric fermentation and manure, nitrous oxide ($N_2O$) from manure and fertilizer. Since enteric emissions are a major contributor of $CH_4$ than that of manure emissions hence primary efforts were made on reducing enteric emissions, with minor attention to dung emissions. Many researches were conducted by dietary manipulation to mitigate enteric $CH_4$ emission. However dietary manipulation also had significant effects on manure GHGs emissions too. Several works proved that manure $CH_4$ emissions were increased with high level of concentrate supplementation despite reduction in enteric $CH_4$. Fat and CP content of the diet has shown inconsistent results on manure $CH_4$ emissions. Amount of concentrate in the diet has shown little effect whereas dietary CP content exhibited conflicting effects on manure $N_2O$ emissions.

• Journal of Microbiology and Biotechnology
• /
• v.31 no.1
• /
• pp.104-114
• /
• 2021

Petroleum-contaminated soil is considered among the most important potential anthropogenic atmospheric methane sources. Additionally, various rhizoremediation factors can affect methane emissions by altering soil ecosystem carbon cycles. Nonetheless, greenhouse gas emissions from soil have not been given due importance as a potentially relevant parameter in rhizoremediation techniques. Therefore, in this study we sought to investigate the effects of different plant and soil amendments on both remediation efficiencies and methane emission characteristics in diesel-contaminated soil. An indoor pot experiment consisting of three plant treatments (control, maize, tall fescue) and two soil amendments (chemical nutrient, compost) was performed for 95 days. Total petroleum hydrocarbon (TPH) removal efficiency, dehydrogenase activity, and alkB (i.e., an alkane compound-degrading enzyme) gene abundance were the highest in the tall fescue and maize soil system amended with compost. Compost addition enhanced both the overall remediation efficiencies, as well as pmoA (i.e., a methane-oxidizing enzyme) gene abundance in soils. Moreover, the potential methane emission of diesel-contaminated soil was relatively low when maize was introduced to the soil system. After microbial community analysis, various TPH-degrading microorganisms (Nocardioides, Marinobacter, Immitisolibacter, Acinetobacter, Kocuria, Mycobacterium, Pseudomonas, Alcanivorax) and methane-oxidizing microorganisms (Methylocapsa, Methylosarcina) were observed in the rhizosphere soil. The effects of major rhizoremediation factors on soil remediation efficiency and greenhouse gas emissions discussed herein are expected to contribute to the development of sustainable biological remediation technologies in response to global climate change.

• Proceedings of the Korean Society of Crop Science Conference
• /
• 2017.06a
• /
• pp.319-319
• /
• 2017

Methane is the main greenhouse gas released from rice paddy field. Methane from paddy fields accounts for 11 % of the global total methane emission. The global warming potential (GWP) of methane is 25 times more than that of carbon dioxide on a mass basis. It is well known that most effective practice to mitigate methane in paddy is related to the water management during rice growing season and the use of organic matters. This study was conducted to investigate the effects of tillage and cultivation method on methane emission in paddy. Tillage (tillage and no-tillage) and cultivation methods (transplanting and direct seeding) were combined tillage-transplanting (T-T), tillage-wet hill seeding (T-W), tillage-dry seeding (T-D) and no-till dry seeding (NT-D) to evaluate methane mitigation efficiency. Daily methane emission was decreased on seeding treatments (T-W, T-D, NT-D) than transplanting treatment (T-T). Amount of methane emission during rice growing season is highest in T-T ($411.7CH_4\;kg\;ha^{-1}y^{-1}$) and lowest in NT-D treatment (89.7). In T-W and T-D treatments, methane emissions were significantly decreased by 36 and 51 % respectively compared with T-T. Methane emissions were highly correlated with the dry weight of whole rice plant ($R^2=0.62{\sim}0.93$). T-T treatment showed highest $R^2$ (0.93) among the four treatments. Rice grain yields did not significantly differ with the tillage and cultivation methods used. These results suggest that direct seeding practice in rice production could mitigate the methane emissions without loss in grain yield.

• Journal of Animal Science and Technology
• /
• v.60 no.6
• /
• pp.15.1-15.10
• /
• 2018

Methane emission from the enteric fermentation of ruminant livestock is a main source of greenhouse gas (GHG) emission and a major concern for global warming. Methane emission is also associated with dietary energy lose; hence, reduce feed efficiency. Due to the negative environmental impacts, methane mitigation has come forward in last few decades. To date numerous efforts were made in order to reduce methane emission from ruminants. No table mitigation approaches are rumen manipulation, alteration of rumen fermentation, modification of rumen microbial biodiversity by different means and rarely by animal manipulations. However, a comprehensive exploration for a sustainable methane mitigation approach is still lacking. Dietary modification is directly linked to changes in the rumen fermentation pattern and types of end products. Studies showed that changing fermentation pattern is one of the most effective ways of methane abatement. Desirable dietary changes provide two fold benefits i.e. improve production and reduce GHG emissions. Therefore, the aim of this review is to discuss biology of methane emission from ruminants and its mitigation through dietary manipulation.

• Proceedings of the Korea Water Resources Association Conference
• /
• 2022.05a
• /
• pp.462-462
• /
• 2022

Wetlands are one of the most vital natural habitats on the planet. India is incredibly blessed to have a number of multifunctional wetland ecosystems. Wetlands, in addition to their functional importance, can act as sources or sinks for greenhouse gases (GHGs) depending on their intrinsic factors. Carbon (CO2) and Methane (CH4) are the major greenhouse gases (GHG's) emitted in wetlands. It is demonstrated that, despite having 4.6 percent of its area covered by natural or man-made wetlands, being home to a large number of wetlands, and being the world's second largest cultivator of paddy, India's wetlands, including paddy fields that are intermittently flooded as typical wetlands, have been very poorly studied in terms of GHG emissions. The purpose of this paper is to examine the status of Indian wetlands and wetlands in terms of CH4 and CO2 emissions. The present study also reviews various literature to provide the equations, parameters that are required for estimating carbon and methane and some of the best strategies for conserving carbon in wetlands. The findings suggest that both non-manipulative and manipulative measures can be used to improve Carbon Sequestration (CS). Non-manipulative measures aim to improve CS by increasing the spatial extent of wetlands, whereas manipulative measures aim to change the characteristics of specific wetland components that influence CS. Uncertainty in carbon dynamics projections under changing environmental conditions is caused by a number of Knowledge gaps: i) There is a lack of knowledge on how organic matter mineralizes and partitions into carbon dioxide, methane, and dissolved organic carbon, ii) With the notable exception of methane dynamics, models that represent the dynamic interaction of processes and their controls have yet to be established. As a result, more research is needed to fully understand the importance of wetlands in terms of GHG emissions and carbon sequestration in India.