Paul Devos

Polyphasic characterization of Bacillus coagulans strains, illustrating heterogeneity within this species, and emended description of the species.

Because of its food spoiling capacity on the one hand and its significant role in the production of industrially valuable products on the other, Bacillus coagulans is of economic concern. Several studies have revealed a great deal of diversity within the species and this has led to a number of taxonomic adjustments. The present study aims to clarify the diversity within Bacillus coagulans sensu stricto and determine the taxonomic status of the species. Therefore, a polyphasic study was performed on a set of B. coagulans strains from diverse habitats. Techniques as ARDRA, SDS-PAGE of whole cell proteins, FAME analysis, routine phenotypic tests and rep-PCR illustrate considerable intra-species heterogeneity, while 16S rDNA sequence comparison and DNA-DNA relatedness support the accommodation of these strains in one species. Although most techniques demonstrate appreciable heterogeneity among the Bacillus coagulans strains, the intraspecies groupings are not consistent throughout all the methods applied and are not supported by any economic, historic or practical traits. Therefore, a division in subspecies seems inappropriate. In attempt to achieve a better species delineation, an emended description of Bacillus coagulans is included.

Dickeya aquatica sp. nov., isolated from waterways.

Pectinolytic Gram-negative bacteria were isolated from different waterways in the UK and Finland. Three strains (174/2(T), 181/2 and Dw054) had the same 16S rRNA gene sequences which shared 99% sequence similarity to species of the genus Dickeya, and a phylogeny of related genera confirmed attribution to this genus. Fatty acid profile analysis of all three strains found a high proportion of C16 : 1ω7c/C16 : 1ω7c and C16 : 0 fatty acids, and library profile searches found closest matches to Dickeya chrysanthemi. Production of a concatenated phylogeny using six loci, recA, gapA, atpD, gyrB, infB and rpoB, provided a high-resolution phylogeny which placed strains 174/2(T) and 181/2 as a distinct clade, separated from the other species of the genus Dickeya by a relatively long branch-length. DNA-DNA hybridization analysis with a limited number of reference species also supported the distinctiveness of strains 174/2(T) and 181/2 within the genus Dickeya. All three strains could be phenotypically distinguished from other species of the genus by fermentation of melibiose and raffinose but not D-arabinose or mannitol. The name Dickeya aquatica sp. nov. is proposed for the new taxon; the type strain is 174/2(T) (u200a= NCPPB 4580(T)u200a= LMG 27354(T)).

Does sociality imply a complex vocal communication system? A case study for Fukomys micklemi (Bathyergidae, Rodentia)

African mole-rats (Bathyergidae) display different levels of sociality, ranging from solitary to eusocial. To integrate individuals into a social group, communication is necessary. In this study, we examined vocalizations of a social bathyergid, Fukomys micklemi, in order to investigate the relationship between sociality and communication. Because of its social organization and subterranean lifestyle, we expected this species to have an extensive vocal repertoire. Fifteen different adult specific call-types and four juvenile specific call-types could be recognized, similar to those in other social species. A new call-category, linked to submissive behaviour, is described. These submissive calls were exclusively observed in males, indicating their subordinance. The vocal repertoire of F. micklemi was compared with published results on vocalizations in other subterranean rodents, both in social and solitary species. This comparison confirmed the observation that the vocal repertoire of social species is not only more extensive, but also more diverse than that of solitary species.

Exploiting the dependency of the doppler spectrum on the position and insonation direction of an intra-vascular doppler wire to estimate volumetric flow

Until now, there are no clinically useful minimally invasive techniques for continuously monitoring regional arterial blood flow. Commercial intra-vascular Doppler wire (IVDW) pulsed wave systems only estimate flow velocities and are highly dependent on wire position. Measurement of true volumetric arterial flow (Q) requires the flow velocity distribution over the cross-sectional area (CA) of the vessel. We modeled the dependency of the power density spectrum (PDS) at different range gate (RG) on the position of the wire in a cylindrical tube. Q was estimated by fitting the modeled to the measured PDS. This methodology was tested in-vitro. Methods: Setup: Pulsatile flow was generated in silicon tubes (diameters: 3 and 4mm) and time collected flow (TCF) was recorded. We used a FloMap system (Volcano Therapeutics, USA) equipped with a .014 IVDW (12MHz). From the Doppler signals at different RG (4-10mm) the normalized PDS at peak flow was estimated as a function of frequency and RG. Spectral model: The model contained 5 free parameters: vessel diameter (R), velocity distribution (parabolic (p0=2) to blunted (p0=∞)), wire position (offset from vessel center) and insonation direction (two angles). The maximal flow velocity was calculated from the wire position, insonation direction, velocity distribution, and the measured peak velocity (vmax). From the resulting velocity distribution in the RG of the beam the normalized PDS was calculated. Flow estimation: By fitting the model to the measured normalized PDS, the free parameters were estimated. Q was estimated at each point in the cycle from the vmax, R and velocity distribution. The temporal average of Q (Qavg) was compared to TCF. Results: There was a reasonable correlation between TCF and Qavg (r = 0.82, p = 0.001). In the 3mm tube the estimated R was 3.22 ± 0.78mm and in the 4mm tube R was 4.26 ± 0.34mm. The velocity distribution was estimated as p0 = 2.23 ± 0.30.

Using a Doppler wire to measure intravascular flow

There is a medical need to continuously monitor the flow of blood towards organs, for instance in the situation of sceptic shock in the intensive care unit. Commercially available Doppler flow wire systems allow assessment of instantaneous peak flow velocity (IPV) in a sample volume. However, for blood flow measurements, assessment of mean flow velocity (averaged over the vessel cross section) is more appealing. Jenni et al. recently developed a method for simultaneous calculation of the mean flow velocity and the cross-sectional area with a Doppler flow wire in coronaries, making use of the fact that the Doppler beam widens with distance Jenni et al. (2000). The long term purpose of our investigation is to expand the applicability of this method in larger blood vessels. In this study, we report intermediate results focused on the processing of Doppler audio data obtained from a commercially available Doppler flow wire system (FloMap, Volcano Therapeutics, Inc., Rancho Cardova, CA, USA) for assessment of flow characterising parameters. Tests were performed in an in vitro setup.