Biotransformation of butyltin compounds and microbiome diversity in the bottom sediments of the Gulf of Finland, the Baltic Sea

Abstract

Pollution of the marine environment with organotin compounds is a serious environmental problem due to their extreme toxicity to a wide range of organisms. A high level of contamination with butytin compounds was detected in the bottom sediments of the Koporye Bay, the Gulf of Finland, the Baltic Sea. The concentration of tributyltin and dibutyltin reached up to 35.7 ng(Sn)/g DW and 9.7 ng(Sn)/g DW, respectively. The butyltin compounds transformed in bottom sediments due to the activity of autochthonous sediment microbiota. The degradation rate of tributyltin and dibutyltin was 0.014 day-1 and 0.022 day-1, their half-life, 49.5 and 31.5 days, respectively. Metagenomic analysis revealed the changes in taxonomic composition and the decrease in species diversity of the bottom sediment microbiomes during the transformation of organotin compounds. During the biodegradation of butyltin compounds in bottom sediments, the abundance of bacteria of the genera Acidithiobacillus, Halothiobacillus, Alicyclobacillus, Sulfurospirillum, Denitrovibrio, as well as of methanogenic archaea of the genus Methanolobus increases, which may indicate their potential participation in the biodegradation of organotin compounds. These results may be used to identify active tributyltin degraders for developing self-purification methods of bottom sediments contaminated with organotin compounds.

Keywords

• tributyltin
• dibutyltin
• monobutyltin
• biotransformation
• microbial diversity
• bottom sediments