Brooklawnia propionicigenes sp. nov., a facultatively anaerobic, propionate-producing bacterium isolated from a methanogenic reactor treating waste from cattle farms.

Facultatively anaerobic bacterial strains were isolated from samples of a methanogenic reactor and, based on 16S rRNA gene sequences, found to be affiliated with the family Propionibacteriaceae in the phylum Actinomycetota. Four strains with almost-identical 16S rRNA gene sequences were comprehensively characterized. The most closely related species to the strains was Brooklawnia cerclae BL-34T (96.4 % sequence similarity). Although most of the phenotypic characteristics of the four strains were identical, distinct differences in some cellular and physiological properties were also detected. Cells of the strains were Gram-stain-positive, non-spore-forming, pleomorphic rods. The strains utilized carbohydrates and organic acids. The strains produced acetate, propionate and lactate from glucose, but the molar ratios of the products were variable depending on the strains. The strains grew at 10-40 °C (optimum at 35 °C) and pH 5.3-8.8 (optimum at pH 6.8-7.5.) The major cellular fatty acids of the strains were anteiso-C15 : 0, C15 : 0 and C15 : 0 dimethylacetal (as a summed feature). The major respiratory quinone was menaquinone MK-9(H4) and the diagnostic diamino acid in the peptidoglycan was meso-diaminopimelic acid. The genome size of the type strain (SH051T) was 3.21 Mb and the genome DNA G+C content was 65.7 mol%. Genes responsible for propionate production through the Wood-Werkman pathway were detected in the genome of strain SH051T. Based on the results of phylogenetic, genomic and phenotypic analyses of the novel strains, the name Brooklawnia propionicigenes sp. nov. is proposed to accommodate the four strains. The type strain of the novel species is SH051T (=NBRC 116195T=DSM 116141T).

Phylogeny and Physiological Diversity of Cold-adapted Anaerobic Bacteria Isolated from Rice Field Soil in Japan.

Cold-adapted or psychrotrophic fermentative anaerobic bacteria were isolated from rice field soil in a temperate area in Japan using anaerobic enrichment cultures incubated at 5°C. Most isolates were obligately anaerobic, spore-forming rods and affiliated with different lineages of the genus Clostridium based on 16S rRNA gene sequences. The growth temperature ranges and physiological properties of three representative clostridial isolates (C5S7, C5S11T, and C5S18) were examined. Strain C5S7 grew at 0°C, but not at 20°C, and was identified as Clostridium estertheticum, a psychrophile isolated from spoiled, vacuum-packed, chilled meat (blown pack spoilage, BPS). Strain C5S7 produced butyrate, n-butanol, and abundant gases (H2 and CO2) as major fermentation products from the carbohydrates utilized. Strain C5S11T, which was recently described as Clostridium gelidum sp. nov., possessed psychrotrophic properties and grew at temperatures between 0 and 25°C. Strain C5S11T was saccharolytic, decomposed polysaccharides, such as inulin, pectin, and xylan, and produced acetate, butyrate, and gases. Strain C5S18 also grew at 0°C and the optimum growth temperature was 15°C. Strain C5S18 did not ferment carbohydrates and grew in a manner that was dependent on proteinaceous substrates. This strain was identified as the psychrotolerant species, Clostridium tagluense, originally isolated from a permafrost sample. Collectively, the present results indicate that psychrotrophic anaerobic bacteria with different physiological properties actively degrade organic matter in rice field soil, even in midwinter, in a cooperative manner using different substrates. Furthermore, different psychrotrophic species of the genus Clostridium with the ability to cause BPS inhabit cultivated soil in Japan.

Prevotella herbatica sp. nov., a plant polysaccharide-decomposing anaerobic bacterium isolated from a methanogenic reactor.

An obligately anaerobic bacterial strain (WR041T) was isolated from a plant residue sample in a methanogenic reactor. Cells of the strain were Gram-stain-negative, non-motile, non-spore-forming rods. Prevotella paludivivens JCM 13650T was the closest species of the strain based on 16S rRNA gene sequencing (98.9 % similarity). Genome analysis of strain WR041T indicated that the genome size of the strain was 3.52 Mb and the genomic DNA G+C content was 37.5 mol%. Although the 16S rRNA gene sequence similarity of strain WR041T with the closest species was higher than the threshold value of the recommended species delineation (98.7 %), the average nucleotide identity and the digital DNA-DNA hybridization value between them were 91-92 and 45.5 %, respectively, suggesting that strain WR041T represents a novel species in the genus. Strain WR041T essentially required haemin and CO2/Na2CO3 for growth. The strain was saccharolytic and decomposed various polysaccharides (glucomannan, inulin, laminarin, pectin, starch and xylan) and produced acetate and succinate. The optimum growth conditions were 35 °C and pH 6.8. The major cellular fatty acids were branched-chain fatty acids such as anteiso-C15 : 0 and iso-C15 : 0. Menaquinones MK-11 and MK-12 were the major respiratory quinones. Many protein-coding genes which were not found in the genome of P. paludivivens as orthologous genes were detected in the genome of strain WR041T. Based on the differences in the phylogenetic, genomic and physiological characteristics between strain WR041T and related species, the name Prevotella herbatica sp. nov. is proposed to accommodate strain WR041T (=NBRC 115134T = DSM 112534T).

Anaerocolumna chitinilytica sp. nov., a chitin-decomposing anaerobic bacterium isolated from anoxic soil subjected to biological soil disinfestation.

An obligately anaerobic bacterial strain (CTTWT) belonging to the family Lachnospiraceae within the class Clostridia was isolated from an anoxic soil sample subjected to biological or reductive soil disinfestation. Cells of the strain were Gram-stain-positive, short rods with peritrichous flagella. The strain was saccharolytic and decomposed polysaccharides, chitin, xylan and ß-1,3-glucan. Strain CTTWT decomposed cell biomass and cell-wall preparations of an ascomycete plant pathogen, Fusarium oxysporum f. sp. spinaciae. The strain produced acetate, ethanol, H2 and CO2 as fermentation products from the utilized substrates. The major cellular fatty acids of the strain were C16 : 1 ω7c dimethylacetal (DMA), C16 : 0 DMA and C18 : 1 ω7c DMA. The closely related species of strain CTTWT based on the 16S rRNA gene sequences were species in the genus Anaerocolumna with sequence similarities of 95.2-97.6 %. Results of genome analyses of strain CTTWT indicated that the genome size of the strain was 5.62 Mb and the genomic DNA G+C content was 38.3 mol%. Six 16S rRNA genes with five different sequences from each other were found in the genome. Strain CTTWT had genes encoding chitinase, xylanase, cellulase, ß-glucosidase and nitrogenase as characteristic genes in the genome. Homologous genes encoding these proteins were found in the genomes of the related Anaerocolumna species, but the genomic and phenotypic properties of strain CTTWT were distinct from them. Based on the phylogenetic, genomic and phenotypic analyses, the name Anaerocolumna chitinilytica sp. nov., in the family Lachnospiraceae is proposed for strain CTTWT (=NBRC 112102T=DSM 110036T).

ß-1,3-Glucanase production as an anti-fungal enzyme by phylogenetically different strains of the genus Clostridium isolated from anoxic soil that underwent biological disinfestation.

Biological (or reductive) soil disinfestation (BSD or RSD) is a bioremediation process to control soil-borne plant pathogens using activities of indigenous bacteria in the soil. Three obligate anaerobic bacterial strains (TW1, TW10, and TB10), which were isolated from anoxic soil subjected to BSD treatments, were examined for their abilities to produce anti-fungal enzymes. All strains were affiliated with the different lineages of the genus Clostridium. The three strains decomposed ß-1,3-glucans (curdlan and laminarin), and ß-1,3-glucanase activities were detected from their culture supernatants with these glucans. The three strains also produced the enzyme with wheat bran as a growth substrate and killed the Fusarium pathogen (Fusarium oxysporum f. sp. spinaciae) in the anaerobic co-incubation conditions. Observation by fluorescence microscopy of the pathogen cells showed that the three strains had degraded the fungal cells in different manners upon co-incubation with wheat bran. When the three strains were cultivated with the dead cells or the cell wall samples prepared from the Fusarium pathogen, strain TW1 utilized these materials as easily decomposable substrates by releasing ß-1,3-glucanase. When observed by fluorescence microscopy, it appeared that strain TW1 degraded the mycelial cell wall nearly thoroughly, with the septa remaining as undecomposed luminous rings. In contrast, the other two strains decomposed neither the dead cells nor the cell wall samples directly. The results indicate that the various anaerobic bacteria proliferated in the soil under the BSD treatments should play key roles as an organized bacterial community to eliminate fungal pathogens, namely by release of anti-fungal enzymes with different properties.Key points•Three clostridial strains isolated from BSD-treated soils produced ß-1,3-glucanase.•All strains killed the Fusarium pathogen in the anaerobic co-incubation conditions.•One of the strains produced ß-1,3-glucanase with the fungal cell wall as a substrate.•The strain degraded the cell wall almost completely, except for the mycelial septa.

Production of ß-1,3-glucanase and chitosanase from clostridial strains isolated from the soil subjected to biological disinfestation.

Biological soil disinfestation (BSD) or anaerobic (reductive) soil disinfestation (ASD/RSD) is a bioremediation method used to eliminate soil-borne plant pathogens by exploiting the activities of anaerobic bacteria in soil. In this study, two obligate anaerobic bacterial strains isolated from BSD-treated soil and identified as Clostridium beijerinckii were examined for their abilities to suppress the spinach wilt disease pathogen (Fusarium oxysporum f. sp. spinaciae) as a representative soil-borne fungal plant pathogen. Both strains degraded ß-1,3-glucan and chitosan, two major polysaccharide components of ascomycetes fungal cell wall, supplemented in the medium. ß-1,3-Glucanase was detected in the supernatants of cultures supplemented with different types of glucan. Similarly, chitosanase was detected in cultures supplemented with chitosan. Both the enzyme activities were also detected in cultures containing glucose as a substrate. Live cells of F. oxysporum f. sp. spinaciae that were co-incubated with each anaerobic strain under anaerobic conditions using glucose as a substrate died during incubation. Freeze-dried dead fungal biomass of the pathogen, when added to the culture, supported good growth of both anaerobes and production of both enzymes. Severe and nearly complete degradation of both live and dead fungal cells during incubation with anaerobic bacteria was observed by fluorescence microscopy. When individual anaerobic bacterial strain was co-incubated with live pathogenic fungal cells in wheat bran, a popular material for BSD-treatment, both the strains grew well and killed the fungal pathogen promptly by producing both enzymes. These results indicate that both the bacterial strains attack the fungal cells by releasing extracellular fungal cell wall-degrading enzymes, thereby eliminating the pathogen.

Clostridium fungisolvens sp. nov., a new ß-1,3-glucan-decomposing bacterium isolated from anoxic soil subjected to biological soil disinfestation.

Biological soil disinfestation (BSD) or reductive soil disinfestation (RSD) is a bioremediation method used to suppress or eliminate soil-borne plant pathogens by stimulating activities of indigenous anaerobic bacteria of the soil. An anaerobic bacterial strain (TW1T) was isolated from an anoxic soil sample subjected to the BSD treatment and comprehensively characterized. Cells of the strain were Gram-stain-positive, slightly curved and motile rods producing terminal spores. The strain was aerotolerant. Strain TW1T was saccharolytic and produced acetate, butyrate, H2 and CO2 as fermentation end products. Strain TW1T decomposed ß-1,3-glucan (curdlan and laminarin) and degraded mycelial cells of an ascomycete Fusarium plant pathogen. Major cellular fatty acids of strain TW1T were C14 : 0, C14 : 0 dimethylacetal (DMA), C16 : 0 aldehyde and C16 : 0 DMA. Strain TW1T made a group on the phylogenetic tree constructed based on 16S rRNA gene sequences with species such as Clostridium fallax (96.3 %) and Clostridium polyendosporum (96.0 %). Whole genome analysis of strain TW1T showed that the total length of the genome was 5.28 Mb with the DNA G+C content of 31.3 mol%. The average nucleotide identity (ANIb) between strain TW1T and C. fallax was 71.2 %. Presence of the genes encoding laminarinase or GH16 ß-glucosidase was confirmed from the genome analysis of strain TW1T. Based on the genomic, phylogenetic and phenotypic properties obtained, we propose strain TW1T should be assigned in the genus Clostridium in the family Clostridiaceae as Clostridium fungisolvens sp. nov. The type strain TW1T (=NBRC 112097T=DSM 110791T).

Role of anaerobic bacteria in biological soil disinfestation for elimination of soil-borne plant pathogens in agriculture.

Biological soil disinfestation (BSD) or reductive soil disinfestation (RSD) is an environmental biotechnology to eliminate soil-borne plant pathogens based on functions of indigenous microbes. BSD treatments using different types of organic materials have been reported to effectively control a wide range of plant pathogens. Various studies have shown that development of reducing or anoxic conditions in soil is the most important aspect for effective BSD treatments. Substances such as organic acids, FeS, or phenolic compounds generated in the treated soil have been suggested to contribute to inactivation of pathogens. Additionally, anaerobic bacteria grown in the BSD-treated soil may produce and release enzymes with anti-pathogenic activities in soil. Clone library analyses as well as a next-generation sequence analysis based on 16S rRNA genes have revealed prosperity of obligate anaerobic bacteria from the class Clostridia in differently treated BSD soils. Two anaerobic bacterial strains isolated from BSD-treated soil samples and identified as Clostridium beijerinckii were found to decompose major cell wall polysaccharides of ascomycetous fungi, chitosan and ß-1,3-glucan. C. beijerinckii is a species most frequently detected in the clone library analyses for various BSD-treated soils as a closely related species. The two anaerobic isolates severely degraded mycelial cells of the Fusarium pathogen of spinach wilt disease during anaerobic co-incubation of each isolate and the Fusarium pathogen. These reports suggest that antifungal enzymes produced by predominant anaerobic bacteria grown in the BSD-treated soil play important roles to control soil-borne fungal pathogens. Further studies using different bacterial isolates from BSD-treated soils are expected to know their anti-pathogenic abilities.

Aminipila butyrica gen. nov., sp. nov., a strictly anaerobic, arginine-decomposing bacterium isolated from a methanogenic reactor of cattle waste.

A strictly anaerobic bacterial strain (FH042T) was isolated from a methanogenic reactor treating waste from cattle farms. Cells were stained Gram-positive, straight to gently curved rods with polar flagella. The strain was asaccharolytic. The strain fermented amino acids (l-arginine, l-lysine and l-serine) as growth substrates and produced acetate and butyrate. The optimum temperature for growth was 30 °C and the optimum pH was 6.1-6.8. Oxidase, catalase and nitrate-reducing activities were negative. Hydrogen sulfide was produced. The genomic DNA G+C content of strain FH042T was 44.7±0.2 mol%. The major cellular fatty acids were C18 : 1ω9c DMA, C17 : 2/C17 : 1ω9c (as summed feature), C16 : 0 DMA and C14 : 0. The cell-wall peptidoglycan contained meso-diaminopimelic acid as a diagnostic amino acid. The most closely related described species on the basis of 16S rRNA gene sequences was Anaerovorax odorimutans in the family XIII Incertae Sedis in the order Clostridiales of the class Clostridia with sequence similarity of 95.1 %. Based on the distinct differences in phylogenetic and phenotypic characteristics between strain FH042T and related species, Aminipila butyrica gen. nov., sp. nov. is proposed to accommodate the strain. Type strain is FH042T (=JCM 31555T=DSM 103574T).

Degradation of the fungal cell wall by clostridial strains isolated from soil subjected to biological soil disinfestation and biocontrol of Fusarium wilt disease of spinach.

Biological soil disinfestation (BSD) involves elimination of soil-borne plant pathogens in an environmentally friendly manner. Two anaerobic bacterial strains (H110 and TB8) isolated from BSD-treated soil samples were analyzed for their roles in elimination of pathogenic fungi. The two strains were identified as Clostridium beijerinckii based on 16S rRNA gene sequences and phenotypic properties. The strains fermented various carbohydrates and produced acetate, butyrate, and n-butanol as major products as well as abundant gases (H2 and CO2). For evaluation of the antifungal potential of these strains, cells of a pathogen (spinach wilt disease, Fusarium oxysporum f. sp. spinaciae) were co-inoculated into anaerobic media with each anaerobic strain. After incubation for ~3 weeks at 30 °C, 10-30% of the cells of the pathogen survived when incubated without the anaerobic isolates, whereas the pathogen was eliminated when co-incubated with each anaerobe because of the growth of the anaerobic bacterium. It was found by microscopic examination that mycelial cells of the fungal pathogen were severely degraded during the first 3-7 days of the co-incubation. The two strains utilized major cell wall polysaccharides of ascomycetous fungi-chitosan and ß-1,3-glucan (curdlan and laminarin)-as fermentative substrates added to the medium. Furthermore, both isolates degraded a cell wall preparation isolated from the mycelium of the Fusarium pathogen of spinach wilt disease. We concluded that the two anaerobic strains kill the pathogen of spinach wilt disease by degrading major fungal cell wall components as antifungal activities.

Description of Anaerotignum aminivorans gen. nov., sp. nov., a strictly anaerobic, amino-acid-decomposing bacterium isolated from a methanogenic reactor, and reclassification of Clostridium propionicum, Clostridium neopropionicum and Clostridium lactatifermentans as species of the genus Anaerotignum.

A strictly anaerobic bacterial strain (SH021T) was isolated from a methanogenic reactor. Cells were Gram-stain-positive, motile, straight or slightly curved rods. The optimum temperature for growth was 35 °C, and the optimum pH was 6.1-7.7. The strain was asaccharolytic and utilized amino acids as growth substrates. The strain produced acetate and propionate from l-alanine and l-serine, and propionate and butyrate from l-threonine. Branched-chain amino acids (l-isoleucine, l-leucine and l-valine) were utilized weakly, and isovalerate or isobutyrate was produced. Strain SH021T utilized pyruvate and lactate, and converted them to acetate and propionate. The genomic DNA G+C content was 38.2 mol%. Compounds related to iso-C15 : 0 were detected as major components in the cellular fatty acids analysis. The diagnostic diamino acid of the cell-wall peptidoglycan was meso-diaminopimelic acid. On the basis of 16S rRNA gene sequences, the most closely related known species were Clostridium propionicum, Clostridium neopropionicum and Clostridium lactatifermentans in cluster XIVb of the class Clostridia. Based on the phylogenetic and phenotypic data, Anaerotignum aminivorans gen. nov., sp. nov. is proposed to accommodate strain SH021T (=JCM 31556T=DSM 103575T). For the three related species of the genus Clostridium, Anaerotignum propionicum comb. nov. (type strain DSM 1682T=JCM 1430T=ATCC 25522T=CCUG 9280T=NCIMB 10656T=VPI 5303T), Anaerotignum neopropionicum comb. nov. (type strain X4T=DSM 3847T=KCTC 15564T) and Anaerotignum lactatifermentans comb. nov. (type strain G17T=DSM 14214T=LMG 20954T) are proposed with emended descriptions of these species.

Falcatimonas natans gen. nov., sp. nov., a strictly anaerobic, amino-acid-decomposing bacterium isolated from a methanogenic reactor of cattle waste.

A strictly anaerobic bacterial strain (WN011T) was isolated from a methanogenic reactor treating waste from cattle farms. Cells of the strain were Gram-stain-negative curved rods with a polar flagellum. Spores were not produced. The optimum temperature for growth was 35-37 °C and the optimum pH was 6.7. The strain did not utilize carbohydrates as growth substrates. The strain grew in PY medium and produced acetate, butyrate, isovalerate and H2 as well as propionate and isobutyrate as minor products. Amino acids (l-isoleucine, l-leucine, l-lysine, l-serine, l-threonine and l-valine) added to PY medium enhanced growth of the strain and increased the amounts of fermentation products. Oxidase, catalase and nitrate-reducing activities were negative. Hydrogen sulfide was produced. The genomic DNA G+C content was 38.8 mol%. Compounds related to iso-C15 : 0 (fatty acid, dimethylacetal and aldehyde) were detected as predominant components by the cellular fatty acids analysis. The diagnostic diamino acid of the cell-wall peptidoglycan was meso-diaminopimelic acid. On the basis of 16S rRNA gene sequences, three clones from wastewater were very closely related to strain WN011T (up to 99.9 % sequence similarity). The most closely related described species were those in cluster XIVa of the class Clostridia such as Ruminococcus gauvreauii (93.8 % 16S rRNA gene sequence similarity), Clostridium fimetarium (93.5 %) and Clostridium bolteae(93.5 %). Based on the distinct differences in phylogenetic and phenotypic characteristics of strain WN011T from those of related species, it is concluded that strain WN011T represents a novel species of a new genus in the family Lachnospiraceae, for which the name Falcatimonas natans gen. nov., sp. nov. is proposed. The type strain of the type species is WN011T (=JCM 16476T=DSM 22923T).

Descriptions of Anaerotaenia torta gen. nov., sp. nov. and Anaerocolumna cellulosilytica gen. nov., sp. nov. isolated from a methanogenic reactor of cattle waste and reclassification of Clostridium aminovalericum, Clostridium jejuense and Clostridium xylanovorans as Anaerocolumna species.

Strictly anaerobic bacterial strains (FH052T and SN021T) belonging to clostridial cluster XIVa were isolated from a methanogenic reactor. Cells of the two strains were Gram-stain-positive, slender or curved rods producing terminal spores. The strains were slightly alkaliphilic. They fermented various carbohydrates including xylan and produced acetate, ethanol and H2. Strain SN021T decomposed cellulose. The genomic DNA G+C contents were 47.2 mol% for strain FH052T and 38.1 mol% for strain SN021T. The two strains had common cellular fatty acids such as C16 : 0, C16 : 0 dimethylacetal and C18 : 1ω7c dimethylacetal as major components. 16S rRNA gene sequence similarity between the two strains was 94.3 % and they shared closely related species such as Clostridium jejuense, Clostridium xylanovorans and Clostridium aminovalericum (92.6-95.7 % sequence similarity). Phenotypic and phylogenetic analyses suggested that these two isolates should be assigned to novel genera other than the genus Clostridium, and thus the genera Anaerotaenia gen. nov. and Anaerocolumna gen. nov. in the family Lachnospiraceae were proposed to accommodate them as Anaerotaenia torta gen. nov., sp. nov. for strain FH052T (=JCM 30820T=DSM 100431T) and Anaerocolumna cellulosilytica gen. nov., sp. nov. for strain SN021T (=JCM 30819T=DSM 100423T). For the three related Clostridium species, Anaerocolumna aminovalerica DSM 1283T (=JCM 11016T=ATCC 13725T) comb. nov., Anaerocolumna jejuensis HY-35-12T (=DSM 15929T=KCTC 5026T) comb. nov. and Anaerocolumna xylanovoransstrain HESP1T (=DSM 12503T=JCM 31057T) comb. nov. are proposed with emended descriptions of these species.

Aminocella lysinolytica gen. nov., sp. nov., a L-lysine-degrading, strictly anaerobic bacterium in the class Clostridia isolated from a methanogenic reactor of cattle farms.

A strictly anaerobic bacterial strain (WN037(T)) was isolated from a methanogenic reactor. Cells were Gram-positive rods. Strain WN037(T) was asaccharolytic. The strain fermented L-lysine in the presence of B-vitamin mixture or vitamin B12 and produced acetate and butyrate. L-arginine and casamino acids poorly supported the growth. Strain WN037(T) used neither other amino acids nor organic acids examined. The strain had C18:1 ω7c, C16:0 and C18:1 ω7c DMA as the predominant cellular fatty acids. The genomic DNA G + C content was 44.2 mol %. Phylogenetic analysis based on the 16S rRNA gene sequence placed strain WN037(T) in the family Eubacteriaceae in the class Clostridia. The closest relative was Eubacterium pyruvativorans (sequence similarity, 92.8 %). Based on the comprehensive analyses, the novel genus and species, Aminocella lysinolytica gen. nov., sp. nov. was proposed to accommodate the strain. The type strain is WN037(T) (= JCM 19863(T) = DSM 28287(T)).

Description of Propionispira arcuata sp. nov., isolated from a methanogenic reactor of cattle waste, reclassification of Zymophilus raffinosivorans and Zymophilus paucivorans as Propionispira raffinosivorans comb. nov. and Propionispira paucivorans comb. nov. and emended description of the genus Propionispira.

A strictly anaerobic bacterial strain, WK011(T), was isolated from a methanogenic reactor treating waste from cattle farms. The cells stained Gram-negative and were curved rods with a polar or subpolar flagellum. Spore formation was not observed. The optimum temperature for growth was 35 °C and the optimum pH was 6.7. Tests for oxidase, catalase and nitrate-reduction activities were negative. Hydrogen sulfide was produced. The strain fermented carbohydrates and produced acetate and propionate as major fermentation products. The genomic DNA G+C content was 41.7 mol%. The major cellular fatty acids were C15:0, C16:1ω9c and C18:1 dimethylacetal. The diagnostic diamino acid of the cell-wall peptidoglycan was meso-diaminopimelic acid. The most closely related species to strain WK011(T) on the basis of 16S rRNA gene sequences were Propionispira arboris and Zymophilus raffinosivorans (95.6% sequence similarity to the type strains of both species). It was shown by phylogenetic and phenotypic examination of the type strains of related species, including the second species of the genus Zymophilus, Zymophilus paucivorans, that the two genera should be combined and that the two species of the genus Zymophilus should be transferred to the genus Propionispira, as Propionispira raffinosivorans comb. nov. (type strain SH2(T) = ATCC 49691(T) = DSM 20765(T)) and Propionispira paucivorans comb. nov. (type strain AA1(T) = ATCC 49689(T) = DSM 20756(T)), with an emended description of the genus Propionispira. Based on differences in the phylogenetic and phenotypic characteristics of strain WK011(T) from those of closely related species, the novel species Propionispira arcuata sp. nov. is proposed to accommodate the strain. The type strain is WK011(T) ( = JCM 16475(T) = DSM 22929(T)).

Changes and recovery of soil bacterial communities influenced by biological soil disinfestation as compared with chloropicrin-treatment.

Soil bacterial composition, as influenced by biological soil disinfestation (BSD) associated with biomass incorporation was investigated to observe the effects of the treatment on the changes and recovery of the microbial community in a commercial greenhouse setting. Chloropicrin (CP) was also used for soil disinfestation to compare with the effects of BSD. The fusarium wilt disease incidence of spinach cultivated in the BSD- and CP-treated plots was reduced as compared with that in the untreated control plots, showing effectiveness of both methods to suppress the disease. The clone library analyses based on 16S rRNA gene sequences showed that members of the Firmicutes became dominant in the soil bacterial community after the BSD-treatment. Clone groups related to the species in the class Clostridia, such as Clostridium saccharobutylicum, Clostridium tetanomorphum, Clostridium cylindrosporum, Oxobacter pfennigii, etc., as well as Bacillus niacini in the class Bacilli were recognized as the most dominant members in the community. For the CP-treated soil, clones affiliated with the Bacilli related to acid-tolerant or thermophilic bacteria such as Tuberibacillus calidus, Sporolactobacillus laevolacticus, Pullulanibacillus naganoensis, Alicyclobacillus pomorum, etc. were detected as the major groups. The clone library analysis for the soil samples collected after spinach cultivation revealed that most of bacterial groups present in the original soil belonging to the phyla Proteobacteria, Acidobacteria, Bacteroidetes, Gemmatimonadetes, Planctomycetes, TM7, etc. were recovered in the BSD-treated soil. For the CP-treated soil, the recovery of the bacterial groups belonging to the above phyla was also noted, but some major clone groups recognized in the original soil did not recover fully.

Proliferation of diversified clostridial species during biological soil disinfestation incorporated with plant biomass under various conditions.

Biological soil disinfestation (BSD) involves the anaerobic decomposition of plant biomass by microbial communities leading to control of plant pathogens. We analyzed bacterial communities in soil of a model experiment of BSD, as affected by biomass incorporation under various conditions, to find out the major anaerobic bacterial groups which emerged after BSD treatments. The soil was treated with Brassica juncea plants, wheat bran, or Avena strigosa plants, irrigated at 20 or 30 % moisture content and incubated at 25-30 °C for 17 days. The population of Fusarium oxysporum f. sp. spinaciae incorporated at the start of the experiment declined markedly for some BSD conditions and rather high concentrations of acetate and butyrate were detected from these BSD-treated soils. The polymerase chain reaction-denaturing gradient gel electrophoresis analysis based on the V3 region of 16S rRNA gene sequences from the soil DNA revealed that bacterial profiles greatly changed according to the treatment conditions. Based on the clone library analysis, phylogenetically diverse clostridial species appeared exceedingly dominant in the bacterial community of BSD soil incorporated with Brassica plants or wheat bran, in which the pathogen was suppressed completely. Species in the class Clostridia such as Clostridium saccharobutylicum, Clostridium acetobutylicum, Clostridium xylanovorans, Oxobacter pfennigii, Clostridium pasteurianum, Clostridium sufflavum, Clostridium cylindrosporum, etc. were commonly recognized as closely related species of the dominant clone groups from these soil samples.

Anaerocella delicata gen. nov., sp. nov., a strictly anaerobic bacterium in the phylum Bacteroidetes isolated from a methanogenic reactor of cattle farms.

A strictly anaerobic bacterial strain (WN081(T)) was isolated from rice-straw residue in a methanogenic reactor treating waste from cattle farms in Japan. Cells were Gram-staining negative, non-motile, non-spore-forming straight rods. The strain grew rather well on PY agar slants supplemented with a B-vitamin mixture as well as sugars (PYV4S medium) and made translucent and glossy colonies. Growth in liquid medium with the same composition, however, was scanty, and growth was not improved in spite of various additives to the medium. Strain WN081(T) produced small amounts of acetate, propionate, isobutyrate, butyrate, isovalerate and H(2) from PYV liquid medium. The strain did not use carbohydrates or organic acids. The pH range for growth was narrow (pH 6.8-8.2), having a pH optimum at 6.8-7.5. The temperature range for growth was 10-37°C, the optimum being 25-30°C. The strain was sensitive to bile, and did not have catalase or oxidase activities. Hydrogen sulfide was produced from L-cysteine and L-methionine as well as peptone. Indole was produced from L-tryptophan and peptone. The strain had iso-C(15:0) as the exclusively predominant cellular fatty acid (70%) together with some branched chain components (such as iso-C(15:0) DMA, iso-C(17:0) 3-OH and iso-C(15:0) aldehyde) as minor components. The genomic DNA G+C content was 32.3 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence placed strain WN081(T) in the phylum Bacteroidetes with rather low sequence similarities with the related species such as Rikenella microfusus (85.7% sequence similarity), Alistipes putredinis (85.5%) and Alistipes finegoldii (85.5%) in the family Rikenellaceae. Based on the phylogenetic, physiological and chemotaxonomic analyses, the novel genus and species Anaerocella delicata gen. nov., sp. nov. is proposed to accommodate the strain. The type strain is WN081(T) (= JCM 17049(T) = DSM 23595(T)).