التحري عن مواقع جينات إنتاج صبغة البيتا-كاروتين في الخميرة Rhodotorula mucilaginosa BA61

Two procedures was followed to determine the position of β-carotene pigment coding genes. The first procedure is curing of plasmid nucleic acid content using ethidium bromide with 150 μg/ml concentration for each the yeasts Rhodotorula. mucilaginosa BA61, Sacharomyces cervisiae BA179 and Escherichia coli BA252. The results revealed that success of curing of plasmid DNA for the yeast R. mucilaginosa BA61. The cured colonies was bearing β-carotene pigment production characteristic and the genes responsible for this characteristic laid on the chromosome, as long as, the curing did not occur. The curred colonies showed sensitivity against the studied antibiotics with percentage ranged from 16-80% with exception with Ampicillin, Erythromycin, Lamisil and Vancomycin. Also results of curing of the yeast S. cervisiae strain BA179 losing of antibiotic resistance with the range 15-92%. Results of curring of E. coli BA252 strain showed losing of antibiotic resistance with percentage 15-23%, with exception with the Trimethoprim, Erythromycin and Lamisil. The second procedure for determine the position of coding genes was done by conjugation, which two conjugation attempts was done. The first one for determine the ability of plasmid nucleic acid for mobilization and transferation in yeast strains. There was success conjugation between donor yeast strain R. mucilaginosa BA61 and the curred yeast S. cervisiae BA179 as recipient with conjugation frequency 0.65× 10-8, this study proved that the transferred plasmid nucleic acid from R. mucilaginosa BA61 bearing Gentamicin antibiotic genes, but not genes responsible for β-carotene pigment production, as well as, two attempts of conjugation was done through kingdoms between R.mucilaginosa BA61 as a donor and E. coli BA252 as recipient. Results revealed that plasmid nucleic acid bearing Rifampin resistance genes has the ability ofmobilization and transferation from the yeast to the bacteria with conjugation frequency 3.05×10-8. Results also showed that the curred bacteria has the ability of receiving and stability of plasmid from the yeast by conjugation, whereas the resulting was not bear production of the β-carotene pigment characteristic and this confirm that the genes coding for pigment production characteristic bearing laid on chromosomal nucleic acid.