Aromatic sulfonates are synthetic compounds that are widely used in European industry and households, in applications as diverse as detergents, pharmaceuticals, tanning agents and cement additives. Although these chemicals are regarded as xenobiotics, and accumulate in certain environmental compartments, natural sultonates of unknown structure also make up a large proportion (>50%) of the sulfur in forest and agricultural soils. The SUITE project will investigate the desulfonation of synthetic and natural sulfonates by aerobic and anerobic bacteria in soils from various European climate zones, and relate this to the sulfur status in the soils studied and to sulfur cycling in soil organic matter. This emphasis on the sulfur cycle is a novel one in biodegradation/bioremediation studies, and will provide a model for investigations of other sulfur-containing xenobiotics in the environment. In addition, by characterizing the structure and cycling of naturally-occurring sulfonates for the first time, SUITE aims not only to achieve an understanding of sulfur cycling which will be of value in agriculture and forest management, but also to link microbial processes in uncontaminated environments to potential bioremediation problems throughout Europe, for predictive and management purposes.
The main objectives of the project are:
1) Characterization of the desulfonation enzymes and their genes in aerobic and anaerobic bacteria, and development of new methods (RT-PCR) for direct analysis of the expression of these desulfonation genes in various soil environments. The soil environments tested will include:
a) uncontaminated soils ("pristine soils"), representative of the different climatic conditions of Europe on a north-south gradient from North Sweden to Italy, and carrying different vegetation types,
b) contaminated soils, including soils which have been subject to acid precipitation and soils which have been directly contaminated with aromatic sulfonates (activated sludge, landfill).
2) Characterization of the biodiversity of microorganisms able to desulfonate natural and synthetic sulfonates in the soils tested
3) Structural characterization of naturally-occurring sulfonates in soils,
4) Analysis of the cycling of sulfur between organic matter and inorganic sulfur forms in the tested soils, in dependence on climatic conditions and the sulfate and carbon content of the soils,
5) Analysis of the sulfur composition of the tested soils (i.e. inorganic sulfate, sulfate ester, amino acid sulfur, sulfonate sulfur), and correlation of sulfonatase gene expression with the levels of inorganic sulfate and other sulfur compounds,
6) Analysis of the desulfonation of added xenobiotic sulfonates in microcosms set up with the soils studied, and investigations of the pathways and complexity of desulfonation and mineralization processes with and without the addition of specific bacterial inocula.
Funding SchemeCSC - Cost-sharing contracts
W8 7AH London