Comparison of bacterial and fungal biomass determined by phospholipid fatty acid and direct microscopical analysis in 4 types of upland soils
2001
Arao, T. (National Inst. of Agro-Environmental Sciences, Tsukuba, Ibaraki (Japan)) | Okano, S. | Nishio, T.
We investigated the relationship between the phospholipid fatty acid (PLFA) content and bacterial and fungal biomass in soils incubated in the presence/absence of cellulose or glucose. PLFA content except for 18:2 omega 6 in soil was correlated with the bacterial biomass estimated by direct bacterial counts (r = 0.75; p<0.01, n = 66) and the average ratio of bacterial biomass to PLFA content was 4.7 =+- 0.2 in 3 types of upland soils. These results suggest that the bacterial biomass can be estimated based on the PLFA content in soil. A positive correlation (r = 0.50; P<0.01, n = 86) was also found between the content of PLFA 18:2 omega 6 and the fungal biomass determined by direct microscopical analysis in 4 types of upland soils. This correlation coefficient increased when the soils containing PLFA 18:2 omega 6 below 0.1 mg g**-1 dry soil were omitted (r = 0.64; p<0.01, n = 38). In this case, the average ratio of fungal biomass to PLFA 18:2 omega 6 content was 822 =+- 71. A similar average ratio was observed in a Low Humic Andosol after application of pig compost (769 =+- 149). These results suggest that the PLFA 18:2 omega 6 content could be used to estimate the fungal biomass in soils containing PLFA 18:2 omega 6 above 0.1 mg g**-1 dry soil. The content of PLFA 18:2 omega 6 increased about three times more than did the fungal biomass just after application of pig compost. In such cases, the PLFA 18:2 omega 6 content could be a relative measure of fungal biomass.
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