A review of the effects of iron compounds on methanogenesis in anaerobic environments

Baek, Gahyun,Kim, Jinsu,Lee, Changsoo Elsevier 2019 RENEWABLE & SUSTAINABLE ENERGY REVIEWS Vol.113 No.-

<P><B>Abstract</B></P> <P>Iron compounds are abundantly present in both natural and engineered anaerobic environments where various biological processes including methanogenesis take place. Iron is an essential trace element for methanogens, and also other microorganisms involved in anaerobic digestion (AD). Dissolved iron can be readily taken up and used as a micronutrient by microorganisms; however, different iron species and compounds can influence methanogenesis in significantly different ways, both positive and negative, according to their physicochemical properties. This suggests that controlling methanogenic activity (i.e., stimulation or inhibition) in an AD system may be possible by adding a suitable type and amount of iron compound. The different effects of iron compounds on methanogenesis in anaerobic environments have not been systematically reviewed, and more comprehensive information is needed to look into the possible applications of iron compounds in biogas production. This review summarizes recent findings on the effects of different iron compounds on methanogenesis and discusses the underlying mechanisms and implications. Previous studies on the effects of iron addition on AD have reported contradictory observations for different iron sources, and the solubility, crystallinity, conductivity, and redox activity of iron compounds are the key factors that determine the direction and extent of effect on methanogenesis. These physicochemical properties are directly related to the bioavailability and/or electron-mediating capability of an iron compound, which affect the energy metabolism of methanogens and their syntrophic partners. This review will help deepen our understanding of the role and function of iron in AD and provide a reference for the control or promotion of methanogenesis, which is of particular interest from the perspective of energy production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Iron can promote or inhibit methanogenesis in natural and engineered systems. </LI> <LI> Iron affects the energy metabolism of methanogenesis and/or their syntrophic partners. </LI> <LI> Solubility, conductivity and redox activity are crucial factors. </LI> <LI> Promoting or controlling methanogenesis using iron compounds may be possible. </LI> <LI> A new possibility to improve the energy balance of an anaerobic digester is opened. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Changes in Microbial Diversity, Methanogenesis and Fermentation Characteristics in the Rumen in Response to Medicinal Plant Extracts

Kim, Eun Tae,Moon, Yea Hwang,Min, Kwan-Sik,Kim, Chang-Hyun,Kim, Sam Churl,Ahn, Seung Kyu,Lee, Sung Sill Asian Australasian Association of Animal Productio 2013 Animal Bioscience Vol.26 No.9

This study evaluated the in vitro effect of medicinal plant extracts on ruminal methanogenesis, four different groups of methanogens and ruminal fermentation characteristics. A fistulated Holstein cow was used as a donor of rumen fluid. Licorice and mugwort extracts (Glycyrrhiza uralensis and Artemisia capillaris, 0.5% and 1% of total substrate DM, respectively), previously used as folk remedies, were added to an in vitro fermentation incubated with buffered-rumen fluid. Total gas production in Glycyrrhiza uralensis extract treatment was not significantly different between treatments (p<0.05) while total gas production in the Artemisia capillaris extract treatment was lower than that of the control. Artemisia capillaris extract and Glycyrrhiza uralensis extract reduced $CH_4$ emission by 14% (p<0.05) and 8% (p<0.05), respectively. Ciliate-associated methanogens population decreased by 18% in the medicinal plant extracts treatments. Medicinal plant extracts also affected the order Methanobacteriales community. Methanobacteriales diversity decreased by 35% in the Glycyrrhiza uralensis extract treatment and 30% in the Artemisia capillaris extract treatment. The order Methanomicrobiales population decreased by 50% in the 0.5% of Glycyrrhiza uralensis extract treatment. These findings demonstrate that medicinal plant extracts have the potential to inhibit in vitro ruminal methanogenesis.

Effects of nanoscale zero valent iron (nZVI) concentration on the biochemical conversion of gaseous carbon dioxide (CO₂) into methane (CH₄)

Dong, Dandan,Aleta, Prince,Zhao, Xin,Choi, Oh Kyung,Kim, Sungpyo,Lee, Jae Woo Elsevier 2019 Bioresource technology Vol.275 No.-

<P><B>Abstract</B></P> <P>This study presents the effects of nanoscale zero valent iron (nZVI) concentration on the biomethanation of gaseous CO<SUB>2</SUB>. During anaerobic batch experiment with 9 times injection of CO<SUB>2</SUB>, the CO<SUB>2</SUB> concentration in the headspace rapidly decreased by dissolution. Then, when nZVI was added at 6.25 and 12.5 g/L, the dissolved CO<SUB>2</SUB> was biochemically transformed into CH<SUB>4</SUB> at a maximum production rate of 2.38 and 3.93 μmol/hr, respectively. Biomethanation at these two nZVI concentrations continued until the end of experiment. In spite of more H<SUB>2</SUB> evolution by nZVI at 25 g/L, biomethanation did not occur, due to the significant inhibition of methanogenesis by nZVI. As the nZVI concentration increased, relative abundance of the hydrogenotrophic methanogens, especially <I>Methanobacteriales</I>, increased. However, at 25 g/L of nZVI concentration, acetic acid was accumulated and the relative abundance of <I>Clostridium</I> became predominant, indicating that homoacetogenesis was superior over methanogenesis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Biomethanation of CO<SUB>2</SUB> coupling with nZVI corrosion was suggested. </LI> <LI> Biomethanation rate was highly affected by the nZVI concentration. </LI> <LI> Excessive nZVI addition promoted homoacetogenesis rather than methanogenesis. </LI> <LI> qPCR supported the biomethanation depending nZVI concentration. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Effects of an applied voltage on direct interspecies electron transfer via conductive materials for methane production

Lee, J.Y.,Park, J.H.,Park, H.D. Pergamon Press ; Elsevier Science Ltd 2017 Waste management Vol.68 No.-

<P>Direct interspecies electron transfer (DIET) between exoelectrogenic bacteria and methanogenic archaea via conductive materials is reported as an efficient method to produce methane in anaerobic organic waste digestion. A voltage can be applied to the conductive materials to accelerate the DIET between two groups of microorganisms to produce methane. To evaluate this hypothesis, two sets of anaerobic serum bottles with and without applied voltage were used with a pair of graphite rods as conductive materials to facilitate DIET. Initially, the methane production rate was similar between the two sets of serum bottles, and later the serum bottles with an applied voltage of 0.39 V showed a 168% higher methane production rate than serum bottles without an applied voltage. In cyclic voltammograms, the characteristic redox peaks for hydrogen and acetate oxidation were identified in the serum bottles with an applied voltage. In the microbial community analyses, hydrogenotrophic methanogens (e.g. Methanobacterium) were observed to be abundant in serum bottles with an applied voltage, while methanogens utilizing carbon dioxide (e.g., Methanosaeta and Methanosarcina) were dominant in serum bottles without an applied voltage. Taken together, the applied voltage on conductive materials might not be effective to promote DIET in methane production. Instead, it appeared to generate a condition for hydrogenotrophic methanogenesis. (C) 2017 Elsevier Ltd. All rights reserved.</P>

Feasibility For Application of Application of Methanogenesis/Denitrification Process To Municipal Leachate Treatment

Jeong Hoon Im,Hae Jin Woo,Tae Ho Lee,Hae Ill Lee,Chang Won Kim 대한환경공학회 2003 Environmental Engineering Research Vol.8 No.5

백하수오 추출물이 In vitro 반추위 발효성상 및 메탄가스 생성에 미치는 영향

양승학,임정수,김별,황옥화,조성백,최동윤,최석근,황성구,Yang, Seung-Hak,Lim, Joung-Soo,Kim, Byul,Hwang, Ok-Hwa,Cho, Sung-Back,Choi, Dong-Yoon,Choi, Seok-Geun,Hwang, Seong-Gu 한국축산환경학회 2013 한국축산시설환경학회지 Vol.19 No.2

The objective of this study is to investigate the effects of Cynanchum wilfordii (CW) on cell viability, anti-oxidant activity, volatile fatty acid (VFA) production and methane gas production. Collected rumen fluid incubated with CW powder (1% w/v) for 12 and 24 hours were analyzed for pH, VFAs and methane. Alamar blue assay showed no significant difference on the viability of 3T3-L1 and C2C12 cells treated with CW for 24 hours. TBARS data showed a dose dependent increase on the antioxidant activity of CW. VFAs increased in the CW-treated groups compared to the control group. In addition, propionate increased more than other VFAs by the treatment with CW. There was a significant decrease in methane gas production in batch culture treated with CW in 12hrs. In conclusion, it was suggested that Cynanchum wilfordii could manipulate rumen fermentation considered by increasing VFA production and inhibition of methanogenesis.

Strategies to Mitigate Enteric Methane Emissions from Ruminant Animals

( Tenzin Tseten ),( Rey Anthony Sanjorjo ),( Moonhyuk Kwon ),( Seon-won Kim ) 한국미생물 · 생명공학회 2022 Journal of microbiology and biotechnology Vol.32 No.3

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.

식종슬러지 종류에 따른 이산화탄소 이용 바이오메탄 생산 비교

김태훈(Tae-Hoon Kim),임병서(Byung-Seo Lim),이승주(Sung-Ju Yi),윤광수(Gwang-Sue Yun),안병규(Byung-Kyu Ahn),미치드마(Michidmaa Enkhtsog),윤여명(Yeo-Myeong Yun) 유기성자원학회 2020 유기물자원화 Vol.28 No.1

본 연구는 초기 식종슬러지 종류별 CO₂의 생물학적 바이오메탄 생산 적용 가능성을 비교를 위해 국내 혐기성 소화조로부터 획득한 식종미생물을 종류에 따라 Specific methanogenic activity (SMA) test를 수행한 결과이다. 36일간의 실험 결과 CH₄ yield는 2,434-2,051mL CH₄/g COD의 범위를 얻었고 생산된 가스 내 CH₄ 분압은 맥주공장과 음식물류 폐기물 식종슬러지에서 가장 높은 89.3-91.9% CH₄ 분포를 보인 반면 하수슬러지 식종슬러지로부터 가장 낮은 효율을 나타냈다. 반응조의 CH₄ production rate/CO₂ consumption rate 비교를 통해 CH₄전환 속도 및 CO₂소비율의 간접적 물질 수지 비교가 가능했으며 SMA test 실험 기간 중 반응조 내 아세트산의 농도의 검출이 확인되었다. 이는 식종슬러지 내부의 잔류 유기물들의 분해, 식종미생물의 사멸 및 이들의 분해, Homoacetogenic bacteria의 활성에 의해 반응조 내 Metabolic pathway가 부분적으로 Hydrogenotrophic methanogenesis 단계에서 Acetoclasctic methanogenesis로의 변환됨에 따른 결과로 사료된다. The aims of this study were to compare the biomethanation of CO₂ through specific methanogenic activity(SMA) test which was inoculated with four different types of mixed microbial culture obtained from full-scale anaerobic digestion (AD) plants. The experimental results showed that CH₄ conversion was the highest in the samples inoculated by seed sludge taken from ADs of food waste and brewery; under this condition, the produced biomethane contains 89.3-91.9% of CH₄. Meanwhile, the lowest level was obtained in the sample from sewage sludge. The measured ratio of CH₄ production rate to CO₂ consumption rate in all reactors was higher than the theoretical value (1) in the middle of the period and soon dropped to 0.7-0.8. It might be due to changed metabolic pathways in the reactor by the degradation of residual organic matter and the increased activity of homoacetogenic bacteria.

Metagenomic analysis reveals the contribution of anaerobic methanotroph-1b in the oxidation of methane at the Ulleung Basin, East Sea of Korea

Jin-Woo Lee,Kae Kyoung Kwon,Jang-Jun Bahk,Dong-Hun Lee,Hyun Sook Lee,Sung Gyun Kang,Jung-Hyun Lee 한국미생물학회 2016 The journal of microbiology Vol.54 No.12

We have previously identified a sulfate methane transition zone (SMTZ) within the methane hydrate-bearing sediment in the Ulleung Basin, East Sea of Korea, and the presence of ANME-1b group in the sediment has been shown by phylogenetic analysis of a 16S rRNA gene. Herein, we describe taxonomic and functional profiling in the SMTZ sample by metagenomic analysis, comparing with that of surface sediment. Metagenomic sequences of 115 Mbp and 252 Mbp were obtained from SMTZ and surface sediments, respectively. The taxonomic profiling using BLASTX against the SEED within MG-RAST showed the prevalence of methanogens (19.1%), such as Methanosarcinales (12.0%) and Methanomicrobiales (4.1%) predominated within the SMTZ metagenome. A number of 185,200 SMTZ reads (38.9%) and 438,484 surface reads (62.5%) were assigned to functional categories, and methanogenesis-related reads were statistically significantly overrepresented in the SMTZ metagenome. However, the mapping analysis of metagenome reads to the reference genomes, most of the sequences of the SMTZ metagenome were mapped to ANME-1 draft genomes, rather than those of methanogens. Furthermore, the two copies of the methyl-coenzyme M reductase gene (mcrA) segments of the SMTZ metagenome were clustered with ANME-1b in the phylogenetic cluster. These results indicate that ANME- 1b reads were miss-annotated to methanogens due to limitation of database. Many of key genes necessary for reverse methanogenesis were present in the SMTZ metagenome, except for N5,N10-methenyl-H4MPT reductase (mer) and CoBCoM heterodisulfide reductase subunits D and E (hdrDE). These data suggest that the ANME-1b represents the primary player the anaerobic methane oxidation in the SMTZ, of the methane hydrate-bearing sediment at the Ulleung Basin, East Sea of Korea.

A long-term study on the effect of magnetite supplementation in continuous anaerobic digestion of dairy effluent – Magnetic separation and recycling of magnetite

Baek, Gahyun,Jung, Heejung,Kim, Jaai,Lee, Changsoo Elsevier 2017 Bioresource technology Vol.241 No.-

<P><B>Abstract</B></P> <P>Promotion of direct interspecies electron transfer (DIET) between exoelectrogenic bacteria and electron-utilizing methanogens has recently been discussed as a new method for enhanced biomethanation. This study evaluated the effect of magnetite-promoted DIET in continuous anaerobic digestion of dairy effluent and tested the magnetic separation and recycling of magnetite to avoid continuous magnetite addition. The applied magnetite recycling method effectively supported enhanced DIET activity and biomethanation performance over a long period (>250days) without adding extra magnetite. DIET via magnetite particles as electrical conduits was likely the main mechanism for the enhanced biomethanation. Magnetite formed complex aggregate structures with microbes, and magnetite recycling also helped retain more biomass in the process. <I>Methanosaeta</I> was likely the major methanogen group responsible for DIET-based methanogenesis, in association with <I>Proteobacteria</I> and <I>Chloroflexi</I> populations as syntrophic partners. The recycling approach proved robust and effective, highlighting the potential of magnetite recycling for high-rate biomethanation.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Magnetic separation and recycling was tested to support magnetite-promoted DIET. </LI> <LI> Magnetite recycling was effective in maintaining enhanced DIET and biomethanation. </LI> <LI> Biomass retention was enhanced by recycling of microbes associated with magnetite. </LI> <LI> Enhanced performance was maintained for long periods without adding extra magnetite. </LI> <LI> <I>Methanosaeta</I> was likely the major group responsible for DIET-based methanogenesis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>