International Journal of Marine Science 2015, Vol.5, No.27: 1-11
7
Exogenous effective microbes which pre-adapted with
the projected pollutant and intended environment may
increase metabolic capability of indigenous bacteria in
oil polluted area. In this study, a combination of
Gramafix and synthetic consortium of selected three
oil degrading bacteria collected from Jakarta Bay and
pre-adapted to Cilacap coastal environment was able
to degrade 74 % oil after 2 weeks inoculation. It was
more effective than a combination of Gramafix and a
single strain amendment. It might be caused by
consortium have more diverse enzyme that increase
their capability. Westlake (1982) noted that no single
microbial species has the enzymatic ability to metabolize
more than two or three classes of compounds typically
found in a crude oil. A consortium composed of many
different bacterial species is thus required to degrade a
crude oil spill significantly. This result was in
agreement with other previous study (Baek et al.,
2007; Mittal and Singh, 2009; Subaphol et al., 2006).
The consortium formulated in this study was consisted
of
Alcanivorax
sp. TE9,
Pseudomonas balearica
st
101 and RCO/B/08015. Except RCO/B/08015 strain
that has not been identified yet, the genus of other two
strains have been known as oil degrading bacteria
(Yakimov et al., 2005; Rolling et al., 2002; Darmayati
et al., 2008). The combination of bioaugmentation and
inoculation consortium showed rapid degradation until
the first 16 days. It is a common pattern observed for
the combination treatment. Therefore, it is proposed
that combination of biostimulation - bioaugmentation
with the consortium is relatively better alternative for
combating oil-pollution on sandy beaches for a short
period. Further study to find method for maintaining a
good rate of oil degradation is needed to be done.
4 Materials and Methods
4.1 Site description
This research was conducted at a shoreline along the
mouth of the Donan river estuary in the Cilacap region,
Indonesia, between August – October 2011. The site
was estuarine which has semi diurnal tidal pattern. In
a downstream area was located Cilacap industrial
estate, harbor for oil refinery and other industries
which potentially contribute oil to the environment.
4.2 Sediment preparation and Spiking
Seashore sand uncontaminated by oil was collected
(surface layer : 0 – 15 cm) from the north coast of
Nusakambangan Island (
Figure
1). Prior to spiking,
the sandy sediment was airdried for 24 hr and then
homogenized by sieving to 8 mm. Moisture content
was determined through oven drying at 105
o
C for 24h.
Total oil concentration was determined gravimetrically
(US EPA,1999).
For experimental work, Arabian Light crude oil (Table
3) was applied by sprayer into sediment to provide
100,000 ppm of oil-polluted sediment and then
homogenized thoroughly. Oil-polluted sediment was
put outdoor for 5 days to allow weathering. Oiled
sediment was prepared in volumes of 0.45 m
3
for 12
plots. Each box, filled with 0.0375 m
3
of oil-polluted
sediment, was 50 x 50 x 15 cm in dimension. Tilling
up to 15 cm depth in each plot was conducted once a
week throughout the experiment (90 days).
Table 3 Physicochemical Characteristics of Arabian Light
Crude oil used (provided by PERTAMINA, 2011)
No
Parameters (Units,
Analysis Methode)
Arabian
Light
Crude Oil
(ALC)
Naphtha
Fraction
Light Heavy
1
API Gravity at
60/60
o
F (-, ASTM D
1298)
33.3
2
Sulphur content
(mass %, ASTM D
1552)
2.24
3
Nitrogen content
(mass ppm, ASTM D
3228)
ND
4
Nickel (Ni) (mass
ppm, IP 470 )
2
5
Vanadium (mass
ppm, IP 470)
<1
6
Hydrocarbon Types
Saturates (vol. %,
ASTM D 5134)
99.3
83.9
Aromatics (vol. %,
ASTM D 1319)
0.6
16. 0
Olefins (vol. %,
ASTM D 1319)
0.1
0.1
Resin & Asphaltenes
(-,-)
NA
NA
4.3 Slow release fertilizer
Fertilizer used in the study was local production SRF
(Gramafix©, PT.CV. Sinar Kencana, Bandung,
