Halotolerant streptomycetes isolated from soil at Taif region, Kingdom of Saudi Arabia (KSA) I: Purification, salt tolerance range, biological and molecular identification

Abstract

This study focuses on isolation and purification of some halotolerant streptomycetes from soil and sea water of western region, KSA as a source of salt tolerance gene(s). A few numbers (32) of streptomycetes-like colonies (SLC) were isolated and purified from two regions. From Jeddah, a number of 22 out of the 32 SLC were obtained, distributed between the sea water 12 (54.55%) and sea sediment soil 6 (27.27%).From Taif-soil, only 10 SLC were isolated. Results show that 31 SLC were grown on 3.5% salt, while, in the presence of 7.0% salt, 2, 3, 18, and 4 showed abundant (+++), moderate (++), weak (+), and in doubt (±) growth, respectively. Only five SLC were not able to grow at 7% salt. At the level of 10.5% salt, the number of SLC was decreased up to 4 (2 (+++), 1 (++) and 1(+)). In either 14% or 21% salt, four isolates were varied in their ability in growth as moderate or weak growth was recorded. These isolates were considered as halotolerant as they were able to grow in either the presence or normal growth medium. The four isolates which tolerate 14% salt (isolates 4 and 6) and 21% salt (isolates 2 and 8) were completely identified. The streptomycete isolate 2 appeared to be related to Streptomyces cirratus. Comparing the cultural, morphological and physiological characteristics of Streptomyces isolate 4 and 6, they were very likely to be strains of S. rishiriensis and S. alboflavus, respectively. Streptomyces isolate 8 was identified as a strain of S. luteogriseus. The nucleotide sequences of 16S rRNA gene was partially determined using the DNA template of the Streptomyces isolate 8. Results show that a final sequence of about 1462 nts was obtained and compared with eight universal Streptomyces and bacterial strains. This isolate could be classified as a new species of gray Streptomyces, and it was suggested to be named a new halotolerant Streptomyces sp. TSA-KSA strain (GenBank AB731746).

Keywords: Streptomyces, halotolerant, identification, 16S rRNA, Taif, Kingdom of Saudi Arabia (KSA)

African Journal of Biotechnology Vol. 12(19), pp. 2565-2574