Insights on yeast bioremediation processes

The augmentation of industrial and house wastes and the accidental oil spills raised the problem of their storage and treatment. Bioremediation is an interesting alternative for restauring the ecological equilibrum in polluted environments, based on microbial population dynamics and its ability to consume xenobiotics as carbon source. The yeast species described as having biodegrading abilities belong especially to Pichia, Rhodosporidium, Rhodotorula, Trichosporon and Yarrowia. Successful bioremediation require knowledge on limiting factors such as pollutant composition and nature, microbial community structure, contaminants accessibility, physical state of hydrocarbons, temperature, nutrients and oxygen. Studies on yeasts able to use various petroleum components as sole carbon source, showed that their biodegrability decreases from n-alkanes to high molecular weight aromatic and polar compounds. The alkanes are mainly degraded using the monoterminal oxidation pathway through cytochrome P450 system, and transformed into fatty acids with the same length of the carbon chain. Extensive studies showed that there are more than 80 genes involved in obtaining the alkane specific phenotype. In present, bioremediation technologies may be applied ex situ, in situ or in combination with conventional technologies.