A pinboard by
Emmanuel Michael

Research Doctoral Student, University of Aberdeen


Evaluate interactions of exopolymeric substances exuded by certain marine bacterial isolates.

To evaluate interactions of exopolymeric substances and possible required cost-effective specialty chemical additives tailored to provide optimal well drilling, completion and intervention services due to rheological properties of exopolymeric substances produced by certain bacterial strains to serve as oilfield chemical to enhance effective drilling.
Generally, rheological properties of bacterial exopolysaccharides is one of its kind due to high purity and regular structure. Some unique bacterial strains produce a large diversity of exopolymers that enhance adaptation, with extreme environment. Some reduces interfacial tension barriers, thus making it applicable as thickeners, emulsifiers, and suspending agents in food, dairy product, pharmaceutical and petroleum industries. A classical polymer known as xanthan gum produced as microbial exopolysaccharide by gram-negative bacterium known as Xanthonomas campestris, it employs fermentation of simple and complex sugars such as glucose, sucrose, or other carbohydrate sources. Biopolymers are applied in food production, manufacturing pharmaceutical, cosmetic and petrochemical industrial application as thickeners, stabilizer, or agent of emulsification when mixed with gelling potentials. Xanthonomas campestris produces exopolymeric substances composed of repeated units of pentasaccharides of two glucose, two mannose and one glucoronic acid residues as its primary structure. It is expected that a patent on the exopolymeric substances produced by bacterial strains will be developed for industrial application and of economic and environmental importance. I am so passionate about utilization/transformation of basic biomaterials into finished goods so as to satisfy human want and also create a household brand.


Biosorption of metal elements by exopolymer nanofibrils excreted from Leptothrix cells.

Abstract: Leptothrix species, aquatic Fe-oxidizing bacteria, excrete nano-scaled exopolymer fibrils. Once excreted, the fibrils weave together and coalesce to form extracellular, microtubular, immature sheaths encasing catenulate cells of Leptothrix. The immature sheaths, composed of aggregated nanofibrils with a homogeneous-looking matrix, attract and bind aqueous-phase inorganics, especially Fe, P, and Si, to form seemingly solid, mature sheaths of a hybrid organic-inorganic nature. To verify our assumption that the organic skeleton of the sheaths might sorb a broad range of other metallic and nonmetallic elements, we examined the sorption potential of chemically and enzymatically prepared protein-free organic sheath remnants for 47 available elements. The sheath remnants were found by XRF to sorb each of the 47 elements, although their sorption degree varied among the elements: >35% atomic percentages for Ti, Y, Zr, Ru, Rh, Ag, and Au. Electron microscopy, energy dispersive x-ray spectroscopy, electron and x-ray diffractions, and Fourier transform infrared spectroscopy analyses of sheath remnants that had sorbed Ag, Cu, and Pt revealed that (i) the sheath remnants comprised a 5-10 nm thick aggregation of fibrils, (ii) the test elements were distributed almost homogeneously throughout the fibrillar aggregate, (iii) the nanofibril matrix sorbing the elements was nearly amorphous, and (iv) these elements plausibly were bound to the matrix by ionic binding, especially via OH. The present results show that the constitutive protein-free exopolymer nanofibrils of the sheaths can contribute to creating novel filtering materials for recovering and recycling useful and/or hazardous elements from the environment.

Pub.: 10 Jun '17, Pinned: 19 Aug '17