Gracilibacillus bigeumensis sp. nov., a moderately halophilic bacterium from solar saltern soil.

A Gram-staining-positive, moderately halophilic bacterium, designated strain BH097(T), was isolated from solar saltern soil of Bigeum Island in south-west Korea. Cells were motile rods, producing spherical endospores at a terminal position in swollen sporangia. Strain BH097(T) was strictly aerobic, grew at pH 5.5-9.5 (optimum, pH 8.0), at 10-52 °C (optimum, 37 °C) and at salinities of 1-22% (w/v) NaCl (optimum, 7% NaCl). On the basis of 16S rRNA gene sequence analysis, strain BH097(T) was shown to belong to the genus Gracilibacillus within the phylum Firmicutes, and showed closest sequence similarity to Gracilibacillus saliphilus DSM 19802(T) (95.8%), Gracilibacillus thailandensis TP2-8(T) (95.6%), Gracilibacillus boraciitolerans DSM 17256(T) (95.5%), 'Gracilibacillus quinghaiensis' DSM 17858 (95.4%) and Gracilibacillus halophilus DSM 17856(T) (95.2%). The DNA G+C content of this novel isolate was 37.9 mol%. The major cellular fatty acids of strain BH097(T) were anteiso-C(15:0), iso-C(15:0) and C(16:0), and its polar lipid pattern consisted of diphosphatidylglycerol, phosphatidylglycerol two unknown phospholipids and a glycolipid. The isoprenoid quinone was MK-7, and the peptidoglycan type was A1γ, with meso-diaminopimelic acid as the diagnostic diamino acid. On the basis of polyphasic evidence from this study, strain BH097(T) represents a novel species of the genus Gracilibacillus for which the name Gracilibacillus bigeumensis sp. nov. is proposed. The type strain is BH097(T) ( = KCTC 13130(T) = DSM 19028(T)).

Transforming growth factor-beta-induced protein (TGFBIp/beta ig-h3) activates platelets and promotes thrombogenesis.

Transforming growth factor-beta-induced protein (TGFBIp)/beta ig-h3 is a 68-kDa extracellular matrix protein that is functionally associated with the adhesion, migration, proliferation, and differentiation of various cells. The presence of TGFBIp in platelets led us to study the role of this protein in the regulation of platelet functions. Upon activation, platelet TGFBIp was released and associated with the platelets. TGFBIp mediates not only the adhesion and spread of platelets but also activates them, resulting in phosphatidylserine exposure, alpha-granule secretion, and increased integrin affinity. The fasciclin 1 domains of TGFBIp are mainly responsible for the activation of platelets. TGFBIp promotes thrombus formation on type I fibrillar collagen under flow conditions in vitro and induces pulmonary embolism in mice. Moreover, transgenic mice, which have approximately a 1.7-fold greater blood TGFBIp concentration, are significantly more susceptible to collagen- and epinephrine-induced pulmonary embolism than wild-type mice. These results suggest that TGFBIp, a human platelet protein, plays important roles in platelet activation and thrombus formation. Our findings will increase our understanding of the novel mechanism of platelet activation, contributing to a better understanding of thrombotic pathways and the development of new antithrombotic therapies.

Human monoclonal antibody against Hepatitis B virus surface antigen (HBsAg).

Hepatitis B virus (HBV) is one of the main pathogens responsible for hepatitis and hepatocellular carcinoma. Human plasma-derived Hepatitis B immune globulin (HBIG) is being used for prophylactic and liver transplantation currently. However, it may be necessary to replace a HBIG with a recombinant one because of limited availability of human plasma with high anti-HBsAg antibody titer and possible contamination of human pathogens. A Chinese hamster ovary (CHO) cell line, HB-C7A, was established which produces a fully human IgG1 that binds HBsAg. The HB-C7A exhibits approximately 2600 units/mg of antibody. The affinity (K(a)) of HB-C7A is 1.1 x 10(8) M(-1) by Biacore analysis and estimated 6.7-fold higher than that of Hepabig (a plasma-derived HBIG from Green Cross Corp., Yongin, Korea) by competition ELISA. The HB-C7A recognizes the conformational "a" determinant of HBsAg and binds HBV particle more efficiently than the Hepabig. The HB-C7A binds to HBV-infected human liver tissue but does not bind to normal human tissues. This HB-C7A has several advantages compared to plasma-derived Hepabig such as activity, safety and availability.

Identification of an antibacterial compound, benzylideneacetone, from Xenorhabdus nematophila against major plant-pathogenic bacteria.

An entomopathogenic bacterium, Xenorhabdus nematophila, is known to have potent antibiotic activities to maintain monoxenic condition in its insect host for effective pathogenesis and ultimately for optimal development of its nematode symbiont, Steinernema carpocapsae. In this study we assess its antibacterial activity against plant-pathogenic bacteria and identify its unknown antibiotics. The bacterial culture broth had significant antibacterial activity that increased with development of the bacteria and reached its maximum at the stationary growth phase. The antibiotic activities were significant against five plant-pathogenic bacterial strains: Agrobacterium vitis, Pectobacterium carotovorum subsp. atrosepticum, P. carotovorum subsp. carotovorum, Pseudomonas syringae pv. tabaci, and Ralstonia solanacearum. The antibacterial factors were extracted with butanol and fractionated using column chromatography with the eluents of different hydrophobic intensities. Two active antibacterial subfractions were purified, and the higher active fraction was further fractionated and identified as a single compound of benzylideneacetone (trans-4-phenyl-3-buten-2-one). With heat stability, the synthetic compound showed equivalent antibiotic activity and spectrum to the purified compound. This study reports a new antibiotic compound synthesized by X. nematophila, which is a monoterpenoid compound and active against some Gram-negative bacteria.