Enterocin X,a Novel Two-Peptide Bacteriocin from Enterococcus faecium KU-B5, Has an Antibacterial Spectrum Entirely Different from Those of Its Component Peptides

Enterocin X, composed of two antibacterial peptides (Xα and Xβ), is a novel class IIb bacteriocin from Enterococcus faecium KU-B5. When combined, Xα and Xβ display variably enhanced or reduced antibacterial activity toward a panel of indicators compared to each peptide individually. In E. faecium strains that produce enterocins A and B, such as KU-B5, only one additional bacteriocin had previously been known.Bacteriocins are gene-encoded antibacterial peptides and proteins. Because of their natural ability to preserve food, they are of particular interest to researchers in the food industry. Bacteriocins are grouped into three main classes according to their physical properties and compositions (11, 12). Of these, class IIb bacteriocins are thermostable non-lanthionine-containing two-peptide bacteriocins whose full antibacterial activity requires the interaction of two complementary peptides (8, 19). Therefore, two-peptide bacteriocins are considered to function together as one antibacterial entity (14).Enterocins A and B, first discovered and identified about 12 years ago (2, 3), are frequently present in Enterococcus faecium strains from various sources (3, 5, 6, 9, 13, 16). So far, no other bacteriocins have been identified in these strains, except the enterocin P-like bacteriocin from E. faecium JCM 5804^T (18). Here, we describe the characterization and genetic identification of enterocin X in E. faecium KU-B5. Enterocin X (identified after the enterocin P-like bacteriocin was discovered) is a newly found class IIb bacteriocin in E. faecium strains that produce enterocins A and B.     

Haplorchis taichui as a Possible Etiologic Agent of Irritable Bowel Syndrome-Like Symptoms

The aim of this study is to clarify the clinical features of Haplorchis taichui infection in humans in Nan Province, Thailand, and to correlate the clinical features with irritable bowel syndrome (IBS)-like symptoms. In this study area, only H. taichui, but neither other minute intestinal flukes nor small liver flukes were endemic. The degree of infection was determined by fecal egg counts and also by collecting adult worms after deworming. The signs and symptoms of individual patients together with their hematological and biochemical laboratory data were gathered to evaluate the relationship between the clinical features and the severity of infection. Special emphasis was made to elucidate the possible similarities of the clinical features of H. taichui infection and IBS-like symptoms. The results showed useful clinical information and the significant (> 50%) proportion of haplorchiasis patients complained of abdominal pain, lassitude, and flatulence, which were the important diagnostic symptoms of IBS. This study has reported a possible link between H. taichui and IBS, and H. taichui might probably play a role in the etiology of these IBS-like symptoms.     

Biosynthesis of intracellular 5-aminolevulinic acid by a newly identified halotolerant <Emphasis Type="Italic">Rhodobacter sphaeroides</Emphasis>

Of 23 strains of halotolerant (up to 12% w/v NaCl) photosynthetic bacteria isolated from various sources, one isolate, SH5, accumulated intracellular 5-aminolevulinic acid (ALA) at 0.45 μg/g dry cell wt (DCW) growing aerobically in the dark. The strain was identified as Rhodobacter sphaeroides using 16S rDNA sequencing. Biosynthesis of ALA was enhanced to 14 μg/g DCW using modified glutamate/glucose (50 mM) medium with the addition of 10 mM levulinic acid after 24 h cultivation. Addition of 30 μM Fe²⁺ to this medium increased the yield to 226 μg/g DCW.     

Plasmodium vivax Drug Resistance Genes; Pvmdr1 and Pvcrt-o Polymorphisms in Relation to Chloroquine Sensitivity from a Malaria Endemic Area of Thailand

The aim of the study was to explore the possible molecular markers of chloroquine resistance in Plasmodium vivax isolates in Thailand. A total of 30 P. vivax isolates were collected from a malaria endemic area along the Thai-Myanmar border in Mae Sot district of Thailand. Dried blood spot samples were collected for analysis of Pvmdr1 and Pvcrt-o polymorphisms. Blood samples (100 μl) were collected by finger-prick for in vitro chloroquine susceptibility testing by schizont maturation inhibition assay. Based on the cut-off IC₅₀ of 100 nM, 19 (63.3%) isolates were classified as chloroquine resistant P. vivax isolates. Seven non-synonymous mutations and 2 synonymous were identified in Pvmdr1 gene. Y976F and F1076L mutations were detected in 7 (23.3%) and 16 isolates (53.3%), respectively. Analysis of Pvcrt-o gene revealed that all isolates were wild-type. Our results suggest that chloroquine resistance gene is now spreading in this area. Monitoring of chloroquine resistant molecular markers provide a useful tool for future control of P. vivax malaria.     

Photoautotrophic Production of Lipids by Some <Emphasis Type="Italic">Chlorella</Emphasis> Strains

The microalgae Chlorella protothecoides UTEX 25, Chlorella sp. TISTR 8991, and Chlorella sp. TISTR 8990 were compared for use in the production of biomass and lipids under photoautotrophic conditions. Chlorella sp. TISTR 8990 was shown to be potentially suitable for lipid production at 30°C in a culture medium that contained only inorganic salts. For Chlorella sp. TISTR 8990 in optimal conditions in a stirred tank photobioreactor, the lipid productivity was 2.3 mg L⁻¹ h⁻¹ and after 14 days the biomass contained more than 30% lipids by dry weight. To attain this, the nitrogen was provided as KNO₃ at an initial concentration of 2.05 g L⁻¹ and chelated ferric iron was added at a concentration of 1.2 × 10⁻⁵ mol L⁻¹ on the ninth day. Under the same conditions in culture tubes (36 mm outer diameter), the biomass productivity was 2.8-fold greater than in the photobioreactor (0.125 m in diameter), but the lipid productivity was only 1.2-fold higher. Thus, the average low-light level in the photobioreactor actually increased the biomass specific lipid production compared to the culture tubes. A light-limited growth model closely agreed with the experimental profiles of biomass production, nitrogen consumption, and lipid production in the photobioreactor.     

A comparison of clinical and epidemiological characteristics of fatal human infections with H5N1 and human influenza viruses in Thailand, 2004-2006

Background

The National Avian Influenza Surveillance (NAIS) system detected human H5N1 cases in Thailand from 2004–2006. Using NAIS data, we identified risk factors for death among H5N1 cases and described differences between H5N1 and human (seasonal) influenza cases.

Methods and Findings

NAIS identified 11,641 suspect H5N1 cases (e.g. persons with fever and respiratory symptoms or pneumonia, and exposure to sick or dead poultry). All suspect H5N1 cases were tested with polymerase chain reaction (PCR) assays for influenza A(H5N1) and human influenza viruses. NAIS detected 25 H5N1 and 2074 human influenza cases; 17 (68%) and 22 (1%) were fatal, respectively. We collected detailed information from medical records on all H5N1 cases, all fatal human influenza cases, and a sampled subset of 230 hospitalized non-fatal human influenza cases drawn from provinces with ≥1 H5N1 case or human influenza fatality.Fatal versus non-fatal H5N1 cases were more likely to present with low white blood cell (p = 0.05), lymphocyte (p<0.02), and platelet counts (p<0.01); have elevated liver enzymes (p = 0.05); and progress to circulatory (p<0.001) and respiratory failure (p<0.001). There were no differences in age, medical conditions, or antiviral treatment between fatal and non-fatal H5N1 cases. Compared to a sample of human influenza cases, all H5N1 cases had direct exposure to sick or dead birds (60% vs. 100%, p<0.05). Fatal H5N1 and fatal human influenza cases were similar clinically except that fatal H5N1 cases more commonly: had fever (p<0.001), vomiting (p<0.01), low white blood cell counts (p<0.01), received oseltamivir (71% vs. 23%, p<.001), but less often had ≥1 chronic medical conditions (p<0.001).

Conclusions

In the absence of diagnostic testing during an influenza A(H5N1) epizootic, a few epidemiologic, clinical, and laboratory findings might provide clues to help target H5N1 control efforts. Severe human influenza and H5N1 cases were clinically similar, and both would benefit from early antiviral treatment.     

Effects of the mixed biocide Bacillus thuringiensis–abamectin on the development of the parasitoid Microplitis mediator and its host Helicoverpa armigera

The effects of the mixed biocide Bacillus thuringiensis Berliner with abamectin (BtA) on the development of the parasitoid Microplitis mediator (Haliday) (Hymenoptera: Braconidae) and its cotton bollworm host, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), were evaluated in the laboratory. Weight gain in larvae of H. armigera was initially delayed, but larval developmental period increased and pupal weight increased when they were fed on a diet containing BtA. Due to increased longevity of the host larvae, the susceptible period to parasitization of H. armigera by M. mediator increased when the host larvae were reared on diets containing BtA at concentrations of 0.5, 1, 2, and 4 μg g^?1. The longevity of female and male parasitoids significantly decreased when newly emerged wasps were fed a honey solution containing 200 μg ml^?1 BtA in comparison with those fed only a honey solution. Mean longevity was significantly prolonged when parasitoids were fed a honey solution and BtA–honey solution in comparison with those fed BtA–distilled water, distilled water, or nothing. There were no significant differences compared with the control in any biological characteristics for the offspring of female parasitoids fed the honey solutions containing BtA at concentrations of 50, 100, and 200 μg ml^?1; characteristics measured include the egg‐larval period, pupal weight, male and female pupal periods, adult fresh weight, and adult longevity. When female parasitoids parasitized host larvae that had been fed the diet containing BtA, their male and female pupal periods were significantly prolonged compared with the control (without BtA).     

Sequence variations of the first ribosomal internal transcribed spacer of Penaeus species in Thailand

The ribosomal DNA internal transcribed spacer 1 (ITS1) was investigated in the search for additional genetic marker that is suitable for population studies of the penaeid shrimps. The sequence variations of the ITS1 were determined and found to be informative in estimating phylogenies in that they differentiate four species of penaeid shrimps, namely Penaeus merguiensis, Penaeus silasi, Penaeus monodon and Penaeus semisalcatus and the populations of P. merguiensis collected in the Gulf of Thailand and the Andaman Sea. The length of the ITS1 ranged from 499 to 772 bp, with a GC content of 63.30-67.37%. Four microsatellite loci are found in the ITS1 at 5′ end and the middle of region and seem to be associated with sequence divergence and size variation in Penaeus species. Some microsatellites were found in only one specie, (GCGA)₄ in P. semisalcatus and (CGGA)_4-9 in P. monodon. These microsatellite regions are considerably long enough and the level of intragenomic variation in P. merguiensis is less than that between different species, hence, provide a great potential use in the population studies.     

Characterization of a novel binding protein for Fortilin/TCTP--component of a defense mechanism against viral infection in Penaeus monodon

The Fortilin (also known as TCTP) in Penaeus monodon (PmFortilin) and Fortilin Binding Protein 1 (FBP1) have recently been shown to interact and to offer protection against the widespread White Spot Syndrome Virus infection. However, the mechanism is yet unknown. We investigated this interaction in detail by a number of in silico and in vitro analyses, including prediction of a binding site between PmFortilin/FBP1 and docking simulations. The basis of the modeling analyses was well-conserved PmFortilin orthologs, containing a Ca(2+)-binding domain at residues 76-110 representing a section of the helical domain, the translationally controlled tumor protein signature 1 and 2 (TCTP_1, TCTP_2) at residues 45-55 and 123-145, respectively. We found the pairs Cys59 and Cys76 formed a disulfide bond in the C-terminus of FBP1, which is a common structural feature in many exported proteins and the "x-G-K-K" pattern of the amidation site at the end of the C-terminus. This coincided with our previous work, where we found the "x-P-P-x" patterns of an antiviral peptide also to be located in the C-terminus of FBP1. The combined bioinformatics and in vitro results indicate that FBP1 is a transmembrane protein and FBP1 interact with N-terminal region of PmFortilin.