Study On The Diversity Of Culturable Actinobacteria In Saudi Arabian Desert And Their Antibacterial Activities

Desert environment is the largest terrestrial ecosystem in the world,but scanty works have been done to explore their microbial resources and diversity.In the present study,we try to analyse the diversity and distribution of actinobacteria in the Saudi Arabian Desert environment by utilizing a culture-based laboratory method and screen these microbial resources for their antibacterial activities.521 actinobacterial strains were isolated in this study.Unique pretreatment method and a series of isolation media had been used to culture more actinobacteria.Initial characterization of these isolates on the basis of its morphology,there were grouped into 37 genera in 22 families and 11 order of the class Actinobacteria.65 of these isolates were further characterized by 16 S rRNA gene sequence analysis to be potential novel species of the families Streptomycetaceae,Pseudonocardiaceae,Actinophytocola,Blastococcus,Isoptericola,Xylanimicrobium,Planobispora,Pseudoclavibacter,Cellulosimicrobium and Paeniglutamicibacter.A total of 200 strains were further screened for antibacterial activities against indicator strains.The results indicated that 46 strains were inhibitory towards at least one of the three indicator bacteria.Of these 46 potential strains,sixteen showed strong inhibitory effect against at least 5 indicator strains.Majority of these potent strains were affiliated to the genus Streptomyces,while few belongs to other genera,thereby indicating that the desert actinobacterial resources have great potential for screening and development of active natural products.Through a polyphasic characterization method involving polyphase sort method,four new species were identified and named as Microbacterium album sp.nov.,Microbacterium deserti sp.nov.,Saccharopolyspora deserti sp.nov.and Georgenia deserti sp.nov..In conclusion,this study present the vast actinobacterial diversity of the Saudi Arabian desert environment by a culture dependent method and lays the root for the further systematic study of actinomycetes community and resources in desert environment.In addition,the screening results of the antibacterial activities indicated us that the desert environment lives a large number of strains which has a strong secondary metabolism ability and Illustrate that the desert environment is the treasure house of the new natural products.