Biodiversité de la flore bactérienne du palmier dattier poussant au sud est Algérien. Effet du climat sur le comportement de cette flore.

Abstract

Bacterial flora of the three parts of the date palm (Phoenix dactylifera L.) (Leaves, fruits and trunk) was isolated and then identified following phenotypic and molecular tests (using 16S rDNA). Evaluation of the bacterial population through the different seasons (in 2012) was carried out to demonstrate the temporal dynamics of the cultivable population. Statistical analysis revealed significant differences in the distribution of bacterial strains with increase or decrease of bacterial levels during the different seasons. Morphological characters and simple orientation tests allowed selecting 78 representative isolates from more than 200. The results of phenotypic identification made it possible to classify the majority of isolates at the genus level. As well as, the study of the effect of a biotic factors on the growth of isolates revealed that the tested isolates tolerate and survive under severe a biotic conditions. According to the partial analysis of the gene coding for 16S rRNA, 2 isolates were identified perfectly with 100% similarities, some isolates were identified between 97% to 99% similarity to the strains conserved in Genbank, while others strains were identified between 78% to 96%. Overall, there were 33 bacterial species belonging to 16 genera. The most common genera in all parts of the tree are Bacillus (36.84%), Pseudemonas and Enterobacter representing 17.1% for each, but however its distribution is heterogeneous. The genus Lysinibacillus is the third most isolated genus (10.52%). Unlike other genera that remain minority such as Staphylococcus, Serratia, Microbacterium, Kluyvera, Arthrobacter, Stenotrophomonas, Exiguobacterium, Micrococcus, Klebsiella, Massilia, Erwinia, and Brevibacterium. This work gave for the first time in Algeria a global idea about the diversity of the date palm bacterial flora and highlighted the impact of climate on the dynamics of this flora.