Impact of pesticides and oxygen on microbial cellulose degradation in aerated agricultural soils: A microscaled analysis of processes and prokaryotic populations

Principal investigators: Dr. S. Kolb, Prof. Dr. H.L. Drake

Co-worker: Dipl.-Biol. S. Schellenberger

Cellulose is one of the most abundant carbonaceous compounds in terrestrial ecosystems, and its mineralization in agricultural soils contributes significantly to the global CO2 budget. Pesticides may affect the activities (e.g. beta-glucosidase) of soil microbes; however, their potential effect on the degradation of cellulose has not been resolved. Likewise, although it is common knowledge that microbes in soil aggregates are exposed to dynamic oxygen concentrations, the importance of steep oxygen gradients over soil aggregate surfaces to the mineralization of cellulose is unclear. Indeed, despite the relatively large amount of information available on novel cellulose-utilizing microbes in aerated soils the in situ relevance of these isolates is unresolved.

Objectives:
To elucidate the effect of the pesticides on cellulose degradation rates in an agricultural soil, and to resolve the differential effect on specific phylotypes.
To resolve the activity and function of specific phylotypes during cellulose degradation under different oxygen and pesticide regimes.

Cooperation within the priority programme:
Dr. M. Horn, Dr. M.Schloter, Prof. J.C. Munch, Prof. Dr. C. Tebbe

Kolb1

Degradation of cellulosic fibres by the celluloytic community (Diplom Thesis Gutmann 2008, modified from Bayer et al. 2006, in 'The Prokaryotes').

Kolb2

Soil slurry microcosms (S. Schellenberger 2008)

Poster Kolb

Publications

2011

Schellenberger, S., Drake, H.L., Kolb, S. 2011. Functionally redundant cellobiose-degrading soil bacteria respond differentially to oxygen. Appl. Environ. Microbiol. 77, 6043-6048.

2010

Schellenberger, S., Kolb, S., Drake, H.L. 2010. Metabolic responses of novel cellulolytic and saccharolytic agricultural soil bacteria to oxygen. Environ. Microbiol. 12, 845-861.