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Comparison of soil fungal/bacterial ratios in a pH gradient using physiological and PLFA-based techniques

Bååth, Erland LU and Anderson, T H (2003) In Soil Biology & Biochemistry 35(7). p.955-963
Abstract
We have compared the total microbial biomass and the fungal/bacterial ratio estimated using substrate-induced respiration (SIR) in combination with the selective inhibition technique and using the phospholipid fatty acid (PLFA) technique in a pH gradient (3.0-7.2) consisting of 53 mature broad-leaved forest soils. A fungal/bacterial biomass index using the PLFA technique was calculated using the PLFA 18:2w6,9 as an indicator of fungal biomass and the sum of 13 bacterial specific PLFAs as indicator of the bacterial biomass. Good linear correlation (p < 0.001) was found between the total microbial biomass estimated with SIR and total PLFAs (totPLFA), indicating that 1 mg biomass-C was equivalent to 130 nmol totPLFA. Both biomass estimates... (More)
We have compared the total microbial biomass and the fungal/bacterial ratio estimated using substrate-induced respiration (SIR) in combination with the selective inhibition technique and using the phospholipid fatty acid (PLFA) technique in a pH gradient (3.0-7.2) consisting of 53 mature broad-leaved forest soils. A fungal/bacterial biomass index using the PLFA technique was calculated using the PLFA 18:2w6,9 as an indicator of fungal biomass and the sum of 13 bacterial specific PLFAs as indicator of the bacterial biomass. Good linear correlation (p < 0.001) was found between the total microbial biomass estimated with SIR and total PLFAs (totPLFA), indicating that 1 mg biomass-C was equivalent to 130 nmol totPLFA. Both biomass estimates were positively correlated to soil pH. The fungal/bacterial ratio measured using the selective inhibition technique decreased significantly with increasing pH from about 9 at pH 3 to approximately 2 at pH 7, while the fungal/bacterial biomass index using PLFA measurements tended to increase slightly with increasing soil pH. Good correlation between the soil content of ergosterol and of the PLFA 18:2w6,9 indicated that the lack of congruency between the two methods in estimating fungal/bacterial ratios was not due to PLFA 18:2w6,9-related non-fungal structures to any significant degree. Several PLFAs were strongly correlated to soil pH (R-2 values > 0.8); for example the PLFAs 16:1w5 and 16:1w7c increased with increasing soil pH, while i16:0 and cy19:0 decreased. A principal component analysis of the total PLFA pattern gave a first component that was strongly correlated to soil pH (R-2 = 0.85, p < 0.001) indicating that the microbial community composition in these beech/beech-oak forest soils was to a large extent determined by soil pH. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Soil Biology & Biochemistry
volume
35
issue
7
pages
955 - 963
publisher
Elsevier
external identifiers
  • wos:000184125500009
  • scopus:0037628100
ISSN
0038-0717
DOI
language
English
LU publication?
yes
id
ecfd798c-fbf3-43e8-99b9-38a52c94916b (old id 135718)
date added to LUP
2007-06-29 09:13:35
date last changed
2018-06-17 04:50:53
@article{ecfd798c-fbf3-43e8-99b9-38a52c94916b,
  abstract     = {We have compared the total microbial biomass and the fungal/bacterial ratio estimated using substrate-induced respiration (SIR) in combination with the selective inhibition technique and using the phospholipid fatty acid (PLFA) technique in a pH gradient (3.0-7.2) consisting of 53 mature broad-leaved forest soils. A fungal/bacterial biomass index using the PLFA technique was calculated using the PLFA 18:2w6,9 as an indicator of fungal biomass and the sum of 13 bacterial specific PLFAs as indicator of the bacterial biomass. Good linear correlation (p &lt; 0.001) was found between the total microbial biomass estimated with SIR and total PLFAs (totPLFA), indicating that 1 mg biomass-C was equivalent to 130 nmol totPLFA. Both biomass estimates were positively correlated to soil pH. The fungal/bacterial ratio measured using the selective inhibition technique decreased significantly with increasing pH from about 9 at pH 3 to approximately 2 at pH 7, while the fungal/bacterial biomass index using PLFA measurements tended to increase slightly with increasing soil pH. Good correlation between the soil content of ergosterol and of the PLFA 18:2w6,9 indicated that the lack of congruency between the two methods in estimating fungal/bacterial ratios was not due to PLFA 18:2w6,9-related non-fungal structures to any significant degree. Several PLFAs were strongly correlated to soil pH (R-2 values &gt; 0.8); for example the PLFAs 16:1w5 and 16:1w7c increased with increasing soil pH, while i16:0 and cy19:0 decreased. A principal component analysis of the total PLFA pattern gave a first component that was strongly correlated to soil pH (R-2 = 0.85, p &lt; 0.001) indicating that the microbial community composition in these beech/beech-oak forest soils was to a large extent determined by soil pH.},
  author       = {Bååth, Erland and Anderson, T H},
  issn         = {0038-0717},
  language     = {eng},
  number       = {7},
  pages        = {955--963},
  publisher    = {Elsevier},
  series       = {Soil Biology & Biochemistry},
  title        = {Comparison of soil fungal/bacterial ratios in a pH gradient using physiological and PLFA-based techniques},
  url          = {http://dx.doi.org/},
  volume       = {35},
  year         = {2003},
}