Microbial utilization of organic nitrogen petrochemical compounds : an approach for fuel biodenitrogenation

Other Title(s)

الاستهلاك الميكروبي للمركبات النيتروجينية بترولية المصدر : اتجاه نحو الإزالة البيولوجية للنيتروجين من الوقود

Dissertant

Al Muhsin, Hasan Muhammad Hasan

Thesis advisor

Muhammad, Majdi al-Said
al-Baharinah, Basmah Sadiq

Comitee Members

Golbahar, Jamal
Ghanim, Isam Husayn

University

Arabian Gulf University

Faculty

College of Graduate Studies

Department

Biotechnology

University Country

Bahrain

Degree

Master

Degree Date

2008

English Abstract

The utilization of some organic nitrogen compounds encountered in crude oils such as carbazole (CAR), indole (IND) and quinoline (QUN) by newly isolated 17 bacterial strains was investigated.

Nine of the bacterial strains had been previously shown to be closely related to different species of family Bacillaceae.

In the present study, the tentative identification of the other eight strains was performed depending on amplification and partial sequencing of their 16S rDNA gene.

Three strains (4A, 6C, and 15C) exhibited high sequence identity (95-98% sequence identity) with 16S rDNA gene from Bacillus subtilis and B.amyloliquefaciens, two bacterial strains (6B and 9B') exhibited close relation with 16S rDNA gene from Brevibacillus borstelenis (91- 95% sequence identity), one strain was closely related to Pseudomonas stutzeri (92 - 95% sequence identity).

The remaining strains (2 and 15B) showed doubtful 16S rDNA sequence homology due to the small number of nucleotides obtained after sequencing.

The capability of the bacterial strains to utilize CAR, IND and QUN as N-and /or C-sources in a chemically defined medium was screened depending on following the bacterial growth at 600rmi and consumption of the substrate by HPLC analysis.

Only few bacterial strains grew and utilized CAR (4 strains) or QUN (6 strains) or IND (4 strains) and no one single bacterial strain was able to exhibit clear growth with all of CAR, QUN and IND when present as the sole C-and N-source.

Addition of glucose as an alternative C-source stimulated the growth of more strains with CAR (11 strains), QUN (9 strains) and IND (12 strains) as the sole N-source.

All bacterial strains showing signs of growth with CAR, QUN or IND in absence of glucose were considered as degraders that most probably capable of C-C and C-N bond cleavage.

The growth of CAR-degrader strains were dependent on CAR-concentration.

Interestingly, three bacterial strains (2, 4B and 4A) which were not able to grow and utilize CAR, QUN and IND, respectively exhibited growth in presence of glucose as an alternative C-source.

Accordingly, it seems likely that strains 2, 4B and 4A posses the metabolic capability for the specific cleavage of only C-N bonds in CAR, QUN or IND.

Presumably these bacterial strains represent novel potential bacterial strains for denitrogenation of nitrogenous compounds present in crude oil.

However, further studies are required to explore the metabolic pathways involved in the denitrogenation of CAR, QUN and IND by these bacterial strains.

All tested bacterial strains exhibited faster growth with 2-aminobenzoic acid which is a common intermediate in CAR degradation pathway.

Using some degenerate primers for amplification of the genes carAa and carBa in PCR assays resulted in some amplicons.

However, sequencing and data base homology search for DNA amplicons of the expected size did not give homology with the corresponding genes in known CAR-degrading bacterial strains.

RT-PCR assays for CAR-growing cells failed to detect the expression of these amplicons in comparison with NH4Cl-grown cells.

Main Subjects

Biology

No. of Pages

106

Table of Contents

• APA
• MLA
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Language

English

Data Type

Arab Theses

Record ID

BIM-735487