Contrasting Soil pH Effects on Fungal and Bacterial Growth Suggests Functional Redundancy in Carbon Mineralisation.
Publikation/Tidskrift/Serie: Applied and environmental microbiology
Nummer: Online 16 January 2009
Förlag: American Society for Microbiology
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: Hoosfield acid strip, Rothamsted Research, UK. This experiment 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/thymidine incorporation to measure bacterial growth. The growth-based measurements revealed a five-fold decrease in bacterial growth, and a five-fold increase in fungal growth, with lower pH. This resulted in an about 30-fold increase in fungal importance, as indicated by the fungal:bacterial growth ratio, from pH 8.3 to pH 4.5. In contrast, corresponding effects on biomass markers for fungi (ergosterol and PLFA 18:2omega6,9) and bacteria (bacterial PLFAs) showed only a two- to three-fold increase in fungal importance in the same pH interval. The shift in fungal and bacterial importance along the pH gradient only affected the total carbon mineralisation, measured as basal respiration, by about one third, possibly suggesting functional redundancy. Below pH 4.5 there was a universal inhibition of all microbial variables probably derived from increased inhibitory effects by release of free aluminium or decreasing plant productivity. To investigate decomposer group importance using growth measurements provided significantly increased sensitivity over biomass-based measurements.
- Biological Sciences
- Carbon drivers and microbial agents of soil respiration
- Effect of environmental factors on fungal and bacterial growth in soil
- Interaction between fungi and bacteria in soil
- Microbial carbon-use efficiency
- Microbial Ecology
- ISSN: 1098-5336