Plant growth and arbuscular mycorrhizae development in oil sands processing by-products.

Soil pollutants such as hydrocarbons can induce toxic effects in plants and associated arbuscular mycorrhizal fungi (AMF). This study was conducted to evaluate if the legume Lotus corniculatus and the grass Elymus trachycaulus and arbuscular mycorrhizal fungi could grow in two oil sands processing by-products after bitumen extraction from the oil sands in northern Alberta, Canada. Substrate treatments were coarse tailings sand (CTS), a mix of dry mature fine tailings (MFT) with CTS (1:1) and Pleistocene sandy soil (hydrocarbon free); microbial treatments were without AMF, with AMF and AMF plus soil bacteria isolated from oil sands reclamation sites. Plant biomass, root morphology, leaf water content, shoot tissue phosphorus content and mycorrhizal colonization were evaluated. Both plant species had reduced growth in CTS and tailings mix relative to sandy soil. AMF frequency and intensity in roots of E. trachycaulus was not influenced by soil hydrocarbons; however, it decreased significantly over time in roots of L. corniculatus without bacteria in CTS. Mycorrhizal inoculation alone did not significantly improve plant growth in CTS and tailings mix; however, inoculation with mycorrhizae plus bacteria led to a significantly positive response of both plant species in CTS. Thus, combined inoculation with selected mycorrhizae and bacteria led to synergistic effects. Such combinations may be used in future to improve plant growth in reclamation of CTS and tailings mix.

Effects of cadmium stress on seed germination and seedling growth of Elymus dahuricus infected with the Neotyphodium endophyte.

Various cadmium (Cd) concentrations (0, 50, 100, 200 and 300 µmol L(-1)) affected Elymus dahuricus seed germination, seedling growth, antioxidative enzymes activities (AEA), and amounts of malondialdehyde (MDA) and proline present. These influences were determined for separate E. dahuricus cohorts known to be either infected (E+) or non-infected (E-) by a Neotyphodium endophyte. Under high Cd concentrations (100, 200 and 300 µmol L(-1)), E+ specimens showed a significantly (P<0.05) higher germination rate and index, as well as higher values for shoot length, root length and dry biomass. However, the germination rate and index, root length and dry weight did not show a significant (P<0.05) difference under the low Cd concentrations (0 and 50 µmol L(-1)). AEA and proline content increased, as did MDA content, in the E+ (vs. E-) specimens under high Cd concentrations. There was no significant (P>0.05) difference under low Cd concentrations. Endophyte infection was concluded to be of benefit to E. dahuricus exposed to high Cd concentrations.

Bacillus graminis sp. nov., an endophyte isolated from a coastal dune plant.

A Gram-stain-positive endophytic bacterium, designated strain YC6957(T), was isolated from surface-sterilized roots of a halophyte (Elymus mollis Trin.) inhabiting coastal tidal flats of Namhae Island, located on the southern coast of Korea, and was subjected to a polyphasic taxonomic study. Cells were facultatively anaerobic, endospore-forming rods to coccoid rods, motile by a single flagellum. Strain YC6957(T) was catalase-positive, oxidase-negative and able to grow in the presence of 0-8 % (w/v) NaCl, with optimum growth at 4-5 % (w/v) NaCl. Growth occurred at 15-45 °C (optimal growth at 30-35 °C) and pH 6.0-8.5 (optimal growth at pH 7.0-8.0). The predominant isoprenoid quinone was menaquinone 7 (MK-7). The major cellular fatty acids were C(16 : 0) (11.3 %), iso-C(15 : 0) (19.2 %) and anteiso-C(15 : 0) (36.4 %). The cell-wall peptidoglycan contained meso-diaminopimelic acid. The major polar lipids were diphosphatidylglycerol, phosphatidylglycerol and phosphatidylethanolamine. The DNA G+C content was 41.6 mol%. Phylogenetic analysis based on the 16S rRNA gene sequence revealed that the isolate belonged to the genus Bacillus. Strain YC6957(T) exhibited high 16S rRNA gene sequence similarity to its closest neighbours, Bacillus ruris LMG 22866(T) (96.14 %), Bacillus lentus NCIMB 8773(T) (95.97 %) and Bacillus galactosidilyticus LMG 17892(T) (95.91 %), and less than 95.84 % similarity to all other type strains in the genus Bacillus. On the basis of the phylogenetic, physiological and biochemical data, it is suggested that strain YC6957(T) represents a novel species of the genus Bacillus, for which the name Bacillus graminis sp. nov. is proposed. The type strain is YC6957(T) ( = KACC 13779(T)  = DSM 22162(T)).

Chryseobacterium soldanellicola sp. nov. and Chryseobacterium taeanense sp. nov., isolated from roots of sand-dune plants.

Two Gram-negative, yellow-pigmented bacteria designated PSD1-4T and PHA3-4T, isolated from two sand-dune plant species inhabiting coastal areas in Tae-an, Korea, were subjected to taxonomic investigation. 16S rRNA gene sequence analysis indicated that both isolates should be placed in the genus Chryseobacterium of the family Flavobacteriaceae. The phenotypic properties of the strains were also consistent with their classification into this genus. The levels of 16S rRNA gene sequence similarity between strain PSD1-4T and other Chryseobacterium species were 95.2-97.2%; those between PHA3-4T and others were 93.7-97.8%. The DNA-DNA relatedness data indicated that strains PSD1-4T and PHA3-4T were clearly different from the nearest species, Chryseobacterium indoltheticum and Chryseobacterium taichungense. The major fatty acids were 13-methyltetradecanoic acid (iso-C15:0), 3-hydroxy-15-methylhexadecanoic acid (iso-C17:0 3-OH) and omega-9-cis-15-methylhexadecenoic acid (iso-C17:1omega9c) for both strains. On the basis of polyphasic taxonomic analysis results, it is evident that each of these strains represents a novel species of Chryseobacterium, for which the names Chryseobacterium soldanellicola sp. nov. (type strain PSD1-4T=KCTC 12382T=NBRC 100864T) and Chryseobacterium taeanense sp. nov. (type strain PHA3-4T=KCTC 12381T=NBRC 100863T) are proposed.