1.Microbial isolation and degradation of selected haloalkanoic aliphatic acids by locally isolated bacteria: A review
Siti Nurul Fasehah Ismail ; Fahrul Huyop
Malaysian Journal of Microbiology 2017;13(3):261-272
The liberation of halogenated compounds by both natural processes and man-made activities has led to extensive
contamination of the biosphere. Bioremediation via the dehalogenation process offers a sustainable way to eliminate
such hazardous contaminants. Whereas, a large number of natural soil microorganisms (i.e., bacteria and fungi) that
have been isolated are capable of degrading and detoxifying such contaminants, information on the preferred types of
halogenated compounds that they catalyze is lacking. In this review, we discuss those microorganisms that have the
potential to perform bioremediation of such environmental contaminants. We also present a method for isolating novel
dehalogenase-producing microorganisms from cow dung.
2.Isolation and identification of bacteria isolated from ruminant animal waste that able to degrade 2,2-dichloropropionic acid (2,2-DCP)
Siti Nurul Fasehah Ismail ; Roswanira Abdul Wahab ; Fahrul Huyop
Malaysian Journal of Microbiology 2016;12(2):155-163
Aims: A 2,2-dichloropropionic acid (2,2-DCP) naturally degrading bacterial species, strain SN1 was successfully
isolated from cow dung capable of utilizing the substance as the sole carbon source and energy.
Methodology and results: Strain SN1 was preferred over other strains (SN2, SN3 and SN4) following observations on
its rapid growth in 20 mM 2,2-DCP liquid minimal media. Since strain SN1 clearly exhibited tolerance towards 2,2-DCP,
its growth in various concentrations (10 mM, 20 mM, 30 mM and 40 mM) of the substance was evaluated. The study
found the bacteria grew particularly well in 20 mM 2,2-DCP with the highest chloride release of 39.5 µmole Cl-
/mL while
exhibiting a remarkably short doubling time of 3.85 h. In view of such notable characteristics, species identification via
Biolog GEN III system and 16S rRNA analysis was performed and established strain SN1 as Bacillus cereus.
Conclusion, significance and impact of study: Considering the rapid growth of B. cereus strain SN1 in such medium,
its employment as a bioremediation agent to treat 2,2-DCP contaminated soils may prove beneficial. Moreover, this is
the first reported case of a Bacillus sp. isolated from cow dung capable of utilizing 2,2-DCP. Therefore, further
assessment into its ability to degrade other types of haloalkanoic acids merit special consideration.
Bacillus cereus
3.Purification and characterization of dehalogenase from Bacillus cereus SN1 isolated from cow dung
Siti Nurul Fasehah Ismail ; Mohamed Faraj Edbeib ; Wan Mohd Khairul ikhsan Wan Seman ; Mahzan Md. Tab ; Farahayu Khairuddin ; Amin Retnoningsih ; Roswanira Abdul Wahab ; FahrulHuyop
Malaysian Journal of Microbiology 2018;14(3):244-253
Aims:
This study was aimed to characterize a dehalogenase derived from Bacillus cereus SN1 isolated from cow dung.
Methodology and results:
Cell-free extract of Bacillus cereus SN1 was purified using ion exchange and gel filtration chromatography. Fraction B2 of gel filtration gave the highest enzyme specific activity (0.155 μmol CI¯/min/mg). The results of SDS-PAGE showed the enzyme was 25 kDa in size. The enzyme reached its optimum activity at 30 °C at pH 6, and was inhibited by Mercury(II) sulfate (HgSO4). The Km and kcat values were 0.2 mM and 1.22/sec, respectively. The partial dehalogenase gene sequence was amplified using Group I dehalogenase primers. The amplified gene sequence was designated as DehSN1.
Conclusion, significance and impact of study
Dehalogenase from Bacillus cereus strain SN1 revealed new characteristics of dehalogenase protein. The findings indicated that the DehSN1 dehalogenase is a promising candidate for further studies as a bioremediation agent for agricultural applications.
4.Dehalogenase producing bacteria from extreme environment: A review
Siti Nurul Fasehah Ismail ; Arman Shah ; Mohamed Faraj Edbeib ; Aliyu Adamu ; Firdausi Aliyu ; Roswanira Abdul Wahab ; Fahrul Huyop
Malaysian Journal of Microbiology 2018;14(5):424-434
Halogenated compounds create the most important class of xenobiotic which commonly lead to pollution. Some of these compounds are very toxic and cause enormous problems to human health and to the environment. Many of these toxic chemicals have been shown to occur in various extreme habitats. Pollutant-degrading microorganisms, adapted to grow in various environments, play an important role in the biological treatment of polluted extreme habitats. The presence of dehalogenase producing microorganisms in extreme habitat in particular is necessary since the enzyme can catalyze the removal of a halogen atom from a substrate. Therefore, it can reduce the toxicity of the halogenated compound and some are of interest for study in industrial application. Thermophiles, psychrophiles, acidophiles, alkaliphiles and halophiles are types of extremophiles. Knowledge of the biodegradation of toxic chemicals in extreme environment is limited. Here, examples of dehalogenase producing bacteria isolated from various extreme conditions and its special characteristics/features will be discussed in this review.