Identification of flea species using MALDI-TOF/MS

In the present study, a molecular proteomics (MALDI-TOF/MS) approach was used as a tool for identifying flea vectors. We measured the MS spectra from 38 flea specimens of 5 species including Ctenocephalides felis, Ctenocephalides canis, Archaeopsylla erinacei, Xenopsylla cheopis and Stenoponia tripectinata. A blind test performed with 24 specimens from species included in a library spectral database confirmed that MALDI-TOF/MS is an effective tool for discriminating flea species. Although fresh and 70% ethanol-conserved samples subjected to MALDI-TOF/MS in blind tests were correctly classified, only MS spectra of quality from fresh specimens were sufficient for accurate and significant identification. A cluster analysis highlighted that the MALDI Biotyper can be used for studying the phylogeny of fleas.     

Fungal colonization of phyllosphere and litter of<Emphasis Type="Italic"> Quercus rotundifolia</Emphasis> Lam. in a holm oak forest (High Atlas,Morocco)

The microfungal flora of holm oak living, senesced and litter leaves was studied at five different stages of decomposition using three different isolation methods. Holm oak leaves are first colonized on the tree by a variety of primary saprophytes such as Trichothecium, Aureobasidium, Cladosporium, Epicoccum and Alternaria. After leaf fall there is an intensive development of the fungal flora, including both species already present in the phyllosphere and new colonizers from the litter layer. With increasing decomposition initial colonizers gradually disappear, being replaced by other forms. When all isolation methods were pooled, maximum biodiversity (species richness) of the fungus flora was observed during the first three stages of leaf litter decomposition, but strong variation occurred according to the isolation method. Sterilization of the leaf material revealed that a number of fungal strains were present inside the holm oak leaves before abscission, increasing from living to senescent stages, and that a strong decrease in the internal colonization of leaf litter was observed at late decomposition stages.     

Composition and antibacterial activity of Pseudocytisus integrifolius (Salisb.) essential oil from Algeria

The essential oil composition of an endemic Algerian Cruciferae, Pseudocytisus integrifolius (Salisb.) Rehder, was analyzed by gas chromatography (GC) and GC-mass spectrometry (MS). Eighty-three components representing more than 96.5% of the oil were identified. The major components were dimethyl disulfide (33.4%), dimethyl trisulfide (24.2%), and an unsaturated nitrile (31.7%). Fractionation on a silica gel column led to the identification of trace-level compounds, in particular, polar compounds such as nitriles and aldehydes, and to the isolation of dimethyl disulfide, dimethyl trisulfide, and an unsaturated nitrile. Structural analysis using high-resolution mass spectrometry (HRMS) and 1H,13C NMR techniques enabled the identification of pent-4-enenitrile. Variation in essential oil composition and yields was studied according to harvesting time, drying, and parts of the plant. The essential oil of aerial parts was tested for its antibacterial activity using a paper disk method. The oil was effective on the inactivation of Escherichia coli and Pseudomonas aeruginosa and ineffective on the inactivation of Staphylococcus aureus.     

Feeding preferences of the collembolan Onychiurus sinensis for fungi colonizing holm oak litter (Quercus rotundifolia Lam.)

Ten fungi isolated from decaying holm oak leaves (Quercus rotundifolia Lam.) have been presented to the collembolan species Onychiurus sinensis (Hexapoda). The attractiveness and selectivity of the ten fungi was investigated taken into account the effect of the substrate on which the fungus was growing (malt-agar or litter) and the effect of fungal odour. Furthermore, moulting, growth, survival and reproduction of O. sinensis in the presence of each of the ten test fungi were studied. Mucor plumbeus and Trichothecium roseum were the most preferred whatever the culture substrate and their odour was the most attractive. Two fungi (Penicillium spinulosum and the Basidiomycete S41) attracted Collembola by their odour but were not preferred as food sources. The animals could survive and reproduce on a mono-diet of several of our test fungi, but not on the Basidiomycete S41 and on Trichoderma polysporum.     

Effect of Capsicum annuum cultivated in sub-alkaline soil on bacterial community and activities of cultivable plant growth promoting bacteria under field conditions

In literature, it remains little explored the soil–plant relationships within Capsicum agroecosystem. We studied how chili peppers plants contribute to influence microbial diversity. Across the bulk and rhizosphere soils of three genotypes of Capsicum annuum, the structure, the diversity and the abundance of bacteria was evaluated by means of DNA-based culture-independent approach. Furthermore, 515 bacterial strains isolated from the bulk and rhizosphere soil, were used to investigate the effect of C. annuum on four plant growth promoting bacteria (PGPB) abilities. Our results indicated that the three genotypes influence differently the physical-chemical and microbial properties of soil around the roots. Bacterial abundance resulted in increasing with different trend rhizospheres to bulk soil ratio; however, bacterial diversity was significantly higher only in the rhizosphere of one genotype. Only the indolic compounds production was stimulated in the rhizosphere of the three cultivars. Inhibition of Fusarium oxysporum was stimulated just with one genotype, where 53 of rhizosphere isolates showed more than 10% of inhibition. 165 of isolates produced siderophores and the major part belonged to the high production level. Interactions between PGPB features revealed that anti-phytopathogenic activity was not associated with the others characteristics; however, phosphate solubilization was associated with both siderophores and indolic compounds productions.     

Soil animal communities in holm oak forests: influence of horizon, altitude and year

Soil animals (macro and microarthropods, annelids, nematodes) were sampled along an altitudinal gradient and over 2 years in holm oak (Quercus rotundifolia) forests of the Moroccan Atlas. We studied the influence of elevation and year on the vertical distribution of soil fauna. Whatever the elevation (1500, 1700 and 1900 m), the humus form was a Dysmull, with a thick litter horizon and a fine crumb A horizon. Thirty-six categories of fauna were found and classified at the group level. The influence of horizon, altitude and year was analysed by analyses of variance (ANOVA, on seven broad zoological groups and on total fauna) and correspondence analysis (on 36 zoological groups). There was a decrease in the population size of most zoological groups from organic (OL, OF) to mineral horizons (A, S), but OL and OF horizons varied as the most populated horizon according to years and animal groups. More animals and more animal groups were present at higher elevation, following an increase in food and habitat availability.