Antibacterial activity of Lactobacillus strains isolated from dry fermented sausages

One hundred strains of lactic acid bacteria isolated from dry cured sausages were tested for antagonistic activity against a set of test strains. Nine of 52 strains of Lactobacilus casei and three of 48 strains of Lact. plantarun produced inhibition zones against the indicator species. The substance excreted by Lact. casei CRL 705 was active against Lact. plantarum, Listeria monocytogenes, Staphylococcus aureus and a wide range of Gram-negative bacteria. The activity of the antibacterial compound from Lact. casei CRL 705 was destroyed by papain, trypsin and pepsin, but was resistant to heat (100°C for 20 min), lysozyme and catalase. The agent was produced during the growth cycle and when the concentrated and neutralized supernatant fluid was added to a fresh culture of sensitive cells it produced a rapid inactivation. A decrease in optical density (O.D.) over time, indicative of cell lysis, was also observed. These characteristics allowed us to identify the inhibitory compound as a bacteriocin which we termed Lactocin 705.     

Spatial patterns of DNA replication, protein synthesis, and oxygen concentration within bacterial biofilms reveal diverse physiological states

It has long been suspected that microbial biofilms harbor cells in a variety of activity states, but there have been few direct experimental visualizations of this physiological heterogeneity. Spatial patterns of DNA replication and protein synthetic activity were imaged and quantified in staphylococcal biofilms using immunofluorescent detection of pulse-labeled DNA and also an inducible green fluorescent protein (GFP) construct. Stratified patterns of DNA synthetic and protein synthetic activity were observed in all three biofilm systems to which the techniques were applied. In a colony biofilm system, the dimensions of the zone of anabolism at the air interface ranged from 16 to 38 microm and corresponded with the depth of oxygen penetration measured with a microelectrode. A second zone of activity was observed along the nutrient interface of the biofilm. Much of the biofilm was anabolically inactive. Since dead cells constituted only 10% of the biofilm population, most of the inactive cells in the biofilm were still viable. Collectively, these results suggest that staphylococcal biofilms contain cells in at least four distinct states: growing aerobically, growing fermentatively, dead, and dormant. The variety of activity states represented in a biofilm may contribute to the special ecology and tolerance to antimicrobial agents of biofilms.     

Introduction of the Exocelina ekari-group with descriptions of 22 new species from New Guinea (Coleoptera,Dytiscidae, Copelatinae)

The Exocelina ekari-group is here introduced and defined mainly on the basis of a discontinuous outline of the median lobe of the aedeagus. The group is known only from New Guinea (Indonesia and Papua New Guinea). It contained four species to date: Exocelina astrophallus (Balke, 1998), Exocelina atowaso (Shaverdo, Sagata & Balke, 2005), Exocelina munaso (Shaverdo, Sagata & Balke, 2005), and Exocelina polita (Sharp, 1882). Twenty two new species are described herein: Exocelina alexanderi sp. n., Exocelina anggiensis sp. n., Exocelina arfakensis sp. n., Exocelina bifida sp. n., Exocelina brahminensis sp. n., Exocelina bundiensis sp. n., Exocelina edeltraudae sp. n., Exocelina ekari sp. n., Exocelina eme sp. n., Exocelina evelyncheesmanae sp. n., Exocelina hansferyi sp. n., Exocelina irianensis sp. n., Exocelina kakapupu sp. n., Exocelina knoepfchen sp. n., Exocelina oceai sp. n., Exocelina pseudosoppi sp. n., Exocelina soppi sp. n., Exocelina unipo sp. n., Exocelina utowaensis sp. n., Exocelina waigeoensis sp. n., Exocelina weylandensis sp. n., and Exocelina wondiwoiensis sp. n. The lectotype of Copelatus politus Sharp, 1882 is designated. A checklist and identification key to all species of the group are provided and important diagnostic characters (habitus, color, male antennae and protarsomeres 4–5, median lobes and parameres) are illustrated. Data on the distribution and habitat requirements are given. Representatives of the Exocelina ekari-group are so far mostly known from lowland to lower montane habitats of the northern and central parts of New Guinea, the group is less diverse in higher altitudes.     

DNA barcoding for community ecology--how to tackle a hyperdiverse, mostly undescribed Melanesian fauna

Background

Trigonopterus weevils are widely distributed throughout Melanesia and hyperdiverse in New Guinea. They are a dominant feature in natural forests, with narrow altitudinal zonation. Their use in community ecology has been precluded by the “taxonomic impediment”.

Methodology/Principal Findings

We sampled >6,500 specimens from seven areas across New Guinea; 1,002 specimens assigned to 270 morphospecies were DNA sequenced. Objective clustering of a refined dataset (excluding nine cryptic species) at 3% threshold revealed 324 genetic clusters (DNA group count relative to number of morphospecies = 20.0% overestimation of species diversity, or 120.0% agreement) and 85.6% taxonomic accuracy (the proportion of DNA groups that “perfectly” agree with morphology-based species hypotheses). Agreement and accuracy were best at an 8% threshold. GMYC analysis revealed 328 entities (21.5% overestimation) with 227 perfect GMYC entities (84.1% taxonomic accuracy). Both methods outperform the parataxonomist (19% underestimation; 31.6% taxonomic accuracy). The number of species found in more than one sampling area was highest in the Eastern Highlands and Huon (Sørensen similarity index 0.07, 4 shared species); ⅓ of all areas had no species overlap. Success rates of DNA barcoding methods were lowest when species showed a pronounced geographical structure. In general, Trigonopterus show high α and β-diversity across New Guinea.

Conclusions/Significance

DNA barcoding is an excellent tool for biodiversity surveys but success rates might drop when closer localities are included. Hyperdiverse Trigonopterus are a useful taxon for evaluating forest remnants in Melanesia, allowing finer-grained analyses than would be possible with vertebrate taxa commonly used to date. Our protocol should help establish other groups of hyperdiverse fauna as target taxa for community ecology. Sequencing delivers objective data on taxa of incredible diversity but mostly without a solid taxonomic foundation and should help pave the road for the eventual formal naming of new species.     

Validation of a <Emphasis Type="Italic">Burkholderia pseudomallei</Emphasis> Hypothetical Protein and Determination of Its Translational Start Codon Using Chromosomal Integration of His-Tag Coding Sequence

In this post genomic era, there are a great number of in silico annotated hypothetical genes. However, experimental validation of the functionality of these genes remains tentative. Two of the major challenges faced by researcher are whether these hypothetical genes are protein-coding genes and whether their corresponding predicted translational start codons are correct. In this report, we demonstrate a convenient procedure to validate the presence of a hypothetical gene product of BPSS1356 from Burkholderia pseudomallei as well as its start codon. It was done by integration of a His-Tag coding sequence into C-terminal end of BPSS1356 gene via homologous recombination. We then purified the native protein using affinity chromatography. The genuine start codon of BPSS1356 was then determined by protein N-terminal sequencing.     

Australasian sky islands act as a diversity pump facilitating peripheral speciation and complex reversal from narrow endemic to widespread ecological supertramp

The Australasian archipelago is biologically extremely diverse as a result of a highly puzzling geological and biological evolution. Unveiling the underlying mechanisms has never been more attainable as molecular phylogenetic and geological methods improve, and has become a research priority considering increasing human‐mediated loss of biodiversity. However, studies of finer scaled evolutionary patterns remain rare particularly for megadiverse Melanesian biota. While oceanic islands have received some attention in the region, likewise insular mountain blocks that serve as species pumps remain understudied, even though Australasia, for example, features some of the most spectacular tropical alpine habitats in the World. Here, we sequenced almost 2 kb of mitochondrial DNA from the widespread diving beetle Rhantus suturalis from across Australasia and the Indomalayan Archipelago, including remote New Guinean highlands. Based on expert taxonomy with a multigene phylogenetic backbone study, and combining molecular phylogenetics, phylogeography, divergence time estimation, and historical demography, we recover comparably low geographic signal, but complex phylogenetic relationships and population structure within R. suturalis. Four narrowly endemic New Guinea highland species are subordinated and two populations (New Guinea, New Zealand) seem to constitute cases of ongoing speciation. We reveal repeated colonization of remote mountain chains where haplotypes out of a core clade of very widespread haplotypes syntopically might occur with well‐isolated ones. These results are corroborated by a Pleistocene origin approximately 2.4 Ma ago, followed by a sudden demographic expansion 600,000 years ago that may have been initiated through climatic adaptations. This study is a snapshot of the early stages of lineage diversification by peripatric speciation in Australasia, and supports New Guinea sky islands as cradles of evolution, in line with geological evidence suggesting very recent origin of high altitudes in the region.     

Helicobacter pylori–Positive Duodenal Ulcer: A Long-Term Double-Blind Randomized Study in Patients Healed with H2-Receptor Antagonists

Background. The NIH Consensus Conference in 1994 (1) concluded that all patients with peptic ulcr disease should be tested and treated for Helicobacter pylori and that further evaluation was needed for patients in remission.
Materials and Methods. We evaluated in a double blind randomization 30 patients whose duodenal ulcers had been healed with H₂-receptor antagonists and who remained in remission on maintenance therapy. After ulcer healing and the presence of H. pylori had been confirmed, these patients were randomized to receive eradication therapy or placebo and were followed for a mean period of 23 months.
Results. Almost all patients receiving placebo had ulcer recurrence, whereas the patients treated with antibiotics demonstrate a low recurrence rate.
Conclusion. These data suggest, for the first time to our knowledge, the importance of treating with antibiotics duodenal ulcer patients whose disease is in remission.