Alexis joined the Environmental Engineering Program at Yale in 2002, and is currently working with Professor Menachem Elimelech. His research focuses on the transport, deposition, and interactions of bacteria and biomolecules in engineered and natural aquatic environments.
Before coming to Yale, Alexis completed his double BS and MS degrees in Life-Sciences and Chemical Engineering at the Université Catholique de Louvain in 2002. For his MS in biology, Alexis joined a collaborative work project with the Ocean Lab (Aberdeen, Scotland), under the guidance of Dr. Jean-François Rees, aimed at assessing changes in metabolism of deep-sea organisms. During the project, he joined two research expeditions on board the RRS Discovery, constantly experiencing the changing moods of the North Atlantic Ocean. (If French doesn't bother you, read online his daily notes for his first and second expeditions.) For his MS in chemical engineering, Alexis was accepted as a visiting researcher in the Department of Plant Sciences at Oxford University (UK) to investigate defects in the secretory pathway of proteins in plant cells. During his work, Alexis benefited from the co-advisorship of Dr. Ian Moore (Oxford University) and Dr. Marc Boutry (Université Catholique de Louvain). In his free-time, Alexis enjoys traveling, oil painting, skiing, sailing, and scuba diving.
Alexis' research deals with the transport and deposition dynamics of bacteria and biomolecules at the solid-water interface in well-defined flowing systems. His ultimate goal is to develop a better understanding of the environmental factors that control the conditioning of substrates by polyelectrolytes and the subsequent formation of biofilm by deposition of planktonic bacterial cells. In the course of his research, Alexis has employed advanced analytical and modeling tools from the fields of molecular biology, microbiology, interfacial sciences, and chemical engineering. Alexis' research naturally evolves in three subsequent phases:
1. Design of polyelectrolyte films in well-defined flow systems
Multilayered microfilms were obtained by subsequent adsorption of oppositely charged polyelectrolytes—poly-L-lysine and alginates. The homogeneity and structural characteristics of the film were assessed by quartz crystal microbalance with dissipation (QCM-D) and atomic force microscopy (AFM). Specific effects of solution chemistry (e.g. ionic strength and the presence of multivalent ions) on the film structure were investigated.
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2. Construction of genetically-modified microbial strains
In a collaborative project with Dr. Barbara Kazmierczak's laboratory (Section of Infectious Diseases, School of Medicine, Yale University), genetically-modified Pseudomonas aeruginosa strains were contructed by allelic displacement. From the wild type strain PA01, 3 mutant strains were designed with specific defects in the biosynthesis of surface appendages that control the bacterium motility: PA01 ΔFliC is defective in the biosynthesis of flagellar proteins, PA01 ΔPilA is defective in the biosynthesis of pilus protein, and PA01 ΔFliC ΔPilA is defective in the synthesis of both types of proteins.
3. Control the deposition kinetic of microbes on conditioning films in well-defined flow systems
The deposition kinetics of the motile and non-motile bacterial strains on alginate conditioning film are studied in a radial stagnation point flow. Under controlled hydrodynamic flow, the effects of solution chemistry, such as ionic strength and the presence of divalent cations, on the deposition behavior of these microbes are investigated. Results may lead to the development of appropriate methods for effective cleaning of fouled membranes in membrane processes.
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1. de Kerchove, A. J. and Elimelech, M. "Deposition Kinetics of Motile and Non-Motile Pseudomonas aeruginosa: Impact of Alginate Conditioning Film", Applied and Environmental Microbiology, Submitted.
2. de Kerchove, A. J., Genard, A., Bailey, D. M., Bagley, P. M., Collins, M. A., Priede, I. G. and Rees, J.-F. "Apparent violation of the decrease in metabolism with depth paradigm: Comparison of metabolic enzymes in muscles of two demersal deep-sea fish", Journal of Experimental Marine Biology and Ecology, Submitted.
3. de Kerchove, A. J. and Elimelech, M. "Formation of Polysaccharide Gel Layers in the Presence of Ca2+ and K+ Ions: Measurements and Mechanisms", Biomacromolecules, 2007, 8 (1), 113-121. PDF File
4. de Kerchove, A. J. and Elimelech, M. "Structural Growth and Viscoelastic Properties of Adsorbed Alginate Layers in Monovalent and Divalent Salts", Macromolecules, 2006, 39 (19), 6558-6564. PDF File
5. de Kerchove, A. J. and Elimelech, M. "Relevance of Electrokinetic Theory for "Soft" Particles to Bacterial Cells: Implications for Bacterial Adhesion", Langmuir, 2005, 21 (14), 6462-6472. PDF File
6. de Kerchove, A. J. and Elimelech, M. "Deposition Kinetics of PA01 ΔfliC ΔpilA and PA01 ΔpilA on Alginate Films: Roles of Divalent Cations, Applied and Environmental Microbiology, In preparation.
7. de Kerchove, A. J. and Elimelech, M. "Enhancement of Cell Deposition and Maximum Surface Coverage of Pseudomonas aeruginosa by Cell Motility", Langmuir, In preparation.
