A review on non-stereospecific haloalkanoic acid dehalogenases

Haloalkanoic acid dehalogenases remove halides from organic haloacids and have potential as bioremediation agents. DehE from Rhizobium sp. RC1, DehI from Pseudomonas putida PP3 and D,LDEX 113 from Pseudomonas sp. 113 are non-stereospecific dehalogenases that invert the configurations of D- and L- carbons bound to a halogen. The kinetics of DehE has been partially characterized and brominated compounds have greater specificity constant values than do the corresponding chlorinated compounds. The sequence of DehE is similar to that of DehI; therefore, the two enzymes may have similar structures and functions. The three-dimensional structure of DehI is known and its reaction mechanism was inferred from its structure and a mutagenesis study of D,L-DEX 113. Aspartate residues at positions 189 and 194 in DehI and D,L-DEX 113 were predicted to be involved in catalysis. These residues activate a water molecule that directly attacks the chiral carbon. Because DehE and DehI are sequentially related, delineating the structure of DehE is important to ascertain if the catalytic residues and reaction mechanism are the same for both enzymes. A structural prediction, sequence-homology modeling and a site-directed mutagenesis study of DehE might help achieve this goal.Key words: Haloalkanoic acids, non-stereospecific dehalogenase, DehE, Rhizobium sp. RC1, enzyme kinetics, protein structure prediction, site-directed mutagenesis

Detection of AML1-ETO Fusion Gene in Iraqi Patients with Acute Myeloid Leukemia using Nested PCR and Flow Cytometry

The rearrangement and instability of genomic material causes the occurrence of fusion genes. Over 800 distinct fusion genes have been found in human cancer, most observed in hematological cancers. Chromosomal rearrangements such as deletion, inversion, translocation, and amplification are the primary forms that lead to fusion gene formation, which are ultimately resulting from aberrant DNA transcription. The purpose of this research was to use nested polymerase chain reaction (PCR) and flow cytometry to determine how frequent the AML1-ETO fusion gene is among Iraqi AML patients. The AML1-ETO fusion gene was detected and documented in twenty-seven percent (27%) of acute myeloid leukemia (AML) patients were found to have the AML1-ETO fusion gene. The results of this study add to our understanding of the prevalence of the AML1-ETO fusion gene in Iraqi AML patients and have implications for the development of more effective treatment options

Further analysis of burkholderia pseudomallei mf2 and identification of putative dehalogenase gene by pcr

Halogenated organic compounds are extensively and widely used as pesticides, herbicides, and antibiotics that contribute to the pollution. This research was aimed to further analyze and characterize a bacterium that has the ability to utilize 2,2-dichloropropionic acid (2,2-DCP) as a model to study dehalogenase enzyme production. Microscopic observation, biochemical tests and PCR technique were carried out in order to characterize the isolated bacterium. Strain MF2 showed its ability to grow on 10 mM 2,2-DCP liquid minimal medium with doubling time of 13 h with maximum chloride ion released of 19.8 μmolCl–/mL. The 16S rDNA analysis suggested that strain MF2 belongs to the genus Burkholderia. This was supported by the microscopic observation and biochemical tests. Dehalogenase gene was observed when using only primers dehIfor1 and dehIrev2 derived from group I deh PCR primer sequences, whereas no amplification using dhlB-314-forward and dhlB-637-reverse (group II dehalogenase) and haloacetate dehalogenase (H2-1157-forward and H2-1662-reverse) PCR primer sequences. The results suggested that, possibly, dehalogenase from MF2 was related to group I deh. In conclusion, strain MF2 showed the ability to utilize 2,2-DCP as sole source of carbon and energy. Further analysis revealed the MF2 strain consisted of dehalogenase gene that could be used for degradation of man-made halogenated compounds present in the environment. Using existing dehalogenase PCR primers, it was possible to amplify the dehalogenase genes sequence

Customised structural, optical and antibacterial characteristics of cinnamon nanoclusters produced inside organic solvent using 532 nm q-switched nd:yag-pulse laser ablation

Biomedical values of organic natural cinnamon that are buried in their bulk counterpart can be exposed and customised via nanosizing. Based on this factor, a new type of spherical cinnamon nanoclusters (Cin-NCs) were synthesised using eco-friendly nanosecond pulse laser ablation in liquid (PLAL) approach. As-grown nontoxic Cin-NCs suspended in the citric acid of pH 4.5 (acted as organic solvent) were characterised thoroughly to evaluate their structural, optical and bactericidal properties. The effects of various laser fluences (LF) at the fixed wavelength (532 nm) on the physiochemical properties of these Cin-NCs were determined. The FTIR spectra of the Cin-NCs displayed the symmetric-asymmetric stretching of the functional groups attached to the heterocyclic/cinnamaldehyde compounds. The HR-TEM image of the optimum sample revealed the nucleation of the crystalline spherical Cin-NCs with a mean diameter of approximately 10 ± 0.3 nm and lattice fringe spacing around 0.14 nm. In addition, the inhibition zone diameter (IZD) and optical density (OD600) of the proposed Cin-NCs were measured to assess their antibacterial potency against the Staphylococcus aureus (IZD ≈ 24 mm) and Escherichia coli (IZD ≈ 25 mm) bacterial strains. The strong UV absorption (in the range of 269 and 310 nm) shown by these NCs was established to be useful for the antibacterial drug development and food treatment

Identification of novel bacterial species capable of degrading dalapon using 16S rRNA sequencing

2,2-dichloropropionic acid (2,2DCP) is used as herbicide in agricultural industry and it is one of the halogenated organic compounds distributed widely in the world causing contamination. In this study, a bacterial strain isolated from contaminated soil where halogenated pesticides applied in Universiti Teknologi Malaysia and it was named “JHA1”. Bacterium JHA1 was able to utilize 2,2 dichloropropionate 2,2-DCP or (Dalapon) as a source of carbon and energy. Based on 16S rRNA analysis, the isolate showed 87% identity to Terrabacter terrae strain PPLB. The identity score was lower than 98% so that it was suggested to be new organisms that worth for further investigations if it will be proven that this is novel. Therefore, current isolate was designated as Terrabacter terrae JHA1. The isolate grew in the minimal media containing 10 mM, 15 mM, 20 mM and 25 mM of 2,2- DCP as the sole energy and carbon source and the best growth rate was in 20 mM as the optimum concentration of 2,2-DCP while bacterial growth was inhibited in medium with 30 mM 2,2-DCP

Purification and properties of a new dehalogenase enzyme from Pseudomonas sp. B6P grow in 3- chloropropionate (3CP)

Halogenated compounds are widely used in agriculture and industries and have been associated with environmental pollution. Degradation of 3-chloropropionate (3CP) by microorganism has been established and this enzyme could only remove halogen atom at the â- position of 3-carbon alkanoic acids. Pseudomonas sp. B6P was originally isolated from paddy field which was able to degrade 3CP therefore, suggesting it may have some desirable properties. The enzyme was purified from cell-free extracts having a monomer of 56,000 Da. It was found to be stable between pH 5 to 8 and its optimal pH was 8. Its activity was not affected by metal ions such as Mn2+, Fe3+ and Mg2+, but was inhibited by Hg2+ and Ag2+. The enzyme is specific for 3CP, and the Km value (0.20 mM ± 0.05).Key words: Biodegradation, 3-chloropropionic acid, dehalogenase,  bioremediation, haloalkanoic acid, Pseudomonas sp.B6P

Genomic analysis of mesorhizobium loti strain tono reveals dehalogenases for bioremediation

Halogenated compounds are extensively utilized in different industrial applications such as pesticides and herbicides and cause severe environmental problems because of their toxicity and persistence. Degradation of these compounds by the biological method is a significant method to reduce these recalcitrant. Mesorhizobium loti is im-portant for nitrogen fixation in legume roots. Up to now, there is no report to indicate M. loti can produce dehalogenase enzymes. Thus, a total of twenty-five genomes of M. loti strains from the National Center for Biotechnology Information (NCBI) were an-alyzed. These strains notably carry dehalogenase genes and were further investigated. The relative ratio of haloalkane and haloacid dehalogenase type II or L-type from all twenty-five genomes was 26% and 74%, respectively, suggesting type II dehalogen-ase is common. Surprisingly, only M. loti strain TONO carries four dehalogenases and therefore it was further characterized. The chromosome of M. loti strain TONO con-tains four haloacid dehalogenase type II genes namely, dehLt1 (MLTONO_2099), dehLt2 (MLTONO_3660), dehLt3 (MLTONO_4143), and dehLt4 (MLTONO_6945), and their corresponding enzymes were designated as DehLt1, DehLt2, DehLt3, and DehLt4, respectively. The only haloalkane dehalogen-ase gene (MLTONO_4828) was located upstream of the dehLt3 gene and its amino acid share 88% identity with DmlA of Mesorhizobium japonicum MAFF 303099. The putative haloacid permease gene designated as dehrPt (MLTONO_0284) was located downstream of the dehLt1 and its amino acids show 69% identity with haloacid per-mease of Rhizobium sp. RC1. The gene encoding helix-turn-helix (HTH) motif family DNA-binding protein regulator and LysR family transcriptional regulator genes were also identified, possibly for regulatory functions. The genomic studies as such, have good potential to be screened for new type of dehalogenases based on basic molecular structure and functions analysis

Microbial isolation and degradation of selected haloalkanoic aliphatic acids by locally isolated bacteria: A review

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

Evaluation of trichoderma isolates as potential biological control agent against soybean charcoal rot disease caused by Macrophomina phaseolina

Macrophomina phaseolina (Tassi) Goid remains the prevailing causal agent of charcoal rot disease that significantly suppresses the yield of a variety of oilseed crops. Its wide host range and ability to survive under arid conditions, coupled with the ineffective use of fungicides against it, have spurred scientific endeavours for alternative avenues to control this phytopathogen. Hence, the present study aimed to provide empirical evidence of the efficacy of three fungal isolates (T2, T10 and T12) of Trichoderma harzianum as biological control agents against charcoal rot in soybean (Glycine max L.). The results of the in vitro studies revealed that all three fungal isolates significantly inhibited the growth of M. phaseolina phytopathogen, with T12 showing considerably higher inhibition effect than T2 and T10 isolates. T12 inhibited the growth of M. phaseolina in the dual culture (72.31%) and volatile production (63.36%) assays, and the hyperparasitism test indicated cell lysis following the interactions with T12 mycelia. T12 isolate was mostly effective in field experiments, observable in the attained minimum plant disease indices both in the soil incorporation (11.98%) and seed inoculation (5.55%) treatments, in comparison to isolates T2 and T10. Moreover, the stem and root lengths, as well as the seed weight, were considerably increased, as compared to the control. Hence, the findings reported in the present study supported the applicability of T12 isolate as possible alternative to fungicides for the control of charcoal rot in soybean

Dehalogenases for pollutant degradation: a mini review

Dehalogenases are microbial enzyme catalysed the cleavage of carbon-halogen bond of halogenated organic compounds. It has potential use in the area of biotechnology such as bioremediation and chemical industry. Halogenated organic compounds can be found in a considerable amount in the environment due to utilization in agriculture and industry, such as pesticides and herbicides. The presence of halogenated compound in the environment have been implicated on the health and natural ecosystem. Microbial dehalogenation is a significant method to tackle this problem. This review intends to briefly describe the microbial dehalogenases in relation to the environment where they are isolated. The basic information about dehalogenases in relation to dehalogenation mechanisms, classification, sources and the transportation of these pollutants into bacterial cytoplasm will be described. We also summarised readily available synthetic halogenated organic compound in the environment