Pedobacter endophyticus sp. nov., an endophytic bacterium isolated from Carex pumila.

An aerobic, Gram-stain-negative, weak-motile, short-rod-shaped bacterial strain, designated JBR3-12T, was isolated from halophyte Carex pumila plants, and its taxonomic position was investigated by using a polyphasic taxonomic approach. The strain produced a pink pigment on tryptic soy agar and grew optimally at 25 °C, pH 8 and in the presence of 3 % (w/v) NaCl. Results of phylogenetic analysis based on 16S rRNA gene sequences showed that strain JBR3-12T formed a lineage within the genus Pedobacter and was most closely related to Pedobacter sandarakinus DS-27T (98.0 %) and Pedobacter agri PB92T (97.6 %). The DNA G+C content of the genome was 41.3 mol%; the whole genome length was 5 426 070 bp. The major fatty acids of JBR3-12T were iso-C15 : 0, summed feature 3 (comprising C16 : 1 ω6c and/or C16 : 1 ω7c) and iso-C17 : 0 3-OH. The predominant polar lipid was phosphatidylethanolamine. The predominant quinone was menaquinone-7. Based on its phenotypic, phylogenetic and genotypic features, strain JBR3-12T is proposed to represent a novel species of the genus Pedobacter, for which the name is Pedobacter endophyticus sp. nov. The type strain is JBR3-12T (=KCTC 82363T=NBRC 114901T).

A Chromosome-Scale Genome Assembly Resource for Myriosclerotinia sulcatula Infecting Sedge Grass (Carex sp.).

The fungus Myriosclerotinia sulcatula is a close relative of the notorious polyphagous plant pathogens Botrytis cinerea and Sclerotinia sclerotiorum but exhibits a host range restricted to plants from the Carex genus (Cyperaceae family). To date, there are no genomic resources available for fungi in the Myriosclerotinia genus. Here, we present a chromosome-scale reference genome assembly for M. sulcatula. The assembly contains 24 contigs with a total length of 43.53 Mbp, with scaffold N50 of 2,649.7 kbp and N90 of 1,133.1 kbp. BRAKER-predicted gene models were manually curated using WebApollo, resulting in 11,275 protein-coding genes that we functionally annotated. We provide a high-quality reference genome assembly and annotation for M. sulcatula as a resource for studying evolution and pathogenicity in fungi from the Sclerotiniaceae family.

Hahyoungchilella caricis gen. nov., sp. nov., isolated from a rhizosphere mudflat of a halophyte (Carex scabrifolia), transfer of Thioclava arenosa Thongphrom et al. 2017 to Pseudothioclava as Pseudothioclava arenosa gen. nov., comb. nov. and proposal of Thioclava electrotropha Chang et al. 2018 as a later heterosynonym of Thioclava sediminum.

A Gram-stain-negative strictly aerobic, marine bacterium, designated GH2-2T, was isolated from a rhizosphere mudflat of a halophyte (Carex scabrifolia) in Gangwha Island, the Republic of Korea. The cells of the organism were oxidase-positive, catalase-positive, flagellated, short rods that grew at 10-40°C, pH 4-10, and 0-13% (w/v) NaCl. The predominant ubiquinone was Q-10. The major polar lipids were phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol. The major fatty acid is C18:1. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the novel isolate formed an independent lineage at the base of the radiation encompassing members of the genus Thioclava, except for Thioclava arenosa. The closest relatives were T. nitratireducens (96.03% sequence similarity) and T. dalianensis (95.97%). The genome size and DNA G+C content were 3.77 Mbp and 59.6 mol%, respectively. Phylogenomic analysis supported phylogenetic distinctness based on 16S rRNA gene sequences. Average nucleotide identity values were 73.6-74.0% between the novel strain and members of the genus Thioclava. On the basis of data obtained from a polyphasic approach, the strain GH2-2T (= KCTC 62124T = DSM 105743) represents a novel species of a new genus for which the name Hahyoungchilella caricis gen. nov., sp. nov. is proposed. Moreover, the transfer of Thioclava arenosa Thongphrom et al. 2017 to Pseudothioclava gen. nov. as Pseudothioclava arenosa comb. nov. is also proposed. Finally, Thioclava electrotropha Chang et al. 2018 is proposed to be a later heterosynonym of Thioclava sediminum Liu et al. 2017.

Interactions between arbuscular mycorrhizal fungi and non-host Carex capillacea.

A topic of confusion over the interactions between arbuscular mycorrhizal (AM) fungi and plants is the mycorrhizal status of some plant families such as Cyperaceae, which is generally considered to be non-mycorrhizal. Here, we conducted experiments to explore how the abiotic environmental conditions and AM network influence the interactions between AM fungi and Carex capillacea. We grew Carex capillacea alone or together with a mycorrhizal host species Medicago sativa in the presence or absence of AM fungi (soil inoculum from Mount Segrila and Rhizophagus intraradices from the Chinese Bank of the Glomeromycota, BGC). Plants were grown in a growth chamber and at two elevational sites of Mount Segrila, respectively. The results indicate that mycorrhizal host plants ensured the presence of an active AM fungal network whether under growth chamber or alpine conditions. The AM fungal network significantly depressed the growth of C. capillacea, especially when native inocula were used and the plants grew under alpine site conditions, although root colonization of C. capillacea increased in most cases. Moreover, the colonization level of C. capillacea was much higher (≤ 30%) when growing under alpine conditions compared with growth chamber conditions (< 8.5%). Up to 20% root colonization by Rhizophagus intraradices was observed in monocultures under alpine conditions. A significant negative relationship was found between shoot phosphorus concentrations in M. sativa and shoot dry mass of C. capillacea. These results indicate that growing conditions, AM network, and inoculum source are all important factors affecting the susceptibility of C. capillacea to AM fungi, and growing conditions might be a key driver of the interactions between AM fungi and C. capillacea.

Martelella caricis sp. nov., isolated from a rhizosphere mudflat.

A novel marine bacterium, designated GH2-8T, was isolated from a rhizosphere mudflat of a halophyte (Carexscabrifolia) in Gangwha Island, Republic of Korea and its taxonomic status was investigated by a polyphasic approach. Cells of strain GH2-8T were Gram-stain-negative, strictly aerobic, oxidase-positive, catalase-positive and non-motile rods that showed growth at 10-30 °C, pH 5-10 and 0-11 % (w/v) NaCl. The predominant respiratory quinone was Q-10. The polar lipids were phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, an unidentified aminolipid, an unidentified glycolipid and two unidentified lipids. The major fatty acids were summed feature 8, C16 : 0, C19 : 0cyclo ω8c, C18 : 1ω7c 11-methyl and summed feature 2. The G+C content of the genomic DNA was 53.4 mol%. Comparative analysis of the 16S rRNA gene sequences revealed that the organism belonged to the order 'Rhizobiales' and formed a distinct subline at the root of radiation encompassing members of the genus Martelella. The 16S rRNA gene sequence similarities to the phylogenetic neighbours were Martelella mediterranea (97.1 %), Martelella suaedae (96.9 %), Martelella endophytica (96.6 %), Martelella limonii (96.3 %), Martelella mangrovi (96.1 %) and Martelella radicis (95.5 %). Strain GH2-8T showed low 16S rRNA gene sequence similarities (<93.8 %) to other representatives of the order 'Rhizobiales'. On the basis of the results of phenotypic and phylogenetic analyses, strain GH2-8T (=KACC 19402T=KCCM 90275T=KCTC 62126T=NBRC 113213T) is considered to represent a novel species of the genus Martelella for which the name Martelellacaricis sp. nov. is proposed.

Large elevation and small host plant differences in the arbuscular mycorrhizal communities of montane and alpine grasslands on the Tibetan Plateau.

Understanding the diversity and community structure of arbuscular mycorrhizal fungi (AMF) in extreme conditions is fundamental to predict the occurrence and evolution of either symbiotic partner in alpine ecosystems. We investigated the AMF associations of three plant species at elevations ranging between 3105 and 4556 m a.s.l. on Mount Segrila on the Tibetan Plateau. Three of four locations were studied in two consecutive years. The AMF diversity and community composition in the roots of Carex pseudofoetida, Pennisetum centrasiaticum, and Fragaria moupinensis differed little. However, at high elevations, the abundance of members of Acaulosporaceae increased relative to that of Glomeraceae. Plants at lower elevation sites, where Glomeraceae predominated as root symbionts, had higher leaf nitrogen and phosphorus concentrations than plants at higher elevation sites, where Acaulosporaceae predominated. The overall phylogenetic relatedness of the AMF increased with increasing elevation. This suggests that abiotic filtering may play an important role in the structuring of symbiotic AMF communities along elevational gradients. The functional role of Acaulosporaceae whose relative abundance was found to increase with elevation in alpine environments needs to be clarified in future studies.

Calling from distance: attraction of soil bacteria by plant root volatiles.

Plants release a wide set of secondary metabolites including volatile organic compounds (VOCs). Many of those compounds are considered to function as defense against herbivory, pests, and pathogens. However, little knowledge exists about the role of belowground plant VOCs for attracting beneficial soil microorganisms. We developed an olfactometer system to test the attraction of soil bacteria by VOCs emitted by Carex arenaria roots. Moreover, we tested whether infection of C. arenaria with the fungal pathogen Fusarium culmorum modifies the VOCs profile and bacterial attraction. The results revealed that migration of distant bacteria in soil towards roots can be stimulated by plant VOCs. Upon fungal infection, the blend of root VOCs changed and specific bacteria with antifungal properties were attracted. Tests with various pure VOCs indicated that those compounds can diffuse over long distance but with different diffusion abilities. Overall, this work highlights the importance of plant VOCs in belowground long-distance plant-microbe interactions.

Antifungal Rhizosphere Bacteria Can increase as Response to the Presence of Saprotrophic Fungi.

Knowledge on the factors that determine the composition of bacterial communities in the vicinity of roots (rhizosphere) is essential to understand plant-soil interactions. Plant species identity, plant growth stage and soil properties have been indicated as major determinants of rhizosphere bacterial community composition. Here we show that the presence of saprotrophic fungi can be an additional factor steering rhizosphere bacterial community composition and functioning. We studied the impact of presence of two common fungal rhizosphere inhabitants (Mucor hiemalis and Trichoderma harzianum) on the composition of cultivable bacterial communities developing in the rhizosphere of Carex arenaria (sand sedge) in sand microcosms. Identification and phenotypic characterization of bacterial isolates revealed clear shifts in the rhizosphere bacterial community composition by the presence of two fungal strains (M. hiemalis BHB1 and T. harzianum PvdG2), whereas another M. hiemalis strain did not show this effect. Presence of both M. hiemalis BHB1 and T. harzianum PvdG2 resulted in a significant increase of chitinolytic and (in vitro) antifungal bacteria. The latter was most pronounced for M. hiemalis BHB1, an isolate from Carex roots, which stimulated the development of the bacterial genera Achromobacter and Stenotrophomonas. In vitro tests showed that these genera were strongly antagonistic against M. hiemalis but also against the plant-pathogenic fungus Rhizoctonia solani. The most likely explanation for fungal-induced shifts in the composition of rhizosphere bacteria is that bacteria are being selected which are successful in competing with fungi for root exudates. Based on the results we propose that measures increasing saprotrophic fungi in agricultural soils should be explored as an alternative approach to enhance natural biocontrol against soil-borne plant-pathogenic fungi, namely by stimulating indigenous antifungal rhizosphere bacteria.

Phylogenetic congruence of parasitic smut fungi (Anthracoidea, Anthracoideaceae) and their host plants (Carex, Cyperaceae): Cospeciation or host-shift speciation?

UNLABELLED: • PREMISE OF THE STUDY: Fahrenholz's rule states that common ancestors of extant parasites were parasites of the common ancestors of extant hosts. Consequently, parasite phylogeny should mirror host phylogeny. The smut fungi genus Anthracoidea (Anthracoideaceae) is mainly hosted by species of the genus Carex (Cyperaceae). Whether smut fungi phylogeny mirrors sedge phylogeny is still under debate.• METHODS: The nuclear large subunit DNA region (LSU; 57 accessions) from 31 Anthracoidea species and the ITS, ETS, and trnL-F spacer-trnL intron complex from 41 Carex species were used to infer the phylogenetic history of parasites and their hosts using a maximum likelihood approach. Event-based and distance-based cophylogenetic methods were used to test the hypothesis of whether the phylogeny of smut fungi from the genus Anthracoidea matches the phylogeny of the sedge Carex species they host.• RESULTS: Cophylogenetic reconstructions taking into account phylogenetic uncertainties based on event-based analyses demonstrated that the Anthracoidea phylogeny has significant topological congruence with the phylogeny of their Carex hosts. A distance-based test was also significant; therefore, the phylogenies of Anthracoide and Carex are partially congruent.• CONCLUSIONS: The phylogenetic congruence of Anthracoidea and Carex is partially based on smut fungi species being preferentially hosted by closely related sedges (host conservatism). In addition, many different events rather than only codivergence events are inferred. All of this evidence suggests that host-shift speciation rather than cospeciation seems to explain the cophylogenetic patterns of Anthracoidea and Carex.

Presence and persistence of wastewater pathogen Escherichia coli O157:H7 in hydroponic reactors of treatment wetland species.

Treatment wetlands (TWs) efficiently remove many pollutants including a several log order reduction of pathogens from influent to effluent; however, there is evidence to suggest that pathogen cells are sequestered in a subsurface wetland and may remain viable months after inoculation. Escherichia coli is a common pathogen in domestic and agricultural wastewater and the O157:H7 strain causes most environmental outbreaks in the United States. To assess attachment of E. coli to the TW rhizosphere, direct measurements of E. coli levels were taken. Experiments were performed in chemostats containing either Teflon nylon as an abiotic control or roots of Carex utriculata or Schoenoplectus acutus. Flow of simulated wastewater through the chemostat was set to maintain a 2 hour residence time. The influent was inoculated with E. coli O157:H7 containing DsRed fluorescent protein. Root samples were excised and analyzed via epifluorescent microscopy. E. coli O157:H7 was detected on the root surface at 2 hours after inoculation, and were visible as single cells. Microcolonies began forming at 24 hours post-inoculation and were detected for up to 1 week post-inoculation. Image analysis determined that the number of microcolonies with >100 cells increased 1 week post-inoculation, confirming that E. coli O157:H7 is capable of growth within biofilms surrounding wetland plant roots.

Methanotrophic and Methanogenic Communities in Swiss Alpine Fens Dominated by Carex rostrata and Eriophorum angustifolium.

Vascular plants play a key role in controlling CH4 emissions from natural wetlands, because they influence CH4 production, oxidation, and transport to the atmosphere. Here we investigated differences in the abundance and composition of methanotrophic and methanogenic communities in three Swiss alpine fens dominated by different vascular plant species under natural conditions. The sampling locations either were situated at geographically distinct sites with different physicochemical properties but the same dominant plant species (Carex rostrata) or were located within the same site, showing comparable physicochemical pore water properties, but had different plant species (C. rostrata or Eriophorum angustifolium). All three locations were permanently submerged and showed high levels of CH4 emissions (80.3 to 184.4 mg CH4 m(-2) day(-1)). Soil samples were collected from three different depths with different pore water CH4 and O2 concentrations and were analyzed for pmoA and mcrA gene and transcript abundance and community composition, as well as soil structure. The dominant plant species appeared to have a significant influence on the composition of the active methanotrophic communities (transcript level), while the methanogenic communities differed significantly only at the gene level. Yet no plant species-specific microbial taxa were discerned. Moreover, for all communities, differences in composition were more pronounced with the site (i.e., with different physicochemical properties) than with the plant species. Moreover, depth significantly influenced the composition of the active methanotrophic communities. Differences in abundance were generally low, and active methanotrophs and methanogens coexisted at all three locations and depths independently of CH4 and O2 concentrations or plant species.

Gynuella sunshinyii gen. nov., sp. nov., an antifungal rhizobacterium isolated from a halophyte, Carex scabrifolia Steud.

An antifungal bacterial strain, designated YC6258(T), was isolated from the rhizosphere of a halophyte (Carex scabrifolia Steud.) growing in a tidal flat area of Namhae Island, Korea. Cells of the strain were Gram-stain-negative, facultatively anaerobic, moderately halophilic, rod-shaped and motile by a single polar flagellum. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain YC6258(T) formed a phyletic lineage distinct from members of the most closely related genera, Saccharospirillum and Reinekea, with less than 91.2 % sequence similarities. The major cellular fatty acids were C18 : 1ω7c, C16 : 0 and Summed feature 3 (C16 : 1ω7c/ C16 : 1ω6c). The quinone system of strain YC6258(T) consisted mainly of ubiquinone Q-8. The polar lipid profile exhibited phosphatidylethanolamine, phosphatidylglycerol, diphosphatidylglycerol and unknown lipids. The DNA G+C content was 48.9 mol%. Based on the phylogenetic and phenotypic characteristics, strain YC6258(T) should be classified as a representative of a novel species in a novel genus for which the name Gynuella sunshinyii gen. nov., sp. nov. is proposed. The type strain is YC6258(T) (KCCM 43015(T) = NBRC 109345(T)).

Contribution of arbuscular mycorrhizal fungi of sedges to soil aggregation along an altitudinal alpine grassland gradient on the Tibetan Plateau.

The diversity of arbuscular mycorrhizal fungi (AMF) in sedges on the Tibetan Plateau remains largely unexplored, and their contribution to soil aggregation can be important in understanding the ecological function of AMF in alpine ecosystems. Roots of Kobresia pygmaea C.B. Clarke and Carex pseudofoetida Kük. in alpine Kobresia pastures along an elevational transect (4149-5033 m) on Mount Mila were analysed for AMF diversity. A structural equation model was built to explore the contribution of biotic factors to soil aggregation. Sedges harboured abundant AMF communities covering seven families and some operational taxonomic units are habitat specific. The two plant species hosted similar AMF communities at most altitudes. The relative abundance of the two sedges contributed largely to soil macroaggregates, followed by extraradical mycorrhizal hyphae (EMH) and total glomalin-related soil protein (T-GRSP). The influence of plant richness was mainly due to its indirect influence on T-GRSP and EMH. There was a strong positive correlation between GRSP and soil total carbon and nitrogen. Our results indicate that mycorrhization might not be a major trait leading to niche differentiation of the two co-occurring sedge species. However, AMF contribute to soil aggregation and thus may have the potential to greatly influence C and N cycling in alpine grasslands.

Degradation kinetics of chlorinated aliphatic hydrocarbons by methane oxidizers naturally-associated with wetland plant roots.

Chlorinated aliphatic hydrocarbons (CAHs) are common groundwater contaminants that can be removed from the environment by natural attenuation processes. CAH biodegradation can occur in wetland environments by reductive dechlorination as well as oxidation pathways. In particular, CAH oxidation may occur in vegetated wetlands, by microorganisms that are naturally associated with the roots of wetland plants. The main objective of this study was to evaluate the cometabolic degradation kinetics of the CAHs, cis-1,2-dichloroethene (cisDCE), trichloroethene (TCE), and 1,1,1-trichloroethane (1,1,1TCA), by methane-oxidizing bacteria associated with the roots of a typical wetland plant in soil-free system. Laboratory microcosms with washed live roots investigated aerobic, cometabolic degradation of CAHs by the root-associated methane-oxidizing bacteria at initial aqueous [CH4] ~1.9mgL(-1), and initial aqueous [CAH] ~150µgL(-1); cisDCE and TCE (in the presence of 1,1,1TCA) degraded significantly, with a removal efficiency of approximately 90% and 46%, respectively. 1,1,1TCA degradation was not observed in the presence of active methane oxidizers. The pseudo first-order degradation rate-constants of TCE and cisDCE were 0.12±0.01 and 0.59±0.07d(-1), respectively, which are comparable to published values. However, their biomass-normalized degradation rate constants obtained in this study were significantly smaller than pure-culture studies, yet they were comparable to values reported for biofilm systems. The study suggests that CAH removal in wetland plant roots may be comparable to processes within biofilms. This has led us to speculate that the active biomass may be on the root surface as a biofilm. The cisDCE and TCE mass losses due to methane oxidizers in this study offer insight into the role of shallow, vegetated wetlands as an environmental sink for such xenobiotic compounds.

Fe and P solubilization under limiting conditions by bacteria isolated from Carex kobomugi roots at the Hasaki coast.

Our objective was simply to report a sedge species, Carex kobomugi Ohwi that has beneficial bacterial associations under low Fe and P conditions of the Hasaki coast, Japan. C. kobomugi is the dominant species in our study area and grows closest to the sea. C. kobomugi showed higher Fe and P content, while these nutrients were less available under alkaline root-zone soil. Within the roots, mycorrhizal fungal colonization was absent, and endophytic fungal colonization was low. On the contrary, endophytic bacteria (e.g. Bacillus sp., Streptomyces luteogriseus, and Pseudomonas fluorescens) were isolated, which exhibited both siderophore production and inorganic phosphate solubilization under Fe or P limited conditions. Our results suggest that colonization of root tissue by these bacteria contribute to the Fe and P uptakes by C. kobomugi by increasing availability in the soil.

Anthracoidea caricis-meadii is a new North American smut fungus on Carex sect. Paniceae.

The morphology and phylogeny of Anthracoidea on Carex meadii (sect. Paniceae) collected in Illinois, Iowa, Wisconsin, USA, were studied by light microscopy, scanning electron microscopy and LSU rDNA sequence analyses. As a result A. caricis-meadii sp. nov. is described. The fungus differs morphologically from Anthracoidea laxae and A. paniceae, which also occur on sedges from the section Paniceae. Molecular analyses support the placement of the latter species and Anthracoidea caricis-meadii in different phylogenetic lineages. Because of morphological discrepancies in the literature, A. laxae and A. paniceae also are described and illustrated based on re-examination of respective holotype and isotype specimens.

Two new Tricladium species from streams in Alaska.

Two new species of aquatic hyphomycetes in the genus Tricladium are described from streams in Alaska, USA. Both species were isolated from submerged decaying sedges. Tricladium kelleri has blackish colonies and typical tricladioid conidia formed on sympodial conidiogenous cells. Tricladium alaskense has conidia with fine elements and 0-4 lateral branches; conidia are formed on sympodial conidiogenous cells. The two species are compared to other species in the genus and related genera using morphological characters and/or rDNA sequencing data (ITS and 28S). Molecular phylogenetic analysis placed both species in the Helotiales.

Description of Herbiconiux flava sp. nov. and emended description of the genus Herbiconiux.

A non-motile and non-endospore-forming rod, strain NBRC 16403T, was isolated from the phyllosphere of a sedge (Carex sp.). 16S rRNA gene sequence analysis indicated that strain NBRC 16403T was closely related to Herbiconiux solani DSM 19813T (98.6 % 16S rRNA gene sequence similarity), Herbiconiux ginsengi wged11T (97.8 %) and Herbiconiux moechotypicola RB-62T (97.8 %). The peptidoglycan (B2γ type) contained D- and l-2,4-diaminobutyric acids, d-alanine, glycine and threo-3-hydroxyglutamic acid, which replaced glutamic acid almost completely. The predominant menaquinones were MK-10 and MK-11. The polar lipid pattern comprised diphosphatidylglycerol, phosphatidylglycerol, three glycolipids and minor amounts of other polar lipids. The major fatty acids were anteiso-C15:0, iso-C16:0 and anteiso-C17:0; no cyclohexyl-C17:0 was detected. The DNA G+C content was 71.0 mol%. The results of phylogenetic and DNA-DNA relatedness studies, along with phenotypic differences between strain NBRC 16403T and recognized members of the genus Herbiconiux, indicated that the isolate should be assigned to a novel species of the genus Herbiconiux, for which the name Herbiconiux flava sp. nov. is proposed. The type strain is NBRC 16403T (=VKM Ac-2058T).

Aerobic cometabolic degradation of trichloroethene by methane and ammonia oxidizing microorganisms naturally associated with Carex comosa roots.

The degradation potential of trichloroethene by the aerobic methane- and ammonia-oxidizing microorganisms naturally associated with wetland plant (Carex comosa) roots was examined in this study. In bench-scale microcosm experiments with washed (soil free) Carex comosa roots, the activity of root-associated methane- and ammonia-oxidizing microorganisms, which were naturally present on the root surface and/or embedded within the roots, was investigated. Significant methane and ammonia oxidation were observed reproducibly in batch reactors with washed roots incubated in growth media, where methane oxidation developed faster (2 weeks) compared to ammonia oxidation (4 weeks) in live microcosms. After enrichment, the methane oxidizers demonstrated their ability to degrade 150 µg l(-1) TCE effectively at 1.9 mg l(-1) of aqueous CH(4). In contrast, ammonia oxidizers showed a rapid and complete inhibition of ammonia oxidation with 150 µg l(-1) TCE at 20 mg l(-1) of NH(4)(+)-N, which may be attributed to greater sensitivity of ammonia oxidizers to TCE or its degradation product. No such inhibitory effect of TCE degradation was detected on methane oxidation at the above experimental conditions. The results presented here suggest that microorganisms associated with wetland plant roots can assist in the natural attenuation of TCE in contaminated aquatic environments.

Characterization, synthesis and self-aggregation of (-)-alternarlactam: a new fungal cytotoxin with cyclopentenone and isoquinolinone scaffolds.

(-)-Alternarlactam [(-)-1], a new promising cytotoxin against two human cancer cell lines, was isolated from an endophyte culture and synthesized (along with (+)-1) from readily available starting materials. The absolute configuration, chirality-activity relevance and self-aggregation of (-)-1 were assigned by a combination of synthetic, spectroscopic and computational approaches. The full characterization of the new fungal cytotoxin may provide valuable information in the discovery of new antitumor agents.