IJMS-2017v7n42 - page 10

International Journal of Marine Science, 2017, Vol.7, No.42, 399-410
http://ijms.biopublisher.ca
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2 Results and Discussion
2.1 Identification of bacteria
Sixty five isolates of gram negative bacilli was isolated from Khor Al-Zubair channel southern Iraq, Fifty-six of
them were identified correctly to the species level as V. vulnificus, Sphingomonas aucimobilis, Brevundimonas
diminuta/ vesicularis and Ochrobactrum anthropi, while 9 strains were not identified. Direct identification,
reporting time of the VITEK II was 4.5 to 10 hours after incubation (Table 1). Four species were isolated by the
VITEK II system and their ability to degrade four concentrations of crude oil was examined.
Table 1 Identification of bacteria isolates by Vitek II
Organism Correctly identified% Not identified%
V. vulnificus 15 (98)
9
Sphingomonas paucimobilis 25 (95)
Brevundimonas diminuta/vesicularis 8 (91)
Ochrobactrum anthropi 8
Total 56 9
2.2 Degradation study of PAH
In the present study, four species were examined their capability to degrade 4 concentrations of crude oil. Table 2
shows the percentage of degradation of PAH for each genus. Sphingomonas paucimobilis was the most effective
bacteria to degrade PAH (97.39%) especially in concentration 2.0 mg/l, while Ochrobactrum anthropi was the
lowest (13.15%) in the same concentration. Figure 2, Figure 3, Figure 4 and Figure 5 show GC results of control
samples (0.25%; 0.5%; 1% and 2%). Brevundimonas diminuta/ vesicularis showed high PAH degradation
(73.41%) in concentration 1.0 mg/l and low degradation (25.66%) in concentration 2.0 mg/l (Table 2; Figure 6;
Figure 7; Figure 8; Figure 9).
Table 2 Degradation percentage of PAH
Bacterial types 0.25 mg/l 0.5 mg/l 1.0 mg/l 2.0 mg/l
Brevundimonas diminuta/vesicularis 27.71% 62.08% 73.41% 25.66%
Vibrio vulnificus 64.03% 22.91% 42.18% 84.23%
Sphingomonas paucimobilis 33.76% 27.26% 31.22% 97.39%
Ochrobactrum anthropic ND 19.00% 14.45% 13.15%
Figure 2 Crude oil (aromatic faction 0.25%)
min 10 20 30 40 50
pA
0
10
20
30
40
50
60
70
FID1A,FrontSignal(FADIL1\1.D)
2-methylnaphthalene1-methylnaphthaleneAcenaphthleneAcenaphthene
Fluorene
PhenanthreneAnthracene FluoranthenePyrene Benzo(a)fluorantheneChrysene Benzo(b)fluoranthene+Benzo(k)fluorantheneDibenz(a)pyrene Indeno(1,2,3-cd)pyrene+Dibenz(a,h)anthraceneBenzo(g,h,i)perylene