Bacterial pH-optima for growth track soil pH, but are higher than expected at low pH

A - Papers appearing in refereed journals

Fernandez-Calvino, D., Rousk, J., Brookes, P. C. and Baath, E. 2011. Bacterial pH-optima for growth track soil pH, but are higher than expected at low pH. Soil Biology and Biochemistry. 43 (7), pp. 1569-1575.

AuthorsFernandez-Calvino, D., Rousk, J., Brookes, P. C. and Baath, E.

One of the most influential factors determining the growth and composition of soil bacterial communities is pH. However, soil pH is often correlated with many other factors, including nutrient availability and plant community, and causality among factors is not easily determined. If soil pH is directly influencing the bacterial community, this must lead to a bacterial community growth optimised for the in situ pH. Using one set of Iberian soils (46 soils covering pH 4.2–7.3) and one set of UK grassland soils (16 soils covering pH 3.3–7.5) we measured the pH-optima for the growth of bacterial communities. Bacterial growth was estimated by the leucine incorporation method. The pH-optima for bacterial growth were positively correlated with soil pH, demonstrating its direct influence on the soil bacterial community. We found that the pH from a water extraction better matched the bacterial growth optimum compared with salt extractions of soil. Furthermore, we also showed a more subtle pattern between bacterial pH growth optima and soil pH. While closely matched at neutral pHs, pH-optima became higher than the in situ pH in more acid soils, resulting in a difference of about one pH-unit at the low-pH end. We propose that an explanation for the pattern is an interaction between increasing overall bacterial growth with higher pHs and the unimodal pH-response for growth of bacterial communities.

KeywordsSoil acidity; pH-tolerance; Bacterial growth; pH-optima; Leucine incorporation
Year of Publication2011
JournalSoil Biology and Biochemistry
Journal citation43 (7), pp. 1569-1575
Digital Object Identifier (DOI)
Open accessPublished as non-open access
FunderBiotechnology and Biological Sciences Research Council
Funder project or codeSEF
Carbon, nutrient and energy flows through the soil microbial biomass and soil ecosystem functioning
Publisher's version
Copyright license
Publisher copyright
Output statusPublished
Publication dates
Online24 Apr 2011
Publication process dates
Accepted11 Apr 2011

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