Rice Field Soil Research Articles

Geobacter, Anaeromyxobacter and Anaerolineae populations are enriched on anodes of root exudate-driven microbial fuel cells in rice field soil.

Plant-based sediment microbial fuel cells (PMFCs) couple the oxidation of root exudates in living rice plants to current production. We analysed the composition of the microbial community on anodes from PMFC with natural rice field soil as substratum for rice by analysing 16S rRNA as an indicator of microbial activity and diversity. Terminal restriction fragment length polymorphism (TRFLP) analysis indicated that the active bacterial community on anodes from PMFCs differed strongly compared with controls. Moreover, clones related to Deltaproteobacteria and Chloroflexi were highly abundant (49% and 21%, respectively) on PMFCs anodes. Geobacter (19%), Anaeromyxobacter (15%) and Anaerolineae (17%) populations were predominant on anodes with natural rice field soil and differed strongly from those previously detected with potting soil. In open circuit (OC) control PMFCs, not allowing electron transfer, Deltaproteobacteria (33%), Betaproteobacteria (20%), Chloroflexi (12%), Alphaproteobacteria (10%) and Firmicutes (10%) were detected. The presence of an electron accepting anode also had a strong influence on methanogenic archaea. Hydrogenotrophic methanogens were more active on PMFC (21%) than on OC controls (10%), whereas acetoclastic Methanosaetaceae were more active on OC controls (31%) compared with PMFCs (9%). In conclusion, electron accepting anodes and rice root exudates selected for distinct potential anode-reducing microbial populations in rice soil inoculated PMFC.

Arsenic in Rice grains at Sonargaon, Bangladesh

Rice plants absorb substantial amount of arsenic when grown in rice field soil containing 3.21 mg/kg arsenic and irrigated with contaminated groundwater from a shallow tube-well having 476 ± 3 ?g arsenic/l at Sonargaon, Bangladesh. It is revealed that highest total arsenic accumulation occurred in roots (5.790 ± 0.337 mg/kg) followed by shoots (3.766 ± 0.370 mg/kg) and brown-rice grains (2.552 ± 0.507 mg/kg). The concentration of total arsenic in rice grains was beyond permissible limit (1.00 mg/kg) for human consumption. At the time of harvest 4.90 ± 1.11 - 8.27 ± 1.35 mg As/kg soil remained in the rice field soil. However, majority of the soil arsenic is washed out by rain and flood water leaving more than 3.00 mg As/kg soil after flood period which along with high level of As contaminated groundwater for irrigation, elevated the level (up to 8.27 ± 1.35 mg As/kg soil) beyond permissible limit of e.g. in USA it is 5 mg/kg soils for agriculture use. To keep the environment clean, surface water for irrigation has been suggested. DOI: http://dx.doi.org/10.3329/bjb.v44i1.22728 Bangladesh J. Bot. 44(1): 85-89, 2015 (March)

The differential effects of ammonium and nitrate on methanotrophs in rice field soil

It has been known that nitrogenous fertilizers can either stimulate or inhibit methane oxidation in soils. The mechanism, however, remains unclear. Here we conducted laboratory incubation experiments to evaluate the effects of ammonium versus nitrate amendment on CH4 oxidation in a rice field soil. The results showed that both N forms stimulated CH4 oxidation. But nitrate stimulated CH4 oxidation to a greater extent than ammonium per unit N base. The 16S rRNA genes and the pmoA genes were analyzed to determine the dynamics of total bacterial and methanotrophic populations, respectively. The methanotrophic community consisted of type I and type II methanotrophs and was dominated by type I group after two weeks of incubation. Nitrate promoted both types of methanotrophs, but ammonium promoted only type I. DNA-based stable isotope probing confirmed that ammonium stimulated the incorporation of 13CH4 into type I methanotrophs but not type II, while nitrate caused almost homogenous distribution of 13CH4 in type I and type II methanotrophs. Our study suggests that nitrate can promote CH4 oxidation more significantly than ammonium and is probably a better N source for both types of methanotrophs in rice field soil. More investigations, e.g. using 15N labeling, are necessary to elucidate this possibility.

Arenimonas taoyuanensis sp. nov., a novel bacterium isolated from rice-field soil in China.

A Gram-stain negative, aerobic, rod-shaped bacterial strain, YN2-31A(T), was isolated from rice-field soil, Taoyuan Village, Yunnan province of China. The bacterium was observed to grow at 20-45 °C (optimum 28 °C), at pH 5.0-10.0 (optimum 7.0), and in the presence of 0-2% (w/v) NaCl (optimum 0-1%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain YN2-31A(T) is most closely related to Arenimonas daejeonensis DSM 18060(T) (96.1%), Arenimonas malthae DSM 21305(T) (95.9%), Arenimonas donghaensis DSM 18148(T) (95.1%), Arenimonas composti DSM 18010(T) (94.8%) and Arenimonas maotaiensis JCM 19710(T) (94.8%). The major cellular fatty acids (>10%) were found to be iso-C(18:1) ω9c, iso-C(15:0), Sum In Feature 3 (C(16:1) ω7c/C(16:1) ω6c), and C(16:0). The major ubiquinone was identified as Q-8 and the major cellular polar lipids were identified as diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and unidentified phospholipids. The genomic DNA G+C content was determined to be 72.3 mol%. The results of the phylogenetic, genetic, phenotypic and chemotaxonomic analyses suggest that strain YN2-31A(T) represents a novel species of the genus Arenimonas, for which the name Arenimonas taoyuanensis sp. nov. is proposed. The type strain is YN2-31A(T) (=DSM 26777(T) = CCTCC AB2012964(T)).

Seasonal dynamics of bacterial and archaeal methanogenic communities in flooded rice fields and effect of drainage.

We studied the resident (16S rDNA) and the active (16S rRNA) members of soil archaeal and bacterial communities during rice plant development by sampling three growth stages (vegetative, reproductive and maturity) under field conditions. Additionally, the microbial community was investigated in two non-flooded fields (unplanted, cultivated with upland maize) in order to monitor the reaction of the microbial communities to non-flooded, dry conditions. The abundance of Bacteria and Archaea was monitored by quantitative PCR showing an increase in 16S rDNA during reproductive stage and stable 16S rRNA copies throughout the growth season. Community profiling by T-RFLP indicated a relatively stable composition during rice plant growth whereas pyrosequencing revealed minor changes in relative abundance of a few bacterial groups. Comparison of the two non-flooded fields with flooded rice fields showed that the community composition of the Bacteria was slightly different, while that of the Archaea was almost the same. Only the relative abundance of Methanosarcinaceae and Soil Crenarchaeotic Group increased in non-flooded vs. flooded soil. The abundance of bacterial and archaeal 16S rDNA copies was highest in flooded rice fields, followed by non-flooded maize and unplanted fields. However, the abundance of ribosomal RNA (active microbes) was similar indicating maintenance of a high level of ribosomal RNA under the non-flooded conditions, which were unfavorable for anaerobic bacteria and methanogenic archaea. This maintenance possibly serves as preparedness for activity when conditions improve. In summary, the analyses showed that the bacterial and archaeal communities inhabiting Philippine rice field soil were relatively stable over the season but reacted upon change in field management.

Clostridium oryzae sp. nov., from soil of a Japanese rice field.

An obligately anaerobic bacterial strain designated KC3(T) was isolated from a rice straw-degrading culture, for which soil of a Japanese rice field was used as the inoculum. Cells of strain KC3(T) were determined to be non-cellulolytic, Gram-stain-positive, non-motile, ellipsoidal, spore-forming rods, 0.8-1×4-25 µm. Endospores were formed at a terminal position in elongated cells (12-25 µm, mean 15 µm). The temperature range for growth was 20-50 °C, with an optimum at 37 °C. The pH range for growth was 5.0-7.5, with an optimum at pH 6.0 (slightly acidophilic). Strain KC3(T) fermented cellobiose to lactate, butyrate, acetate, formate, hydrogen and carbon dioxide. The major cellular fatty acids (>10 %) were C14 : 0, C16 : 0 and C19 : 0 cyclo 11,12 dimethylacetal. The DNA G+C content of strain KC3(T) was 37.5 mol%. 16S rRNA gene sequence analysis revealed that strain KC3(T) shared low sequence similarity (<93 %) with type strains of the genus Clostridium sensu stricto (Clostridium rRNA cluster I). Analyses of the DNA gyrase A and ATP synthase beta subunit sequences supported the affiliation of strain KC3(T) to the genus Clostridium sensu stricto. The evidence presented here indicates that strain KC3(T) represents a novel species of the genus Clostridium, for which the name Clostridium oryzae sp. nov. is proposed. The type strain of Clostridium oryzae is KC3(T) ( = DSM 28571(T) = NBRC 110163(T)).

Dynamics and Activity of Sulfate-Reducing Bacterial Populations in Paddy Soil under Subsurface Drainage: Case Study of Kamboinse in Burkina Faso

Sulfide toxicity is a common disease generally associated with iron toxicity which occurs in rice fields when the Sulfate-Reducing Bacteria (SRB) produce sulfides ions in anaerobic conditions. The high quantity of sulfides ions in the soil solution upsets the mineral element balance in the rice, affects its growth and causes crop yield losses. In Burkina Faso, many rice field soils are abandoned due to sulfides toxicity. The present study was developed to evaluate the impact of subsurface drainage on SRB dynamics and activity during rice cultivation and the incidence on rice production. Twelve concrete microplots with a clay-loam soil and a rice variety susceptible to sulfides toxicity (FKR 19) were used for the experiment. Soil in microplots was drained for 7 days (P1), 14 days (P2), and 21 days (P3), respectively. Control (T) microplots without drainage were prepared similarly. The evolution of SRB populations and the content of sulfides ions in the paddy soil and in soil near rice roots were monitored throughout the cultural cycle using MPN and colorimetric methods, respectively. Data obtained were analyzed in relation to drainage frequency, rice growth stage, and rice yield using the Student’s t-test and XLSTAT 7.5.2 statistical software. From the results obtained, the subsurface drainage did not affect significantly SRB populations (P = 0.187). However, the drainage affected significantly sulfides concentration in the soil near rice roots (P = 0.032). The concentration of sulfides (P < 0.0001) in soil near rice roots and the number of SRB (P < 0.0001) were significantly higher during the rice tillering and maturity stages. Although no significant difference was observed for rice yield among treatments (P = 0.209), the P2 subsurface drainage showed the highest yield and a low concentration of sulfides in soil near rice roots.

Optimization Studies of Alkaline Cellulase from Bacillus licheniformis SM1 Isolated from Rice Agricultural Soil using Taguchi Methodology

The aim of the present work was to screen microbes related to alkaline cellulase production from rhizosphere of rice field soil from Phagwara, Punjab. Out of 9 isolates screened, isolate 6 th designated as SM1 was selected for alkaline cellulase study. Results of 16S rRNA revealed this strain as Bacillus licheniformis. Various medium conditions affecting cellulase activity such as pH, C/N ratio, Tween-20 and lactose were optimized using L9 conditions by Taguchi methodology in submerged conditions. Factors having significant impact over alkaline cellulase activity were in order pH > C/N ratio > Tween20 > Lactose. The most optimum conditions for cellulase production was pH 9; C/N, 1:2; Lactose, 1 % (w/v) and Tween 20, 1 %(v/v) at 50 0C.

Effect of temperature on the structure and activity of a methanogenic archaeal community during rice straw decomposition

In recent years, the rice fields in Sanjiang Plain of Northeast China have drawn more and more attention because of the unique high-latitude location and the important contributions to rice production and methane emission. In the present study, a rice field soil in Sanjiang Plain was anaerobically incubated in presence and absence of rice straw at three temperatures (10 °C, 30 °C and 45 °C). The community structure and activity dynamics of methanogenic archaea were investigated by the terminal restriction fragment length polymorphism analyses in combination with cloning and sequencing of mcrA genes and transcripts and archaeal 16S rRNA genes. We found rice straw addition significantly shortened the lag phase of methanogenesis and enhanced the production of CH4 and the accumulation of methanogenic precursors (CO2, H2 and acetate). The T-RFLP analysis of mcrA gene revealed that structure of methanogenic archaeal community was relatively stable during the anoxic incubation. By contrast, analysis at the transcript level showed a highly dynamic composition of the active methanogens. In the beginning and early stages of incubation, Methanosarcinaceae actively utilized the accumulated acetate and H2/CO2 for CH4 production. Then the different methanogenic community developed along with the incubation time, and each representative methanogen group became predominant in different temperatures and treatments. At 10 °C, Methanobacteriales became more abundant in the soil without straw, while Methanosarcinaceae dominated in the soil with straw. The acetoclastic Methanosaetaceae, in particular, appeared to be active at 30 °C, probably due to the low concentration of acetate. High temperature of 45 °C significantly favored the hydrogenotrophic methanogens, with the increasing abundance of Methanobacteriales early and then the Methanocellales in the later stages.

Impact of long-term fertilizer treatment on the microeukaryotic community structure of a rice field soil

Microeukaryotes play many different functional roles in soil ecosystems, but the environmental factors that shape their community composition are poorly understood. Here we studied the impact of chemical and organic fertilizers on the microeukaryotic soil communities of rice field plots under long-term (82 years) fertilizer management. Terminal restriction fragment polymorphism (T-RFLP) and clone library analyses of 18S rRNA genes and their transcripts obtained from soils subjected to five different fertilizer treatments showed that fertilizer management strongly influenced microeukaryotic community composition in the soils and that its impact was greater than that of water management or seasonality. Among the different chemical fertilizers, the effects of phosphorus fertilizer on community composition were more pronounced than those of either nitrogen or potassium. Soils without phosphorus fertilizer were characterized by a high relative abundance of diatoms and algivorous nematodes whereas in phosphorus-fertilized soils green algae predominated. Different rates of organic fertilizer (rice straw compost) application had distinctive effects on the DNA-based microeukaryotic community, especially its algal composition. Thus, protistan grazers were the largest group in the potentially active community from soils with a higher amount of organic fertilizer application. Our findings provide evidence that long-term fertilization shapes the microeukaryotic community composition of rice field soils. The results imply that fertilizer management of rice field soils is an important determinant of the structure and function of the microbial food web.

Kaedah Penggantian Tanah untuk Meningkatkan Kekuatan Struktur Tanah di Kawasan Tanah Jerlus

Soft soil in rice field has a hardpan layer of less than 0.3Mpa. The usage of farm mechanization in rice field cannot be performed due to the hardpan structure cannot accommodate the load of heavy machinery. To overcome this problem, the method of soft soil replacement is used in order to revitalize the hardpan layer which has been damaged due to the stagnant water problem. Field study was conducted to test the soft soil replacement method to solve the problem of land on soft soil plot in Alor Senibung. A total of 4 plots have been prepared for the experiments where the top layer of paddy soil has been removed and replaced with other soil. After the soil has been compacted, the hardness of the hardpan was measured from time to time and is presented in this paper. The results from this study are expected to overcome the soft soil problems.

Soil-geographical characteristics of the western part of the democratic People’s Republic of Korea

The specific character of soil cover in the territory of the Democratic People’s Republic of Korea (DPRK) is revealed, and the soil interpretation schemes in the key areas are compiled. It is established that the main soil resource for agriculture within the region’s low and middle mountains is provided by areas of weakly developed brown forest soils in the lower parts of slopes as well as by alluvial soils along the valleys of large and medium-sized rivers. Specifically, brown forest soils of slopes are used largely in dry farming and forestry, while soils along river valleys are utilized in rice cultivation. Soils of terraced slopes and rice fields have been transformed anthropogenically to the greatest extent.

Bioassay of soils on rice fields in Vietnam

The results of bioassays for the integrated environmental assessment of soils of rice fields in Vietnam which have a dangerous pesticide load are discussed. The results of the chemical-analytical analysis confirm the high informativity when three bioassays are used: on infusoria, daphnia, and plants (phytotest). We discuss the feasibility of using two soil extracts.

Physical and Chemical Properties of Mineral in Soils of Paddy Rice Fields from Chonburi Province, Thailand

The aim of this study is to investigate the some chemical and physical properties in the soils collected from the paddy rice fields in Chonburi Province. The chemical analysis of soil samples was performed on an Energy Dispersive X-rays spectrometer (EDXRF). It was found that the soils samples consist of Si, Al, Ca, Fe, K, Mn, Ti, Cr, Zn, Ag and Cu. Another that, the structural in whole soil samples were carried out by X-ray Diffraction (XRD) technique. It was found that Silica (SiO2) is the major minerals in all soil layers. In this study, we also used Thermo-Gravimetric Analysis (TGA) investigated the removal of moisture from the paddy rice fields.

Effect of fungal and bacterial bioagent application on total phenolic content in rice leaves pre-inoculated with Xanthomonas oryzae pv. oryzae (Uyeda and Ishiyama) Dowson

Present study was carried out to observe the effect of fungal and bacterial bioagents on total phenolic content in rice leaves pre-inoculated with Xanthomonas oryzae pv. oryzae and on disease severity of bacterial leaf blight of rice. Two commercial formulations of Trichoderma harzianum (PBA-1) and Pseudomonas fluorescens (PBA-2) and four formulations of fluorescent pseudomonads and Trichoderma spp. viz, P. fluorescens (Pf 83, rice leaf isolate), fluorescent pseudomonad (FLP 88, rice leaf isolate), T. harzianum (rice leaf isolate), Trichoderma spp. (isolate 40, isolated from rice field soil) were evaluated. Significantly higher mean value of total phenolic content of rice leaves was observed with the application of bioagent formulations as compared to check (pre-inoculated with X. oryzae pv. oryzae), chemical treatment and healthy plant. Maximum mean total phenolic content (342.22 ?l/g) in rice leaves was observed with Pf 83, which was followed by PBA-2 (334.44 ?l/g) and T. harzianum (330.00 ?l/g). Decrease in disease severity of bacterial leaf blight was observed with the increase of total phenolic content in rice leaves which resulted in increased grain yield and 1000 grain weight.

Developments in Cyanobacterial Biofertilizer

Rice is the world’s most important food crop as more than 40% of the world’s population depends on rice as a major source of calories. Rice yield in India is about 1990 kg/ha against a maximum of 3346 kg/ha in Punjab. Though the rice yields in Punjab is highest in the country, it is quite low compared to China (5807 kg/ha). Such diversity in yields is due to insufficient use of fertilizer nitrogen. Nitrogen is present as elemental nitrogen in the atmosphere and constitutes more than 79 per cent of total gases. However, crop plants cannot utilize nitrogen in elemental form. On global level, out of 180 million tonnes of nitrogen added annually on the earth’s surface, 2/3 is through biological processes, largely microbial activities. Cyanobacteria colonize rice fields and provide biologically fixed nitrogen to the rice crop to the extent of 25-30 kg nitrogen per hectare. In India, on an average, cyanobacteria accounts to about 33% of total algal flora of Indian rice field soils [66], whereas in some of the southern and eastern states this reaches up to 50%. Virtually all the dominant cyanobacteria in rice fields are nitrogen fixing. Apart from increase in yield and saving of fertilizer nitrogen, cyanobacterial inoculation improves the physico-chemical properties of soil, gradual build-up of residual soil nitrogen and carbon, improvement in soil pH and electrical conductivity. The grain quality in terms of protein content was improved. Our recent studies have shown that the cyanobacteria ( Nostoc and Anabaena ) were capable of forming associations with wheat roots grown in liquid culture. Probably, such cyanobacteria contribute nitrogen and growth promoting substances to plants in the rhizosphere.

Spirosoma radiotolerans sp. nov., a gamma-radiation-resistant bacterium isolated from gamma ray-irradiated soil.

A Gram-negative, short-rod-shaped bacterial strain with gliding motility, designated as DG5A(T), was isolated from a rice field soil in South Korea. Phylogenic analysis using 16S rRNA gene sequence of the new isolate showed that strain DG5A(T) belong to the genus Spirosoma in the family Spirosomaceae, and the highest sequence similarities were 95.5 % with Spirosoma linguale DSM 74(T), 93.4 % with Spirosoma rigui WPCB118(T), 92.8 % with Spirosoma luteum SPM-10(T), 92.7 % with Spirosoma spitsbergense SPM-9(T), and 91.9 % with Spirosoma panaciterrae Gsoil 1519(T). Strain DG5A(T) revealed resistance to gamma and UV radiation. Chemotaxonomic data showed that the most abundant fatty acids were summed feature C(16:1) ω7c/C(16:1) ω6c (36.90 %), C(16:1) ω5c (29.55 %), and iso-C(15:0) (14.78 %), and the major polar lipid was phosphatidylethanolamine (PE). The DNA G+C content of strain DG5A(T) was 49.1 mol%. Together, the phenotypic, phylogenetic, and chemotaxonomic data supported that strain DG5A(T) presents a novel species of the genus Spirosoma, for which the name Spirosoma radiotolerans sp. nov., is proposed. The type strain is DG5A(T) (=KCTC 32455(T) = JCM19447(T)).

Enrichment of amino acid-oxidizing, acetate-reducing bacteria

In anaerobic condition, amino acids are oxidatively deaminated, and decarboxylated, resulting in the production of volatile fatty acids. In this process, excess electrons are produced and their consumption is necessary for the accomplishment of amino acid degradation. In this study, we anaerobically constructed leucine-degrading enrichment cultures from three different environmental samples (compost, excess sludge, and rice field soil) in order to investigate the diversity of electron-consuming reaction coupled to amino acid oxidation. Constructed enrichment cultures oxidized leucine to isovalerate and their activities were strongly dependent on acetate. Analysis of volatile fatty acids (VFAs) profiles and community structure analysis during batch culture of each enrichment indicated that Clostridium cluster I coupled leucine oxidation to acetate reduction in the enrichment from the compost and the rice field soil. In these cases, acetate was reduced to butyrate. On the other hand, Clostridium cluster XIVb coupled leucine oxidation to acetate reduction in the enrichment from the excess sludge. In this case, acetate was reduced to propionate. To our surprise, the enrichment from rice field soil oxidized leucine even in the absence of acetate and produced butyrate. The enrichment would couple leucine oxidation to reductive butyrate synthesis from CO2. The coupling reaction would be achieved based on trophic link between hydrogenotrophic acetogenic bacteria and acetate-reducing bacteria by sequential reduction of CO2 and acetate. Our study suggests anaerobic degradation of amino acids is achieved yet-to-be described reactions.

Deinococcus soli sp. nov., a Gamma-Radiation-Resistant Bacterium Isolated from Rice Field Soil

A Gram-negative, non-motile, short rod-shaped bacterial strain, designated N5(T), was isolated from a rice field soil in South Korea. Phylogenetic analysis based on the 16S rRNA gene sequence of the new isolate showed that strain N5(T) belongs to the genus Deinococcus, family Deinococcaceae, showing the highest sequence similarity to Deinococcus grandis KACC 11979(T) (98.4 %) and Deinococcus daejeonensis KCTC 13751(T) (97.5 %). Strain N5(T) exhibits resistance to gamma-radiation similar to that of other members of the genus Deinococcus, with a D10 value in excess of 4 kGy. Chemotaxonomic data showed that the most abundant fatty acids are C16:1ω7c (25.25 %), C15:1ω6c (19.77 %), C17:1ω6c (11.87 %), and C17:0 (9.41 %), and the major polar lipid is an unknown phosphoglycolipid. The predominant respiratory quinone is menaquinone MK-8. The DNA G+C content is 71.4 mol%. Phenotypic, phylogenetic, and chemotaxonomic data support designation of strain N5(T) as a novel species of the genus Deinococcus, for which the name Deinococcus soli sp. nov. is proposed. The type strain is N5(T) (=KCTC 33153(T) = JCM 19176(T)).

Description of Anaerobacterium chartisolvens gen. nov., sp. nov., an obligately anaerobic bacterium from Clostridium rRNA cluster III isolated from soil of a Japanese rice field, and reclassification of Bacteroides cellulosolvens Murray et al. 1984 as Pseudobacteroides cellulosolvens gen. nov., comb. nov.

An obligately anaerobic bacterial strain designated T-1-35(T) was isolated as a dominant cultivable cellulose-degrading bacterium from soil of a Japanese rice field as an anaerobic filter-paper degrader. Cells of strain T-1-35(T) stained Gram-positive and were non-spore-forming rods with rounded ends, 0.8-1.0×3.5-15.0 µm, and motile by means of two to four polar flagella. Cells of strain T-1-35(T) exhibited pleomorphism: in aged cultures (over 90 days of incubation), almost all cells were irregularly shaped. Although no spore formation was observed, cells tolerated high temperatures, up to 90 °C for 10 min. The temperature range for growth was 15-40 °C, with an optimum at 35 °C. The pH range for growth was 5.5-9.0, with an optimum at pH 8.0-8.5 (slightly alkaliphilic). Strain T-1-35(T) fermented some carbohydrates to produce ethanol and lactate as the major products. Major cellular fatty acids were iso-C16 : 0 and iso-C13 : 0 3-OH. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that strain T-1-35(T) belonged to Clostridium rRNA cluster III. The closest relative of strain T-1-35(T) was Bacteroides cellulosolvens WM2(T), with 16S rRNA gene sequence similarity of 93.4 %. Phenotypic, physiological and molecular genetic methods demonstrated that strain T-1-35(T) was distinct from its phylogenetic relatives (members of Clostridium rRNA cluster III) because it predominantly produced ethanol, iso-C13 : 0 3-OH was a major cellular fatty acid and it always exhibited pleomorphism. On the basis of the results of a polyphasic taxonomic study, strain T-1-35(T) is considered to represent a novel genus and species, Anaerobacterium chartisolvens gen. nov., sp. nov. The type strain of Anaerobacterium chartisolvens is T-1-35(T) ( = DSM 27016(T) = NBRC 109520(T)). In addition, from the results of our phylogenetic analysis and its phenotypic features, the species Bacteroides cellulosolvens Murray et al. 1984 is proposed to be reclassified in the new genus Pseudobacteroides as Pseudobacteroides cellulosolvens gen. nov., comb. nov., with the type strain WM2(T) ( = ATCC 35603(T) = DSM 2933(T) = NRCC 2944(T)).