Hussein H. Abulreesh

Wild birds and human pathogens in the context of ringing and migration

Wild birds carry a diversity of micro‐organisms that are pathogenic to humans, may be transmitted over long distances during migrations, and are potentially transmissible to people who handle and ring birds. High‐profile diseases that are associated with carriage by birds include avian influenza, West Nile fever, and Lyme disease. Also potentially important is the existence of an avian reservoir of bacteria that are enteric human pathogens; for example species of Campylobacter and Salmonella, and toxin‐producing strains of Escherichia coli. Wild birds have been implicated in the transfer of these enteric pathogens to people. The subject of wild birds as potential reservoirs of pathogens that may be transmitted to humans in the context of ringing and migration is reviewed and it is recommended that appropriate precautions to minimise risk should be taken during and subsequent to the handling of wild birds.

Leaf Extracts of Mangifera indica L. Inhibit Quorum Sensing – Regulated Production of Virulence Factors and Biofilm in Test Bacteria

Quorum sensing (QS) is a global gene regulatory mechanism in bacteria for various traits including virulence factors. Disabling QS system with anti-infective agent is considered as a potential strategy to prevent bacterial infection. Mangifera indica L. (mango) has been shown to possess various biological activities including anti-QS. This study investigates the efficacy of leaf extracts on QS-regulated virulence factors and biofilm formation in Gram negative pathogens. Mango leaf (ML) extract was tested for QS inhibition and QS-regulated virulence factors using various indicator strains. It was further correlated with the biofilm inhibition and confirmed by electron microscopy. Phytochemical analysis was carried out using ultra performance liquid chromatography (UPLC) and gas chromatography–mass spectrometry (GC-MS) analysis. In vitro evaluation of anti-QS activity of ML extracts against Chromobacterium violaceum revealed promising dose-dependent interference in violacein production, by methanol extract. QS inhibitory activity is also demonstrated by reduction in elastase (76%), total protease (56%), pyocyanin (89%), chitinase (55%), exopolysaccharide production (58%) and swarming motility (74%) in Pseudomonas aeruginosa PAO1 at 800 μg/ml concentration. Biofilm formation by P. aeruginosa PAO1 and Aeromonas hydrophila WAF38 was reduced considerably (36–82%) over control. The inhibition of biofilm was also observed by scanning electron microscopy. Moreover, ML extracts significantly reduced mortality of Caenorhabditis elegans pre-infected with PAO1 at the tested concentration. Phytochemical analysis of active extracts revealed very high content of phenolics in methanol extract and a total of 14 compounds were detected by GC-MS and UPLC. These findings suggest that phytochemicals from the ML could provide bioactive anti-infective and needs further investigation to isolate and uncover their therapeutic efficacy.

Characterization of Insecticidal Genes of Bacillus thuringiensis Strains Isolated from Arid Environments

This study aimed at characterizing the insecticidal genes of eight Bacillus thuringiensis isolates that were recovered from the local environment of western Saudi Arabia. The screening for the presence of lepidopteran-specific cry1A family and vip3A genes, dipteran-specific cry4 family and coleopteran-specific cry3A, vip1A and vip2A genes, was carried out by PCR. All eight isolates produced PCR products that confirmed the presence of cry1Aa, cry1Ab, cry1Ac, cry4A, cry4B genes, but not cry3A, vip1A and vip2A genes. However, three isolates only were found to carry vip3A genes as revealed by PCR. The observation of cry1 and cry4 genes suggests that these eight isolates may have dual activity against Lepidoptera and Diptera species, while three isolates possessed vip3 genes in addition to cry1 and cry4 which suggests that these three isolates have toxic crystals and vegetative proteins. The results of this study are interesting in the sense that they may help developing new strategies for controlling insects of economic and medical importance in Saudi Arabia, using B. thuringiensis strains that naturally exist in the local environment instead of the current control strategies that are based solely on chemical insecticides.

Bioactive Compounds of Cold-pressed Thyme (Thymus vulgaris) Oil with Antioxidant and Antimicrobial Properties

Herbs rich in bioactive phytochemicals were recognized to have biological activities and possess many health-promoting effects. In this work, cold-pressed thyme (Thymus vulgaris L.) oil (TO) was studied for its lipid classes, fatty acid profile, tocols and phenolics contents. Antioxidant activity and radical scavenging potential of TO against free radicals (DPPH(・) and galvinoxyl) was determined. Antimicrobial activity (AA) of TO against food borne bacteria, food spoilage fungi and dermatophyte fungi were also evaluated. Neutral lipids accounted for the main lipid fraction in TO, followed by glycolipids and phospholipids. The major fatty acids in TO were linoleic, oleic, stearic, and palmitic. γ-Tocopherol (60.2% of total tocols) followed by α-tocotrienol (26.9%) and α-tocopherol (9.01% of total tocols) were the main tocols. TO contained high amounts of phenolic compounds (7.3 mg/g as GAE). TO had strong antiradical action wherein 65% of DPPH(・) radicals and 55% of galvinoxyl radical were quenched after 60 min of incubation. Rancimat assay showed that induction time (IT) for TO: sunflower oil blend (1:9, w/w) was 6.5 h, while TO: sunflower oil blend (2:8, w/w) recorded higher IT (9 h). TO inhibited the growth of all tested microorganisms. TO exhibited various degrees of AA against different food borne bacteria, food spoilage fungi and dermatophyte fungi, wherein the highest AA was recorded against dermatophyte fungi and yeasts including T. mentagrophytes (62 mm), T. rubrum (40 mm), and C. albicans (20 mm) followed by food spoilage fungi including A. flavus (32 mm) with minimal lethal concentrations (MLC) ranging between 80 to 320 μg/mL. Furthermore, TO exhibited broad-spectra activity against food borne bacteria including S. aureus (30 mm), E. coli (25 mm) and L. Monocytogenes (20 mm) with MLC ranging between 160 to 320 μg/mL. The results suggest that TO could be used economically as a valuable natural product with novel functional properties in food, cosmetics and pharmaceutical industries.

Circulation of Dengue Virus Serotypes in the City of Makkah, Saudi Arabia, as Determined by Reverse Transcription Polymerase Chain Reaction

The present study was aimed to investigate the circulation of four dengue virus (DENV) serotypes in Makkah, Western Saudi Arabia. Blood samples were collected from 25 dengue fever-suspected patients and were subjected to molecular typing for DENV-1, DENV-2, DENV-3, and DENV-4 serotypes of dengue virus, by reverse transcription polymerase chain reaction (RT-PCR), using six sets of primers. Of the 25 samples, only six samples (24%) were found to be positive for dengue virus infection. The prevalence of DENV-1 was higher (50% of DENV-positive samples), as compared to DENV-2 (33.3%) and DENV-3 (16.6%) serotypes. The fourth serotype, DENV-4, was not detected in any of the DENV-positive samples. Although Makkah is considered endemic to dengue fever, we observed low prevalence of dengue virus in the city, which may be attributed to various factors. Nonetheless, the results presented herein confirm the circulation of DENV serotypes in the Western region of Saudi Arabia. To the best of our knowledge, the current study so far is the first report demonstrating the prevalence of the DENV-1 serotype in the city Makkah, Saudi Arabia.

Detection, Identification and Characterization of Some Heavy MetalsTolerant Bacteria

The threat of heavy metals pollution to public health and wildlife has led to an increased interest in developing systems that can remove or neutralize its toxic effects in industrial effluents and municipal wastewater. Tolerance to a range of heavy metal ions was determined for bacteria which had been isolated from wastewater collected from Makkah city, Saudi Arabia. Isolates were tolerant to cupper, cadmium, zinc, and cobalt although the levels of tolerance to the different concentrations of metal ions were specific for each isolate. One isolate was able to tolerate all four metal ions tested; phenotypic and genotypic investigation revealed that isolate (S7) resembled similarities with Pseudomonas aeruginosa. The results of this study showed the potential applicability of the isolated heavy metal-tolerant strain Pseudomonas aeruginosa (S7) in the treatment of heavy metal containing solutions. Further studies on the genomic structure of isolate (S7) are required to investigate its capabilities to remove/reduce heavy metals in contaminated microcosms.

First report of detection of the putative receptor of Bacillus thuringiensis toxin Vip3Aa from black cutworm (Agrotis ipsilon)

Black cutworm (BCW) Agrotis ipsilon, an economically important lepidopteran insect, has attracted a great attention. Bacillus thuringiensis (Bt) is spore forming soil bacteria and is an excellent environment-friendly approach for the control of phytophagous and disease-transmitting insects. In fact, bio-pesticide formulations and insect resistant transgenic plants based on the bacterium Bt delta-endotoxin have attracted worldwide attention as a safer alternative to harmful chemical pesticides. The major objective of the current study was to understand the mechanism of interaction of Bt toxin with its receptor molecule(s). The investigation involved the isolation, identification, and characterization of a putative receptor – vip3Aa. In addition, the kinetics of vip toxin binding to its receptor molecule was also studied. The present data suggest that Vip3Aa toxin bound specifically with high affinity to a 48-kDa protein present at the brush border membrane vesicles (BBMV) prepared from the midgut epithelial cells of BCW larvae.

Horizontal Gene Transfer in Soil and the Rhizosphere: Impact on Ecological Fitness of Bacteria

The ecological fitness of soil- and root-associated bacterial communities is a key element for soil fertility and plant health as well as plant stress tolerance. Genetic variability in bacterial populations is maintained through mutation and gene acquisition. Horizontal gene transfer (HGT) is accomplished by conjugation, transformation, and transduction both in vitro and under natural conditions. Mobile genetic elements (MGEs) play a significant role in gene dissemination in bacterial communities and increase their adaptability, survival, and ability to colonize different environmental niches. In this context, bacterial conjugative plasmids encoding resistance genes, degradative genes, and tolerance to stress conditions are of much significance. The biofilm mode of bacterial growth further enhances gene exchange and increase the fitness and competitiveness of bacteria. Microcosm studies reveal a number of factors influencing the HGT process in soil. Considering the importance of HGT, a better understanding of genetic processes in the rhizosphere will further help in effective exploitation of naturally engineered bacteria for sustainable agriculture.

Isolation, characterization, cloning and bioinformatics analysis of a novel receptor from black cut worm ( Agrotis ipsilon ) of Bacillus thuringiensis vip 3Aa toxins

Black cutworm (BCW) is an economically important lepidopteran insect. The control of this insect by a Bt toxin and the understanding of the interaction between the Bt toxin and its receptor molecule were the objectives of this research work. A gene coding for a Vip3A receptor molecule was identified, characterized, and cloned, from the brush border membrane vesicles (BBMV) of the BCW. The nucleotide sequence analysis of the cloned putative Vip3A-receptor gene revealed that the gene was 1.3-kb long and exhibited no homology with any gene in the gene bank. We succeeded in identifying and characterizing most of the Vip3A-receptor gene sequence; and the nucleotide sequence analysis of the cloned putative Vip3A-receptor gene (accession no. KX858809) revealed about 92% of the expected sequence was recovered, which exhibited no homology with any gene in the GenBank.

Diversity and Applications of Penicillium spp. in Plant-Growth Promotion

Abstract Maintaining soil health and increased crop productivity are the two major challenges for sustainable agriculture and food security. Effective microorganisms are considered as the key elements to overcome this problem. Soil fungi are known to play a significant role in soil fertility and plant nutrient turnover. In this chapter, we focus on the characteristics, diversity, and role of a common soil fungus, Penicillium in plant-growth promotion. Penicillium is widely known for its secondary metabolite production. In this chapter the various plant-growth promoting activities of Penicillium such as phosphate solubilization, production of siderophore, and plant-growth regulators are highlighted. The effect of Penicillium as a bioinoculant in enhancing crop productivity and its potential role in sustainable agriculture is also reviewed.