Prerequisites and susceptibility of humic acids to microbial utilization and transformation – a review

Abstract

In the last decades, structural complexity and importance to natural environments of humic substances have been elucidated. Their persistence and/or susceptibility to biological decomposition, however, requires further research. Here we present a contribution on humic acids (HA) extracted by alkali from soils differing in metal contents. These compounds represent organic-mineral-metal complexes naturally occurring in soils. If exposed to microbial activities, especially in the absence of easily utilizable carbon and nitrogen sources, HA from arable soils with elevated metal contents or from a soil site near a magnesium re-working factory and heavily contaminated with this element, were found to support the microbial growth. Simultaneously, different structural transformations occurred in the HA. Furthermore, the FT-IR spectroscopic investigations indicated a loss in metal and silicate constituents from the HAs preparations.

Keywords:

• humic substances
• microbial utilization
• microbial transformation

Acknowledgements

The senior author (Z.F.) gratefully acknowledges a Visiting Professorship (Marie Curie Chair) granted by courtesy of the European Commission, Brussels, and established at the Institute of Chemical Technology, Prague, Czech Republic.