Khaled Elbanna

Safe biodegradation of textile azo dyes by newly isolated lactic acid bacteria and detection of plasmids associated with degradation.

Since azo dyes are recalcitrant to complete biodegradation due to their complex structure, lactic acid bacteria under an anaerobic/aerobic sequential system was used in an attempt to achieve complete mineralization of textile azo dyes for safe degradation products. A total of 120 lactic acid bacteria (LAB) were screened for decolorization of the textile azo dyes; Reactive Lanasol Black B (RLB), Eriochrome Red B (RN) and 1, 2 metal complexes I. Yellow (SGL). The screening results showed that a total of 80 out of 120 LAB isolates were able to decolorize the dyes, in 4 h ranging from 75 to 100%. Based on API 50 CHL and 16S rDNA sequences, Lactobacillus casei and L.paracasei were the nearest phylogenetic neighbour for both strains Lab11 and Lab13, with an identity of 99 %, while L.rhamnosus was the nearest phylogenetic neighbour for isolate Lab2 with an identity of 99 %. The biodegradation products of RLB (as a model of textile azo dyes) by Lab2 formed during anaerobic and sequential anarobic/aerobic treatments were analyzed by HPLC. Peaks at different retention times were observed in the anaerobic stage, and these peaks completely disappeared at the end of anarobic/aerobic incubation. This result clearly indicates that the dye had been catabolized and utilized by Lab2 isolate. Among the different plasmid curing treatments, SDS at 42°C was found to be an effective treatment for curing of these isolates. Plasmid profiles of wild-type strains and their cured derivatives indicates that the loss of the ability to decolorize azo dyes correlated to loss of a 3 kb plasmid, suggesting that the genes required for textile azo dye degradation were located on this plasmid. Azo dye degradation products were less toxic to growing Sorghum bicolor than the original azo dyes.

Genotypic and phenotypic characterization of rhizobia that nodulate snap bean (Phaseolus vulgaris L.) in Egyptian soils.

Snap bean fields in 12 of the 25 governorates of Egypt were surveyed to determine the distribution and taxonomy of snap bean-nodulating rhizobia. Nodulation rates in the field were very low, indicating that Egyptian soils do not have sufficient numbers of snap bean-compatible Rhizobium spp. A total of 87 rhizobial isolates were assayed on the most commonly grown cultivars in order to identify the most effective strains. The five most effective isolates (R11, R13, R28, R49 and R52) were fast-growing and utilized a wide range of carbon and nitrogen sources. A phylogenetic assignment of these strains by analysis of the 16S ribosomal RNA gene suggested that all fell within the Rhizobium etli-Rhizobium leguminosarum group. Strains R11, R49 and R52 all clustered with other identified R. etli strains, while strains R13 and R28 were more distinct. The distinctness of R13 and R28 was supported by physiological characteristics, such as their ability to utilize citrate, erythritol, dulcitol and lactate. Strains R13 and R28 also yielded the highest plant nitrogen content of all isolates. The highly effective strains isolated in this study, in particular strains R13 and R28, are promising candidates for improving crop yields. The data also suggested that these two strains represented a novel sub-group within the R. etli-R. leguminosarum group. As snap bean is a crop of great economic value to Egypt, the identification of highly effective rhizobial strains adapted to Egyptian soils, such as strains R13 and R28, is of great interest.

Field Evidence for the Potential of Rhodobacter capsulatus as Biofertilizer for Flooded Rice

In a previous study, we evaluated the effects of inoculating rice plants with the phototrophic purple nonsulfur bacterium Rhodobacter capsulatus (Rc) on growth and yield of rice in pots and lysimeter experiments and the results obtained have been highly encouraging. In this study, we carried out two field experiments: one in the experimental farm of the Faculty of Agriculture, Fayoum University, and the second in a farmer’s field in Kafr El-sheikh, to assess the effects of Rc on growth and yield of rice in comparison and in combination with chemical nitrogen fertilizer (CNF) and farmyard manure. The results indicated that both biological and grain yields in all the Rc inoculated treatments were significantly higher than those in the uninoculated corresponding treatments in both fields. With regard to grain yield, the major factor for determining the effectiveness of any agricultural treatment, inoculation with Rc in combination with 50% of the recommended CNF rate gave a grain yield that was statistically equivalent to that obtained with 100% of the recommended CNF rate. These results provide a clear evidence for the potential of Rc as biofertilizer for flooded rice under field conditions.

Impact of floral sources and processing on the antimicrobial activities of different unifloral honeys

Objective To study in vitro antibacterial activity and physicochemical properties of three unifloral honeys (citrus, clover and cotton honeys), and to study the impacts of storage, dilution with water (33%, w/v) and autoclaving (121 °C for 15 min) on honeys characteristics.

Characterization of Egyptian Fluorescent Rhizosphere Pseudomonad Isolates with High Nematicidal Activity against the Plant Parasitic Nematode Meloidogyne Incognita

A total of 52 Egyptian rhizosphere fluorescent pseudomonad isolates (ERFP) were screened for their nematicidal activity in vitro. The screening results showed an inhibitory effect on hatching of Meloidogyne incognita eggs ranging from 57 % to 100 %. Similar to the chemical nematicide Videt in vitro experiment, cultures or cell-free supernatants (CFS) of the ERFP isolates showed complete inhibition of egg hatching and killed 100 % of the J2. In glasshouse pot experiments, cultures of these isolates, CFS and the chemical nematicide showed reduction in root galling ranging from 81.0-95.4, 61.3-84.5, 97.3%, respectively. Also, the reduction in nematode multiplication in soil was 91.9-95.7, 83.5-84.5 and 96.5% for cultures, CFS and the chemical nematicide, respectively, compared to the positive control (nematode only). Furthermore, these isolates showed significant increases in plant growth characters, phenolic content and activities of the plant defense-related enzymes. Based on 16S rDNA sequences and API NE kits, two major clusters were observed; strains Ps 36 and Ps 54 appeared to fall within the variability range of P. putida, while Ps 21, Ps 22 and Ps 14 are likely to be strains of P. aeruginosa. The distinctness of Ps 36 and Ps 54 from Ps 14, Ps 21 and Ps 22 was supported by their physiological characteristics, such as the ability of Ps 14 and Ps 21 and Ps 22 to utilize mannitol, N-acetyl-glucose amine and adipate.

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.

Egyptian honeybee pollen as antimicrobial, antioxidant agents, and dietary food supplements

In this study, three Egyptian bee pollen types from different plant sources, namely maize (Zea mays), clover (Trifolium alexandrinum), and date palm (Phoenix dactylifera), were evaluated as natural antimicrobial agents, antioxidants, and food additives. A methanolic extract of maize bee pollen exhibited the highest antibacterial activity, followed by clover and date palm bee pollen. Staphylococcus aureus and Escherichia coli were the most sensitive, followed by Listeria monocytogenes, Salmonella enteritidis, and Pseudomonas aeruginosa. In ghee, all methanolic extracts, especially that of maize bee pollen, showed high antioxidant activities as radical scavenger substances and as inhibitors of lipid peroxidation. Sensory evaluation of yoghurt supplemented with different bee pollens revealed that maize bee pollen improve texture, increased gel strength, and decreased syneresis and had favorable nutty flavor, while clover and date palm pollen added a sweet taste and bean-like flavor, respectively. These findings establish the potential of Egyptian maize and clover bee pollen as antioxidants, antimicrobial agents, promising natural food supplements, and natural preservatives.

In vitro and in vivo evidences for innate immune stimulators lactic acid bacterial starters isolated from fermented camel dairy products

Probiotics are commensals with special characteristics that are essential for the development of the immune system, and may protect mucosal surfaces against pathogens. In this study, a total of 40 lactic acid bacteria (LAB) were isolated from different raw and fermented camel’s milk samples collected from Saudi Arabia (Makkah area) and Egypt (Fayoum), and tested for the probiotic properties. Among them, Pro 4 and Pro 7 isolates exhibited excellent probiotic potential including bile salt (0.2–0.6%), phenol tolerance (0.2–0.4%) and salt tolerance (0.0–10%). Furthermore, both strains exhibited antimicrobial activity against wide range of food-borne pathogens and Dermatophytes with average zone inhibition of 37.5, 35.5, 34.5, 27.5, 25 and 23.5 mm for Staphylococcus aureus, Trichophyton mentagrophytes, Escherichia coli, Listeria monocytogens, Candida albicans and Salmonella typhi, respectively. Furthermore, the in vivo study indicated that these strains significantly improved the mucosal immune responses through an increase in expression of TLR2 and IFNγ mRNA in mice intestine as well as increased the synthesis of polyclonal IgG, IgM and IgA in mice blood sera. Accordingly, due to these unique probiotic properties, both selected strains could be potentially used as probiotic starter cultures for fermented dairy foods as well as functional food and health products.