Comparative metagenomics approaches to characterize the soil fungal communities of western coastal region, Saudi Arabia.

A total of 145007 reads were obtained from pyrosequencing for all the 4 samples. The total count ranged from 11,301,014 (Mecca old road) to 23,503,512 bp (Thuwal). A total of 460 fungal species belonging to 133 genera, 58 families, 33 orders, 13 classes and 4 phyla was identified across the four sites. The most abundant phylum at all four sites was Ascomycota followed by Basidiomycota. Four phyla (Ascomycota-99.31%, Basidiomycota-0.59%, Chytridiomycota-0.04%, Glomeromycota-0.03%) were detected in Khulais. Except for Glomeromycota, all phyla were detected at Mecca old road (Ascomycota-74.26%, Basidiomycota-25.71%, Chytridiomycota-0.01%) and Thuwal (Ascomycota-99.59%, Basidiomycota-0.40%, Chytridiomycota-0.002%); while only Ascomycota-90.98% and Basidiomycota-9.01% were detected in Asfan road. At the class level, Sordariomycetes was predominantly observed at Asfan road-59.88%, Khulais-68.26% and Thuwal-94.84%; while Pezizomycetes was dominant at Mecca old road-56.01%, was absent at Asfan road. Agaricomycetes was present only at Mecca old road-25.73%; while Tremellomycetes-5.77%, Malasseizomycetes-2.13% and Microbotryomycetes-1.10% were found only at Asfan road. The phylogenetic trees revealed that clear genus level differences are visible across all the four sites, with an overall predominance of Thielavia followed by Madurella, Aspergillus, and Gelasinospora. Chaetomium sp., Aspergillus caespitosus and Aspergillus sp. were found in moderate (Mecca old road and Thuwal) to abundant (Asfan road and Khulais) quantities. Thielavia sp., Thielavia hyalocarpa and Madurella sp. are found in moderate quantities at Khulais and Mecca old road, while in abundant levels at Asfan road and Thuwal. Fusarium equisati and F. oxysporum were detected at Thuwal and Khulais. Sordaria araneosa was present at Khulais, while Malasseiza globosa species was detected in moderate quantities across all sites except Khulais.

The Impact of Silver Nanoparticles Produced by Bacillus pumilus As Antimicrobial and Nematicide.

This study evaluates the potential application of silver nanoparticles (AgNPs) as antimicrobial or nematicidal agents produced by the extremophile Bacillus pumilus, which was isolated from the alkaline Wadi El-Natrun Lake in Egypt. The AgNPs were characterized by ultraviolet-visible absorption spectroscopy, transmission electron microscopy, and energy dispersive x-ray spectroscopy. The size of AgNPs formed ranged from 20.12 to 29.48 nm. Panagrellus redivivus was exposed to different concentrations (0, 50, 100, 150, and 200 µg/mL) of AgNPs in a 5 mL nematode suspension (1 × 103 mL-1). The best result occurred at AgNP concentrations of 150 and 200 µg/mL, with death rates of 80 and 91%, respectively, following 48 h of exposure. AgNPs also exhibited potent antimicrobial properties when using Gram-negative and Gram-positive human pathogens, with MIC and MBC values of 5 and 10 µg/mL, respectively. These laboratory assays prove that biologically synthesized AgNPs are an ecofriendly material that can be used in lieu of solvents or toxic chemicals.

Influence of inoculation with plant growth promoting rhizobacteria (PGPR) on tomato plant growth and nematode reproduction under greenhouse conditions.

Numerous species of soil bacteria which flourish in the rhizosphere of plants or around plant tissues stimulate plant growth and reduce nematode population by antagonistic behavior. These bacteria are collectively known as PGPR (plant growth promoting rhizobacteria). The effects of six isolates of PGPR Pseudomonas putida, Pseudomonas fluorescens, Serratia marcescens, Bacillus amyloliquefaciens, Bacillus subtilis and Bacillus cereus, were studied on tomato plant growth and root knot nematode reproduction after 45 days from nematode infection. The highest number of shoot dry weight/g (43.00 g) was detected in the plant treated with S. marcescens; then P. putida (34.33 g), B. amyloliquefaciens (31.66 g), P. fluorescens (30.0 g), B. subtilis (29.0 g), B. cereus (27.0 g) and nematode alone (untreated) 20 g/plant. While the highest number of plant height was observed when plant was treated with S. marcescens, P. fluorescens, P. putida, B. amyloliquefaciens and P. putida 52.66, 50.66, 48 and 48 cm respectively. No significant differences were seen between previous treatments but only had significant differences compared with untreated plant. The highest number of fruit/plant was observed when plants were treated with S. marcescens (10.66), then B. amyloliquefaciens (8.66), P. putida (8), P. fluorescens (8) and B. cereus (7.66). No significant differences between the last 4 treatments, but all had significant differences compared with untreated plants. The highest weight of plant yield (g) was observed with S. marcescens (319.6 g/plant) and the lowest weight of plant yield was observed in plants treated with nematode alone (untreated). On the other hand, the lowest numbers of J2/10 g of soil (78), galls/root, (24.33) galls/root, egg masses/root (12.66) and egg/egg masses were observed in the plants treated with S. marcescens.