A. Okabe et al., Seasonal variations of phospholipid fatty acid composition in the floodwater of a Japanese paddy field under a long-term fertilizer trial, SOIL SCI PL, 46(1), 2000, pp. 177-188
The concentration and composition of phospholipid fatty acids (PLFAs) in th
e floodwater of a Japanese paddy field under a long-term fertilizer trial f
or more than 70 y [no fertilizers (NoF) plot, chemical fertilizers (CF) plo
t, and chemical fertilizers and composts (CM) plot] were determined. The am
ount of PLFAs ranged from 2.8 to 14.1 mu g L-1 for the NoF plot, from 3.2 t
o 8.6 mu g L-1 for the CF plot, and from 4.4 to 13.0 mu g L-1 for the CM pl
ot, respectively. Dominant PLFAs in the floodwater were 16:1 omega 7, 16:0,
and 18:1 omega 7 in all the plots. Straight, mono-unsaturated PLFAs accoun
ted for about 40% of the total, suggesting the predominance of Gram-negativ
e bacteria in the floodwater. Principal component analysis and cluster anal
ysis of PLFA composition clearly revealed the variations of microbiota in t
he floodwater with the kinds of fertilizer and the growth stages of rice pl
ants. An indicator of the environmental stress imposed upon microbiota expr
essed by the trans vs, cis ratio of 16:1 omega 7 was consistently low, indi
cating that the floodwater environment was a low-stress environment upon th
e microbiota.