Paenibacillus brasilensis sp nov., a novel nitrogen-fixing species isolated from the maize rhizosphere in Brazil

Sixteen nitrogen-fixing strains isolated from the rhizosphere of maize planted in Cerrado soil, Brazil, which showed morphological and biochemical characteristics similar to the gas-forming Paenibacillus spp., were phenotypically and genetically characterized. Their identification as members of the genus Paenibacillus was confirmed by using specific primers based on the 16S rRNA gene. SDS-PAGE of whole-cell proteins, API 50CH, morphological and biochemical tests, amplified rDNA-restriction analysis (ARDRA), DNA-relatedness analyses, denaturing-gradient gel electrophoresis (DGGE) and 16S rRNA gene sequence determinations were performed to characterize the novel isolates and to compare them to strains of other nitrogen-fixing Paenibacillus spp. Phenotypic analyses showed that the 16 strains were very homogeneous and shared a high level of relatedness with Paenibacillus polymyxa and Paenibacillus peoriae. However, none of the novel isolates was able to ferment glycerol (positive test for P. polymyxa), L-arabinose or D-xylose (positive tests for P. polymyxa and P. peoriae) or utilize succinate (positive test for P. peoriae). Genetic approaches also indicated a high level of similarity among the novel isolates and P. polymyxa and P. peoriae, but the novel strains clearly could not be assigned to either of these two recognized species. On the basis of the features presented in this study, the 16 novel isolates were considered to represent members of a novel species within the genus Paenibacillus, for which the name Paenibacillus brasilensis is proposed. The type strain is PB172(T) (=ATCC BAA-413(T)=DSM 14914(T)

Biochemical and molecular characterisation of the bacterial endophytes from native sugarcane varieties of Himalayan region

Seven endophytic bacterial isolates were finally recovered from native sugarcane varieties at hilly areas namely Berinag, Champawat and Didihat of Uttarakhand state in northern Himalayan region. New isolates and two standard cultures—Azospirillum brasilense and Gluconacetobacter diazotrophicus, were evaluated for their morphological, biochemical and molecular characteristics. Morphologically all were rod shaped, Gram-negative bacteria. Their plant growth promotory properties were also assessed which proved isolates RtBn and StBn as IAA producing. Except isolate StBn, all were phosphate solubilising and except RtBn all produced siderophores. Molecular characterisation of the isolates was performed using amplified 16S r-DNA restriction analysis. Similarity index in unweighted pair group method with arithmetic mean programme clustered the isolates according to their geographical distribution. Native isolates showed insignificant similarity with South American strains used as standards. nifH amplification was observed with all the isolates used in the study which again establish them as potential N-fixers

Dinitrogen-Fixing Cyanobacteria in Microbial Mats of Two Shallow Coral Reef Ecosystems

Dinitrogen-fixing organisms in cyanobacterial mats were studied in two shallow coral reef ecosystems: La Reunion Island, southwestern Indian Ocean, Sesoko (Okinawa) Island, and northwestern Pacific Ocean. Rapidly expanding benthic miniblooms, frequently dominated by a single cyanobacterial taxon, were identified by microscopy and molecular tools. In addition, nitrogenase activity by these blooms was measured in situ. Dinitrogen fixation and its contribution to mat primary production were calculated using 15N2 and 13C methods. Dinitrogen-fixing cyanobacteria from mats in La Reunion and Sesoko showed few differences in taxonomic composition. Anabaena sp. among heterocystous and Hydrocoleum majus and Symploca hydnoides among nonheterocystous cyanobacteria occurred in microbial mats of both sites. Oscillatoria bonnemaisonii and Leptolyngbya spp. occurred only in La Reunion, whereas Hydrocoleum coccineum dominated in Sesoko. Other mats dominated by Hydrocoleum lyngbyaceum, Phormidium laysanense, and Trichocoleus tenerrimus occurred at lower frequencies. The 24-h nitrogenase activity, as measured by acetylene reduction, varied between 11 and 324 nmoles C2H2 reduced µg−1 Chl a. The highest values were achieved by heterocystous Anabaena sp. performed mostly during the day. Highest values for nonheterocystous cyanobacteria were achieved by H. coccineum mostly during the night. Daily nitrogen fixation varied from nine (Leptolyngbya) to 238 nmoles N2µg−1 Chl day−1 (H. coccineum). Primary production rates ranged from 1,321 (S. hydnoides) to 9,933 nmoles C µg−1 Chl day−1 (H. coccineum). Dinitrogen fixation satisfied between 5% and 21% of the nitrogen required for primary production.Ocean Development Sub-Committee of France–Japan S&T Cooperation; Mitsubishi cooperation; The Ministry of Education, Science, Sport, and Culture of Japan; Hanse Wissenschaftskolleg; Delmenhorst and Alexander-von-Humboldt Foundation; Bad Godesberg; Germany supported collaborative research on cyanobacterial diversit

Distance 2-domination in prisms of graphs

A set of vertices D of a graph G is a distance 2-dominating set of G if the distance between each vertex u ¿ ( V ( G ) - D ) and D is at most two. Let ¿ 2 ( G ) denote the size of a smallest distance 2 -dominating set of G . For any permutation p of the vertex set of G , the prism of G with respect to p is the graph pG obtained from G and a copy G ' of G by joining u ¿ V ( G ) with v ' ¿ V ( G ' ) if and only if v ' = p ( u ) . If ¿ 2 ( pG ) = ¿ 2 ( G ) for any permutation p of V ( G ) , then G is called a universal ¿ 2 - fixer. In this work we characterize the cycles and paths that are universal ¿ 2 -fixers.Peer ReviewedPostprint (author's final draft

Explaining essences

This paper explores the prospects of combining two views. The first view is metaphysical rationalism : all things have an explanation. The second view is metaphysical essentialism: there are real essences. The exploration is motivated by a conflict between the views. Metaphysical essentialism posits facts about essences. Metaphysical rationalism demands explanations for all facts. But facts about essences appear to resist explanation. I consider two solutions to the conflict. Exemption solutions attempt to exempt facts about essences from the demand for explanation. Explanation solutions attempt to explain facts about essences. I argue that exemption solutions are less promising than explanation solutions. I then consider how explanation solutions might be developed. I suggest that a “generative” approach is most promising. I tentatively conclude that the prospects for combining metaphysical rationalism and metaphysical essentialism turn on the viability of a generative approach. This sets the agenda for defending the combination as well as the more general project of explaining essences

Selection and evaluation of Bradyrhizobium inoculum for peanut, Arachis hypogea production in the Lao People’s Democratic Republic

The interaction between leguminous plants and Bradyrhizobium is limited, known as host specificity. Therefore, the selection of an appropriate Bradyrhizobia for use as biofertilizer inoculum for legumes is necessary. The Arachis hypogea L. is the most popular legume produced in the Lao People's Democratic Republic (PDR). Therefore, this research aimed to obtain the appropriate Bradyrhizobia that provides high efficiency in A. hypogea production in the Lao PDR. The 14 isolates were obtained from root nodules of A. hypogea L. trapped with Lao PDR soil samples. Three were the top isolates PMVTL-01, SMVTL-02, and BLXBL-03 showing high efficiency for peanut growth promotion. Strains PMVTL-01 and SMVTL-02 were closely related to the Bradyrhizobium geno sp. SA-3 Rp7b and B. zhanjiangense, respectively, whilst strain BLXBL-03 was closely related to Bradyrhizobium sp. CCBAU51745 and B. manausense BR3351. The competitiveness of these strains with Bradyrhizobium sp. SUTN9-2::GFP was analyzed, and only Bradyrhizobium sp. SMVTL-02 performed a number of occupied nodules higher than SUTN9-2::GFP. In addition, the competitiveness of the selected strain Bradyrhizobium sp. SMVTL-02 in a soil sample from the Lao PDR in the pot level was employed by tagging the SMVTL-02 with the DsRed gene. The results demonstrated that the DsRed-expressing tagged strain showed higher nodule occupancy than indigenous strains. Moreover, the results of the acetylene reduction assay (ARA), nodule number, nodule dry weight, and total plant dry weight from the pot experiment that inoculated with the SMVTL-02::DsRed were presented as having high potential to promote peanut growth as compared to non-inoculation. Thus, Bradyrhizobium sp. SMVTL-02 could be considered a potential biofertilizer inoculum for A. hypogea production in the Lao PDR

Market Share and Exchange Rate Pass-through:Competition among Exporters of the Same Nationality

Using a sample from January 1988 to December 2005 for exports of five Japanese major ports to six destination countries, we examine the effect of market share (with respect to competitors from the same country) on exchange rate pass-through (henceforth, ERPT). Our dataset is unique, allowing us to control for market shares among competing exporters with the same nationality. We provide empirical evidence that the effect of market shares on exchange rate pass-through is consistent with the findings of Feenstra et al. (1996), who show a non-linear relationship between market share and exchange rate pass-through. However, our evidence also indicates that the relationship between market share and exchange rate sensitively relies on market characteristics. With regard to recent studies on declining ERPT, our evidence shows that the ERPTs of Japanese exports are relatively stable over the last two decades and any observed changes are of small magnitude. Especially for the U.S., our evidence indicates that Japanese exports do not account for the recent decline in ERPT of U.S. imports.Exchange rate pass-through; Local ports; Market share