Quantification of the different pools of enzyme activity in soils (intra- a
nd extracellular) is desired to assess the contribution of the microbial co
mmunity to specific enzyme reactions and ecological changes in soils. Aryls
ulfatase activity was assayed at optimal pH (acetate buffer, pH 5.8) in 10
surface soils before and after chloroform-fumigation, and microbial biomass
C (C-mic) was determined by a chloroform-fumigation-extraction method, and
microbial biomass N (N-mic) by a chloroform-fumigation-incubation method.
The C-mic values ranged from 31 to 784 mg kg(-1) soil (average = 252 mg kg(
-1) soil) and the N-mic values ranged from 6 to 28 mg kg(-1) soil (average
= 12 mg kg(-1) soil), resulting in (C/N)(mic) ratios ranging from 5.2 to 30
.3 (average = 20.3). The C/N ratios of the soils ranged from 8.6 to 18.1 (a
verage = 12.3). Expressed as percentages of organic C or N, the C-mic value
s ranged from 0.24 to 1.8% (average = 1.0%) and the N-mic values ranged fro
m 0.36 to 1.2% (average = 0.63%). The activities of total (intra- and extra
cellular) arylsulfatase after chloroform fumigation without toluene treatme
nt; intracellular arylsulfatase (activity of the microbial biomass), i.e.,
[(total activity) - (extracellular activity)]; and extracellular arylsulfat
ase (before chloroform fumigation without toluene treatment) were significa
ntly correlated with C-mic (r = 0.88**, 0.85"*, and 0.94***, respectively)
and N-mic (r = 0.81**, 0.83**, and 0.89***, respectively). The total arylsu
lfatase activity, the activity of the microbial biomass, and the extracellu
lar activity were significantly correlated with organic C (r = 0.88***, 0.9
0***, and 0.72*, respectively) and total N (r = 0.89***, 0.90***, and 0.77*
, respectively). Clay content was also correlated with the activity of tota
l (r = 0.75*) and extracellular arylsulfatase (r = 0.83**). Expressed as pe
rcentages of total activity, the arylsulfatase activity of the microbial bi
omass ranged from 39.6 to 73.1% (average = 57.7%). The remaining activity (
26.9-60.4%, average = 42.8%) was extracellular. When toluene was used as a
plasmolytic agent in the nonfumigated soils, the arylsulfatase activity res
ulting from this treatment ranged from 24.6 to 48.1% (average = 40.3%). Whe
n expressed per milligram of C-mic (specific activity), the arylsulfatase a
ctivity of the microbial biomass ranged from 65 to 955 (average = 455) mu g
PN h(-1). The total arylsulfatase activity and the activity of the microbi
al biomass were underestimated, because tests with arylsulfatase purified f
rom two molluscs (Helix pomatia and Patella vulgata) showed that chloroform
fumigation decreased the activity by 50 and 23%, respectively.