Table of Contents
In Vitro Degradation Test of Phenol in Surface, Deep and Mixed
Seawater
SEIJI IWASAKI*, TETSUYA KIMURA, MAKIKO SAKKA and KAZUO SAKKA**
*Mie Prefectural of Public Health and Environmental Institute, Yokkaichi 512-1211,
Japan
**Faculty of Bioresources Mie University, Tsu 514-8507, Japan
Introduction
Some heterotrophic bacteria in surface seawater, living on natural organic
compounds such as sugars and lipids, can decompose artificial chemical substances.
The enriched nature of deep seawater may facilitate the activities of those bacteria. In
the present study, degradation of one, ten and one hundred mg/L of phenol was
compared in vitro among the four media, surface seawater, deep seawater, mixture of
surface seawater and deep seawater (1:1) and distilled freshwater. The deep seawater
and surface seawater were pumped from depth of 440 and 0 m, respectively, in the
Pacific Ocean off Owase, Mie Prefecture. Tested concentrations of phenol were
degraded in surface seawater and deep seawater (but not in distilled freshwater) as
follows: 1 mg/L of phenol was almost completely degraded in surface seawater, deep
seawater and the mixture in two days; 10 mg/L of phenol was almost completely
degraded in two days in deep seawater and the mixture, while degradation rate was less
than 60 % in SSW; although 100 mg/L of phenol was not perfectly degraded in any
seawater after five days, the degraded amounts of phenol increased unlike with lower
phenol concentrations. Initial numbers of bacteria in surface seawater, deep seawater
and the mixture were 89000, 530 and 41000 CFU mL, respectively. The number
increased most in the mixture of surface seawater (bacteria-rich, nutrient-poor) and deep
seawater (bacteria- poor, nutrient- rich) was optimal and that the in situ release of deep
seawater can be a good tool for enhancing bioremediation to degrade artificial chemical
compounds.
Keywords: surface seawater, deep seawater, phenol, bioremediation
Materials and Methods
Field site and sample collection. Surface seawater was sampled from the Pacific
Ocean near Owase, Japan. Deep seawater was pumped from 440 m below the sea
surface.
Reproduced from Biotechnology of Lignocellulose Degradation, Biomass Utilization
and Biorefinery, eds.: Ito Print Publishing Div., Tsu, 555-558 (2009).
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Analytical method
Parameters of water quality shown in table and phenol were
examined by JIS (Japanese Industrial Standards) K 0102. Bacteria was examined by
Marine Broth 2216 (Difco Co. Ltd.).
Test of Degradation of phenol in seawater
Two milliliter of deep seawater,
surface seawater and 1:1 mixture of these seawaters were placed in sterilized 2.5 L of
glass bottle, and one w/v % of phenol dissolved in sterilized deionized water was added
to prepare 1, 10 and 100 mg/L of phenol solution in each seawaters. These seawaters
were shaken for 5 days at 25 degree centigrade. One hundred milliliter aliquots of the
samples were taken for various analysis each one day.
Results and Discussion
Components of deep seawater and surface seawater
Results of examination of deep seawater and surface seawater were shown in
Table 1. Value of nitrate and phosphate in deep seawater were 0.45 mg/L and 0.065
mg/L respectively (22-fold and 34-fold, compared to surface seawater). On the other
hand, bacteria in surface seawater were 89000 CFU /ml and 170-fold bacteria in deep
seawater were present. These values show general characterization of deep seawater (i.e.
nutrition rich and purify). Other difference among these seawaters are, pH, and COD.
Commonly, the value of pH of seawater is 8.0-8.3, although the value of deep seawater
was lower.
Table 1. Components of deep seawater and surface seawater
Parameters
Unit
Water Temperature
℃
pH
Salinity
Surfacep Sea Water
16.9
28.2
7.74
8.19
3.42
3.27
COD
-1
mg　l
0.8
1.4
NO3-N
mg　l-1
0.51
0.023
NO2-N
mg　l
-1
<0.005
<0.005
NH4-N
mg　l
-1
<0.005
<0.005
PO4-P
mg　l-1
0.068
0.002
Chlorophyll a
mg　l-1
<0.001
<0.001
500
3200
Bacteria
PSU
Deep Sea Water
CFU　ml
-1
Degradation of phenol in various seawaters
Degradation test of phenol in deep seawater, surface seawater and 1:1 mixture of
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Concentration of phenol (mg ℓ-1)
1
0.8
Surface Sea Water
1:1Mixture
Deep Sea Water
0.6
0.4
0.2
0
0
1
2
3
Cultivation time (day)
4
5
Fig. 1. Degradation of 1 mg/L of phenol in seawater.
10
Concentration of phenol (mg ℓ -1)
Surface Sea Water
1:1Mixture
8
Deep Sea Water
6
4
2
0
0
1
2
3
Cultivation time (day)
4
5
Fig. 2. Degradation of 10 mg/L of phenol in seawater.
these seawaters was shown in Fig. 1-3 (Fig. 1: concentration of phenol 1 mg/L, Fig. 2:
10 mg/L, Fig. 3: 100mg/L). Figure 1 shows that 1 mg/L of phenol containing in these
three seawaters was almost completely degraded by cultivation for two days. Ten mg/L
of phenol in surface seawater was degraded about 50 % for 5 days, although in deep
seawater and 1:1 mixture were completely degraded within two days. One day
cultivation of 10 mg/L of phenol, in 1:1 mixture seawater, chemical compound was
already degraded over 90 %, although in deep seawater, less chemical compound was
degraded. In surface seawater, nutrients (nitrogen and phosphorous) are poor and not
enough to growing bacteria1) degrading 10 mg/L of phenol completely. In deep
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Table of Contents
Concentration of phenol (mg ℓ-1)
100
80
Surface Sea Water
60
1:1Mixture
Deep Sea Water
40
20
0
0
1
2
3
Cultivation time (day)
4
5
Fig. 3. Degradation of 100 mg/L of phenol in seawater.
seawater, there is much nutrient for growing bacteria degrading the phenol, although
initial number of bacteria in it was few, therefore one day was needed to grow bacteria
enough to degrade 10 mg/L of phenol. As stated above, in surface seawater, bacteria are
rich and nutrient is poor, and in deep seawater, bacteria are poor and nutrient is rich. In
1:1 mixture of these seawaters, there are enough both of nutrients and bacteria, so that
the rate of degradation of phenol was higher than other seawater. was optimal and that
the in situ release of deep seawater can be a good tool for enhancing bioremediation to
degrade artificial chemical compounds2).
References
1) S. Iwasaki, T. Kimura, S. Sakka, K. Sakka, and K. Ohmiya. Annual of
Interdisciplinary Research Institute of Environmental Science 24: 123-127 (2005)
(in Japanese).
2) S. Iwasaki, T. Kimura, S. Sakka, K. Sakka, and K. Ohmiya. J. Japan Society on
Water Environment 26 (11): 687-692 (2003) (in Japanese).
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