Genetic Diversity and Esterase-Profiling of Actinobacteria Isolated from Sahara Desert Stones and Monuments

Stone surfaces in Sahara desert are continuously exposed to higher solar radiation, temperature, aridness and lack of nutrients. With the exception of members of Geodermatophilaceae, actinobacteria inhabiting such hard environments have attracted less interest. Here we addressed the phylogenetic diversity of the culturable Actinobacteria from Sahara desert stones and monuments. Amplified rDNA restriction analysis of the isolates (ARDRA) followed by 16S rRNA gene sequencing permitted us to delineate 25 ARDRA types that have been assigned to 6 actinobacterial genera; Arthrobacter, Micromonospora, Actinoplanes, Kineococcus and Nocardia. The isolates have been typed on the basis of a major group of hydrolytic activities: esterase. The particularly rich pool of esterase patterns previously recorded for members of Geodermatophilaceae was extended to other sympatric prevalent actinobacteria on stone surfaces that belong mainly to the genera Actinoplanes and Kineococcus. The results of the present study were discussed in view of ecological significance of these actinobacteria in stone materials.