Moustafa Y. El-Naggar

In vitro antagonistic activity, plant growth promoting traits and phylogenetic affiliation of rhizobacteria associated with wild plants grown in arid soil

The role of plant growth-promoting rhizobacteria (PGPR) in adaptation of plants in extreme environments is not yet completely understood. For this study native bacteria were isolated from rhizospeheric arid soils and evaluated for both growth-promoting abilities and antagonistic potential against phytopathogenic fungi and nematodes. The phylogentic affiliation of these representative isolates was also characterized. Rhizobacteria associated with 11 wild plant species from the arid soil of Almadinah Almunawarah, Kingdom of Saudi Arabia (KSA) were investigated. From a total of 531 isolates, only 66 bacterial isolates were selected based on their ability to inhibit Fusarium oxysporum, and Sclerotinia sclerotiorum. The selected isolates were screened in vitro for activities related to plant nutrition and plant growth regulation as well as for antifungal and nematicidal traits. Isolated bacteria were found to exhibit capabilities in fix atmospheric nitrogen, produce ammonia, indoleacetic acid (IAA), siderophores, solubilize phosphate and zinc, and showed an antagonistic potential against some phytopathogenic fungi and one nematode species (Meloidogyne incognita) to various extent. Isolates were ranked by their potential ability to function as PGPR. The 66 isolates were genotyped using amplified rDNA restriction analysis (ARDRA) and 16S rRNA gene sequence analysis. The taxonomic composition of the representative genotypes from both rhizosphere and rhizoplane comprised Bacillus, Enterobacter and Pseudomonas. Out of the 10 genotypes, three strains designated as PHP03, CCP05, and TAP02 might be regarded as novel strains based on their low similarity percentages and high bootstrap values. The present study clearly identified specific traits in the isolated rhizobacteria, which make them good candidates as PGPR and might contribute to plant adaption to arid environments. Application of such results in agricultural fields may improve and enhance plant growth in arid soils.

Synthesis, characterization and the antimicrobial activity of new eco-friendly ionic liquids

A green microwave-assisted procedure for the preparation of a series of 24 new 1-alkyl-3-ethylimidazolium ionic liquids with different functional groups in the alkyl chain is described. Moreover, the synthesis of a variety of ten new geminal dicationic ionic liquids is reported. Their structures were characterized by FT-IR, (1)H NMR, (13)C NMR, (11)B, (19)F, (31)P, and mass spectrometry. Several ionic liquids were selected for antimicrobial activity studies, yielding very interesting and promising results.

Critical factors affecting the adherence of Candida albicans to the vaginal epithelium

Abstract A clinical isolate (Candida albicans) was collected from diagnosed cases as vaginal candidiasis. Identification of this isolate was previously reported [11] using both API 20C kit and real-time PCR assay. Adherence of C. albicans to the vaginal epithelium was evaluated. C. albicans recorded the highest rate (63.00%) of adherence among all collected isolates and recorded the highest record for the number (131.00) of adhered yeast cells (data not shown). The evaluation of the critical factors affecting the adherence process revealed that the maximum adherence values were recorded for a logarithmic phase-culture grown at 25 °C, incubation temperature of 37 °C in phosphate buffer saline adjusted at pH 5. Moreover, the adherence pattern of C. albicans cells to the vaginal epithelium was visualized by the scanning electron microscopy (SEM).

Molecular diagnosis of Candida albicans using real-time polymerase chain reaction of a CaYST1 gene

Abstract Candida albicans is an opportunistic pathogen that causes infections in immuno-compromised individuals. Virulence of this organism is a function of a multiplicity of factors working jointly to overwhelm the host defenses. From a previous study, the in vitro adherence capabilities of seven isolates (collected from patients suffering vaginitis) to vaginal epithelial cells were tested. Isolate No. 2 recorded the highest adherence ability. In this part of work, Real-time PCR assay was applied for the identification of isolate No. 2. This isolate could be discriminated by species-specific primers, deduced from the intron nucleotide sequence of the C. albicans CaYSTl gene. To confirm that the isolated strain is a fungal strain, the universal fungal primers (ITS5 and ITS4) were used to amplify the complete internal transcribed spacer (ITS) region including the 5.8S ribosomal gene that is present in all fungi. The ITS region was successfully amplified from the tested yeast, provided a single PCR product of approximately 520 bp. In another run, a single pair of specific primers [Intron Nucleotide Sequence (INT1 and INT2)] was then used to amplify the intron nucleotide sequence of the CaYST1 gene, which present only in C. albicans. The generated amplified product gave the expected single band of 310 bp. The melting points of all PCR products were routinely determined. The results showed that the melting temperatures for the tested isolate and the reference strain of C. albicans (ATCC 10231) using ITS5 and ITS4 primers were 80.09°C and 83.99°C, respectively, while they were 80.78°C and 80.10°C using INT1 and INT2 when assayed individually. Based on their very close melting profiles, the tested isolate proved to be identical to C. albicans reference strain. These results supported the idea of using genes containing intron sequences to design species-specific primers for the identification of fungal strains by real time PCR.

Statistically optimized ceftriaxone sodium biotransformation through Achromobacter xylosoxidans strain Cef6: an unusual insight for bioremediation

The present study underlines a unique promising approach toward efficient biotransformation of ceftriaxone sodium (Ceftx), a highly frequent prescribed cephalosporin antibiotic, by a newly bacterium namely Achromobacter xylosoxidans strain Cef6 isolated from Ceftx contaminated raw materials in pharmaceutical industries. A three step sequential statistical‐mathematical approach (Plackett‐Burman design [PBD], Central Composite Design [CCD], and ridge‐canonical analyses) was anticipated to optimize the biotransformation process. Ceftx concentration and medium volume: bottle volume ratio, two key determinants, significantly (p < 0.05) affected the process outcome deduced by regression analysis of PBD’ data. CCD and ridge‐canonical analyses localized the optimal levels of Ceftx concentration and medium volume: 250 ml bottle volume ratio to be 0.39 and 7.973 g Ceftx/L modified tryptic soy broth achieving Ceftx biotransformation (100%) after 39 h under aerobic static conditions at 30 °C, irrespectively deduced via HPLC analysis. Impressively, only one of five Ceftx byproducts was detected by the end of the biotransformation process. To the best of authors’ knowledge, this is the first report addressing a detailed study regarding efficient biotransformation of Ceftx by single bacterium not bacterial consortium under aerobic conditions. Present data would greatly encourage applying this approach for decontamination of some Ceftx contaminated environmental sites.