This Article
Right arrow Full Text
Right arrow Full Text (PDF)
Right arrow Supplemental material
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrowReprints and Permissions
Right arrow Copyright Information
Right arrow Books from ASM Press
Right arrow MicrobeWorld
Citing Articles
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Rousk, J.
Right arrow Articles by Bååth, E.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Rousk, J.
Right arrow Articles by Bååth, E.
Agricola
Right arrow Articles by Rousk, J.
Right arrow Articles by Bååth, E.

 Previous Article  |  Next Article 

Applied and Environmental Microbiology, March 2009, p. 1589-1596, Vol. 75, No. 6
0099-2240/09/$08.00+0     doi:10.1128/AEM.02775-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.

Contrasting Soil pH Effects on Fungal and Bacterial Growth Suggest Functional Redundancy in Carbon Mineralization{triangledown} ,{dagger}

Johannes Rousk,1* Philip C. Brookes,2 and Erland Bååth1

Department of Microbial Ecology, Lund University, Ecology Building, SE-223 62 Lund, Sweden,1 Soil Science Department, Rothamsted Research, Harpenden, Hertfordshire ALS 2JQ, United Kingdom2

Received 5 December 2008/ Accepted 12 January 2009

The influence of pH on the relative importance of the two principal decomposer groups in soil, fungi and bacteria, was investigated along a continuous soil pH gradient at Hoosfield acid strip at Rothamsted Research in the United Kingdom. This experimental location provides a uniform pH gradient, ranging from pH 8.3 to 4.0, within 180 m in a silty loam soil on which barley has been continuously grown for more than 100 years. We estimated the importance of fungi and bacteria directly by measuring acetate incorporation into ergosterol to measure fungal growth and leucine and thymidine incorporation to measure bacterial growth. The growth-based measurements revealed a fivefold decrease in bacterial growth and a fivefold increase in fungal growth with lower pH. This resulted in an approximately 30-fold increase in fungal importance, as indicated by the fungal growth/bacterial growth ratio, from pH 8.3 to pH 4.5. In contrast, corresponding effects on biomass markers for fungi (ergosterol and phospholipid fatty acid [PLFA] 18:2{omega}6,9) and bacteria (bacterial PLFAs) showed only a two- to threefold difference in fungal importance in the same pH interval. The shift in fungal and bacterial importance along the pH gradient decreased the total carbon mineralization, measured as basal respiration, by only about one-third, possibly suggesting functional redundancy. Below pH 4.5 there was universal inhibition of all microbial variables, probably derived from increased inhibitory effects due to release of free aluminum or decreasing plant productivity. To investigate decomposer group importance, growth measurements provided significantly increased sensitivity compared with biomass-based measurements.

* Corresponding author. Mailing address: Department of Microbial Ecology, Lund University, Ecology Building, SE-223 62 Lund, Sweden. Phone: 46 46 222 3763. E-mail: johannes.rousk{at}mbioekol.lu.se

{triangledown} Published ahead of print on 16 January 2009.

{dagger} Supplemental material for this article may be found at http://aem.asm.org/.

Applied and Environmental Microbiology, March 2009, p. 1589-1596, Vol. 75, No. 6
0099-2240/09/$08.00+0     doi:10.1128/AEM.02775-08
Copyright © 2009, American Society for Microbiology. All Rights Reserved.





Copyright © 2009 by the American Society for Microbiology.   For an alternate route to Journals.ASM.org, visit: http://intl-journals.asm.org | More Info»