Shewanella phaeophyticola sp. nov. and Vibrio algarum sp. nov., isolated from marine brown algae.

Two Gram-stain-negative, rod-shaped bacteria, designated as strains KJ10-1T and KJ40-1T, were isolated from marine brown algae. Both strains were catalase-positive, oxidase-positive, and facultative aerobic. Strain KJ10-1T exhibited optimal growth at 25 °C, pH 7.0, and 3 % NaCl, whereas strain KJ40-1T showed optimal growth at 25 °C, pH 7.0, and 2 % NaCl. The respiratory quinones of strain KJ10-1T were ubiquinone-8, ubiquinone-7, menaquinone-7, and methylated menaquinone-7, while the respiratory quinone of strain KJ40-1T was only ubiquinone-8. As major fatty acids, strain KJ10-1T contained C16 : 0, C17 : 1 ω8c, iso-C15 : 0, and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) and strain KJ40-1T contained C16 : 0 and summed features 3 and 8 (C18 : 1 ω7c and/or C18 : 1 ω6c). The major polar lipids in strain KJ10-1T were phosphatidylethanolamine, phosphatidylglycerol, and an unidentified aminolipid, whereas those in strain KJ40-1T were phosphatidylethanolamine, phosphatidylglycerol, and diphosphatidylglycerol. The DNA G+C contents of strains KJ10-1T and KJ40-1T were 42.1 and 40.8 mol%, respectively. Based on 16S rRNA gene sequences, strains KJ10-1T and KJ40-1T exhibited the closest relatedness to Shewanella saliphila MMS16-UL250T (98.6 %) and Vibrio rumoiensis S-1T (95.4 %), respectively. Phylogenetic analyses, based on both 16S rRNA and 92 housekeeping genes, showed that the strains formed distinct phylogenic lineages within the genera Shewanella and Vibrio. Digital DNA-DNA hybridization and orthologous average nucleotide identity values between strain KJ10-1T and other Shewanella species, as well as between strain KJ40-1T and other Vibrio species, were below the thresholds commonly accepted for prokaryotic species delineation. Based on the phenotypic, chemotaxonomic, and phylogenetic data, strains KJ10-1T and KJ40-1T represent novel species of the genera Shewanella and Vibrio, respectively, for which the names Shewanella phaeophyticola sp. nov. and Vibrio algarum sp. nov. are proposed, respectively. The type strains of S. phaeophyticola and V. algarum are KJ10-1T (=KACC 22589T=JCM 35409T) and KJ40-1T (=KACC 22588T=JCM 35410T), respectively.

Sustainable control of Microcystis aeruginosa, a harmful cyanobacterium, using Selaginella tamariscina extracts.

Eco-friendly reagents derived from plants represent a promising strategy to mitigate the occurrence of toxic cyanobacterial blooms. The use of an amentoflavone-containing Selaginella tamariscina extract (STE) markedly decreased the number of Microcystis aeruginosa cells, thus demonstrating significant anti-cyanobacterial activity. In particular, the Microcystis-killing fraction obtained from pulverized S. tamariscina using hot-water-based extraction at temperatures of 40 °C induced cell disruption in both axenic and xenic M. aeruginosa. Liquid chromatographic analysis was also conducted to measure the concentration of amentoflavone in the STE, thus supporting the potential M. aeruginosa-specific killing effects of STE. Bacterial community analysis revealed that STE treatment led to a reduction in the relative abundance of Microcystis species while also increasing the 16S rRNA gene copy number in both xenic M. aeruginosa NIBR18 and cyanobacterial bloom samples isolated from a freshwater environment. Subsequent testing on bacteria, cyanobacteria, and algae isolated from freshwater revealed that STE was not toxic for other taxa. Furthermore, ecotoxicology assessment involving Aliivibrio fischeri, Daphnia magna, and Danio rerio found that high STE doses immobilized D. magna but did not impact the other organisms, while there was no change in the water quality. Overall, due to its effective Microcystis-killing capability and low ecotoxicity, aqueous STE represents a promising practical alternative for the management of Microcystis blooms.

Biological and Chemical Approaches for Controlling Harmful Microcystis Blooms.

The proliferation of harmful cyanobacterial blooms dominated by Microcystis aeruginosa has become an increasingly serious problem in freshwater ecosystems due to climate change and eutrophication. Microcystis-blooms in freshwater generate compounds with unpleasant odors, reduce the levels of dissolved O2, and excrete microcystins into aquatic ecosystems, potentially harming various organisms, including humans. Various chemical and biological approaches have thus been developed to mitigate the impact of the blooms, though issues such as secondary pollution and high economic costs have not been adequately addressed. Red clays and H2O2 are conventional treatment methods that have been employed worldwide for the mitigation of the blooms, while novel approaches, such as the use of plant or microbial metabolites and antagonistic bacteria, have also recently been proposed. Many of these methods rely on the generation of reactive oxygen species, the inhibition of photosynthesis, and/or the disruption of cellular membranes as their mechanisms of action, which may also negatively impact other freshwater microbiota. Nevertheless, the underlying molecular mechanisms of anticyanobacterial chemicals and antagonistic bacteria remain unclear. This review thus discusses both conventional and innovative approaches for the management of M. aeruginosa in freshwater bodies.

Lineage-specific evolution of Aquibium, a close relative of Mesorhizobium, during habitat adaptation.

The novel genus Aquibium that lacks nitrogenase was recently reclassified from the Mesorhizobium genus. The genomes of Aquibium species isolated from water were smaller and had higher GC contents than those of Mesorhizobium species. Six Mesorhizobium species lacking nitrogenase were found to exhibit low similarity in the average nucleotide identity values to the other 24 Mesorhizobium species. Therefore, they were classified as the non-N2-fixing Mesorhizobium lineage (N-ML), an evolutionary intermediate species. The results of our phylogenomic analyses and the loss of Rhizobiales-specific fur/mur indicated that Mesorhizobium species may have evolved from Aquibium species through an ecological transition. Halotolerant and alkali-resistant Aquibium and Mesorhizobium microcysteis belonging to N-ML possessed many tripartite ATP-independent periplasmic transporter and sodium/proton antiporter subunits composed of seven genes (mrpABCDEFG). These genes were not present in the N2-fixing Mesorhizobium lineage (ML), suggesting that genes acquired for adaptation to highly saline and alkaline environments were lost during the evolution of ML as the habitat changed to soil. Land-to-water habitat changes in Aquibium species, close relatives of Mesorhizobium species, could have influenced their genomic evolution by the gain and loss of genes. Our study indicated that lineage-specific evolution could have played a significant role in shaping their genome architecture and conferring their ability to thrive in different habitats.IMPORTANCEPhylogenetic analyses revealed that the Aquibium lineage (AL) and non-N2-fixing Mesorhizobium lineage (N-ML) were monophyletically grouped into distinct clusters separate from the N2-fixing Mesorhizobium lineage (ML). The N-ML, an evolutionary intermediate species having characteristics of both ancestral and descendant species, could provide a genomic snapshot of the genetic changes that occur during adaptation. Genomic analyses of AL, N-ML, and ML revealed that changes in the levels of genes related to transporters, chemotaxis, and nitrogen fixation likely reflect adaptations to different environmental conditions. Our study sheds light on the complex and dynamic nature of the evolution of rhizobia in response to changes in their environment and highlights the crucial role of genomic analysis in understanding these processes.

Pleiotropic effects of N-acylhomoserine lactone synthase ExpI on virulence, competition, and transmission in Pectobacterium carotovorum subsp. carotovorum Pcc21.

BACKGROUND: Pectobacterium species are necrotrophic phytopathogenic bacteria that cause soft rot disease in economically important crops. The successful infection of host plants relies on interactions among virulence factors, competition, and transmission within hosts. Pectobacteria primarily produce and secrete plant cell-wall degrading enzymes (PCWDEs) for virulence. The regulation of PCWDEs is controlled by quorum sensing (QS). Thus, the QS system is crucial for disease development in pectobacteria through PCWDEs. RESULTS: In this study, we identified a Tn-insertion mutant, M2, in the expI gene from a transposon mutant library of P. carotovorum subsp. carotovorum Pcc21 (hereafter Pcc21). The mutant exhibited reduced production and secretion of PCWDEs, impaired flagellar motility, and increased sensitivity to hydrogen peroxide, resulting in attenuated soft rot symptoms in cabbage and potato tubers. Transcriptomic analysis revealed the down-regulation of genes involved in the production and secretion in the mutant, consistent with the observed phenotype. Furthermore, the Pcc21 wild-type transiently colonized in the gut of Drosophila melanogaster within 12 h after feeding, while the mutant compromised colonization phenotype. Interestingly, Pcc21 produces a bacteriocin, carocin D, to compete with other bacteria. The mutant exhibited up-regulation of carocin D-encoding genes (caroDK) and inhibited the growth of a closely related bacterium, P. wasabiae. CONCLUSION: Our results demonstrated the significance of ExpI in the overall pathogenic lifestyle of Pcc21, including virulence, competition, and colonization in plant and insect hosts. These findings suggest that disease outcome is a result of complex interactions mediated by ExpI across multiple steps. © 2023 Society of Chemical Industry.

Psychroserpens ponticola sp. nov. and Marinomonas maritima sp. nov., isolated from seawater.

Two Gram-stain-negative, catalase- and oxidase-positive, aerobic non-motile and motile rod bacteria, strains MSW6T and RSW2T, were isolated from surface seawater. Strain MSW6T optimally grew at 20 °C, pH 7.0 and 3 % NaCl, while strain RSW2T optimally grew at 25 °C, pH 7.0-8.0 and 2 % NaCl. Strain MSW6T possessed menaquinone-6 as the major respiratory quinone, and its major fatty acids were iso-C15 : 1 G, iso-C15 : 0 and iso-C15 : 0 3-OH. The major polar lipid identified in strain MSW6T was phosphatidylethanolamine (PE). On the other hand, strain RSW2T had ubiquinone-8 as the predominant respiratory quinone, and its major fatty acids consisted of summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), summed feature 8 (C18 : 1 ω7c and/or C18 : 1 ω6c) and C16 : 0. The major polar lipids identified in strain RSW2T were PE and phosphatidylglycerol. As the sole respiratory quinone, strain MSW6T possessed menaquinone-6, while strain RSW2T had ubiquinone-8. The DNA G+C contents of strains MSW6T and RSW2T were 31.9 and 43.4 mol%, respectively. Phylogenetic analyses based on 16S rRNA and core gene sequences showed that strain MSW6T formed a phylogenic lineage with Psychroserpens mesophilus KOPRI 13649T, while strain RSW2T formed a phylogenic lineage with Marinomonas primoryensis KMM 3633T. Strain MSW6T shared 97.9 % 16S rRNA gene sequence similarity and 80.7 % average nucleotide identity (ANI) ith P. mesophilus KOPRI 13649T, and strain RSW2T shared 99.1 % 16S rRNA gene sequence similarity and 93.1 % ANI with M. primoryensis KMM 3633T. Based on the results of phenotypic, chemotaxonomic and phylogenetic analyses, strains MSW6T and RSW2T represent novel species of the genera Psychroserpens and Marinomonas, respectively, for which the names Psychroserpens ponticola sp. nov. and Marinomonas maritima sp. nov. are proposed, respectively. The type strain of P. ponticola is MSW6T (=KACC 22338T=JCM 35022T) and the type strain of M. maritima is RSW2T (=KACC 22716T=JCM 35550T).

Multimodality Imaging of Aortic Valve Calcification and Function in a Murine Model of Calcific Aortic Valve Disease and Bicuspid Aortic Valve.

Calcific aortic valve disease (CAVD) is a prevailing disease with increasing occurrence and no known medical therapy. Dcbld2-/- mice have a high prevalence of bicuspid aortic valve (BAV), spontaneous aortic valve calcification, and aortic stenosis (AS). 18F-NaF PET/CT can detect the aortic valve calcification process in humans. However, its feasibility in preclinical models of CAVD remains to be determined. Here, we sought to validate 18F-NaF PET/CT for tracking murine aortic valve calcification and leveraged it to examine the development of calcification with aging and its interdependence with BAV and AS in Dcbld2-/- mice. Methods: Dcbld2-/- mice at 3-4 mo, 10-16 mo, and 18-24 mo underwent echocardiography, 18F-NaF PET/CT (n = 34, or autoradiography (n = 45)), and tissue analysis. A subset of mice underwent both PET/CT and autoradiography (n = 12). The aortic valve signal was quantified as SUVmax on PET/CT and as percentage injected dose per square centimeter on autoradiography. The valve tissue sections were analyzed by microscopy to identify tricuspid and bicuspid aortic valves. Results: The aortic valve 18F-NaF signal on PET/CT was significantly higher at 18-24 mo (P < 0.0001) and 10-16 mo (P < 0.05) than at 3-4 mo. Additionally, at 18-24 mo BAV had a higher 18F-NaF signal than tricuspid aortic valves (P < 0.05). These findings were confirmed by autoradiography, with BAV having significantly higher 18F-NaF uptake in each age group. A significant correlation between PET and autoradiography data (Pearson r = 0.79, P < 0.01) established the accuracy of PET quantification. The rate of calcification with aging was significantly faster for BAV (P < 0.05). Transaortic valve flow velocity was significantly higher in animals with BAV at all ages. Finally, there was a significant correlation between transaortic valve flow velocity and aortic valve calcification by both PET/CT (r = 0.55, P < 0.001) and autoradiography (r = 0.45, P < 0.01). Conclusion: 18F-NaF PET/CT links valvular calcification to BAV and aging in Dcbld2-/- mice and suggests that AS may promote calcification. In addition to addressing the pathobiology of valvular calcification, 18F-NaF PET/CT may be a valuable tool for evaluation of emerging therapeutic interventions in CAVD.

Homeostatic, Non-Canonical Role of Macrophage Elastase in Vascular Integrity.

BACKGROUND: Matrix metalloproteinase (MMP)-12 is highly expressed in abdominal aortic aneurysms and its elastolytic function has been implicated in the pathogenesis. This concept is challenged, however, by conflicting data. Here, we sought to revisit the role of MMP-12 in abdominal aortic aneurysm. METHODS: Apoe-/- and Mmp12-/-/Apoe-/- mice were infused with Ang II (angiotensin). Expression of neutrophil extracellular traps (NETs) markers and complement component 3 (C3) levels were evaluated by immunostaining in aortas of surviving animals. Plasma complement components were analyzed by immunoassay. The effects of a complement inhibitor, IgG-FH1-5 (factor H-immunoglobulin G), and macrophage-specific MMP-12 deficiency on adverse aortic remodeling and death from rupture in Ang II-infused mice were determined. RESULTS: Unexpectedly, death from aortic rupture was significantly higher in Mmp12-/-/Apoe-/- mice. This associated with more neutrophils, citrullinated histone H3 and neutrophil elastase, markers of NETs, and C3 levels in Mmp12-/- aortas. These findings were recapitulated in additional models of abdominal aortic aneurysm. MMP-12 deficiency also led to more pronounced elastic laminae degradation and reduced collagen integrity. Higher plasma C5a in Mmp12-/- mice pointed to complement overactivation. Treatment with IgG-FH1-5 decreased aortic wall NETosis and reduced adverse aortic remodeling and death from rupture in Ang II-infused Mmp12-/- mice. Finally, macrophage-specific MMP-12 deficiency recapitulated the effects of global MMP-12 deficiency on complement deposition and NETosis, as well as adverse aortic remodeling and death from rupture in Ang II-infused mice. CONCLUSIONS: An MMP-12 deficiency/complement activation/NETosis pathway compromises aortic integrity, which predisposes to adverse vascular remodeling and abdominal aortic aneurysm rupture. Considering these new findings, the role of macrophage MMP-12 in vascular homeostasis demands re-evaluation of MMP-12 function in diverse settings.

Tenacibaculum aquimarinum sp. nov., isolated from a marine alga and seawater.

Two Gram-stain-negative, aerobic and yellow-pigmented bacterial strains, designated K20-16T and MSW2, were isolated from a marine red alga (Chondrus species) and seawater, respectively. Both strains were oxidase-positive, weakly catalase-positive and non-flagellated rods with gliding motility. Menaquinone-6 was detected as the sole isoprenoid quinone in both strains. Iso-C15:0, iso-C15:0 3-OH, iso-C15:1 G, C15:1 ω6c and summed feature 3 (comprising C16:1 ω7c and/or C16:1 ω6c) were identified in both strains as major fatty acids. Phosphatidylethanolamine was not identified in strain K20-16T, but it was identified in strain MSW2. The genomic DNA G+C contents of strains K20-16T and MSW2 were 30.5 and 30.7 %, respectively. Strains K20-16T and MSW2 shared 99.7% 16S rRNA gene sequence similarity, 97.7% average nucleotide identity (ANI), and 80.5% digital DNA-DNA hybridization (DDH) value, indicating that they are the same species. Phylogenetic analyses based on 16S rRNA gene and 92 concatenated core protein sequences revealed that strains K20-16T and MSW2 formed a phylogenic lineage within the genus Tenacibaculum and were most closely related to Tenacibaculum todarodis LPB0136T with 98.3 and 98.0% 16S rRNA gene sequence similarities, respectively. ANI and digital DDH values between strains K20-16T and MSW2 and other type strains were less than 91.4 and 43.1 %, respectively. Based on the phenotypic, chemotaxonomic and molecular features, strains K20-16T and MSW2 represent a novel species of the genus Tenacibaculum, for which the name Tenacibaculum aquimarinum sp. nov. is proposed. The type strain is K20-16T (=KACC 22 342T=JCM 35 023T).

The Self-Bleaching Process of Microcystis aeruginosa is Delayed by a Symbiotic Bacterium Pseudomonas sp. MAE1-K and Promoted by Methionine Deficiency.

Various interactions between marine cyanobacteria and heterotrophic bacteria have been known, but the symbiotic relationships between Microcystis and heterotrophic bacteria remain unclear. An axenic M. aeruginosa culture (NIES-298) was quickly bleached after exponential growth, whereas a xenic M. aeruginosa culture (KW) showed a normal growth curve, suggesting that some symbiotic bacteria may delay this bleaching. The bleaching process of M. aeruginosa was distinguished from the phenomena of previously proposed chlorosis and programmed cell death in various characteristics. Bleached cultures of NIES-298 quickly bleached actively growing M. aeruginosa cultures, suggesting that M. aeruginosa itself produces bleach-causing compounds. Pseudomonas sp. MAE1-K delaying the bleaching of NIES-298 cultures was isolated from the KW culture. Bleached cultures of NIES-298 treated with strain MAE1-K lost their bleaching ability, suggesting that strain MAE1-K rescues M. aeruginosa from bleaching via inactivation of bleaching compounds. From Tn5 transposon mutant screening, a metZ mutant of strain MAE1-K (F-D3) unable to synthesize methionine, promoting the bleaching of NIES-298 cultures but capable of inactivating bleaching compounds, was obtained. The bleaching process of NIES-298 cultures was promoted with the coculture of mutant F-D3 and delayed by methionine supplementation, suggesting that the bleaching process of M. aeruginosa is promoted by methionine deficiency. IMPORTANCE Cyanobacterial blooms in freshwaters represent serious global concerns for the ecosystem and human health. In this study, we found that one of the major species in cyanobacterial blooms, Microcystis aeruginosa, was quickly collapsed after exponential growth by producing self-bleaching compounds and that a symbiotic bacterium, Pseudomonas sp. MAE1-K delayed the bleaching process via the inactivation of bleaching compounds. In addition, we found that a metZ mutant of strain MAE1-K (F-D3) causing methionine deficiency promoted the bleaching process of M. aeruginosa, suggesting that methionine deficiency may induce the production of bleaching compounds. These results will provide insights into the symbiotic relationships between M. aeruginosa and heterotrophic bacteria that will contribute to developing novel strategies to control cyanobacterial blooms.

Differential BMP Signaling Mediates the Interplay Between Genetics and Leaflet Numbers in Aortic Valve Calcification.

Expression of a neuropilin-like protein, DCBLD2, is reduced in human calcific aortic valve disease (CAVD). DCBLD2-deficient mice develop bicuspid aortic valve (BAV) and CAVD, which is more severe in BAV mice compared with tricuspid littermates. In vivo and in vitro studies link this observation to up-regulated bone morphogenic protein (BMP)2 expression in the presence of DCBLD2 down-regulation, and enhanced BMP2 signaling in BAV, indicating that a combination of genetics and BAV promotes aortic valve calcification and stenosis. This pathway may be a therapeutic target to prevent CAVD progression in BAV.

Linear Six-Carbon Sugar Alcohols Induce Lysis of Microcystis aeruginosa NIES-298 Cells.

Cyanobacterial blooms are a global concern due to their adverse effects on water quality and human health. Therefore, we examined the effects of various compounds on Microcystis aeruginosa growth. We found that Microcystis aeruginosa NIES-298 cells were lysed rapidly by linear six-carbon sugar alcohols including mannitol, galactitol, iditol, fucitol, and sorbitol, but not by other sugar alcohols. Microscopic observations revealed that mannitol treatment induced crumpled inner membrane, an increase in periplasmic space, uneven cell surface with outer membrane vesicles, disruption of membrane structures, release of intracellular matter including chlorophylls, and eventual cell lysis in strain NIES-298, which differed from the previously proposed cell death modes. Mannitol metabolism, antioxidant-mediated protection of mannitol-induced cell lysis by, and caspase-3 induction in strain NIES-298 were not observed, suggesting that mannitol may not cause organic matter accumulation, oxidative stress, and programmed cell death in M. aeruginosa. No significant transcriptional expression was induced in strain NIES-298 by mannitol treatment, indicating that cell lysis is not induced through transcriptional responses. Mannitol-induced cell lysis may be specific to strain NIES-298 and target a specific component of strain NIES-298. This study will provide a basis for controlling M. aeruginosa growth specifically by non-toxic substances.

Aggregatimonas sangjinii gen. nov., sp. nov., a novel silver nanoparticle synthesizing bacterium belonging to the family Flavobacteriaceae.

Microbially synthesized nanoparticles has received increasing attentions owing to the broad applications in biology and medicine. In this study, we report a novel bacterium that biologically generates silver nanoparticles (AgNPs). This bacterium, designated strain F202Z8T, was isolated from a rusty iron plate found in the intertidal region of Taean, South Korea. The morphological, biochemical and molecular characteristics predicted that strain F202Z8T belongs to the family Flavobacteriaceae. Phylogenetic analysis based on 16S rRNA gene sequence revealed that strain F202Z8T forms a distinct lineage with closely related genera Maribacter, Pelagihabitans, Pseudozobellia, Zobellia, Pricia, and Costertonia and showed the highest similarity to Maribacter aestuarii GY20T (94.5%). The digital DNA-DNA hybridization and average nucleotide identity values calculated from the whole genome-sequence comparison between strain F202Z8T and other members of the family Flavobacteriaceae were in the ranges of 12.7%-16.9% and 70.3%-74.4%, respectively, suggesting that strain F202Z8T represented a novel genus. The complete genome sequence of strain F202Z8T is 4,723,614 bp, with 43.26% G + C content. Based on the COG, GO, KEGG, NR, and Swiss-Prot databases, the genomic analysis of F202Z8T revealed the presence of 17 putative genes responsible for the synthesis of AgNPs. Our polyphasic taxonomic results suggested that this strain represents a novel species of a novel genus in the family Flavobacteriaceae, for which the name Aggregatimonas sangjinii gen. nov., sp. nov. is proposed. The type strain of Aggregatimonas sangjinii is F202Z8T (= KCCM 43411T = LMG 31494T). Overall, our data provide fundamental information to potentially utilize this novel bacterium for synthesis of nanoparticles.

Colwellia maritima sp. nov. and Polaribacter marinus sp. nov., isolated from seawater.

Two Gram-stain-negative, catalase- and oxidase-positive, and aerobic bacteria, strains MSW7T and MSW13T, were isolated from seawater. Cells of strains MSW7T and MSW13T are motile and non-motile rods, respectively. Strain MSW7T optimally grew at 25 °C and pH 7.0 and in the presence of 3 % (w/v) NaCl, whereas strain MSW13T optimally grew at 25 °C and pH 6.0-7.0 and in the presence of 2 % NaCl. As the sole respiratory quinone and the major fatty acids and polar lipids, strain MSW7T contained ubiquinone-8, C16 : 0, C15 : 1 ω8c, C17 : 1 ω8c and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c), and phosphatidylethanolamine and phosphatidylglycerol, respectively, whereas strain MSW13T contained menaquinone-6, C15 : 1 ω6c, iso-C15 : 0, anteiso-C15 : 0, and iso-C15 : 0 3-OH, and phosphatidylethanolamine, respectively. The DNA G+C contents of strains MSW7T and MSW13T were 37.3 and 29.9 %, respectively. Phylogenetic analyses based on 16S rRNA gene sequences showed that strains MSW7T and MSW13T were most closely related to Colwellia echini A3T and Polaribacter atrinae WP25T with 98.8 and 98.1 % sequence similarities, respectively. The average nucleotide identity and digital DNA-DNA hybridization values between strain MSW7T and C. echini A3T and between strain MSW13T and P. atrinae KACC 17473T were 73.6 and 22.6 % and 80.4 and 23.8 %, respectively. Based on phenotypic, chemotaxonomic and phylogenetic data, strains MSW7T and MSW13T represent novel species of the genera Colwellia and Polaribacter, respectively, for which the names Colwellia maritima sp. nov. and Polaribacter marinus sp. nov. are proposed, respectively. The type strains of C. maritima sp. nov. and P. marinus sp. nov. are MSW7T (=KACC 22339T=JCM 35001T) and MSW13T (=KACC 22341T=JCM 35021T), respectively.

Mesorhizobium microcysteis sp. nov., isolated from a culture of Microcystis aeruginosa.

Strain MaA-C15T, a Gram-stain-negative, non-spore-forming and strictly aerobic bacterium, was isolated from a xenic culture of Microcystis aeruginosa in the Republic of Korea. Cells were motile rods showing positive reactions in catalase and oxidase tests. Growth was observed between 15 and 37 °C (optimum, 30 °C), between pH 6.0 and pH 11.0 (optimum, pH 7.5) and in the presence of 0-2.0 % (w/v) NaCl (optimum, 0 %). Strain MaA-C15T contained C16 : 0, 11-methyl-C18 : 1 ω7c, cyclo-C19 : 0 ω8c and summed feature 8 (C18 : 1 ω6c and/or C18 : 1 ω7c) as the major cellular fatty acids and ubiquinone-10 as the sole respiratory quinone. Phosphatidylethanolamine, phosphatidylmonomethylethanolamine, an unidentified aminophospholipid, an unidentified glycolipid and three unidentified phospholipids were detected as the major polar lipids. The G+C content of the genomic DNA was 64.1 mol%. Phylogenetic and phylogenomic analyses based on 16S rRNA gene and genome sequences revealed that strain MaA-C15T formed a phyletic lineage with Mesorhizobium sediminum YIM M12096T within the family Phyllobacteriaceae. Strain MaA-C15T was most closely related to Mesorhizobium albiziae DSM 21822T with a 98.2 % 16S rRNA sequence similarity. Average nucleotide identity and in silico DNA-DNA hybridization values between strain MaA-C15T and M. albiziae DSM 21822T were 75.4 and 20.1 %, respectively. Based on the results of phenotypic, chemotaxonomic and molecular analyses, strain MaA-C15T represents a novel species of the genus Mesorhizobium, for which the name Mesorhizobium microcysteis sp. nov. is proposed. The type strain is MaA-C15T (=KACC 21226T=JCM 33503T).

Computed tomography imaging of macrophage phagocytic activity in abdominal aortic aneurysm.

Inflammation plays a major role in the pathogenesis of several vascular pathologies, including abdominal aortic aneurysm (AAA). Evaluating the role of inflammation in AAA pathobiology and potentially outcome in vivo requires non-invasive tools for high-resolution imaging. We investigated the feasibility of X-ray computed tomography (CT) imaging of phagocytic activity using nanoparticle contrast agents to predict AAA outcome. Methods: Uptake of several nanoparticle CT contrast agents was evaluated in a macrophage cell line. The most promising agent, Exitron nano 12000, was further characterized in vitro and used for subsequent in vivo testing. AAA was induced in Apoe-/- mice through angiotensin II (Ang II) infusion for up to 4 weeks. Nanoparticle biodistribution and uptake in AAA were evaluated by CT imaging in Ang II-infused Apoe-/- mice. After imaging, the aortic tissue was harvested and used from morphometry, transmission electron microscopy and gene expression analysis. A group of Ang II-infused Apoe-/- mice underwent nanoparticle-enhanced CT imaging within the first week of Ang II infusion, and their survival and aortic external diameter were evaluated at 4 weeks to address the value of vessel wall CT enhancement in predicting AAA outcome. Results: Exitron nano 12000 showed specific uptake in macrophages in vitro. Nanoparticle accumulation was observed by CT imaging in tissues rich in mononuclear phagocytes. Aortic wall enhancement was detectable on delayed CT images following nanoparticle administration and correlated with vessel wall CD68 expression. Transmission electron microscopy ascertained the presence of nanoparticles in AAA adventitial macrophages. Nanoparticle-induced CT enhancement on images obtained within one week of AAA induction was predictive of AAA outcome at 4 weeks. Conclusions: By establishing the feasibility of CT-based molecular imaging of phagocytic activity in AAA, this study links the inflammatory signal on early time point images to AAA evolution. This readily available technology overcomes an important barrier to cross-sectional, longitudinal and outcome studies, not only in AAA, but also in other cardiovascular pathologies and facilitates the evaluation of modulatory interventions, and ultimately upon clinical translation, patient management.

Nonlabens ponticola sp. nov., isolated from seawater and reclassification of Nonlabens sediminis as a later heterotypic synonym of Nonlabens tegetincola.

A Gram-stain-negative, orange-pigmented and strictly aerobic bacterium, designated strain MJ115T, was isolated from seawater in Pohang, South Korea. Cells were non-motile rods and showed positive reactions for catalase and oxidase tests. Growth of strain MJ115T was observed at 4-35 °C (optimum, 30 °C), pH 6.0-7.0 (optimum, pH 6.5) and in the presence of 0-8.0 % (w/v) NaCl (optimum, 2.0%). Strain MJ115T contained iso-C15 : 0, anteiso-C15 : 0, anteiso-C17 : 1 ω9c, C17 : 0 2-OH, iso-C16 : 0 3-OH, iso-C17 : 0 3-OH and summed feature 3 (C16 : 1 ω7c and/or C16 : 1 ω6c) as major cellular fatty acids and menaquinone-6 as the major respiratory quinone. Phosphatidylethanolamine, two unidentified aminolipids and four unidentified lipids were detected as major polar lipids. The G+C content of the genomic DNA was 40.7 mol%. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain MJ115T formed a phyletic lineage with Nonlabens marinus S1-08T, Nonlabens agnitus JC2678T and Nonlabens antarcticus AKS 622T within the genus Nonlabens. Strain MJ115T was also most closely related to N. marinus S1-08T, N. agnitus JC2678T and N. antarcticus AKS 622T with 96.5, 96.4 and 96.0 % 16S rRNA sequence similarities, respectively. Here it is proposed that strain MJ115T represents a new species of the genus Nonlabens, for which the name Nonlabens ponticola sp. nov. is proposed. The type strain is MJ115T (=KCTC 72237T=NBRC 113963T). In addition, the comparison of the whole genome sequences and phenotypic features suggested that Nonlabens tegetincola and Nonlabens sediminis belong to the same species. Therefore, it is proposed that N. sediminis is reclassified as a later heterotypic synonym of N. tegetincola.

Hydroxamate-Based Selective Macrophage Elastase (MMP-12) Inhibitors and Radiotracers for Molecular Imaging.

Macrophage elastase [matrix metalloproteinase (MMP)-12] is the most upregulated MMP in abdominal aortic aneurysm (AAA) and, hence, MMP-12-targeted imaging may predict AAA progression and rupture risk. Here, we report the design, synthesis, and evaluation of three novel hydroxamate-based selective MMP-12 inhibitors (CGA, CGA-1, and AGA) and the methodology to obtain MMP-12 selectivity from hydroxamate-based panMMP inhibitors. Also, we report two 99mTc-radiotracers, 99mTc-AGA-1 and 99mTc-AGA-2, derived from AGA. 99mTc-AGA-2 displayed faster blood clearance in mice and better radiochemical stability compared to 99mTc-AGA-1. Based on this, 99mTc-AGA-2 was chosen as the lead tracer and tested in murine AAA. 99mTc-AGA-2 uptake detected by autoradiography was significantly higher in AAA compared to normal aortic regions. Specific binding of the tracer to MMP-12 was demonstrated through ex vivo competition. Accordingly, this study introduces a novel family of selective MMP-12 inhibitors and tracers, paving the way for further development of these agents as therapeutic and imaging agents.

Flavihumibacter soli sp. nov., Isolated from Soil.

A novel Gram-stain-positive, strictly aerobic, non-motile, rod-shaped bacterium, designated strain R14T was isolated from steep grove soil and taxonomically characterized using a polyphasic approach. Cells showed oxidase-negative and catalase-positive activities and grew at 25-37 °C (optimum, 30 °C), pH 5.0-8.0 (optimum, pH 6.5), and in the presence of 0-0.5% (w/v) NaCl (optimum, 0%). Phylogenetic trees based on 16S rRNA gene sequences revealed that strain R14T formed a phylogenetic lineage with Flavihumibacter genus members within the family Chitinophagaceae. Comparison of 16S rRNA gene sequences showed that strain R14T shared highest similarities with Flavihumibacter solisilvae 3-3T (97.5%), Flavihumibacter petaseus NBRC 106054T (96.7%), and Flavihumibacter stibioxidans YS-17T (96.1%). The G+C content of strain R14T calculated from its whole genome sequence was 44.6 mol%. Strain R14T contained menaquinone-7 and iso-C15:0, iso-C17:0 3-OH, C16:0, C15:1 ω6c, and iso-C15:0-G as the sole respiratory isoprenoid quinone and major cellular fatty acids, respectively. Major polar lipids consisted of phosphatidylethanolamine, two unidentified aminolipids, and four unidentified lipids. Based on phylogenetic, phenotypic, and chemotaxonomic characteristics of strain R14T, it could be concluded that strain R14T represents a novel species of the genus Flavihumibacter, for which the name Flavihumibacter soli sp. nov. is proposed. The type strain is R14T (=KACC 21229T = JCM 33473T).

Novel Matrix Metalloproteinase 12 Selective Radiotracers for Vascular Molecular Imaging.

Matrix metalloproteinase-12 (MMP-12) is highly upregulated in several inflammatory diseases, including abdominal aortic aneurysm (AAA). Here we report four novel 99mTc-labeled radiotracers derived from a highly selective competitive MMP-12 inhibitor. These tracers in their 99gTc version were assessed in vitro on a set of human metalloproteases and displayed high affinity and selectivity toward MMP-12. Their radiolabeling with 99mTc was shown to be efficient and stable in both buffer and mouse blood. The tracers showed major differences in their biodistribution and blood clearance. On the basis of its in vivo performance, [99mTc]-1 was selected for evaluation in murine AAA, where MMP-12 gene expression is upregulated. Autoradiography of aortae at 2 h postinjection revealed high uptake of [99mTc]-1 in AAA relative to adjacent aorta. Tracer uptake specificity was demonstrated through in vivo competition. This study paves the way for further evaluation of [99mTc]-1 for imaging AAA and other MMP-12-associated diseases.