Reserve Carbohydrate Metabolism in Crabtree-Negative and – Positive Yeasts at Different Carbon Sources


Turgut Genç T.

Advancements in Life Sciences, cilt.8, ss.47-51, 2020 (ESCI İndekslerine Giren Dergi)

  • Cilt numarası: 8 Konu: 1
  • Basım Tarihi: 2020
  • Dergi Adı: Advancements in Life Sciences
  • Sayfa Sayıları: ss.47-51

Özet

The fermentation of sugars into ethanol even in the presence of oxygen is referred to as the Crabtree effect. The yeast cells displaying Crabtree effect are indicated as Crabtree-positive yeast. Saccharomyces cerevisiae is Crabtree positive and Debaryomyces occidentalis is Crabtree-negative yeast which does not have Crabtree effect. The reserve carbohydrate metabolism is different in Crabtree-positive and Crabtree-negative yeast cells. The present study aimed to determine the trehalose and glycogen accumulation patterns both in Crabtree-positive and Crabtree-negative yeast species. Methods: In this research, trehalose and glycogen contents of S. cerevisiae and D. occidentalis yeast species were examined in a time course manner in three different carbon sources: glucose, galactose and glycerol. Firstly, yeast cells were grown in rich media supplemented with glucose then all washed and switched to fresh cultures including glucose, galactose and glycerol. Results: In S. cerevisiae yeast cells the overnight accumulated trehalose degraded very rapidly after nonfermentable carbon source replenishment, but this took place in a long time, nearly two days, in D. occidentalis yeast cells. However, whenever D. occidentalis yeast cells shifted to glycerol, all the accumulated trehalose degraded within the twelve hours. Glycogen accumulation in D. occidentalis yeast cells is lower than S. cerevisiae yeast cells both in fermentable and non-fermentable carbon sources. Conclusion: Results indicated that glycogen and trehalose accumulation patterns are completely different in D. occidentalis than S. cerevisiae. Crabtree-negative yeast cells generally, prefer to accumulate glycogen instead of trehalose as reserve carbohydrate. But in our research we proved that Crabtree-negative yeast D. occidentalis, accumulates more trehalose than S. cerevisiae yeast cells in non-fermentable carbon sources.