International Journal of Marine Science 2015, Vol.5, No.27: 1-11
3
was 0.01 day
-1
and biostimulation was 0.13 day
-1
. The
efficacy of biostimulation - only treatment was lower
than combination treatment. However, it was higher
than natural bio attenuation (control).
Table 1 Kvalue in each treatments at different time periods of
experiment, n = 3
No.
Treatment
Kvalue at certain periods of time
( day
-1
)
0
-
8
days
0
-
16
days
0
-
23
days
0
-
90
days
1
Control (C)
0.014
0.025
0.029
0.010
2
Fertilizer
(F)
0.028
0.021
0.036
0.013
3
Fertilizer +
Single strain
(FSC)
0.034
0.050
0.051
0.017
4
Fertilizer +
Consortium
(FCC)
0.038
0.085
0.059
0.015
2.2 Microbial growth
Microbial population density in all treatments varied
during the experiment (Figure
2). Total cell count in
the control sediment (1.98
-
15.61 x 10
7
cells/ g
) over
time of the experiment was lower than other
treatments. The total number of cells in F, FSC and
FCC were in the range of 3.98
-
29.09 x 10
7
cells/ g
;
3.35
-
43.53 x 10
7
cells/ g and 3.65
-
38.80 x 10
7
cells/ g.
A lag phase was observed in all treatments on the first
3 days after treatment, except in the control. An
exponential phase for different treatments occured at
different time periods. The exponential phase of the
FSC and FCC treatments were observed between 8-16
days, whereas it occured at between 16
-
23 days in the
fertilizer-only (F) treatment. In the control, it was not
so clear, it may have been around 16
-
30 days.
The growth of bacterial cells was concomitant with
the loss of oil concentration (Figure 2). There was a
strong negative correlation between oil concentration
and population density. The value of coefficient
Figure 2 Relation of oil depletion (%) and bacterial cell numbers in each treatments during the 90 day mesocosm experiment.
Treatments were C is oiled sediment only, F is oiled sediment with fertilizer (15 g N/kg) , FSC is oiled sediment amended with
Fertilizer (7.5 g N/kg) plus single strain (2.5 L, 8 x 10
8
cells/mL) and FCC is oiled sediment amended with Fertilizer (7.5 g N/kg)
plus consortium (2.5 L, 8 x 10
8
/mL)
