Science Heritage Journal | Galeri Warisan Sains (GWS)

Polychlorinated biphenyls, PCBs are toxic, persistent organic pollutants (POP) which are harmful to human and environment due to their lipophilic characteristic and not easily degraded in the environment. Biodegradation is one of the alternative ways to reduce PCBs contamination. This study intended to isolate bacteria from landfill leachate using enrichment culture technique and optimize the growth condition of selected isolates for degradation of PCBs. PCB biodegradation efficiency by selected bacterial isolates was also determined using GC-MS. Three potential PCBs degraders were isolated from the samples of landfill leachate through enrichment culture technique, which utilised PCBs as sole carbon and energy sources but only isolate T12B shown significant effect on the degradation. Three different growth parameters were optimized involving the temperature, pH, and PCBs concentration. Central composite design (CCD) from Design Expert Software was used to design the experiment. The optimal growth condition of temperature at 37˚C with 10 ppm of PCB concentrations and pH 8 for the culture medium was achieved using Response Surface Methodology (RSM) analysis. Based on GC-MS analysis, the reduction of PCBs concentration indicates that they were utilized by isolates T12B as sole of carbon and energy sources. This may suggest that bacteria in landfill leachate play an important role in biodegradation process as well as more effective and economical.

The understanding of microorganism’s biodiversity in the peatland soil through non-cultivation based approach provide important inputs towards prediction of the ecosystem response towards the changing environment. The challenge that hindered the success to obtain high quality DNA from peat soil lies in the physicochemical characteristics such as low pH and high humic acid content. There are two general approaches that have been extensively applied for soil microbial DNA extraction, which are direct DNA extraction protocol and indirect DNA extraction protocol. The only step differentiate between these two protocols is the later includes additional cell separation method from soil micro-aggregates preceding DNA extraction process. Therefore, several improved and modified methods in conventional DNA extraction and purification methods are reviewed in this paper to cater all the highlighted issues as to obtain high-quality DNA for peatland metagenomics soil studies.

Moringa oleifera is one of the most popular plants in South Asian. It is known as miracle tree because of every parts of the plant including roots, leaves, pods flowers, and seeds containing high nutritional value and medicinal benefits. M. oleifera seed’s oil extracted contains high antioxidants properties and become as a valuable sources of protein, vitamins, beta carotene, amino acids, and various phenolic compounds. Extraction of oil and determination of antioxidants in the oil could give a great potential for commercialization especially in pharmaceutical industries due to its pharmacological properties such as antiflammatory, antihypertensive, antiepileptic, antioxidant, antibacterial and antifungal. The aim of this study were to extract the M. oleifera seeds at different extraction time and ratio of seed to solvent and determine the amount of total phenolic content (TPC) and total flavonoid content (TFC) in the methanol extract. The extraction process was carried out using Soxhlet extraction with methanol as a solvent for different ratio of seed to solvent (1:10, 1:5 and 3:10) and extraction time (2, 3, 4, 5 and 6 hours). The highest extraction yield was found at 36.84% for the seed to solvent ratio (1:10) with the extraction time of 5 hours. The highest percentages of TPC were 2027.07 (mg GAE/g of extract) at 3 hours of extraction time and seed to solvent ratio (1:10). However, the TFC values in M. oleifera seeds were 99.72 (mg QE/g of extract weight) at 5 hours of extraction time and seed to solvent ratio (1:10). The high values of TPC and TFC in methanol extract of M. oleifera seed showing it a good source of natural antioxidant and have a great potential for commercialization in food products and pharmaceutical industries.

The PT7(A1/O4/O3) is a promoter resulted from construction of O3 and O4 operators into PA1, a promoter derived from coliphage T7, that evidenced lower the occupancy of the promoter by RNA polymerase and thereby increases the repression factor. A new expression system, pTEL, was successfully constructed via shuttle vector pUCP19 as the backbone as the former carries pre-existing stabilizing fragment (SF) that enables replication of the plasmid in both E. coli and Pseudomonas sp. The leaky lac operon-based promoter found in pUCP19 was subsequently replaced by the PT7 (A1/O4/O3). Meanwhile, structural gene of the organic solvent tolerant elastase strain K was used as DNA insert (passenger enzyme) for repression and overexpression studies. The success of pTEL was evidenced by detection of non-significant protein expression level in the absence of IPTG as the inducer, indicating tight regulation possessed by the modified promoter. The addition of IPTG, however, relieved repression and demonstrated overexpression of the elastase strain K in various strains of E. coli following several optimization studies.

The exposure of plants to Pb stress increases the generation of reactive oxygen species (ROS) including O2–, H2O2 and ¯OH. ROS are highly reactive substances that capable of altering normal cellular metabolism via oxidative damage to membranes, proteins, and nucleic acids. Compound involves in the detoxification of Pb stress is important to reduce the toxic effect of Pb. Stress signaling compounds like salicylic acid (SA) is one of the plant defense mechanisms to mitigate Pb toxicity. This study aimed to observe the effect of SA on the morpho-physiology, accumulation of Pb content and the production of O2– and H2O2 of N. tabacum grown under Pb stress. N. tabacum was propagated and treated with SA and Pb treatments. Then, the morpho-physiology of N. tabacum was observed and measured, histochemical staining of diaminobenzidine (DAB) and nitro blue tetrazolium (NBT), and Inductively coupled plasma mass spectrometry (ICP-MS) were conducted to assesses the effect of SA on the accumulation of O2– and H2O2, and Pb content in Pb-treated N. tabacum. The finding of this study showed the application of SA improved growth parameters, diminished the accumulation of oxidative stress as well as reduced Pb content. SA might detoxify Pb, thus alleviate Pb toxicity.

Several studies has been conducted to economically cultivate the Monascus sp. However, the potential of using stirred drum bioreactor in solid state fermentation (SSF) for Monascus sp. cultivation has been relatively understudied. Oil palm frond (OPF) petiole has been used as a potential substrate due to its nutritional contents and to add more value to local agricultural waste. This study reports the production of red pigment by Monascus purpureus FTC 5357 in a 2.3 L bench top – stirred-drum bioreactor. The fungus was grown on moistened OPF substrate (60 % (w/w)) supplemented with 2% (w/w) of soy meal peptone. The effects of different aeration rates (0.3-1.0 vvm of humidified air), agitation programme (4-8 cycles per day), and substrate load capacity (25-40 % (v/v) of total drum capacity) on red pigment production are reported. Aeration rate showed a positively correlated interaction to red pigment production in which the highest red pigment were produced using1.0 vvm (6.09 AU/g dry solid), and non-aerated culture showed the lowest red pigment production (0.81 AU/g dry solid). The agitation programme was also showing the positive trend of interaction, in which 8 cycles per day showed the highest red pigment production (4.34 AU/g dry solid) and 4 cycles per day agitation showed the lowest red pigment production. The red pigment production was peaked at 30% (v/v) drum loading capacity (5.61 AU/g dry solid) and the lowest at 25% (v/v) (0.89 AU/g dry solid), whereas 40% (v/v) substrate capacity was incapable of being mixed due to low power output of agitating motor. Results suggested that OPF was a potent source of substrate for the cultivating Monascus purpureus using SSF and all 3 factors (aeration, substrate load capacity and agitation programme) were significantly influenced the red pigment production.

Lactic acid bacteria (LAB) confer many advantages to humans and animals and they provide natural protection against bacterial pathogens such as Salmonella typhymurium and Eschericia coli. LAB strains have been isolated from various animal sources but from this research LAB were isolated from quail’s (Coturnix coturnix Japonica) intestine. About 12 strains were isolated from the quail’s intestine; and out of these, 5 samples (S1-1B, S2-1A, S2-1B, S2-2B and S3-1A) produced lactose on lactose test. All of these strains appeared to be non-motile coccus with gram positive morphology, catalase-negative and oxidase-negative. These strains showed antimicrobial activities (inhibition zones) against indicator bacterium, i.e., Staphylococcus aureus, Escherichia coli and Salmonella typhimurium using agar well methods. PCR amplification of 16S ribosomal RNA revealed that these five isolates show highest sequence similarity with other LAB strains isolated from other animals which include common genera such as Enterococcus and Lactobacillus. Strain S1-1B, S2-1B and S2-2B were highly similar with Enterococcus faecium, strain S3-2B with Enterococcus durans and S2-1A with Lactobacillus salivarius. This work shows that common LAB species were isolated from intestinal tissues of Malaysian quail (Coturnix Japonica) which were able to produce antimicrobial activities against pathogenic strains.

Halotolerant proteases are known as one of the important groups of enzymes that have been used widely in various industries. However, high production cost of proteases in term of energy used for sterilization and high risk of microbial contamination during fermentation become the obstacles during upstream processing. Moreover, proteases that capable to withstand with harsh conditions of salinity, temperature and pH are required in industry. Therefore, this study presents newly isolated halophilic bacteria producing halotolerant proteases. Halophilic bacteria were isolated from fermented fish sauce. Screening of the bacteria producing halotolerant protease enzymes was carried out by using skim milk salt agar containing 10% NaCl at pH 7 and incubated under aerobic condition at 37^oC for 2 days. The selected isolates were identified based on their morphology followed by 16S rDNA gene sequence analysis. 40 colonies of halophiles bacteria were isolated, however, only 20 of them showing proteolytic activity. All of 20 isolates are motile and gram positive bacteria. From 20 isolates, only 6 were chosen for further analysis. B7 showed the highest proteolytic activity compared with others. Results of 16S rDNA gene sequence analysis showed 98% homology to Bacillus amyloliquefaciens subsp. plantarum strain FZB42. Therefore, B7 is identified as Bacillus amyloliquefaciens strain B7.

Synthetic haloalkanoic acid (HA) is one of the synthetics compounds that can be found as active ingredients in herbicides. These compounds are known to pollute our agriculture land due to their toxicity, thus may cause serious environmental and health problems. Biological process such as microbial dehalogenation degrades the harmful compounds and prevents their migration into groundwater source. For instance, Rhizobial Dehalogenase E (DehE) could catalyze these HA compounds and convert them into hydroxylated compounds which are less harmful to the environment. In previous study, DehE was considered to degrade many HA compounds with different Km values. However, the binding interaction of this enzyme towards many HA substrates is still unclear. In this study, docking simulation has been performed to determine the affinity of active site residues of DehE towards 15 HA compounds. Tribromoacetic acid (TBA) was identified to be the most favourable substrate for DehE which has the lowest binding energy (-6.48 Kcal/mol) compared to other haloalkanoic acids. Size of halogen and hydrogen bond numbers are the contributing factor for dehalogenase affinity towards its substrates. Besides, it was found that Trp34, Phe37 and Ser188 served as binding residues and Phe37 was mostly interacted and bound with all of the tested HA compounds. This findings provides an opportunity for rational design of haloacid dehalogenase especially to DehE.

The objectives of this study were to identify and determine the antimicrobial activity of the indigenous microbes isolated from local fermented vegetables. Ninety nine isolates were obtained from fifteen samples of local fermented vegetables including jeruk lobak putih (pickled radish), jeruk lobak (pickled carrot), jeruk petai (pickled bitter bean), jeruk sawi sie park choy (pickled mustard), jeruk rebung (pickled bamboo shoot), jeruk maman (pickled maman), jeruk bawang putih (pickled garlic) and jeruk kobis (pickled cabbage). The antagonistic act of the isolates was assayed using well diffusion assay against five common pathogens namely, Bacillus cereus, Escherichia coli, Listeria monocytogens, Salmonella typhi and Staphylococcus aureus. Fifty three isolates showed inhibitory zones in the range of 10-18 mm under well diffusion assay. B. cereus was inhibited predominantly by the isolates (62 isolates) followed by L…monocytogens (58 isolates), E.coli (57 isolates), S.typhi (51 isolates) and S.aureus (44 isolates). A total of 19 potential isolates exhibited strong antimicrobial activity (≥10 mm) and inhibited more than two types of pathogens were selected and identified by16sRNA sequencing. Lactobacillus plantarum genera, dominates the local fermented vegetable product with 14 isolates followed by Lactobacillus brevis (3 isolates) and Pediococcus pentosaceus (2 isolates). It was acknowledge that fermented vegetable are high in salt and strongly acidic however some lactic acid bacteria are capable to withstand such growth conditions and showed antagonistic activity towards pathogens. This is a positive remark that these strains are promising candidates for development of a starter culture and to further study their potential as probiotics.