Earticle

Dietary supplementation effects with Lactiplantibacillus argentoratensis strain AGMB00912 (LA) on gut microbiota and metabolic functions of weaned piglets were investigated. Eight 25-day-old weaned piglets were evenly divided into a control group and an LA-supplemented group, with the LA group receiving 1.0 × 108 CFU/mL of LA daily for 10 days. Fecal samples taken on the 10th day were analyzed using 16S rRNA gene sequencing to assess microbial composition and metabolic function prediction. Supplementation with LA promoted a stable microbial environment by increasing the relative abundance of short-chain fatty acidproducing bacteria, including Faecalitalea, Catenibacterium, and Butyrivibrio, while reducing harmful genera like Treponema and Campylobacter. Administration of LA significantly influenced the metabolic activity of the microbial community, particularly by upregulating carbohydrate metabolism pathways, which enhanced the capacity for short-chain fatty acid production. This shift in microbial metabolism also extended to pathways involved in the biosynthesis of amino acids, lipids, cofactors, and vitamins, indicating an improved capacity for microbial-driven nutrient assimilation and utilization. Furthermore, LA supplementation promoted the biosynthesis of antimicrobial non-ribosomal peptides within the microbiome, crucial for inhibiting the growth of pathogenic microorganisms and maintaining microbial balance. The modulation of microbial metabolism is also predicted to reduce glycan degradation and increase peptidoglycan biosynthesis, contributing to enhanced gut barrier function and a more regulated immune response. These metabolic changes within the microbial community are predicted to stabilize the gut microbiota, providing enhanced disease resistance and supporting the overall health and growth of weaned piglets.

Nutritional studies in the cattle typically focus on the rumen and its microbial environment, leaving other parts of the gastrointestinal (GI) tract largely unexplored. Thus, underlying molecular mechanisms and the responses to dietary treatment in the lower gut is poorly understood. In this study, we investigated the caecum transcriptome changes and its associated microbial communities in calves with or without artificially dosed rumen content extracted from an adult cow. Eight calves were included in the study, four received artificially dosed adult rumen content (Treated) and the rest received autoclaved rumen content as a control. We observed significant transcriptome changes in the caecum between treatments, with 1,836 differentially expressed genes (DEGs) identified. A predominant portion of the DEGs were down-regulated in the treated group, which showed significant enrichment for molecular pathways related to immune response, host response to pathogens, and inflammatory responses. For the DEGs correlated with the highest number of microbes, gene ontology analysis indicated an enrichment in pathways associated with inflammation and immune response. By comparing the microbial taxa abundance among different GI tissues collected from the same study, we observed that the same dosing strategy may lead to differential retention of the microbial community in different GI tract locations. Our work indicated that the hind gut showed robust response to artificial dosing and the caecum microbial community may interact extensively with the host to shape the development and maturity of the host immune system in early life. Furthermore, our analysis suggested that tissue-specific analysis is required to fully understand the impact of early dosing on animal performance and physiology.

This study determined the substitution effects of rice for corn as the main grain source in a total mixed ration (TMR). In vitro rumen fermentation characteristics and microbes were assessed using two experimental diets. Diets included 33% dry matter (DM) of either corn (Corn TMR) or rice grains (Rice TMR). In a 48-h in vitro incubation, DM digestibility (IVDMD), neutral detergent fiber degradability (IVNDFD), crude protein digestibility (IVCPD), volatile fatty acids (VFAs), pH and ammonia nitrogen (NH3-N) were estimated. Gas production has been calculated at 3, 6, 12, 24 and 48 h. Our results indicate that the gas production, VFAs, IVDMD, and IVNDFD of Rice TMR were higher than those of Corn TMR (p < 0.05). Ruminal pH and total fungi were significantly higher in Corn TMR (p < 0.05) than in Rice TMR; however, NH3-N and IVCPD were not affected by treatment type. In conclusion, substituting rice for corn at 33% DM in TMR appears to have no negative effects on in vitro rumen fermentation characteristics. Therefore, rice grains are an appropriate alternative energy source in early fattening stage diets of beef cattle.

유기 오염물질을 미생물 군집을 이용하여 생물학적으로 분해하거나 제거하는 SBR(Sequencing Batch Reactor)을 이용하여 Acetaminophen 유입 시 제거 및 영향에 관한 연구를 진행하였다. Acetaminophen은 산업폐수, 병원폐수 등으로 도시하수로부터 배출될 경우, 하수처리장으로 유입되어 하 수처리공정과 폐수처리특성의 변화를 일으키고, 활성슬러지 내 미생물에 영향을 미칠 것으로 간주 된다. 본 연구에서는 반응조 내 미생물의 충격 부하 를 고려하여 Acetaminophen의 농도를 10/15/20/40/100 ppm까지 증가시켜 주었다. 반응조 내의 Acetaminophen 노출 전과 후의 수질분석과 미생물 군 집 변화, Acetaminophen의 생분해 및 영양물질 제거에 대한 데이터를 확보하는데 목적을 두고 있다. 분석결과, Nitrogen과 Phosphorus 같은 경우 고농 도(40 ppm) Acetaminophen 유입으로 인해 평균 75±5.2 %, 65±8.1 %의 낮은 제거율을 나타내었다. 이는 Acetaminophen 유입은 질산화 미생물에 영 향을 미쳐 질산화 과정을 억제 하였으며, 호기 조건에서의 PAO 활성도 감소로 인한 인의 흡수능력 감소 및 혐기 상태에서의 인의 방출능력을 감소시키 는 것을 확인할 수 있었다. 미생물 분석결과로는 Acetaminophen 제거에 있어 주된 역할을 하는 박테리아 계통에는 Phylum 계통에서는 Proteobacteria, Actinobacteria 순으로 나타났다. Class 계통에서도 역시 Proteobacteria에 속하는 β-Proteobacteria, Actinobacteria, γ-Proteobacteria가 Acetaminophen 제거에 우위를 차지하였고, Genus 계통에서는 Acetaminophen 노출에 의해 Dechloromonas의 증식이 활발하였음을 확인할 수 있었다.

This study investigated the biological removal and its effect of sequencing batch reactor(SBR) treating Acetaminophen. when discharged from urban sewage such as industrial and hospital wastewater, enters the wastewater treatment plant through the sewer. This can lead to changes in the treatment process and wastewater treatment characteristics, potentially affecting the microorganisms in the activated sludge. In this study, the concentration of Acetaminophen was increased to 10/15/20/40/100 ppm to account for the shock load of microorganisms in the reactor. Water parameters was analyzed two times a week from the reactor. Biomass were collected to analyze microbial community analysis. The results showed that nitrogen and phosphorus had low removal of 75±5.2% and 65±8.1%, respectively, due to the high concentration of Acetaminophen (40 ppm). This suggests that Acetaminophen influenced the nitrifying microorganisms, inhibiting the nitrification process, and decreasing the phosphorus uptake capacity in the aerobic condition due to a decrease in phosphorus-accumulating organism (PAO) activity. The results of the microbiological analysis revealed that the main bacterial strains responsible for removing Acetaminophen were Proteobacteria and Actinobacteria within the Phylum level. In the Class level, β-Proteobacteria, Actinobacteria, and γ-Proteobacteria belonging to Proteobacteria were dominant in the removal of Acetaminophen. In the Genus level, exposure to Acetaminophen actively increased the proliferation of Dechloromonas.

The concentration of atmospheric CO2 is increasing largely due to human activities and it is projected to reach 720ppm by the end of this century. However, the impact of eCO2 on soil microbial communities remains poorly understood. A rhizosphere is a narrow zone of soil affected by root exudates such as amino acids and sugars, and it contains a diverse and complex microbial community. In this study, we aimed to examine effects of eCO2 on the taxonomical diversity, composition, and structure of rhizosphere microbial communities of Pinus densiflora by the use of NGS of 16S rRNA genes. The results showed that the exposure of elevated CO2 altered their microbial populations and diversity in the rhizosphere of Korean red pine. The species richness estimates (Chao1 and ACE) and diversity indices (Shannon and Simpson) for the three sampling chambers are highest from the eCO2 (approximately 1.4×ambient, ≈ 560ppm). In addition, the rarefaction analysis of the OTUs indicated that bacterial diversity and richness were higher in eCO2 than ambient CO2. Thus, these results indicate that eCO2 changes structure and representation of microorganisms associated with roots of pine tree and the elevated eCO2 stimulated tree growth and primary productivity.

Atmospheric fine dust is an emerging problem as a result of growing industrialization and environmental changes. In this study, fine dust could be an alternative fact to contaminate soil property. The soil exposed to fine dust was significantly changed in its porosity as compared with the control. A subsequent experiment revealed that fine dust restricted the production of soil bacteria through the increment of soil porosity and that increased porosity is closely associated to the production of calcium carbonate by soil bacteria. In situ analyses for soils exposed to high amount of atmospheric fine dust revealed the significant attenuation of five different microbial species, which abundantly exists within the ground soil. Moreover, fine dust-mediated growth reduction of soil bacteria resulted in the accelerated growth of E.coli, a bacterial strain. Co-culture of E.coli with soil extracts demonstrated that soil contents significantly lowered the growth rate of E.coli, indicating that soil bacteria is responsible for protecting water quality from the opportunistic bacterial infections. Collectively the data demonstrate that the topic for atmospheric fine dust could be worth deliberation for protecting ground water preservation as a possible resource of drinking water.

유류오염은 우리나라의 대표적인 토양 비점오염원으로 알려져 있으며, 이를 정화하는 토양의 능력은 토양 자원의 기능적 가치 평가에서 매우 유의하다. 특히 절/성토 설계 등의 친환경 건설기술 측면에서 토양의 유류오염정화능력을 평가하는 것은 중요하다. 그러나 마이크로코즘 실험을 포함한 기존의 토양 유류 오염정화능력 평가기법은 경제적, 시간적인 제약이 많아 광범위한 지역에 적용하기 어렵다. 이에 본 연구에서는 유류 오염물질 중 가솔린의 대표적 오염물질인 톨루엔을 선정하여 쉽고 간편하게 측정할 수 있는 토양의 미생물 다양성 지표를 이용, 토양의 유류오염 정화능력을 평가하는 기법을 제시하였다. 연구를 통해 미생물 군집의 다양성 지표 중 Shannon index가 토양의 정화능력 인자인 Specific Degradation Rate ($V_{max}$)와 상관성 관계가 있음을 보였고, 두 인자 간의 상관식을 도출할 수 있었다. 또한 본 상관식을 Michaelis-Menten kinetics에 적용하여 미생물 다양성 인자만으로 토양의 톨루엔 정화능력을 평가할 수 있는 기법을 제시하였다. 본 기법을 통해 간단히 토양의 톨루엔 정화능력을 평가할 수 있으며, 친환경 건설기술분야와 같은 다양한 공학적 분야에 광범위하게 활용될 수 있을 것으로 기대된다.

Since oil leakage is one of the most common nonpoint pollution sources that contaminate soil in Korea, the capacity of soil microbial community for degrading petroleum hydrocarbons should be considered to assess the functional value of soil resource. However, conventional methods (e.g., microcosm experiments) to assess the remediation capacity of soil microbial community are costly and time-consuming to cover large area. The present study suggests a new approach to assess the toluene remediation capacity of soil microbial community using a microbial diversity index, which is a simpler detection method than measuring degradation rate. The results showed that Shannon index of microbial community were correlated with specific degradation rate ($V_{max}$), a degradation factor. Subsequently, a correlation equation was generated and applied to Michaelis-Menten kinetics. These results will be useful to conveniently assess the remediation capacity of soil microbial community and can be widely applied to diverse engineering fields including environment-friendly construction engineering fields.

Background: As pollutants caused by non-point sources flow into rivers, river water quality monitoring for fecal pollution is becoming increasingly important. Objectives: This study was conducted to investigate the distribution of microbial communities in the Yeongsangang River water system and sewage treatment plants in Gwangju and to evaluate their antibiotic resistance. Methods: In the experiment, samples were distributed to five selective media at each point and then cultured for 18 to 24 hours. When bacteria were observed, they were sub-cultured by size and shape and identified using MALDI-TOF MS equipment. When identification was completed, 17 types of antibiotic susceptibility tests were performed using VITEK II equipment, focusing on gram-negative dominant species among the identified strains. Results: During the study period, a total of 266 strains were isolated from 39 samples. Gram-positive bacteria were 37 strains in four genera, or 13.9% of the total, and Gram-negative bacteria were 229 strains in 23 genera, or 86.1% of the total. Antibiotic susceptibility testing of 23 strains, the major dominant species, showed that one strain (4.3%) was resistant to only one antibiotic, and two strains (8.7%) were 100% susceptible to the 17 antibiotics tested. The other 20 strains (87.0%) were multidrug resistant bacteria resistant to two or more antibiotics. There were various types of multidrug resistance. Among them, penicillin and cephalosporin series showed the highest resistance. Conclusions: Based on the results of this study, it was found that the bacterial community structure changed according to regional and environmental factors, and it was judged that continuous research such as genetic analysis of antibiotic-resistant bacteria present in natural rivers is necessary.

Background: Suppressive soil inhibits soil-borne diseases if pathogens are present, and ginseng does not show injury even if replanted in the same field. Methods and Results: Soil chemical properties and microbial community of soil were investigated in soil suppressive and conducive to ginseng root rot. Root rot disease in 2-year-old ginseng was tested by mixing conducive soil, with suppressive or sterilized suppressive soil. The root rot ratio in suppressive soil was 43.3% compared to 96.7% in conducive soil. Biological factors acted to inhibit the root rot because disease ratio was increased in the sterilized suppressive soil compared to that in non-suppressive soil. The suppressive soil had lower pH, nitrate nitrogen and sodium than the conducive soil. Dominat bacteria and fungi (more than 1.0%) were 3 and 17 species in conducive soil and 7 and 23 species in suppressive soil, respectively. The most predominant fungi were Pseudaleuria sp. HG936843 (28.70%) in conducive soil and Pseudogymnoascus roseus (7.52%) in suppressive soil. Conclusion: Microbial diversity was more abundant in the suppressive soil than in the conducive soil, and the proportion of pathogens (Nectriaceae sp.) causing root rot was significantly lower in the suppressive soil than in the conducive soil.

Background: Crop rotation plays an important role in improving soil chemical properties, minimizing the presence of disease pathogens, and assists in neutralizing autotoxic effects associated with allelochemicals. Methods and Results: Five rotation crops of sudan grass, soybean, peanut, sweet potato, and perilla were cultivated for one year with an aim to reduce yield losses caused by repeated cropping of ginseng. In 2-year-old ginseng grown in the same soil as a previous ginseng crop, stem length and leaf area were reduced by 30%, and root weight per plant was reduced by 56%. Crop rotation resulted in a significant decrease in electrical conductivity, NO3, and P2O5 content of the soil, whereas organic matter, Ca, Mg, Fe, Cu, and Zn content remained-unchanged. Soil K content was increased following crop rotation with sudan grass and peanut only. Rotation with all alternate crops increased subsequent ginseng aerial plant biomass, whereas root weight per plant significantly increased following crop rotation with perilla only. A significant positive correlation was observed between root rot ration and soil K content, and a significant negative correlation was observed between ginseng root yield and the abundance of actinomycetes. Crop rotation affected the soil microbial community by increasing gram negative microbes, the ratio of aerobic microbes, and total microbial biomass whereas decreases were observed in actinomycetes and the ration of saturated fatty acids. Conclusions: In soil exhibiting crop failure following replanting, crop rotation for one year promoted both soil microbial activity and subsequent ginseng aerial plant biomass, but did not ameliorate the occurrence of root rot disease.

Background: Some phenolics detected in the soil may inhibit the seed germination and seedling growth of ginseng (Panax ginseng). This study investigated the effect of irrigation and ginseng root residue addition on the soil microbial community and root rot disease in 2-year-old ginseng. Methods and Results: Each 20 ℓ pot was filled with soil infected with ginseng root rot pathogens, and irrigated daily with 2 ℓ of water for one month. After the irrigation treatment, ginseng fine root powder was mixed with the irrigated soil at a rate of 20 g per pot. In descending order, NO3 ?, electric conductivity (EC), exchangeable Na (Ex. Na) and K (Ex. K) decreased due to irrigation. In descending order, NO3 ?, EC, Ex. K, and available P2O5 increased with the additon of ginseng powder to the soil. The abundance of Trichoderma crassum decreased with irrigation, but increased again with the incorporation of ginseng powder. The abundance of Haematonectria haematococca increased with irrigation, but decreased with the incorporation of ginseng powder. The abundance of Cylindrocarpon spp. and Fusarium spp., which cause ginseng root rot, increased with the incorporation of ginseng powder. The abundance of Arthrobacter oryzae and Streptomyces lavendulae increased with irrigation. The abundance of Streptomyces lavendulae decreased, and that of Arthrobacter spp. increased, with the incorporation of ginseng powder. Aerial growth of ginseng was promoted by irrigation, and ginseng root rot increased with the incorporation of ginseng powder. Conclusions: Ginseng root residues in the soil affected soil nutrients and microorganisms, and promoted ginseng root rot, but did not affect the aerial growth of ginseng.

본 연구에서는 하수슬러지를 이용한 Pilot 규모의 고온-중온 병합 혐기성 소화조 연속운전을 통하여 바이오가스 발생 량, 유기물제거특성, 미생물 군집변화 등의 분석을 통하여 성능을 평가 하였다. 초기 운전 시작 후 고온 혐기성 소화조의 바이오가스 발생량은 점차 증가하는 경향을 나타내었으나, 운전 22일부터 급속히 감소되었고, 25일 이후로 유지됨을 확 인하였다. 또한 고온혐기성 소화조에서는 부상된 슬러지와 결합된 스컴 층이 발생한 반면 중온소화조에서는 발생은 전혀 일어나지 않았으며, 이러한 결과는 고온-중온 소화조간의 보완 및 완충작용에 있다고 판단된다. 또한 고온 혐기성 소화를 거친 유출수의 COD제거율은 평균 25.1% VS제거율은 평균 39.8%, 중온 혐기성 소화조에서는 각각 21.2%, 18.9%를 각 각 나타내었다. 유입 하수슬러지의 농도는 다소 큰 차이를 보였음에도 불구하고 고온-중온 유출수의 VS농도는 큰 농도 변화 없이 안정적으로 유지됨을 확인하였다. 또한 혐기성 소화조의 안정성의 지표중의 하나인 pH 변화를 살펴보면 고온 혐기소화조에서는 평균 6.9, 중온 혐기소화조에서는 7.4로 유지되었고, 고온-중온 혐기성 소화을 통해 55.7%의 높은 소 화효율 보였다. 고온-중온 혐기성소화조의 미생물 군집변화를 분석한 결과 고온 혐기성 소화조에서는 organic acid를 기 질로 사용할 수 있는 Firmicutes와 proteobacteria가 27.9%, 28.6%로 나타났다. 반면에 중온 혐기소화에서는 Bacteroidetes가 가장 우점화 되었다. 또한 Archaea 분석에서는 고온 혐기성 소화조에서는 Methanolinea 우점화 되었으 며, 중온 혐기소화의 경우 Methanolinea의 비율은 감소하고, Methanosaeta와 Methanosarcinar의 비율이 대부분을 차지 하고 비슷한 비율로 이루어져 있는 것으로 나타났다.

In this study, performance was evaluated by analyzing biogas production, organic matter removal and microbial community through continuous operation of pilot-scale of anaerobic digester with combined thermophilic and mesophilic using sewage sludge. The biogas production in the thermophilic anaerobic digester after start of the initial operation showed a tendency to increase gradually, but it was rapidly decreased from the 22 day of operation and was maintained after 25 days. In the thermophilic anaerobic digester, scum layer combined with floating sludge occurred, but non occurred in the mesophilic anaerobic digester. As result is considered to be complementary and buffering effect between thermophilic and mesophilic anaerobic digester. In addition, the COD removal rate for subjected to thermophilic anaerobic digester averaged 25.1%, the rate of elimination of VS removal was 39.8% and mesophilic anaerobic digester was 21.7% and 16.8% respectively. Although the concentration of the influent sewage sludge showed a some what large difference, it was confirmed that the VS concentration of the thermophilic-mesophilic effluent was stably maintained without a large concentration change. The pH of the anaerobic digester which is one of the indicators of stability was maintained at 6.9 in the thermophilic and 7.4 in the mesophilic anaerobic digester and The digestion efficiency was 55.7% through the thermophilic and mesophilic digester. As a result of analysis of microbial community changes, 27.9% and 28.6% of Firmicutes and proteobacteria respectively, which grow using organic acid as a substrate, were found in the thermophilic anaerobic digester. On the other hand, in the mesophilic anaerobic digester, the Bacteroidetes were most ratio. In the Archaea analysis, Methanolinea was intensed in the thermophilic anaerobic digester. In the mesophilic anaerobic digester, the proportion of Methanolinea decreased and Methanosaeta and Methanosarcinar were the majority with similar ratio.

In this study, we investigated the microbial community of oyster mushrooms at different growth stages at the species level. Gram-positive bacteria were predominant in the presterilized medium. On the other hand, Gram-negative bacteria were predominant in the culture-completed medium, post-harvest medium, and fruiting bodies. In addition, Pseudomonas tolaasii, which is known to cause disease in mushrooms, was confirmed in the cultured medium, post-harvest medium, and fruiting bodies, and it was determined that the mycelium culture stage was contaminated, and the reason why no disease occurred was Sphingobacterium psychroaquaticum. It was confirmed that this was because the growth of Pseudomonas tolaasii was suppressed by producing a component called tolacin. As a result of confirming the diversity of microorganisms, it was confirmed that the presterilization medium contains a variety of microorganisms compared to other growth stages, and the diversity decreases in the order of culture completion medium, fruiting body, and post-harvest medium. showed a trend. As a result of microbial similarity analysis, it was confirmed that the cultured medium and the post-harvest medium showed similar microbial communities, and in the case of fruiting bodies, there were some similarities but overall differences.

The bacterial community structure in a biological reactor fed influent from a wastewater treatment system was investigated by denaturing gradient gel electrophoresis (DGGE) and in situ hybridization. Sludges were collected from three biological reactors (aerobic,oxic,and anoxic tanks) at the M wastewater treatment facility (WTF). The influent of the MWTF consisted of mixed tannery wastewater (40~65%) and seafood wastewater (35~60%). The treatment processes resulted in a removal efficiency for BOD (biochemical oxygen demand) and COD (chemical oxygen demand) of 83.6~ 98.2% and 72.8~84.6%, respectively for tannery wastewater than for seafood wastewater resulted in greater survival of biomass in the biological reactors and a higher removal of BOD, COD, and T-N of about 8~18%. In contrast, addition of greater amounts of seafood wastewater decreased the amount of biomass in the bioreactors due to the increasing concentration of chromium from that wastewater and it also. The dominant bacterial species during the high seafood wastewater input period were Burkholderia cepacia (JX901049) and an uncultured bacterium (JF247555), while Pseudomonas geniculata (HQ256559) was dominant during the high tannery wastewater input period. Flavobacteriumsp. BF.107 (FM173271) and Hyphomicrobium zavarzinii (Y14306) were dominant under anoxic conditions.

Microbial fuel cell (MFC) wes enriched using sludge in wastewater treatment. The microbial community of activated sludge and enriched MFC were analyzed by FISH (fluorescent in situ hybridization) and 16S rDNA sequencing. Bacteroidetes group were pre-dominant in activated sludge by FISH. α group, γ group and Acintobacter group were dominant and they were similar to distribution. The average value of 10 peak of MFC is 0.44C. When MFC wase enriched by sludge, γ-Proteobacteria, Plantomycetes group increased 70% and 60%, respectively. In results of 16S rDNA sequencing, Sphiringomonas sp. was comprised in α proteobacteria and Enterobacter sp., Klebsiella sp., Acinetobacter sp., Bacillus sp. were comprised in γ proteobacteria and Chryseobacterium sp. was comprised in Flavobacteria were isolated from sludge.

The intestinal microbiome of animals is composed of a diverse and complex community of bacteria. Because of its impact on physiological, developmental, nutritional and immunological processes, the microbial community of animals markedly influences health status and performance of the animal. Thus, in order to verify the effect of probiotics and of other feeding materials, which are likely to influence the composition of the intestinal microbiome and to explain the mechanisms of their actions, it is essential to develop methodological strategies and useful tools to characterize the microbiome of animals. Application of MGA to the comparison of swine fecal metagenomes suggested that the microbial community composition of swine intestine could be dependent on the health state of swine.

PTA (purified terephthalic acid) wastewater contains various aromatic compounds such as phthalate isomers, p-toluate and benzoate, which can be converted into valuable biogas under methanogenic condition. Although many full-scale PTA wastewater treatment processes are currently being operated in the world, the involved microbial reactions have not yet fully elucidated especially for the p-toluate degradation. In this study, a lab-scale PTA wastewater treatment process consisting of two sequentially-connected UASB (upflow anaerobic sludge blanket) reactors was operated and the microbial community at each stage was investigated by comparing the T-RFLP (terminal restriction fragment length polymorphism) patterns together with the 16S rDNA gene clone libraries complementarily. In the first stage reactor, where most contaminants except p-toluate were completely degraded, both Syntrophus and Syntrophobacter species known to have a higher substrate affinity for benzoate were identified to be most predominant. In the second stage reactor, on the other hand, a species belonging to the family of Bacteroidales was most predominant with Syntrophus and Syntrophobacter species diminished. In the second stage reactor mainly treating p-toluate, it was further revealed that an uncultured species belonging to α-proteobacteria was newly present and the relative amounts of Syntrophorhabdaceae and Syntrophomonas species were also remarkably increased compared to the first stage reactor. Considering the substrate availability at each stage, this result strongly suggests that the last three microbial groups are closely related to the p-toluate degradation.

Anaerobic degradation of aromatic compounds plays a major role in bioremediation processes, and there has been increasing information available on the anaerobic oxidation of aromatic compounds recently.1) Utilizing alternate electron acceptors during anaerobic degradation are increasingly considered for bioremediation of hydrocarbon-contaminated sites.2) In this study, we examined the anaerobic biodegradation of benzene and toluene by soil bacteria with nitrate, sulfate, or iron as electron acceptors. Biodegradation of benzene and toluene was more successful under existence of electron acceptor. And nitrate provided the highest efficiency for degradation of individual contaminant, followed by iron and sulfate. We performed DGGE which was for analysis of microbial community degrading benzene and toluene depending on the several different electron acceptor. The DGGE patterns showed that there were very different and diverse microorganisms. We were known that microorganisms were organized mainly by proteobacteria.

The biological reduction of carbon dioxide, one of the global warming gases, has been issued for last decade. Among the technology for biological CO2 reduction, photosynthetic bacteria and algae were mainly used for its reduction or fixation. However, there are many reports on the drawbacks of the photosynthetic bacteria for the CO2 reduction. Main drawbacks are the limitation of light transfer and the inhibition of CO2 itself for the reduction. In this study, we employed methanogens to convert CO2 to methane with hydrogen gas. H2 is converted to methane with reducing CO2 in a novel hollow-fiber membrane biofilm reactor. All gases diffused into water through the membrane without bubbles. We have successfully operated the Hf-MBfR for stable methane production from CO2 and H2 under continuous operations over 70 days. The conversion of CO2 depended on the pH conditions and the compositions of volatile fatty acids in liquid phase also changed by the pH conditions. It means that the microbial community could be affected by the operation condition. However, little is known about the autotrophic methanogen. We have performed DGGE and T-RFLP for bacterial and archaeal 16S rDNA to analysis of microbial community in the reactor.

A lab-scaled (7 L of working volume) continuous autotrophic nitrification system has been operated for 1490 days feeding coke oven gas (COG) wastewater to study the treatability and monitor the long-term performance of the biological nitrification system. Incomplete nitrification occurred for the first 240 days. The periodic fluctuation of nitrite and nitrate observed from day 240 to day 1230. Finally, complete nitrification took place from day 1230. It was postulated that the high free ammonia (FA) concentration (35 mg/L) selectively inhibited nitrite oxidizing bacteria (NOB)1-2), and NOB slowly overcame the toxic effect of FA. Denaturing gradient gel electrophoresis and the analysis of 16S rRNA gene clone library were carried out to investigate the diversity of bacteria in the system with DNA collected at day 1150. Nitrosomonas nitrosa-like ammonia oxidizing bacteria, was the most abundant bacterial group (53.8%) indicating successful enrichment of autotrophic nitrifiers with significant proportion of the entire bacterial community. Thiobacillus denitrificans responsible autotrophic thiocyanate degradation (33.7 % of total population) was also found. No nitrite oxidizing bacteria was found in spite of the detection of nitrate at day 1150.