Isolation, identification and characteristics of a salt-tolerant strain for phenol degradation

A salt-tolerant phenol degrading yeast strain W3 was isolated from the sludge of a sewage plant. It was identified as Candida sp. by morphological and 26S rRNA sequence analysis. The strain was capable of growing in the medium with 1%-10% NaCl and utilizing phenol as sole carbon source and energy. It is found that the optimal conditions for growth and degradation are pH 7.0, temperature 30 °C, 5% NaCl. Under 5% NaCl, 1 500 mg/L of phenol is degraded by W3 within 12 days and the degrading rate is 99.8%. The strain can also degrade various aromatic compounds, such as aniline, salicylic acid, and phenolic mixtures under high salt conditions. The salt-tolerant mechanism of W3 shows that the level of ectoine and betaine inside of cells increases with increasing salinity, which indicats that W3 can use ectoine and betaine as the osmoprotectant in hypersaline environment.