Toluene (C7H8) a hydrocarbon in crude oil, is a common contaminant in soil and groundwater. In this study, the ability to degrade toluene was investigated from twelve bacteria isolates which were isolated from soil contaminated with oil. Out of 12 bacterial isolates tested, most of Pseudomonas sp. showed the capability to grow in 1 mM of toluene compared with other isolates on the third day of incubation. Based on enzyme assays towards toluene monooxygenase, Pseudomonas aeruginosa UKMP-14T and Bacillus cereus UKMP-6G were shown to have the highest ability to degrade toluene. The toluene monoxygenase activity was analysed by using two calorimetric methods, Horseradish peroxidase (HRP) and indole-indigo. Both of the methods measured the production of catechol by the enzymatic reaction of toluene monooxygenase. In the HRP assay, the highest enzyme activity was 0.274 U/mL, exhibited by Pseudomonas aeruginosa UKMP-14T. However, for indole-indigo assay, Bacillus cereus UKMP-6G produced the highest enzyme activity of 0.291 U/ml. Results from both experiments showed that Pseudomonas aeruginosa UKMP-14T and Bacillus cereus UKMP-6G were able to degrade toluene.
Nipah virus has been identified as the causative agent responsible for an outbreak of fatal human viral encephalitis in Malaysia and Singapore in 1998 to 1999. In vitro replication assays with Nipah virus minigenome carrying CAT gene (chloramphenicol acetyltransferase) has been developed without the use of infectious virus to allow further study of the replication of Nipah virus in vitro. It has been reported that the viral RNA replication and transcription activity of paramyxoviruses are controlled by essential sequences located in the terminal regions of viral genomic and antigenomic RNAs. In this study, single base substitution was carried out on the Nipah virus minigenome separately at the three guanine residues (G) located in positions 79, 85 and 91 of the leader promoter within the 5’ non-translated region (NTR) of the nucleocapsid gene (N) mRNA region. The guanine residues of these positions were substituted with the cytosine (C) or adenine (A) residue, respectively by using the overlapping PCR-mediated mutagenesis method. The resultant mutants containing the desired point mutation were confirmed by sequencing. The mutants were analyzed to determine the effect of substitution mutation on the viral transcription activity of the minigenome. It was found that the substitution of G at positions 79 and 85 decreased the efficiency of transcription of Nipah virus minigenome while the substitution of G at position 91 did not. Our findings also showed that the effect of transition mutation gave more impact than the transversion mutation in term of suppression effect upon the transcription activity of minigenome.
Four species of bacteria, Acinetobacter lwoffii, Aeromonas hydrophila, Pseudomonas aeruginosa and Pseudomonas putida, were isolated from soil contaminated with hydrocarbons and selected for the determination of growth requirements and the ability to degrade petroleum hydrocarbon. The bacteria were grown in mineral salt medium (MSM) supplemented with two types of crude oil, either Sumandak or South Angsi at 1% (v/v) concentration. The optimum pH for growth of A. hydrophila and P. aeruginosa was 6.5 when grown with Sumandak and South Angsi oil. For A. lwoffii and P. putida the optimum pH for growth with Sumandak and South Angsi oil was 6.5 or 7.0, respectively. The growth of P. aeruginosa was the highest in MSM when supplemented with 1% South Angsi oil and 0.5% tryptone at pH 6.5 while, in Sumandak oil the growth was the highest when yeast extract was added. Gas chromatography analysis showed that the South Angsi crude oil components of C12 to C25 were more extensively degraded by A. lwoffii after 24 h of incubation compared to the other bacteria over the same period.