Aerobic biodegradability of hydroxypropyl-β-cyclodextrins in soil

Hydroxylpropyl-β-cyclodextrins (HP-β-CDs), hydroxyalkyl derivatives of β-CD, used in a broad range of applications in food, pharmaceutical, agriculture and bioremediation of soil because of their specific chemical properties. The possibility of varying the biodegradation rate of HP-β-CDs by changing the DS and substitution pattern makes HP-β-CDs suitable for various applications. Therefore, their biodegradation fate has been of great concern. In this study, the biodegradation of various HP-β -CDs, which have different degrees and patterns of substitution in different soil ecosystems, was investigated. The degree and pattern of substitution of HP-β-CDs were determined by the reductive-cleavage method and methylation analysis. Two common soils and a contaminated soil were used in the biodegradation test. All CDs were found to be more or less biodegradable. Increasing the degree of substitution (DS) had negative effect on the biodegradation rate of HP-β-CDs. The substitution pattern affected the biodegradation, too. The biodegradation rates of CDs in the contaminated soil were higher than that obtained in the uncontaminated soils. The contamination removing ability of CDs was highly affected by their own biodegradation fate in soil.