Study on effects of boron and arsenic in yeast cells

Atıcı, Sezin
Arsenic (As) has been the center of attention for researchers regarding its toxic effects in metabolism. Boron (B) can be both essential and toxic depending on its concentration level. The largest known boron deposits are in Turkey, the largest producer of boron minerals. Besides, there are some regions such as Balıkesir-Bigadiç and Kütahya-Emet having very high concentration of B and As in natural sources. In this thesis, an analytical method based on growing yeast cells in the presence of B and/or As followed by determination using ICP-OES and ICP-MS was developed to follow the distribution of B(III) and As(III) in yeast cells and growth media separately. Yeast cell growth was followed by optical density measurements at 600 nm. Based on optical density measurements, 9th hour was assigned as logarithmic phase and 24th hour as stationary phase. Yeast cell growth decreased 30% in the presence of As compared to control group of yeast cells fed only with yeast extract peptone dextrose (YPD) solution. However, growth curves did not show differences between 0.25, 0.50 and 1.0 mM B and/or As supplemented groups and nonsupplemented groups. Results of elemental analysis showed that generally more than 90% of B and As remained in supernatant solution. However, arsenic concentration increased by almost 4 times as the spiked concentration level was increased up to 5.0 mM even though in all groups boron concentration was below detection limit with the exception of 5.0 mM. Genomic DNA of yeast cells was followed by agarose gel electrophoresis for supplemented and control groups and no breakage was detected up to 5.0 mM As supplemented groups.