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Genetic Analysis of Pectinolytic and Cellulolytic Activities of Azospirillum Irakense KBC1

My Ali BEKRI researcher laureate


°1966 Morocco
Licence in biology, Université Moulay Ismaïl, Morocco, 1991

Genetic Analysis of Pectinolytic and Cellulolytic Activities of Azospirillum Irakense KBC1

Dr Bekri's work is about the interactions taking place between a nitrogen-fixing bacterium and plants. Atmospheric nitrogen fixation refers to the ability to transform nitrogen, a relatively inert but abundant gas, into ammonium, a universal source of metabolic nitrogen. Only certain bacteria (such as e.g. Azospirillum) have this ability; their interaction with plants in thus of considerable agronomical interest since it may improve the yield of certain cultures by transferring metabolisable nitrogen from the bacterium to the plant. Thanks to enzymes produced by the bacterium (such as pectinases, subject of this work) which can digest components of the plant cell wall the bacterium can colonize the roots, which makes the interaction metabolically productive in situ. However, this nitrogen fixing ability is only one aspect of the beneficial bacterium-plant interaction. It also increases the production of certain plant hormones, which boosts root development and thus improves the uptake of water and minerals.
In his work Dr Bekri identifies and characterises a pectinase gene; he also studies its expression and regulation. He shows that the gene is induced by pectin and expresses itself on the roots of wheat and rice. Moreover, Dr Bekri has partially characterized enzymes attacking other plant cell-wall constituents (endoglucanases, cellobiohydrolases, ß-glucosidases) and has initiated their genetic analysis. The work is well introduced, the experiments are well-carried out and the conclusions are both interesting and original.
In conclusion, this work is an important contribution to the study of a beneficial interaction between a nitrogen fixing bacterium and plants of capital agronomical interest, such as rice, and thus of direct importance to developing countries. Besides, as the author himself emphasizes, the pectinolytic interaction between Azospirillum and plants can be used as a model for the study of certain plant pathologies which are caused by pectinolytic bacteria. This aspect is also of great importance for agriculture in developing countries.

report by Prof. Dr. Nicolas Glansdorff, Laboratory for microbiology, Université Libre de Bruxelles, Belgium