• Animal Bioscience
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• 제35권9호
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• pp.1367-1378
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• 2022

Objective: The present study was conducted to examine the gas production, fermentation characteristics, nutrient degradation, and methanogenic community composition of a rumen fluid culture with Broussonetia papyrifera (B. papyrifera) subjected to ensiling or steam explosion (SE) pretreatment. Methods: Fresh B. papyrifera was collected and pretreated by ensiling or SE, which was then fermented with ruminal fluids as ensiled B. papyrifera group, steam-exploded B. papyrifera group, and untreated B. papyrifera group. The gas and methane production, fermentation characteristics, nutrient degradation, and methanogenic community were determined during the fermentation. Results: Cumulative methane production was significantly improved with SE pretreatment compared with ensiled or untreated biomass accompanied with more volatile fatty acids production. After 72 h incubation, SE and ensiling pretreatments decreased the acid detergent fiber contents by 39.4% and 22.9%, and neutral detergent fiber contents by 10.6% and 47.2%, respectively. Changes of methanogenic diversity and abundance of methanogenic archaea corresponded to the variations in fermentation pattern and methane production. Conclusion: Compared with ensiling pretreatment, SE can be a promising technique for the efficient utilization of B. papyrifera, which would contribute to sustainable livestock production systems.

• Corrosion Science and Technology
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• 제18권6호
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• pp.221-227
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• 2019

During the operation, maintenance and decommissioning of nuclear power plant radioactive contaminated waste is produced. This waste is stored in an underground repository 60-100 meters below the surface. The metallic portion of this waste comprises mostly carbon and stainless steel. A long-term field exposure showed high corrosion rates, general corrosion up to 29 ㎛ a^-1 and localized corrosion even higher. High corrosion rate is possible if microbes produce corrosive products, or alter the local microenvironment to favor corrosion. The bacterial and archaeal composition of biofilm formed on the surface of carbon steel was studied using 16S rRNA gene targeting sequencing, followed by phylogenetic analyses of the microbial community. The functional potential of the microbial communities in biofilm was studied by functional gene targeting quantitative PCR. The corrosion rate was calculated from weight loss measurements and the deposits on the surfaces were analyzed with SEM/EDS and XRD. Our results demonstrate that microbial diversity on the surface of carbon steel and their functionality is vast. Our results suggest that in these nutrient poor conditions the role of methanogenic archaea in corrosive biofilm, in addition to sulphate reducing bacteria, could be greater than previously suspected.

• Journal of Microbiology and Biotechnology
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• 제23권2호
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• pp.137-143
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• 2013

The diversity and distribution of methanogenic archaea in a four-compartment anaerobic baffled reactor (ABR) treating sugar refinery wastewater were investigated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE). At an organic loading rate of 5.33 kg $COD/m^3{\cdot}day$, the ABR could perform steadily with the mean chemical oxygen demand (COD) removal of 94.8% and the specific $CH_4$ yield of 0.21 l/g $COD_{removed}$. The $CH_4$ content in the biogas was increased along the compartments, whereas the percentage of $H_2$ was decreased, indicating the distribution characteristics of the methanogens occurred longitudinally down the ABR. A high phylogenetic and ecological diversity of methanogens was found in the ABR, and all the detected methanogens were classified into six groups, including Methanomicrobiales, Methanosarcinales, Methanobacteriales, Crenarchaeota, Arc I, and Unidentified. Among the methanogenic population, the acid-tolerant hydrogenotrophic methanogens including Methanoregula and Methanosphaerula dominated the first two compartments. In the last two compartments, the dominant methanogenic population was Methanosaeta, which was the major acetate oxidizer under methanogenic conditions and could promote the formation of granular sludge. The distribution of the hydrogenotrophic (acid-tolerant) and acetotrophic methanogens in sequence along the compartments allowed the ABR to perform more efficiently and steadily.

• Asian-Australasian Journal of Animal Sciences
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• 제26권6호
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• pp.856-863
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• 2013

An in vitro gas production technique was used in this study to elucidate the effect of two strains of active live yeast on methane ($CH_4$) production in the large intestinal content of pigs to provide an insight to whether active live yeast could suppress $CH_4$ production in the hindgut of pigs. Treatments used in this study include blank (no substrate and no live yeast cells), control (no live yeast cells) and yeast (YST) supplementation groups (supplemented with live yeast cells, YST1 or YST2). The yeast cultures contained $1.8{\times}10^{10}$ cells per g, which were added at the rates of 0.2 mg and 0.4 mg per ml of the fermented inoculum. Large intestinal contents were collected from 2 Duroc${\times}$Landrace${\times}$Yorkshire pigs, mixed with a phosphate buffer (1:2), and incubated anaerobically at $39^{\circ}C$ for 24 h using 500 mg substrate (dry matter (DM) basis). Total gas and $CH_4$ production decreased (p<0.05) with supplementation of yeast. The methane production reduction potential (MRP) was calculated by assuming net methane concentration for the control as 100%. The MRP of yeast 2 was more than 25%. Compared with the control group, in vitro DM digestibility (IVDMD) and total volatile fatty acids (VFA) concentration increased (p<0.05) in 0.4 mg/ml YST1 and 0.2 mg/ml YST2 supplementation groups. Proportion of propionate, butyrate and valerate increased (p<0.05), but that of acetate decreased (p<0.05), which led to a decreased (p<0.05) acetate: propionate (A: P) ratio in the both YST2 treatments and the 0.4 mg/ml YST 1 supplementation groups. Hydrogen recovery decreased (p<0.05) with yeast supplementation. Quantity of methanogenic archaea per milliliter of inoculum decreased (p<0.05) with yeast supplementation after 24 h of incubation. Our results suggest that live yeast cells suppressed in vitro $CH_4$ production when inoculated into the large intestinal contents of pigs and shifted the fermentation pattern to favor propionate production together with an increased population of acetogenic bacteria, both of which serve as a competitive pathway for the available H2 resulting in the reduction of methanogenic archaea.

• 상하수도학회지
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• 제18권4호
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• pp.515-521
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• 2004

Anaerobic digestion has many advantages over the more conventional aerobic treatment processes such as low levels of excess sludge production, low space (area) requirements, and the production of valuable biogas. The purpose of this study was to evaluate the effect of organic loading rate of anaerobic digestion on thermophilic($55^{\circ}C$) and mesophilic($35^{\circ}C$) conditions. Fluorescent in situ hybridization (FISH) method was also used to study the microbial community in the reactors. The stabilizing time in mesophilic anaerobic reactors was shorter as approximately 20 days than 40 days in the thermophilic anaerobic reactors. The amount of methane production rate in anaerobic reactors was independent of the concentrations of supplied substrates and the amount of methanogens. When the microbial diversity in the mesophilic and thermophilic reactors, which had been treated with acetate-based artificial wastewater, were compared, it was found that methanogenesis was carried out by microbial consortia consisting of bacteria and archaea such as methanogens. To investigate the activity of bacterial and archaeal populations in all anaerobic reactors, the amount of acetate was measured. Archaea were predominant in all reactors. Interestingly, Methanothrix-like methanogens appeared in mesophilic anaerobic reactors with high feed substrate concentrations, whereas it was not observed in thermophilic anaerobic reactors.

• Journal of Microbiology and Biotechnology
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• 제24권11호
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• pp.1464-1472
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• 2014

The microbial community structures of two continuous stirred tank reactors digesting turkey manure with pine wood shavings as well as chicken and swine manure were investigated. The reactor fed with chicken/swine wastes displayed the highest organic acids concentration (up to 15.2 g/l) and ammonia concentration (up to 3.7 g/l ammonium nitrogen) and generated a higher biogas yield (up to $366ml/g_{VS}$) compared with the reactor supplied with turkey wastes (1.5-1.8 g/l of organic acids and 1.6-1.7 g/l of ammonium levels; biogas yield was up to $195ml/g_{VS}$). The microbial community diversity was assessed using both sequencing and profiling terminal restriction fragment length polymorphisms of 16S rRNA genes. Additionally, methanogens were analyzed using methyl coenzyme M reductase alpha subunit (mcrA) genes. The bacterial community was dominated by members of unclassified Clostridiales with the prevalence of specific clostridial phylotypes in each reactor, indicating the effect of the substrate type on the community structure. Of the methanogenic archaea, methanogens of the genus Methanosarcina were found in high proportions in both reactors with specific methanosarcinas in each reactor, whereas the strict hydrogenotrophic methanogens of Methanoculleus sp. were found at significant levels only in the reactor fed with chicken/swine manure (based on the analyses of 16S rRNA gene). This suggests that among methanogenic archaea, Methanosarcina species which have different metabolic capabilities, including aceticlastic and hydrogenotrophic methanogenesis, were mainly involved in anaerobic digestion of turkey wastes.

• Animal Bioscience
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• 제37권4호
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• pp.655-667
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• 2024

Objective: This study aimed to assess the impact of a hydroethanolic extract of walnut green husks (WGH) on rumen fermentation and the diversity of bacteria, methanogenic archaea, and fungi in sheep fed a high-concentrate diet. Methods: Five healthy small-tailed Han ewes with permanent rumen fistula were selected and housed in individual pens. This study adopted a self-controlled and crossover design with a control period and an experimental period. During the control period, the animals were fed a basal diet (with a ratio of concentrate to roughage of 65:35), while during the treatment period, the animals were fed the basal diet supplemented with 0.5% hydroethanolic extract of WGH. Fermentation parameters, digestive enzyme activities, and microbial diversity in rumen fluid were analyzed. Results: Supplementation of hydroethanolic extract of WGH had no significant effect on feed intake, concentrations of total volatile fatty acids, isovalerate, ammonia nitrogen, and microbial protein (p>0.05). However, the ruminal pH, concentrations of acetate, butyrate and isobutyrate, the ratio of acetate to propionate, protozoa count, and the activities of filter paper cellulase and cellobiase were significantly increased (p<0.05), while concentrations of propionate and valerate were significantly decreased (p<0.05). Moreover, 16S rRNA gene sequencing revealed that the relative abundance of rumen bacteria Christensenellaceae R7 group, Saccharofermentans, and Ruminococcaceae NK4A214 group were significantly increased, while Ruminococcus gauvreauii group, Prevotella 7 were significantly decreased (p<0.05). The relative abundance of the fungus Pseudomonas significantly increased, while Basidiomycota, Fusarium, and Alternaria significantly decreased (p<0.05). However, there was no significant change in the community structure of methanogenic archaea. Conclusion: Supplementation of hydroethanolic extract of WGH to a high-concentrate diet improved the ruminal fermentation, altered the structure of ruminal bacterial and fungal communities, and exhibited beneficial effects in alleviating subacute rumen acidosis of sheep.

• Journal of Microbiology and Biotechnology
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• 제26권1호
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• pp.110-119
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• 2016

High-solid anaerobic digestion of sewage sludge achieves highly efficient volatile solid reduction, and production of volatile fatty acid (VFA) and methane compared with conventional low-solid anaerobic digestion. In this study, the potential mechanisms of the better performance in high-solid anaerobic digestion of sewage sludge were investigated by using 454 high-throughput pyrosequencing and real-time PCR to analyze the microbial characteristics in sewage sludge fermentation reactors. The results obtained by 454 highthroughput pyrosequencing revealed that the phyla Chloroflexi, Bacteroidetes, and Firmicutes were the dominant functional microorganisms in high-solid and low-solid anaerobic systems. Meanwhile, the real-time PCR assays showed that high-solid anaerobic digestion significantly increased the number of total bacteria, which enhanced the hydrolysis and acidification of sewage sludge. Further study indicated that the number of total archaea (dominated by Methanosarcina) in a high-solid anaerobic fermentation reactor was also higher than that in a low-solid reactor, resulting in higher VFA consumption and methane production. Hence, the increased key bacteria and methanogenic archaea involved in sewage sludge hydrolysis, acidification, and methanogenesis resulted in the better performance of high-solid anaerobic sewage sludge fermentation.

• 한국산학기술학회논문지
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• 제21권7호
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• pp.312-320
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• 2020

본 연구의 목적은 Ribosomal Database Project에서 공적으로 활용 가능한 16S rRNA 유전자 시퀀스들의 메타분석을 통해 반추위 고세균의 계통발생 다양성을 조사하는 것이다. 총 8,416개의 시퀀스가 Ribosomal Database Project(출시버전 11, 업데이트 5)로부터 회수되었고, taxonomy tree를 구축하는데 사용되었다. Species 수준의 OTUs가 97% sequence 유사성 기준으로 QIIME 프로그램을 사용하여 분석되었다. 총 8,416개의 시퀀스 중에서 8,412개의 시퀀스는 총 3개의 문으로 분류되었고, 나머지 4개의 시퀀스는 어떤 알려진 문으로 분류되지 못했다. Euryarchaeota는 가장 우점하는 문으로, 전체 고세균 시퀀스의 99.8%를 차지하였다. 이 중에서 차례로 Methanobrevibacter가 65.4%, Methanosphaera가 10.4%, Methanomassillicoccus가 10.4%, Methanomicrobium가 7.9%, Methanobacterium가 1.9%, Methanimicrococcus가 0.5%, Methanosarcina가 0.1%, Methanoculleus가 0.1%를 차지하였다. V2와 V3 영역으로 자른 7,544개의 시퀀스는 493개의 OTUs로 분류되었다. 총 493 OTUs 중에서 단지 17개만 우점하였고, 총 7,544 시퀀스 중 1% 이상을 차지하였다. 본 연구는 반추동물로 부터 메탄발생에 크게 기여하는 반추위 우점 메탄생성균 분석에 대한 향후 연구를 인도하는데 도움을 주고, 사료나 가축품종이 달라져도 이러한 메탄생성균을 억제하는 메탄저감제를 개발하는데 도움을 줄 것이다.

• Journal of Animal Science and Technology
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• 제62권6호
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• pp.801-811
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• 2020

The main objective of this in vitro study was to evaluate red ginseng byproduct (RGP) as a protein resource and its effects on rumen fermentation characteristics, microflora, CO2, and CH4 production in ruminants. Four treatments for in vitro fermentation using buffered rumen fluid over a 48 h incubation period were used: 1, RGP; 2, corn gluten feed (CGF); 3, wheat gluten (WG); and 4, corn germ meal. In vitro dry matter digestibility (IVDMD), in vitro neutral detergent fiber digestibility (IVNDFD), in vitro crude protein digestibility (IVCPD), volatile fatty acids, pH, and ammonia nitrogen (NH3-N) were estimated after 48 h incubation. Gas production was investigated after 3, 6, 12, 24, 36 and 48 h. The CO2 and CH4 were evaluated after 12, 24, 36, and 48 h. A significant difference in total gas production and CO2 emissions was observed (p < 0.01) at all incubation times. CH4 production in RGP were higher (p < 0.05) than that in other treatments but a higher CH4 portion in the total gas production was observed in WG (p < 0.05) at 48 h incubation. The IVDMD, IVNDFD, and IVCPD of RGP was lower than those of other conventional ingredients (p < 0.01). The RGP had the lowest NH3-N value among the treatments (p < 0.01). The RGP also had the lowest total VFA concentration (p < 0.01), but presented the highest acetate proportion and acetate to propionate ratio among the treatments (both, p < 0.01). The abundance of Prevotella ruminicola was higher in RGP than in WG (p < 0.01), whereas RGP has lower methanogenic archaea (p < 0.01). In conclusion, based on the nutritive value, IVDMD, low NH3-N, and decreased methanogenic archaea, RGP inclusion as a protein source in ruminant diets can be an option in replacing conventional feed sources.