Properties of Streptomyces Bacteria from the Rhizosphere of Some Halophytes at North-East of Qatar: Al Ghariya Case Study

The biological activities performed by plants and microorganisms in dry and saline soil play an important role in making them thrive in these extreme environmental conditions. Our previous studies have shown the presence of Streptomyces bacteria in various drylands in Qatar. To understand and elucidate the roles of these bacteria in such unfavorable environments, it is important to investigate the distribution and properties of Streptomyces bacteria in rhizospheric soil of halophytes and compare them with non-rhizospheric soils. Therefore, in this research, four halophyte plants namely: Caroxylon imbricatum, Sporobolus ioclados, Tamarix aphylla, and Tetraena qatarensis, were chosen to investigate the properties, characteristics, and activities of Streptomyces isolates in these habitats. The chemical and physical properties of soil at the study area (Al Ghariya Sabkha) revealed that pH levels are almost uniform and homogenous across the Sabkha; ranging between 7.7-7.9, and salinity levels were very high at non-rhizospheric soil as compared to the rhizospheric soils, thus, all elements at the rhizospheres of the studied plants have lower concentrations than those at the non-rhizospheric soils. The colony characteristics of isolates at the rhizospheric soil of halophytes showed various types of isolates with different colony characteristics and peculiarities which indicate that a significant number of strains of Streptomyces bacteria have thrived under such mini-habitats of the canopy of these plants. The enzyme activities of the isolates that have been studied in the rhizospheric and non-rhizospheric soils have shown more variable isolates in the rhizosphere of the plants under investigation than those of non-rhizospheric soils. The antibacterial primary activity of the isolates of Streptomyces at these mini-habitats showed that most of them had clear antibacterial action against the tested strains: Gram-negative (E. coli), and Gram-positive (B. subtilis, S. aureus, and S. epidermidis). The details about these parameters and the possible use of modern approaches to identifying Streptomyces bacteria, and the possible roles of halophytes and their associated microbes in saline lands are also discussed in this paper. Overall, the results of this research showed that the properties and characteristics of Streptomyces bacteria explaining their biodiversity were high in rhizospheric soils of halophytes as compared to non-rhizospheric soils.