Heavy metal tolerant Pseudomonas protegens isolates from agricultural well water in northeastern Algeria with plant growth promoting, insecticidal and antifungal activities

The application of plant growth promoting bacteria (PGPB) with biocontrol activities as inoculants of crop plants against phytopathogenic fungi and insect pests provide a biological alternative to the use of agrochemicals. Two Pseudomonas protegens strains were isolated from agricultural well water in a heavy metal contaminated area near Bejaia, northeastern Algeria. The isolates S4LiBe and S5LiBe had 16S rRNA gene sequence similarities of 99.4%–99.7% with P. protegens CHA0T and other P. protegens strains. The phenotypic profiles tested with BIOLOG-GN2-microplates showed differences in 12 of 95 carbon sources tested, as compared to the type strain P. protegens CHA0T. The isolates S4LiBe and S5LiBe showed plant growth promoting potential which is commonly associated with the production of the phytohormone indole acetic acid and siderophores and the solubilization of insoluble phosphate. In addition, they produce chitinase and other polymer degrading enzymes. As the strains S4LiBe and S5LiBe were isolated from heavy metal polluted well water, they are resistant against several heavy metals (2.0 mM K2Cr2O7 and 3.0 mM CoSO4, HgSO4, CdSO4 8H2O and PbCl2), while the reference strain P. protegens CHA0T was very sensitive to Hg2+ and Cd2+ and had lower tolerance towards Co2+ and Pb2+. The isolates S4LiBe and S5LiBe were active in mycelial growth inhibition assays against Botrytis cinerea, Verticillium dahliae, Fusarium graminearum, Aspergillus niger and Aspergillus flavus (growth inhibition between 88% and 48%). Furthermore, S4LiBe and S5LiBe showed effective insecticidal activities, when tested in the Galleria injection assay and they were tested positive for the insect toxin gene fitD alike the reference strain CHA0T. Finally, inoculation of barley seeds with S5LiBe in non-polluted agricultural soil significantly stimulated the germination rate and growth of seedlings, with increased shoot length (11.96 cm ± 0.59), shoot and root fresh weight (0.10 g ± 0.009, 0.04 g ± 0.006), shoot and root dry weight (0.075 g ± 0.003, 0.03 g ± 0.007) as compared to non-inoculated plants (10.23 cm ± 0.84, 0.06 g ± 0.007, 0.025 g ± 0.006, 0.047 g ± 0.006, and 0.016 g ± 0.004, respectively). In heavy metal contaminated soil, inoculation with strain S5LiBe resulted in similar increase of germination rate and growth parameters of barley like in the non-polluted soil, while P. protegens CHA0T inoculated plants were not stimulated. Thus, the heavy metal tolerant isolates S4LiBe and S5LiBe have a potential as beneficial bacteria for agricultural application even in heavy metal polluted soils, e.g. for the stimulation of biomass crops. The demonstration of successful isolation from agricultural well water may open more ready access for a wide variety of this kind of beneficial bacteria for agricultural application

Pb-doped CuO thin films synthetized by sol-gel method

Abstract Sol-gel thin films of undoped CuO and Pb-doped CuO were deposited using the spin coating method. In three thin layers, the lead was introduced at two different concentrations (5 and 7%). The films produced were in the tenorite phase, with high purity and crystallinity, according to XRD structural characterization. The grain size of CuO films is affected by the Pb concentration and decreases as the Pb concentration increases, although the strain and dislocation density values ​​increase as the Pb doping ratio increases. The structure of CuO was confirmed in all films by Raman and FTIR studies. In the presence of Pb dopants, SEM examinations revealed cubic and spherical nanostructured surfaces. With the value of the optical band gap increasing from 1.92 to 2.74 eV, there was a significant association between increasing Pb doping concentration and widening of the optical band gap.</jats:p

Composition of the Essential Oil of Leaves and Berries of Algerian Myrtle (Myrtus comunis L.)

Myrtus communis L. essential oils were obtained by hydrodistillation, and the yields were 0.3% (w/w) and 0.1% for leaves and berries, respectively. Using GC and GC/ MS techniques, twenty five components were identified in berry oil representing 89.5% of the oil composition. Linalool was the major compound in berry oil (36.2%) followed by estragole (18.4%) and 1,8-cineole (11.4%). Leaf oil was composed of 28 compounds representing 95.4% of the total composition of the oil. α-pinene was the major constituent of leaf oil at concentration of (46.9%), followed by 1,8-cineole (25.2%). The two Algerian oils were characterized by the lack of myrtenyl acetate

Impact of Diazotrophic Bacteria on Germination and Growth of Tomato, with Bio-control Effect, Isolated from Algerian Soil

Abstract: 10 soils samples were collected from the west region of Bejaia-Algeria in aseptic conditions. The preliminary germination test on tomatos seeds allowed screening of 4 simples from which 40 different colonies were isolated and purified. These last were submitted to in vitro germination test, while 20 strains with an inductor effect on the germination were selected and tested for the presence of stimulator effect of growth of tomato in vivo. Biochemical (on API 50 CHB/E gallery), and phylogenetic (DNAr 16S sequencing) identification, tests researching characteristics promoting plant growth (production of IAA (Indol Acetic Acid) phytohormone, enzymes, siderophores, free nitrogen fixation, and an antagonistic test on five phytopathogenic fungi (Botrytis cinerea; Phytophtora cactorum, phytophtora cinnamomi; Fusarium oxysporum and Verticillium dahliae) were applied for the strain showing positive in vivo germination results on tomato.The results of this last test led to select four strains: S11, S6, S15, and S12 that greatly affected tomato growth, with stems length (cm) of 9.212, 9.280, 9.362 and 9.858, respectively, compared to the control (6.400). Biochemical and phylogenic identifications of these strains allowed to affiliate them as following: Arthrobacter agilis (S6), Streptomyces Sp (S11), Bacillus sp13 (S15) and Mycobacterium Sp (S12). The four strains produced several enzymes, high indol acetic acid (phytohormone) quantity (mg/l: 38.47 (S11); 86.90 (S6); 93.96 (S12) and 190.23 (S15), siderophores, nitrogen fixing. It also showed an antagonistic activity against the phytopathogenic fungi tested with variable plant growth inhibition (PGI) %:0-78.51% for Bacillus sp13; 29-74%for Streptomyces sp; 0-72%for Arthrobacter agilis; and 0-69% for Mycobacterium sp. These results prove that the strains are compatible for tomato growth stimulation

Growth stimulation of barley and biocontrol effect on plant pathogenic fungi by a <em>Cellulosimicrobium</em> sp. strain isolated from salt-affected rhizosphere soil in northwestern Algeria.

The plant growth promoting effect of bacterial isolates from salt-affected agricultural rhizospheric soil from Bejaia, Algeria, on barley seedlings as well as biological control abilities of these isolates against phytopathogenic fungi were determined. Four isolates stimulated significantly germination and growth of barley seedlings in an axenic test system and in soil pots. Isolate S16 (Cellulosimicrobium sp.) stimulated the growth of barley seedlings by 185% (stem height of 13.0&plusmn;0.11cm) over non-inoculated control seedlings (7.0&plusmn;0.12cm). Cellulosimicrobium sp. S16 was found also superior in mycelial growth inhibition assays against the plant pathogenic fungi Botrytis cinerea, Fusarium oxysporum and Verticillium dahliae. Furthermore, several plant growth promoting traits (production of indole acetic acid, inorganic phosphate solubilization, siderophore production) and production of enzymes beneficial for soil fertility (protease, chitinase, amylase and urease) were identified. However, no evidence for nitrogen fixation was found by testing acetylene reduction and the presence of nif-genes. Based on comparative sequence analysis of almost full length 16S-rRNA coding gene fragments, Cellulosimicrobium sp. S16 exhibits the highest similarity of 99.7% to Cellulosimicrobium cellulans (accession number AY665978). Cellulosimicrobium sp. S16 could be a successful candidate for the application as a plant growth promoting inoculant