Antarctic Yeasts: Biodiversity and Potential Applications

This review is an attempt in cataloguing the diversity of yeasts in Antarctica, highlight their biotechnological potential and understand the basis of adaptation to low temperature. As of now several psychrophilic and psychrotolerant yeasts from Antarctic soils and marine waters have been characterized with respect to their growth characteristics, ecological distribution and taxonomic significance. Interestingly most of these species belonged to basidiomycetous yeasts which as a group are known for their ability to circumvent and survive under stress conditions. Simultaneously their possible role as work horses in the biotechnological industry was recognized due to their ability to produce novel enzymes and biomolecules such as agents for the breakdown of xenobiotics, and novel pharmaceutical chemi cals. The high activity of psychrophilic enzymes at low and moderate temperatures offers potential economic benefits. As of now lipases from

Pseudozyma antarctica

have been extensively studied to understand their unique thermal stability at 90°C and also because of its use in the pharmaceutical, agriculture, food, cosmetics and chemical industry. A few of the other enzymes which have been studied include extracellular alpha-amylase and glucoamylase from the yeast

Pseudozyma antarctica

(

Candida antarctica

), an extra-cellular protease from

Cryptococcus humicola

, an aspartyl proteinase from

Cryptococcus humicola

, a novel extracellular subtilase from

Leucosporidium antarcticum

, and a xylanase from

Cryptococcus adeliensis

The ability of these yeasts to adapt to the low temperature conditions has also led to investigations directed towards characterizations of cold stress proteins and heat shock proteins so as to understand the role of these stress protein with respect to adaptation. Antarctic yeasts have also been used as model system to study the inter-relationship among free radicals, antioxidants and UV-induced cell damage