Identification of an insecticidal toxin produced by Enterobacter sp. strain 532 isolated from diseased Bombyx mori silkworms.

Although Enterobacter sp. 532 shows pathogenicity in Bombyx mori, the insecticidal mechanisms are unclear. Here, we identified and characterised an insecticidal protein from Enterobacter. The insecticidal protein was purified from the strain and inoculated into B. mori larvae. Intracellular proteins were prepared, purified and separated by preparative native polyacrylamide gel electrophoresis (PAGE); one protein band had insecticidal activity. Sodium dodecyl sulfate-PAGE showed the presence of several bands, indicating that the insecticidal protein formed a complex. Peptide mass fingerprinting of a prominent 255.3-kDa band revealed 64 peptides that matched one protein with 33.0% sequence coverage. This protein was a homologue of the A component of the toxin complex (Tc), and the VRP1 domain was conserved; thus, the gene was named itcA (insecticidal toxin complex A). In the itcA downstream region, B and C component gene homologues were found, and these genes were located on an 86.2-kb contig sequence. Two repA genes and 27 genes related to conjugation transfer of plasmids were located on the contig, suggesting that the contig originated from a mobilisable plasmid. Therefore, these findings suggested that the strain may have acquired the Tc genes by horizontal transfer. This is the first description of Tc produced by the genus Enterobacter.

Alkaline protease contributes to pyocyanin production in Pseudomonas aeruginosa.

The role of the alkaline protease (AprA) in pyocyanin production in Pseudomonas aeruginosa was investigated. AprA was overproduced when a plasmid carrying the aprA gene was introduced to an aprA-deletion mutant strain, EG03; thus, aprA-complemented EG03 was used as an overproducing strain. The complemented strain produced higher pyocyanin than the mutant strain in all commercially available media evaluated. Particularly, pyocyanin production was higher in the complemented than in the parental strain in brain-heart infusion and tryptic soy broths. These results suggested that protein degradation products by AprA were utilized for pyocyanin production. Protein-rich media were used in subsequent validation studies. Similar results were obtained when the basal medium was supplemented with casein or skim milk as the sole organic nitrogen source. However, gelatin failed to induce abundant pyocyanin production in the complemented strain, despite the presence of protein degradation products by AprA as assessed by SDS-PAGE. Thus, gelatin degradation products may not be suitable for pyocyanin synthesis. In conclusion, AprA could contribute to pyocyanin production in the presence of several proteins or peptides.

Antithrombotic effect of taurine in healthy Japanese people may be related to an increased endogenous thrombolytic activity.

INTRODUCTION: Prevention of arterial thrombotic diseases has high priority in developed countries. Taurine (2-aminomethylsulfonic acid), which is rich in sea foods, showed antithrombotic effect in animal models of thrombosis. The present study aimed to investigate such effect in healthy human volunteers. METHODS AND RESULTS: In 101 healthy Japanese people the overall thrombotic status was accessed from non-anticoagulated blood sample by the Global Thrombosis Test (GTT). There was no significant correlation between taurine concentration in urine samples and GTT-Occlusion Times (OT; mainly reactivity of platelets). In contrast, a significant inverse correlation was demonstrated between urine taurine concentrations and GTT-Lysis Times (LT; showing spontaneous thrombolytic activity). CONCLUSIONS: Our findings suggest that taurine enhances endogenous thrombolytic activity which could be a mechanism of the earlier observed cardioprotective and antithrombotic effect.