Biodiversity of diazotrophs associated to the plant cover of north sinai deserts: Biodiversität diazotropher assoziiert mit der pflanendecke der wüsten nordsinais

Efforts are made to record biodiversity of microflora and diazotrophs associated with the plant cover of the major agricultural development areas in north Sinai, around the El-Salam canal, a newly-constructed canal that brings Nile water westward across the Suez canal. Natural plant communities were collected from three major areas. Ectorhizosphere, endorhizosphere and phyllosphere samples were examined for total microbial population and diazotrophs. The vegetation of South Qantara (area I) is characterized by the dominance of Stipagrostis scoparia followed by Nitraria retusa, Convolvulus lanatus, Cornulaca monacantha and Filago desertorum. Rabaa-Bir El Abd (area II) is dominated by Artemisia monosperma, Panicum turgidum and Zygophyllum album. Euphorbia terracina, Oligomeris linifolia, Astragalus kahiricus, Hyoscyamus muticus and Thymelea hirsuta represent the major plants of El Ser and Al Quarir (area III). Microorganisms colonized root surfaces of all tested plants ranging from >?10⁵ to 10¹⁰ cfu g^???1. Diazotrophs were common residents (10¹⁰ cfu g^???1), invaded the root tissue and established endophytically (10²?–?10⁶ cfu g^???1). Fifty-one N₂-fixing isolates were obtained. Among the 32 bacilli isolates, Bacillus polymyxa and Bacillus circulans were more common compared to Bacillus macerans. BNF Gram-negative isolates belonged to Enterobacter agglomerans, Enterobacter gergoviae, Enterobacter amnigenus, Klebsiella pneumoniae, Pseudomonas luteola, Pseudomonas cepacia, Agrobacterium radiobacter and Azospirillum spp.