Comparative genome analysis of rice-pathogenic Burkholderia provides insight into capacity to adapt to different environments and hosts

Background

In addition to human and animal diseases, bacteria of the genus Burkholderia can cause plant diseases. The representative species of rice-pathogenic Burkholderia are Burkholderia glumae, B. gladioli, and B. plantarii, which primarily cause grain rot, sheath rot, and seedling blight, respectively, resulting in severe reductions in rice production. Though Burkholderia rice pathogens cause problems in rice-growing countries, comprehensive studies of these rice-pathogenic species aiming to control Burkholderia-mediated diseases are only in the early stages.

Results

We first sequenced the complete genome of B. plantarii ATCC 43733^T. Second, we conducted comparative analysis of the newly sequenced B. plantarii ATCC 43733^T genome with eleven complete or draft genomes of B. glumae and B. gladioli strains. Furthermore, we compared the genome of three rice Burkholderia pathogens with those of other Burkholderia species such as those found in environmental habitats and those known as animal/human pathogens. These B. glumae, B. gladioli, and B. plantarii strains have unique genes involved in toxoflavin or tropolone toxin production and the clustered regularly interspaced short palindromic repeats (CRISPR)-mediated bacterial immune system. Although the genome of B. plantarii ATCC 43733^T has many common features with those of B. glumae and B. gladioli, this B. plantarii strain has several unique features, including quorum sensing and CRISPR/CRISPR-associated protein (Cas) systems.

Conclusions

The complete genome sequence of B. plantarii ATCC 43733^T and publicly available genomes of B. glumae BGR1 and B. gladioli BSR3 enabled comprehensive comparative genome analyses among three rice-pathogenic Burkholderia species responsible for tissue rotting and seedling blight. Our results suggest that B. glumae has evolved rapidly, or has undergone rapid genome rearrangements or deletions, in response to the hosts. It also, clarifies the unique features of rice pathogenic Burkholderia species relative to other animal and human Burkholderia species.

Electronic supplementary material

The online version of this article (doi:10.1186/s12864-015-1558-5) contains supplementary material, which is available to authorized users.     

Suppression of Inflammatory Cytokine Production by ar‐Turmerone Isolated from Curcuma phaeocaulis

Rhizomes of Curcuma phaeocaulis Valeton (Zingiberaceae) have traditionally been used for controlling inflammatory conditions. Numerous studies have aimed to isolate and characterize the bioactive constituents of C. phaeocaulis. It has been reported that its anti‐inflammatory properties are a result of cyclooxygenase‐2 inhibition; however, its effect on the T‐cell function remains to be elucidated. In this study, four known sesquiterpenoids, viz., ar‐turmerone (TM), germacrone (GM), (+)‐(4S,5S)‐germacrone‐4,5‐epoxide (GE), and curzerenone (CZ), were isolated from C. phaeocaulis rhizomes and evaluated for their effects on the CD4⁺ T‐cell function. While GM, GE, and CZ had no effect on the activation of splenic T cells or CD4⁺ T cells, TM suppressed the interferon (IFN)‐γ production, without affecting the interleukin (IL)‐4 expression. TM also decreased the expression of IL‐2 in CD4⁺ T cells, but did not change their cell‐division rates upon stimulation. These results suggest that TM, a major constituent of C. phaeocaulis rhizomes selectively exerts potent anti‐inflammatory effects via suppression of the inflammatory cytokines IFN‐γ and IL‐2.     

Understanding the Degradation Mechanisms of LiNi0.5Co0.2Mn0.3O2 Cathode Material in Lithium Ion Batteries

LiNi_xCo_yMn_zO₂ (NCM, 0 ≤ x,y,z < 1) has become one of the most important cathode materials for next‐generation lithium (Li) ion batteries due to its high capacity and cost effectiveness compared with LiCoO₂. However, the high‐voltage operation of NCM (>4.3 V) required for high capacity is inevitably accompanied by a more rapid capacity fade over numerous cycles. Here, the degradation mechanisms of LiNi_0.5Co_0.2Mn_0.3O₂ are investigated during cycling under various cutoff voltage conditions. The surface lattice structures of LiNi_0.5Co_0.2Mn_0.3O₂ are observed to suffer from an irreversible transformation; the type of transformation depends on the cutoff voltage conditions. The surface of the pristine rhombohedral phase tends to transform into a mixture of spinel and rock salt phases. Moreover, the formation of the rock salt phase is more dominant under a higher voltage operation (≈4.8 V), which is attributable to the highly oxidative environment that triggers the oxygen loss from the surface of the material. The presence of the ionically insulating rock salt phase may result in sluggish kinetics, thus deteriorating the capacity retention. This implies that the prevention of surface structural degradation can provide the means to produce and retain high capacity, as well as stabilize the cycle life of LiNi_0.5Co_0.2Mn_0.3O₂ during high‐voltage operations.     

Purification of a novel nitric oxide inhibitory peptide derived from enzymatic hydrolysates of Mytilus coruscus

Shellfish contain significant levels of high quality protein and are therefore a potential source for biofunctional high-value peptides. To purify a novel anti-inflammatory peptide from Mytilus coruscus (M. coruscus), we applied enzymatic hydrolysis and tangential flow filtration (TFF) and investigated its nitric oxide inhibitory property. To prepare the peptide, eight proteases were employed for enzymatic hydrolysis. Flavouzyme hydrolysates, which showed clearly superior nitric oxide inhibitory activity on lipopolysaccharide (LPS)-stimulated RAW264.7, were further purified using a TFF system and consecutive chromatographic methods. Finally, a novel anti-inflammatory peptide composed of 10 amino acid residues was obtained, and the sequence was identified as Gly-Val-Ser-Leu-Leu-Gln-Gln-Phe-Phe-Leu at N-terminal position. The peptide from M. coruscus effectively inhibited nitric oxide production on macrophage cells. This is the first report of an anti-inflammatory peptide derived from the hydrolysates of M. coruscus.