Desouky Abd-El-Haleem

Bacillus mojavensis strain 32A, a bioflocculant-producing bacterium isolated from an Egyptian salt production pond

Bacillus mojavensis strain 32A that exhibited 96.11% flocculation efficiency for clay suspensions was selected from other 15 comparative strains. Under growth condition, strain 32A was able to produce 5.2g/L of purified biopolymer. Its constituent was mainly polysaccharide and protein with proportional of 98.4-1.6% respectively. FTIR spectrum was confirming its chemical analysis. This biopolymer attain very fast sedimentation rate. The cost-effective biopolymer and CaCl(2) dosages were 3mg/L and 5 ml/L respectively that posed 89.7% flocculation efficiency. These dosages were suitable only for clay concentrations ≤5g/L. The maximum flocculation efficiency of the biopolymer recorded at pH 1.0 of clay suspension. The too high (>75°C) or too low (<25°C) clay suspension temperature was unfavorable for the biopolymer flocculation performance. The biopolymer solution utilized high thermal stability over the temperature range of 5-60°C. Furthermore, its pH stability recorded at pH range of 5-9.

A luxCDABE-based bioluminescent bioreporter for the detection of phenol

A bioluminescent reporter strain, Acinetobacter sp. DF4-8, was constructed for the detection of phenol by inserting a mopR-like promoter upstream of the Vibrio fischeri bioluminescent luxCDABE gene cassette in a modified mini-Tn5 construct. When introduced into the chromosome of Acinetobacter sp. DF4, the bioreporter produced a sensitive bioluminescent response to phenol at concentrations ranging from 2.5 to 100 ppm. This response was linear (R2=0.986) in the range from 20 to 90 ppm. A significant bioluminescent response was also recorded when strain DF4-8 was incubated with slurries from aged, phenol-contaminated soil.

Long PCR-amplified rDNA for PCR-RFLP- and Rep-PCR-based approaches to recognize closely related microbial species.

Long PCR was used to amplify a 5-kb fragment of the bacterial ribosomal operon (16S-intergenic spacer region (ISR)-23S) from several Ralstonia eutropha strains (16S rDNA sequence similarity: 97-99%). Due to the large product size, amplicons from the different strains could be distinguished using restriction enzyme fragment length polymorphisms (RFLP) and repetitive PCR analysis (Rep-PCR) with the primer 1492r. These methods may prove useful in differentiating other bacterial strains with highly similar 16S rDNA sequences.

The use of bioflocculant and bioflocculant-producing Bacillus mojavensis strain 32A to synthesize silver nanoparticles

It is preferable to use an organism to produce more than one product at the same time. So, the aim of this study was to investigate the ability of bioflocculant-producing Bacillus mojavensis strain 32A as a nanosilver synthesizer beside bioflocculant production. To achieve this target, three media, nutrient broth, bioflocculant-producing medium, and pure bioflocculant, were tested. Produced nanosilver was characterized by UV-vis, XRD, and TEM. In all cases, the results demonstrated that UV-vis showed a peak at ∼420 nm corresponding to the plasmon absorbance of nanosilver. XRD spectrum exhibited 2θ values corresponding to the silver nanocrystal that is produced in hexagonal and cubic crystal configurations. TEM confirmed formation, size, shape, and morphologies of nanosilver particles. The results emphasized that purified bioflocculant has the ability to produce anisotropy clusters of nanosilver ranging in size from 6 to 72 nm proving that the bioflocculant functioned as reducing and stabilizing agent in nanosilver synthesis.

An effective lipid-producing fungal sp. strain DGB1 and its use for biodiesel production.

Among 30 fungal isolates screened for lipid production using Nile-red staining assay, an isolate designated DGB1 was recorded as the highest lipid producer with lipid content up to 40% (w/w). Based on morphological, biochemical and molecular analysis, DGB1 was identified as fungal sp. strain DGB1. Under the optimized time course, lipid content of DGB1 reached its maximum yield (7.2 g/L) after four days of incubation. Gas chromatography/mass spectrometry (GC/MS) analysis revealed presence of five long chain saturated fatty acids, decanoic, tridecanoic, pentadecanoic, hexadecanoic and heptadecanoic. About 50% of these fatty acids was heptadecanoic acid. However, as a maximum, ~ 20% (w/w) of the lipid contents were determined when the basal medium containing 30% glycerol was used for lipid production instead of 5% glucose. This may push us to conclude that glucose is the most suitable carbon source which could be used to produce lipids from strain DGB1. In conclusion, this work revealed the possibility of using the promising fungal strain DGB1 in biodiesel production. Keywords: Biodiesel, lipids, Geotrichum , heptadecanoic. African Journal of Biotechnology Vol. 12(34), pp. 5347-5353

Biosynthesis, Characterization of Some Combined Nanoparticles, and Its Biocide Potency against a Broad Spectrum of Pathogens

The development of environmentally benign procedures for the synthesis of metallic nanoparticles (NPs) is a vital aspect in bionanotechnology applications for health care and the environment. This study describes the biosynthesis of Ag, Co, Ni, and Zn NPs by employing nanobiofactory Proteus mirabilis strain 10B. The physicochemical characterization UV-visible spectroscopy, scanning electron microscopy-energy-dispersive X-ray microanalysis (EDX), X-ray diffraction analysis (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS) technique including potential, and polydispersity index (PDI) confirmed the formation of pure, stable monodisperse quasi-spherical oxide NPs of corresponding metals. The antimicrobial activity of biofabricated NPs was assessed against Gram-negative and Gram-positive bacteria, biofilm, yeast, mold, and algae via a well diffusion method. The results displayed significant antagonistic activity in comparison to their bulk and commercial antibiotics. Interestingly, the combined NPs exhibited promising synergistic biocide efficiency against examined pathogens which encourages their applications in adjuvant therapy and water/wastewater purification for controlling multiple drug-resistant microorganisms. To the best of our knowledge, no previous study reported the synthesis of semiconductor NPs by Proteus mirabilis and the biocide potency of combined NPs against a broad spectrum of pathogens not reported previously.

Concurrent Synthesis of Zero- and One-Dimensional, Spherical, Rod-, Needle-, and Wire-Shaped CuO Nanoparticles by Proteus mirabilis 10B

Natural environment is a wealthy source of bionanofactories that invested in green approaches as the fabrication of biomimetic nanomaterials. The current study points out the importance of microbial activity in metal bioremediation, green synthesis of NPs, and global biogeochemical cycles of bioactive metals as well. It describes for the first time the synchronous biosynthesis of zero- (intracellular) and one-dimensional (extracellular) copper oxide nanoparticles (CuO-NPs) via Proteus mirabilis 10B. This bionanofactory represents key location of reduction and stabilization, and its exopolysaccharide additionally provides nucleation and growth site for CuO-NPs. The as-synthesized CuO-NPs were characterized; UV-Vis spectroscopy revealed surface plasmon resonance at 275 and 430 nm for intracellular and extracellular CuO-NPs, respectively. XRD reflected crystalline, pure phase monoclinic structure CuO-NPs. EDX illustrated strong copper signal with atomic percentages 32.3% (intracellular) and 14% (extracellular) CuO-NPs. However, ζ-potential recorded −62.5 and −43.8 mV with PDI 0.207 and 0.313 for intracellular and extracellular CuO-NPs, respectively, confirming the colloidal stability and monodispersity. Moreover, TEM micrographs depicted quasi-spherical intracellularly sequestered CuO-NPs (10 nm). Unexpectedly, extracellular CuO-NPs exhibited rod-, needle-, and wire-shaped with 17–37.5 nm in width and 112–615 nm in length. The antagonistic activity of both types of CuO-NPs was evaluated against Gram-negative and Gram-positive bacteria (aerobic and anaerobic), biofilm, yeast, mold, and algae. The potent antagonistic efficacy of CuO-NPs was displayed which encourages its utilization in controlling microbial contamination. Finally, the promising metabolic activity of Proteus mirabilis 10B can be exploited in simultaneous and beneficial applications for human and the surrounding ecosystem.

NAP enzyme recruitment in simultaneous bioremediation and nanoparticles synthesis

Graphical abstract Our study aims to exploit the denitrifying bacteria MMT and its NAP enzyme in dual missions, nitrate removal from wastewater and nanoparticles synthesis. Therefore, the crud NAP enzyme was characterized and immobilized by entrapment technique for aforementioned application. To the best of author knowledge, the immobilization for denitrifying bacteria and NAP enzyme for simultaneous bioremediation and bionanoparticles synthesis was not studied previously.

Isolation, characterization, optimization, immobilization and batch fermentation of bioflocculant produced by Bacillus aryabhattai strain PSK1

Among others, isolate PSK1 was selected and identified by 16 S rDNA sequencing as Bacillus aryabhattai. Growth optimization of PSK1 and physicochemical parameters affected bioflocculant production was carried out by Plackett-Burman design and resulted in increasing in the activity by 4.5%. Bioflocculant production by entrapped and adsorbed immobilized microbial cells was performed using different techniques and revealed enhancement in the activity in particular with pumice adsorption. HPLC analysis of sugars and amino acids composition, FTIR and the effect of different factors on the purified PSK1 biopolymer such as presence of cations, thermal stability, pH range and clay concentration was carried out. Scanning electron microscopy (SEM) of free, immobilized cells, PSK1 bioflocculant and formed flocs were performed. The results revealed that bioflocculant PSK1 is mainly glycoprotein consists of glucose and rhamnose with a large number of amino acids in which arginine and phenylalanine were the major. SEM analysis demonstrated that PSK1 have a clear crystalline rod shaped structure. FTIR spectrum reported the presence of hydroxyl and amino groups which are preferred in flocculation process. PSK1 was soluble in water and insoluble in all other tested organic solvents, while it was thermally stable from 40 to 80 °C. Among examined cations, CaCl2 was the best coagulant. The maximum flocculation activity of the PSK1 recorded at 50 °C (92.8%), pH 2.0 (94.56%) with clay concentration range 5–9 g/l. To obtain a large amount of PSK1 bioflocculant with high flocculating activity, batch fermentation was employed. The results recorded ∼6 g/l yield after 24 h of fermentation.