Glaciozyma antarctica PI12 is a psychrophilic yeast isolated from Antarctica. It has an optimal growth in yeast peptone dextrose (YPD) and yeast mould (YM) broth media but not in potato dextrose (PD) broth medium. Early phase G. antarctica PI12 cells had elongated-shape and became oval-shaped as they aged. G. antarctica PI12 exhibited bipolar budding and formed a chain of cells during the lag and early exponential phases. The number of chains decreased as the yeast aged. It appeared mainly as a single cell at the stationary phase, and a small number of them still produced buds. Some cells at the stationary phase entered the quiescence state (G0) as a longterm survival strategy. The G. antarctica PI12 cell size decreased when they entered the stationary phase. G. antarctica PI12 was found to produce hydrolytic enzymes, chitinase, cellulase, mannanase, and xylanase. A higher glucose concentration of 2% in the PD agar medium inhibited the activities of chitinase but not the cellulase, mananase and xylanase.
In this work, an electrochemical method for detection of trace amount of aluminium (Al3+), a heavy metal ion, based on a bare gold electrode (AuE) was developed. Current responses of the AuE under various type of electrolytes, redox indicators, pH, scan rate and accumulation time were investigated using cyclic voltammetry (CV) method to obtain the optimum conditions for Al3+ detection. The sensing properties of the AuE towards the target ion with different concentrations were investigated using differential pulse voltammetry (DPV) method. From the CV results, the optimal conditions for the detection of Al3+ were Tris-HCl buffer (0.1 M, pH 2) supported by 5 mM Prussian blue with scan rate and accumulation time respectively of 100 mVs−1 and 15 s. Under the optimum conditions, the DPV method was detected with different concentrations of aluminium ion ranging from 0.2 to 1.0 ppm resulted in a good linear regression r² = 0.9806. This result suggests that the optimisation of the basic parameters in electrochemical detection using AuE is crucial before further modification of the Au-electrode to improve the sensitivity and selectivity especially for the low concentration of ion detection. The developed method has a great potential for rapid detection of heavy metal ion (Al3+) in drinking water samples.
FK506-binding protein35 of Plasmodium knowlesi (Pk-FKBP35) is a member of peptidyl prolyl cis-trans isomerase (PPIase) and is considered as a promising avenue of antimalarial drug target development. This protein is organized into the N-terminal domain responsible for PPIase catalytic activity followed and the tetratricopeptide repeat domain for its dimerization. The protease-coupling and protease-free assays are known to be the common methods for investigating the catalytic properties of PPIase. Earlier, the protease-coupling assay was used to confirm the catalytic activity of Pk-FKBP35 in accelerating cis-trans isomerization of the peptide substrate. This report is aimed to re-assess the catalytic and substrate specificity of Pk-FKBP35 using an alternative method of a protease-free assay. The result indicated that while Pk-FKBP35 theoretically contained many possible cleavage sites of chymotrypsin, experimentally, the catalytic domain was relatively stable from chymotrypsin. Furthermore, under protease-free assay, Pk-FKBP35 also demonstrated remarkable PPIase catalytic activity with kcat/KM of 4.5 + 0.13 × 105 M−1 s−1, while the kcat/KM of active site mutant of D55A is 0.81 + 0.05 × 105 M−1 s−1. These values were considered comparable to kcat/KM obtained from the protease-coupling assay. Interestingly, the substrate specificities of Pk-FKBP35 obtained from both methods are also similar, with the preference of Pk-FKBP35 towards Xaa at P1 position was Leu>Phe>Lys>Trp>Val>Ile>His>Asp>Ala>Gln>Glu. Altogether, we proposed that protease-free and protease-coupling assays arereliable for Pk-FKBP35.
Cellulases have been vital for the saccharification of lignocellulosic biomass into reduced sugars to produce biofuels and other essential biochemicals. However, the sugar yields achievable for canonical cellulases (i.e. endoglucanases, exoglucanases and β-glucosidases) have not been convincing in support of the highly acclaimed prospects and end-uses heralded. The persistent pursuit of the biochemical industry to obtain high quantities of useful chemicals from lignocellulosic biomass has resulted in the supplementation of cellulose-degrading enzymes with other biological complementation. Also, chemical additives (e.g. salts, surfactants and chelating agents) have been employed to enhance the stability and improve the binding and overall functionality of cellulases to increase product titre. Herein, we report the roadmap of cellulase-additive supplementations and the associated yield performances.
Conservation of plant species plays a vital role in preventing the loss of valuable plant resources. The success of conservation depends on the correct identification and characterization of plant species. Bamboo is one of the most important plants with multiple uses that have contributed to the economy and socio-economy of many people in rural areas. It is under the subfamily of Bambusoideae that includes both woody and herbaceous bamboo. Conventionally, like other plants, bamboo has been classified dependently based on morphological characteristics. However, morphological identification leads to difficulties and misclassification of bamboo species due to their infrequent flowering behaviour and peculiar reproductive biology. Since then, molecular markers have been introduced to overcome the problems associated with bamboo taxonomy and phylogeny. This paper provides an overview of the diverse, predominantly molecular techniques used to assess and determine the genetic diversity of bamboo species.
Rice is the most important staple crop in Malaysia and is cultivated all over the country, including the state of Sabah. The uniqueness of rice cultivation in Sabah lies in the type of rice itself, deriving mainly from local or non-commercial cultivars but with distinctive characteristics including long grains, aromatic properties, and drought tolerance. However, despite having these important agricultural traits, information on the genetic diversity of Sabah rice remains limited. Hence, the purpose of this study was to determine the genetic polymorphisms of Sabah rice using random amplification of polymorphic DNA (RAPD) markers. A total of 101 alleles were profiled, from which 94% were identified as polymorphic. Phylogenetic analysis grouped the rice samples into three clusters, with two clusters classifying the ability of rice to grow under different planting conditions, suitable for growth irrigate and upland condition. The first cluster was dominated by cultivars that could survive in wet (irrigated) areas, while the other featured those that were found in dry (upland) areas. Furthermore, two alleles, OPA-05-B2 and OPA-01-B11, were found to be unique to cultivars within the upland cluster and were thus proposed to be involved in dry environmental adaptation. The results of the present study provide an insight into the genetic relationships and diversity of Sabah rice.
There are many methods to separate or purify the rebaudioside A compound from Stevia rebaudiana extract. However, the ion-exchange chromatography using macroporous resin is still the most popular among those methods. The separation of rebaudioside A from stevia crude extract by macroporous resin AB-8 was optimised in this adsorption separation study. This approach was applied to evaluate the influence of four factors such as the adsorption temperature, desorption time, elution solution ratio, and adsorption volume on rebaudioside A yield of the purified stevia extract. The results showed that the low polarity resin AB-8 is able to separate rebaudioside A from stevia extract with 0.601 in yield compared to the high polarity resin HPD 600 with 0.204 in yield used in Anvari and Khayati study. The best conditions for rebaudioside A separation by macroporous resin AB-8 were at 35°C of adsorption temperature, 30 min of desorption time, elution solution ratio 2:1, and 50 mL of adsorption volume.
Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) are contributors to infection cases among the Asian population. S. aureus is found in the mucous lining of noses and is mainly non-pathogenic while E. coli, mostly harmless bacteria, are found in the intestine. Pathogenic strains of both bacteria have adverse effects on the elderly and younger age group of the population. Samples were collected from recreational parks around Kota Kinabalu as they are hotspots frequently visited by families with both age groups. The bacterial samples were isolated and cultured on selective media such as Baird-Parker agar (BPA), Brain Heart Infusion (BHI) agar, MacConkey agar and Eosin-Methylene Blue (EMB) agar. Morphological characteristics of bacterial growth were observed, where S. aureus had black-shiny growth in BPA and E. coli had a metallic-green sheen in EMB agar. The suspected bacteria samples were then stained and viewed under a light microscope. S. aureus was identified as gram-positive, stained violet with a circular shape and clustered appearance. E. coli was identified as gram-negative, stained red, rod-shaped with 2 – 3 bacterial alignment. Antibiotic resistance test resulted in S. aureus and E. coli samples did not display 100% resistance among 4 antibiotics tested (ampicillin, penicillin, tetracycline and chloramphenicol). Most of the bacteria samples were a minimum inhibitory of 0.1 mg/mL of antibiotic concentration. These results provide a foundation for further research on identifying bacterial strains using molecular methods. The findings can then be used to disseminate information to the public to create awareness of potential disease outbreaks in the city.
Stevia rebaudiana has recently gained the attention of the food industry as one of the natural sweeteners. The sweet flavour is contributed by the glycoside compounds, especially the rebaudioside A and stevioside, which are the stevia main chemical markers. The aim of the work reported here was to compare the different extraction techniques of stevia leaves using different technologies such as the high pressure and ultrasonic on the extraction of steviol glycosides. In this paper, the extraction techniques yielding the highest glycosides from the leaves of Stevia rebaudiana were determined using hot water extraction (HWE), pressurised liquid extraction (PLE) and ultrasound-assisted extraction (UAE). The steviol glycoside yields were quantified by two chemical markers, rebaudioside A and stevioside of Stevia rebaudiana using highperformance liquid chromatography (HPLC) analysis. The result showed that the HWE managed to obtain 1,110 mg of steviol glycosides. The PLE obtained 294 mg steviol glycosides and the UAE obtained 427.5 mg steviol glycosides. As a conclusion, the results suggested the most efficient technique for stevia extraction in this study was the HWE.