Development of a Capacitance-Based Biosensor for the Determination of Histamine Concentration

Histamine level has been suggested as a rapid fish spoilage indicator. Besides that, a biosensor device with low cost, simple and portable is an advantage for fish freshness monitoring. Therefore, a histamine biosensor device was developed using the enzyme diamine oxidase (DAO) and a capacitance (C) concept. A capacitor with two plates system gives linear relationship between frequency (f) and histamine concentration. It has been proven that the relationship between f, dielectric constant (k) and histamine could be used to develop a histamine biosensor. The behavior of histamine reaction can be monitored in the presence of free enzyme in solution. Based on this relationship, immobilized enzyme electrode was developed by immobilizing 1.0 mg DAO/L in the ratio of DAO:polymer= 1:1. Good sensor response could be observed when the shape of the electrode was in a row and the electrode material was made from copper, with a distance between electrode, d=2.5 mm. By using this device, a linear range of histamine from 20 to 100 ppm was obtained (R2=0.9897) with good correlation between biosensor method and HPLC (R2 = 0.9998). For the determination of histamine in prawn tissues, the recovery obtained was 98.13% after spiking with 150 ppm histamine and 98.79% after spiking with 200 ppm histamine (average RSD, 1.16-5.67%). To complete the device, electronic reader was developed comprises PIC (peripheral integrated circuit) microcontroller, LCD (light crystal display), capacitor-resistor circuit and computer-programming in C code (installed in PIC). By using astable operation of capacitor-resistor circuit, a difference sensor response was generated from difference histamine concentration. During histamine reaction, the physicochemical changes was converted into electrical signal and translated in histamine concentration as part per million (ppm). PIC is very useful in modifying the writing process of computerprogramming due to its capability and easily reprogrammed. For the basic test (without enzyme), the device (with electronic reader) gave different (f) values for histamine (50-300 ppm, RSD≤2.01%). After the reader was developed successfully, enzyme electrode was designed with the dimension of copper material at d=2.0 mm and area, A=2.5x10 mm. By immobilizing enzyme onto this electrode, the device showed linear response to histamine concentrations (25 to 100 ppm, R2=0.998, RSD≤2.74%). The biosensor response was still 80% of the initial value after 10 days of storage (4oC). The histamine biosensor exhibited reproducibility characteristic with RSD value equals to 8.88% (n=4). This device can be used up to 30 times without a major change in sensor response (11.76±3.41 Hz/s). Experiment with prawn tissues shows that the performance of histamine biosensor device is comparable to HPLC with R2=0.9895. The histamine biosensor is a promising device for on site screening of fish freshnes

Acetone–butanol–ethanol production by Clostridium acetobutylicum ATCC 824 using sago pith residues hydrolysate

Sago pith residues (58 % starch, 23 % cellulose, 9.2 % hemicellulose, and 4 % lignin) are one of the abundant lignocellulosic residues generated after starch extraction process in sago mill. In this study, fermentable sugars from enzymatic hydrolysis of sago pith residues were converted to acetone–butanol–ethanol (ABE) by Clostridium acetobutylicum ATCC 824. With an initial concentration of 30 g/L of concentrated sago pith residues hydrolysate containing 23 g/L of glucose and 4.58 g/L of cellobiose, 4.22 ± 0.17 g/L of ABE were produced after 72 h of fermentation with yield and productivity of 0.20 g/g glucose and 0.06 g/L/h, respectively. Results are in agreement when synthetic glucose was used as a carbon source. Increasing sago pith residue hydrolysate to 50 g/L (containing 40 g/L glucose) and supplementing with 0.5 g/L yeast extract, approximately 8.84 ± 0.20 g/L of ABE (5.41 ± 0.10 g/L of butanol) were produced with productivity and yield of 0.12 g/L/h and 0.30 g/g glucose respectively, providing a 52 % improvement

Biodegradation of hydrocarbon sludge by pseudomonas sp.strain UPM-KV

Ahydrocarbon-utilizing microorganism isolated locallywas characterized and investigated. This study involved standard biochemical tests and investigation of the bacterial growth based on the uptake of carbon and nitrogen source, temperature and optimum pH growth. The bacterium was found to be a Gram-negative rod, non-motile property with unique property to degrade hydrocarbon sludge. By using diesel as sole carbon source the bacterium was found to be an aerobe as further proven by the oxidase testing. The optimum conditions for the growth was found to be at 30 °C and pH 6.8 with optimum diesel concentration, 1% (v/v). The bacterium ideally used ammonium sulfate as source of nitrogen and was identified as Pseudomonas sp.strain UPM-KV. The ability of this bacterium to efficiently grow on hydrocarbon sludge makes the bacterium an important tool for bioremediation of this toxic sludge that contains high concentration of heavy metals

Sago pith residue as alternative cheap substrate for fermentable sugars production

Sago pith residue is one of the most abundant lignocellulosic biomass which can serve as an alternative cheap substrate for fermentable sugars production. This residue is the fibrous waste left behind after the starch extraction process and contains significant amounts of starch (58%), cellulose (23%), hemicellulose (9.2%) and lignin (3.9%). The conversion of sago pith residue into fermentable sugars is commonly performed using cellulolytic enzymes or known as cellulases. In this study, crude cellulases were produced by two local isolates, Trichoderma asperellum UPM1 and Aspergillus fumigatus, UPM2 using sago pith residue as substrate. A. fumigatus UPM2 gave the highest FPase, CMCase and β-glucosidase activities of 0.39, 23.99 and 0.78 U/ml, respectively, on day 5. The highest activity of FPase, CMCase and β-glucosidase by T. asperellum UPM1 was 0.27, 12.03 and 0.42 U/ml, respectively, on day 7. The crude enzyme obtained from A. fumigatus UPM2 using β-glucosidase as the rate-limiting enzyme (3.9, 11.7 and 23.4 IU) was used for the saccharification process to convert 5% (w/v) sago pith residue into reducing sugars. Hydrolysis of sago pith residue using crude enzyme containing β-glucosidase with 23.4 IU, produced by A. fumigatus UPM2 gave higher reducing sugars production of 20.77 g/l with overall hydrolysis percentage of 73%

Production of rhamnolipids by locally isolated Pseudomonas aeruginosa using sunflower oil as carbon source

Biosurfactants are surface active compounds and amphiphatic in nature which consist of hydrophilic head and hydrophobic tail accumulating at the interphase of two immiscible liquid with different polarity. A study was conducted to investigate the effectiveness of sunflower oil in the production of rhamnolipids (RLs) by locally isolated Pseudomonas aeruginosa in shake flask fermentation. In this process, four different fermentation treatments were done for seven days at 30°C and 180 rpm. Sampling was carried out in time intervals of 24 h followed by monitoring of cell growth and biosurfactants production. Colorimetric Orcinol analysis was used for determination of RLs concentrations (g/L). The RLs were studied for emulsification activity using emulsification index (E24%) methods. In addition, oil displacement activity and thermal stability were also studied (4-120°C). All treatments allow the growth of P. aeruginosa and the utilization of sunflower oil as carbon source and glucose as growth initiator were observed to be the best strategy for maximum RLs production. The maximum RLs production was achieved after 120 h with 3.18 g/L of RLs. Diesel shows the highest emulsification activity among the substrate tested ranging from 55.56% - 60.00%. The oil displacement activity was corresponding to RLs concentration with stability up to 120°C (for 60 min). Therefore, from this research a good potential of RLs that may provide good application for industry were produced

Kojic acid esters: comparative review on its methods of synthesis

In this paper, the syntheses of kojic acid esters via chemical and enzymatic methods are reviewed. The advantages and disadvantages of chemical process in term of process, safety and efficiency are discussed. In enzymatic process, the significant process parameters related to the synthesis of kojic acid esters such as the lipases, solvent, temperature and water content are highlighted. Possible enzymatic synthesis using solvent and solvent-free system taking into consideration of the difference in these systems involving cost, lipase reusability and efficiency is comparatively reviewed. The possible approach for large scale production using various enzyme reactor designs is also discussed and re-evaluated

Effect of different alkaline treatment on the release of ferulic acid from oil palm empty fruit bunch fibres

Serious thought on sustainability of palm oil industry triggers ways to minimise the impacts caused to the environment by recycling oil palm empty fruit bunch (OPEFB). An alkaline treatment strategy was developed for ferulic acid (FA) release from OPEFB fibres. The selected treatment of autoclaving OPEFB (120°C, 3 hr) and hydrolysing it with 20 g kg-1 NaOH (90°C, 3 hr) yielded 62.52±6.24 mg litre-1 FA. Based on alkali selection (5 to 50 g kg-1 of NaOH, KOH and K2CO3), 20 g kg-1 KOH showed almost similar FA release to 20 g kg-1 of NaOH, as it solubilised 56.94±3.52 mg litre-1 FA. The addition of sodium bisulphite (NaHSO3) resulted in an increase of 4.23 mg litre-1 FA using KOH treatment. FA decreased when subjected to prolonged reaction times at high temperature, while at ambient temperature, only about 30 to 35 mg litre-1 FA was released. Fourier transform infrared (FTIR) analysis showed evidence of decrease in aromatic groups, lignin and ester linkage stretching. The selected treatment method using 20 g kg-1 NaOH and KOH solubilised 4.24 mg and 3.84 mg FA from 1 g of OPEFB lignin, respectively. From this finding, OPEFB exhibited a great potential as a feedstock for FA production. FA obtained from this treatment is very useful precursor for vanilic acid, vanillin and other value-added products formation through microbial conversion

Preliminary screening of plant proteases as a potential source for the development of an inhibitive assay for heavy metals

Heavy metals pollution has become a great threat to the world. Since instrumental methods are expensive and need skilled technician, a simple and fast method is needed to determine the presence of heavy metals in the environment. In this work, a preliminary study was carried out on the applicability of various local plants as a source of protease for the future development of the inhibitive enzyme assay for heavy-metals. The crude proteases preparation was assayed using casein as a substrate in conjunction with the Coomassie dye-binding assay. The crude protease from the kesinai plant was found to be the most potent plant protease. The crude enzyme exhibited broad temperature and pH ranges for activity and will be developed in the future as a potential inhibitive assay for heavy metals

Bioremoval of molybdenum from aqueous solution

Molybdenum is very toxic to ruminants with level as low as 2 parts per million can cause severe scouring. Its contamination of waters and soils in agricultural areas needs novel removal technology. In this work we demonstrated a novel method of molybdenum removal from aqueous solution using the dialysis tubing method coupled with molybdenum-reducing activity of Serratia sp. strain Dry5. The enzymatic reduction of molybdenum is molybdenum blue, a colloid that does not pass through dialysis tubing. The calculated maximal rate of molybdenum blue production (VMoblueMax) was 0.264±0.034 mM (Mo-blue h)-1 and the concentration of molybdate resulting in the half-maximal rate of reduction (KMo) was 21.78±3.89 mM molybdate and the specific maximal rate of Mo-blue production was approximately 80 mM (Mo-blue.hr.mg cells)-1 indicating an efficient system with high tolerance towards molybdenum

High-efficiency DNA extraction using poly(4,4′-cyclohexylidene bisphenol oxalate)-modified microcrystalline cellulose magnetite composite

In this study, we studied the DNA extraction capability of poly(4,4-cyclohexylidene bisphenol oxalate) following the surface modification and composite formation with that of microcrystalline cellulose (MCC) and magnetic iron oxide nanoparticles (NPs). The physical characterization techniques like scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, energy-dispersive X-ray analysis (EDX), and thermogravimetric analysis (TGA) were employed for the poly(bisphenol Z oxalate)-MCC-magnetite composite during different stages of its formation. The results confirmed the successful modification of the polymer surface. On testing in the presence of three types of binding buffers, a high value of 72.4% (out of 10,000 ng/μL) efficiency with a total yield of DNA at ng and absorbance ratio of A260/A280 (1.980) was observed for the 2 M GuHCl/EtOH binding buffer. These results were compared against the other two buffers of phosphate-buffered saline (PBS) and NaCl. The lowest value of DNA extraction efficiency at 8125 ng/μL of 58.845% with absorbance ratios of A260/A280 (1.818) for PBS was also observed. The study has concluded an enhancement in the DNA extraction efficiency when the polymer is in the composite stage along with cellulose and magnetite particles as compared against the bare polymer