ISOLATION OF SALT TOLERANCE GENE(S) FROM SOME HALOTOLERANT STREPTOMYCES SPECIES USING POLYMERASE CHAIN REACTION

Abstract

Sixteen halotolerant Streptomyces strains were tested for their salt tolerance as an
attempt to isolate some salt tolerance genes via polymerase chain reaction (PCR). A group of
these strains were isolated from Sedi-creer (S. niveus Sc-2 and S. sendenensis Sc-11); El-
Malahat (Alexandria) (S. graminofaciens Ma-13); Qaroon's lake (S. albovinaceus Qa-44, S.
luteofluorescens Qa-51, S. albidoflavus Qa-53 and S. erthraeus Qa-84). The other group was
isolated from different soils from Damaaita (S. violans Da-3), Ismailia (S. alboflavus Is-10),
Port Said (S. bobili Ps-12) and Sinai sandy soil (Streptomyces species Si-1, S. tuirus Si-4, S.
lateritius Si-6, S. hawaiiensis Si-8, S. muavecolor Si-9 and S. melanogenes Si-11). Results
showed that these strains varied in their salt tolerance range, in particular, with increasing
NaCl concentration in the growth medium up to 140g/L. It was also noted that all the applied
Streptomyces strains tolerated NaCl concentrations up to 70g/L. When NaCl concentration
was raised to 105g/L, strains except S. melanogenes Si-11, gave moderate growth. On the
contrary, NaCl concentration of 140g/L inhibited the growth of 50% of strains under
investigation, but the other 50% of these strains gave moderate growth. On the molecular
level, PCR was successfully used for isolating the mtlD (1150 bp) and P5CR (831 bp) genes
from three (S. albovinaceus Qa-44, S. albidoflavus Qa-53, S. erthraeus Qa-84) and four (S.
albovinaceus Qa-44, Streptomyces species Si-1, S. luteofluorescens Qa-51 and S. lateritius
Si-6) strains, respectively. In addition, the fructan-accumulating (sacB) gene was detected in
Streptomyces species Si-1 by amplification of a fragment of a size of about 1665 bp. These
results confirmed the ability to use of PCR for isolation or detection of any gene based on its
nucleotide sequencing in any microorganism. Furthermore, one can recommend the use of
the applied halotolerant Streptomyces strains, based on their antimicrobial activities for
biologically controlling the phytopathogenic fungi in saline soils