Gordonia pseudamarae sp. nov., a home for novel actinobacteria isolated from stable foams on activated sludge wastewater treatment plants.

The taxonomic status of two Gordonia strains, designated BEN371 and CON9T, isolated from stable foams on activated sludge plants was the subject of a polyphasic study which also included the type strains of Gordonia species and three authenticated Gordonia amarae strains recovered from such foams. Phylogenetic analyses of 16S rRNA gene sequences showed that these isolates formed a compact cluster suggesting a well-supported lineage together with a second branch containing the G. amarae strains. A phylogenomic tree based on sequences of 92 core genes extracted from whole genome sequences of the isolates, the G. amarae strains and Gordonia type strains confirmed the assignment of the isolates and the G. amarae strains to separate but closely associated lineages. Average nucleotide index (ANI) and digital DNA-DNA hybridisation (dDDH) similarities showed that BEN371 and CON9T belonged to the same species and had chemotaxonomic and morphological features consistent with their assignment to the genus Gordonia. The isolates and the G. amarae strains were distinguished using a range of phenotypic features and by low ANI and dDDH values of 84.2 and 27.0 %, respectively. These data supplemented with associated genome characteristics show that BEN371 and CON9T represent a novel species of the genus Gordonia. The name proposed for members of this taxon is Gordonia pseudamarae sp. nov. with isolate CON9T (=DSM 43602T=JCM 35249T) as the type strain.

Draft Genome Sequence of Enterobacter asburiae NCR1, a Plant Growth-Promoting Rhizobacterium Isolated from a Cadmium-Contaminated Environment.

Enterobacter asburiae NCR1 is a plant growth-promoting rhizobacterium isolated from the rhizosphere of Carpobrotus rossii. We report the draft genome sequence of E. asburiae strain NCR1, which revealed many genes facilitating beneficial interactions with plant hosts.

Lytic Bacteriophage EFA1 Modulates HCT116 Colon Cancer Cell Growth and Upregulates ROS Production in an Enterococcus faecalis Co-culture System.

Enterococcus faecalis is an opportunistic pathogen in the gut microbiota that's associated with a range of difficult to treat nosocomial infections. It is also known to be associated with some colorectal cancers. Its resistance to a range of antibiotics and capacity to form biofilms increase its virulence. Unlike antibiotics, bacteriophages are capable of disrupting biofilms which are key in the pathogenesis of diseases such as UTIs and some cancers. In this study, bacteriophage EFA1, lytic against E. faecalis, was isolated and its genome fully sequenced and analyzed in silico. Electron microscopy images revealed EFA1 to be a Siphovirus. The bacteriophage was functionally assessed and shown to disrupt E. faecalis biofilms as well as modulate the growth stimulatory effects of E. faecalis in a HCT116 colon cancer cell co-culture system, possibly via the effects of ROS. The potential exists for further testing of bacteriophage EFA1 in these systems as well as in vivo models.

Characterization of Novel Lytic Bacteriophages of Achromobacter marplantensis Isolated from a Pneumonia Patient.

Achromobacter spp. are becoming increasingly associated with lung infections in patients suffering from cystic fibrosis (CF). A. marplatensis, which is closely related to A. xylosoxidans, has been isolated from the lungs of CF patients and other human infections. This article describes the isolation, morphology and characterization of two lytic bacteriophages specific for an A. marplatensis strain isolated from a pneumonia patient. This host strain was the causal agent of hospital acquired pneumonia-the first clinical report of such an occurrence. Full genome sequencing revealed bacteriophage genomes ranging in size from 45901 to 46,328 bp. Transmission electron microscopy revealed that the two bacteriophages AMA1 and AMA2 belonged to the Siphoviridae family. Host range analysis showed that their host range did not extend to A. xylosoxidans. The possibility exists for future testing of such bacteriophages in the control of Achromobacter infections such as those seen in CF and other infections of the lungs. The incidence of antibiotic resistance in this genus highlights the importance of seeking adjuncts and alternatives in CF and other lung infections.

Haemoglobin degradation underpins the sensitivity of early ring stage Plasmodium falciparum to artemisinins.

Current first-line artemisinin antimalarials are threatened by the emergence of resistant Plasmodium falciparum. Decreased sensitivity is evident in the initial (early ring) stage of intraerythrocytic development, meaning that it is crucial to understand the action of artemisinins at this stage. Here, we examined the roles of iron (Fe) ions and haem in artemisinin activation in early rings using Fe ion chelators and a specific haemoglobinase inhibitor (E64d). Quantitative modelling of the antagonism accounted for its complex dependence on the chemical features of the artemisinins and on the drug exposure time, and showed that almost all artemisinin activity in early rings (>80%) is due to haem-mediated activation. The surprising implication that haemoglobin uptake and digestion is active in early rings is supported by identification of active haemoglobinases (falcipains) at this stage. Genetic down-modulation of the expression of the two main cysteine protease haemoglobinases, falcipains 2 and 3, renders early ring stage parasites resistant to artemisinins. This confirms the important role of haemoglobin-degrading falcipains in artemisinin activation, and shows that changes in the rate of artemisinin activation could mediate high-level artemisinin resistance.

Melittin peptides exhibit different activity on different cells and model membranes.

Melittin (MLT) is a lytic peptide with a broad spectrum of activity against both eukaryotic and prokaryotic cells. To understand the role of proline and the thiol group of cysteine in the cytolytic activity of MLT, native MLT and cysteine-containing analogs were prepared using solid phase peptide synthesis. The antimicrobial and cytolytic activities of the monomeric and dimeric MLT peptides against different cells and model membranes were investigated. The results indicated that the proline residue was necessary for antimicrobial activity and cytotoxicity and its absence significantly reduced lysis of model membranes and hemolysis. Although lytic activity against model membranes decreased for the MLT dimer, hemolytic activity was increased. The native peptide and the MLT-P14C monomer were mainly unstructured in buffer while the dimer adopted a helical conformation. In the presence of neutral and negatively charged vesicles, the helical content of the three peptides was significantly increased. The lytic activity, therefore, is not correlated to the secondary structure of the peptides and, more particularly, on the propensity to adopt helical conformation.