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Acetylcholinesterase (AChE) is a well-known enzyme sensitive to pesticide exposure, but heavy metal sensitivity is rarely reported. Here, AChE extracted from the brain tissue of Diodon hystrix was exploited and used in a fast and economical way to sensitively detect the existence of heavy metals in a water sample. An inhibitive enzyme assay was conducted, and the activity of AChE was found to be sensitive (> 20% inhibition) to sub-million levels of arsenic, cadmium, nickel, and zinc and less sensitive (< 20% inhibition) to copper and lead. While exposure to argentum, cobalt, and chromium shows no significant inhibition, AChE is not sensitive to those metal ions (p < 0.05). Field test work has proved that the assay is suitable for preliminary detecting heavy metal contamination in the river, especially near industrial and mining sites. Secondary validation was performed using ICP-OES to identify and measure the number of elements in the sample and compare them to the inhibition level of AChE activity.

Acetylcholinesterase (AChE) is a well-known enzyme sensitive to pesticide exposure, but heavy metal sensitivity is rarely reported. Here, AChE extracted from the brain tissue of Diodon hystrix was exploited and used in a fast and economical way to sensitively detect the existence of heavy metals in a water sample. An inhibitive enzyme assay was conducted, and the activity of AChE was found to be sensitive (> 20% inhibition) to sub-million levels of arsenic, cadmium, nickel, and zinc and less sensitive (< 20% inhibition) to copper and lead. While exposure to argentum, cobalt, and chromium shows no significant inhibition, AChE is not sensitive to those metal ions (p < 0.05). Field test work has proved that the assay is suitable for preliminary detecting heavy metal contamination in the river, especially near industrial and mining sites. Secondary validation was performed using ICP-OES to identify and measure the number of elements in the sample and compare them to the inhibition level of AChE activity.

Pollutant treatment methods are available for membrane isolation, exchange of ions, precipitation, transformation and biosorption. Biosorption has many positive aspects of all this technology, including low running costs, very effective toxicant detoxification at low concentrations, low levels of disposal materials. In many applications, adsorption plays an important role in concentrating useful compounds or eliminating contaminants. The thermodynamic parameters of the adsorption are often obtained from the relation between the adsorption constant (KC in Lmol-1 unit) and the Gibbs free adsorption energy. When the van’t Hoff plot for the temperature range 298.2 K to 328.2 K was plotted, a nonlinear curve was obtained with poor R2 value (R=0.491). In order to calculate the ΔH° and ΔS° more accurately, the thermodynamics parameters were analysed at two processes: one between 298.2 and 301.2 K and another at between 301.2 and 328.2 K which gave a better R2 values of 1.00 and 0.995, respectively. The ∆G°, ∆H° (kJ/mol) and ∆S° (kJ/mol×K) values for temperatures between 298.2 and 301.2 K and between 301.2 and 328.2 K were –29.4524, 14.65, 0.145 and –30.4787, –14.88 and 0.049, respectively. This paper depicts with the proposed workflow in the analysis of liquid-phase adsorption data from the data acquisition to data analysis and thermodynamics appropriate calculation of the dimensionless KC parameter.

Pollutant treatment methods are available for membrane isolation, exchange of ions, precipitation, transformation and biosorption. Biosorption has many positive aspects of all this technology, including low running costs, very effective toxicant detoxification at low concentrations, low levels of disposal materials. In many applications, adsorption plays an important role in concentrating useful compounds or eliminating contaminants. The thermodynamic parameters of the adsorption are often obtained from the relation between the adsorption constant (KC in Lmol-1 unit) and the Gibbs free adsorption energy. When the van’t Hoff plot for the temperature range 298.2 K to 328.2 K was plotted, a nonlinear curve was obtained with poor R2 value (R=0.491). In order to calculate the ΔH° and ΔS° more accurately, the thermodynamics parameters were analysed at two processes: one between 298.2 and 301.2 K and another at between 301.2 and 328.2 K which gave a better R2 values of 1.00 and 0.995, respectively. The ∆G°, ∆H° (kJ/mol) and ∆S° (kJ/mol×K) values for temperatures between 298.2 and 301.2 K and between 301.2 and 328.2 K were –29.4524, 14.65, 0.145 and –30.4787, –14.88 and 0.049, respectively. This paper depicts with the proposed workflow in the analysis of liquid-phase adsorption data from the data acquisition to data analysis and thermodynamics appropriate calculation of the dimensionless KC parameter.

Cholinesterase-based biosensor well known as a sensitive method to detect the existence of harmful dissolved compounds in any type of water source, especially the river. This alternative biosensor can be used to determine the level of pollution of the water in a short period of time as well as to evaluate the low cost and simple service. The aim of this study was to exceed the effectiveness of acetylcholinesterase source extracted from the brain tissue of Asian swamp eel; Monopterus albus as a potential environmental biosensor. Purified acetylcholinesterase exposed to a different type of metal ions and mercury showed the highest percentage of inhibition at 62.9% followed by chromium at 59.22% while silver, arsenic, cadmium, cobalt, copper, nickel, zinc and lead at not more than 50% (approximately 37-50%). Metal ions such as mercury, zinc, chromium and copper showed exponential decay type inhibition curves with calculated half maximal inhibitory concentration; IC50 in the ascending sensitivity order 0.005, 0.595, 0.687 and 1.329 mgL-1, respectively. Field trial works exhibited that the acetylcholinesterase was applicable in sensing heavy metals pollution from the river which closed to the industrial and agricultural sites at near real-time and verified using ICP-OES. This study proves the potential use of acetylcholinesterase sourced from M. albus as a biomonitoring tool to assess the contamination level of the river.

Copper is extensively released into the environment, affecting the natural habitat of surrounding organisms especially the aquatic life. The aim of this study is to explore the different protein expressions on different concentrations of CuSO4. Puntius javanicus liver was used as a tool to investigate the biomarkers and mechanisms of copper toxicity to P. javanicus through proteomic assessment after being exposed with different concentrations of CuSO4 (0, 0.1, 0.3, 0.5, 1.0 and 5.0 mg/L). P. javanicus liver was extracted (TCA-acetone extraction) and electrophoresed (IEF and 2D PAGE). Ten protein spots were found to be significantly different in their expression and subsequently identified via matrix assisted laser desorption/ionization tandem time-of-flight (MALDITOF). Three protein spots were further identified as new alternative biomarkers for copper toxicity namely, zinc finger C4H2 domain-containing protein, insulin gene enhancer protein isl-2a and synaptic vesicle membrane protein VAT-1 homolog-like. The present study could provide an additional understanding on the hepatotoxic mechanisms of copper as well as enhance the development of biomarkers for an efficient monitoring of the contamination level in the environment based on proteomic assessment.

Diodon hystrix, commonly known as spot-fin porcupine fish is a salt-water fish belonging to the Diodontidae family. It is widely distributed in Sabah wet market due to its commercial value. This study exploits the effectiveness of Cholinesterase (ChE) obtained from the brain tissue of D. hystrix in detecting carbamates inhibitory activities. Carbamate pesticides known to inhibit ChE and toxic towards living organisms can contaminate the water bodies. By using diethylaminoethanol (DEAE) Sepharose ion exchange chromatography, a total of 40% recovery yield of ChE was obtained with a 165.77 purification fold. Furthermore, the ChE showed a high affinity towards acetylthiocholine iodide (ATC) with an optimum activity at pH 7.45 and temperature ranging from 20 to 40℃. Among five different types of carbamates, methomyl was found to have the highest percentage of inhibition analyzed using ChE inhibitory assay, followed by carbofuran, bendiocarb, carbaryl and propoxur with >85% inhibition rate. The results concluded that ChEs extracted from the brain tissue of D. hystrix are applicable to be used as a bioindicator in detecting the presence of carbamates.

The partially purified enzyme of indigenously isolated Serratia marcescensstrain AQ07 was utilised to develop the best form of cyanide detoxification method that is eco-friendly and cost effective. The present study evaluates the feasibility of the enzyme to degrade high cyanide concentrations and the possible metabolic pathways involved, for which the protein concentration and cyanide detoxification activity were quantified. Bacterial cells grown in cyanide incorporated medium were disrupted by sonication and the resultant cell free extract were tested for metabolic pathway. The cell free extract was precipitated by ammonium sulphate precipitation and partially purified by ion exchange chromatography using DEAE cellulose. The maximum enzyme activity achieved was 2125 µM/min. The partially purified enzyme was found to be able to detoxify 82% of 2 mM KCN in 10 min of incubation and cyanide degradation (or depletion) rate showing a linear increase with increasing enzyme concentration. The effective accruing of ammonia as metabolite illustrated that the detoxification was ensued via the function of cyanide dihydratase. Additional confirmation through SDS-Page showed that the molecular weight of enzyme was assessed to be ~38 kDa, which is tandem with the reported cyanide dihydratases. Hence, the use of enzyme as a substitute to live bacterial cells in detoxification of cyanide illustrates various advantages such as the capacity to withstand and detoxify higher cyanide concentration and total reduction in the total cost of process since nutrient provision is immaterial.

The discharge of industrial effluents into nearby water bodies affects the inhabitants including living organisms. The presence of foreign materials such as heavy metals can be a threat to the ecosystem as they are enormously carcinogenic even though in minute concentration. Hence, an economical and time-efficient preliminary screening test is crucial to be developed for the detection of heavy metals, prior to employment of high technology instruments. In this study, cholinesterase (ChE) from Sabah porcupine fish, Diodon hystrix was purified to test for its potential as an alternative biosensor in detecting metal ions. Few enzymatic parameters including specificity of substrate, temperature and pH were applied to determine its optimal enzymatic activity. ChE enzyme was found to be more sensitive towards the presence of substrate, butyrylthiocholine iodide (BTC), in contrast to acetylthiocholine iodide (ATC) and propionylthiocholine iodide (PTC) with the effective coefficient at 7193, 3680.15 and 2965.26 Vmax/Km, respectively. Moreover, the extracted ChE enzyme showed the optimum activity at pH 9 of 0.1 M Tris-HCl and at 25°C to 30°C range of temperature. When subjected to heavy metals, ChE enzyme was significantly inhibited as the enzyme activity was reduced in the sequence of Hg > Ag > Cr > Cu > Cd > Pb ≥ Zn > As. As a conclusion, the partially purified ChE enzyme proved its sensitivity towards metal ion exposure and can be used as an alternative method in screening the level of contamination in the environment.

Cholinesterase-based biosensor well known as a sensitive method to detect the existence of harmful dissolved compounds in any type of water source, especially the river. This alternative biosensor can be used to determine the level of pollution of the water in a short period of time as well as to evaluate the low cost and simple service. The aim of this study was to exceed the effectiveness of acetylcholinesterase source extracted from the brain tissue of Asian swamp eel; Monopterus albus as a potential environmental biosensor. Purified acetylcholinesterase exposed to a different type of metal ions and mercury showed the highest percentage of inhibition at 62.9% followed by chromium at 59.22% while silver, arsenic, cadmium, cobalt, copper, nickel, zinc and lead at not more than 50% (approximately 37-50%). Metal ions such as mercury, zinc, chromium and copper showed exponential decay type inhibition curves with calculated half maximal inhibitory concentration; IC50 in the ascending sensitivity order 0.005, 0.595, 0.687 and 1.329 mgL-1, respectively. Field trial works exhibited that the acetylcholinesterase was applicable in sensing heavy metals pollution from the river which closed to the industrial and agricultural sites at near real-time and verified using ICP-OES. This study proves the potential use of acetylcholinesterase sourced from M. albus as a biomonitoring tool to assess the contamination level of the river.

Diodon hystrix, commonly known as spot-fin porcupine fish is a salt-water fish belonging to the Diodontidae family. It is widely distributed in Sabah wet market due to its commercial value. This study exploits the effectiveness of Cholinesterase (ChE) obtained from the brain tissue of D. hystrix in detecting carbamates inhibitory activities. Carbamate pesticides known to inhibit ChE and toxic towards living organisms can contaminate the water bodies. By using diethylaminoethanol (DEAE) Sepharose ion exchange chromatography, a total of 40% recovery yield of ChE was obtained with a 165.77 purification fold. Furthermore, the ChE showed a high affinity towards acetylthiocholine iodide (ATC) with an optimum activity at pH 7.45 and temperature ranging from 20 to 40℃. Among five different types of carbamates, methomyl was found to have the highest percentage of inhibition analyzed using ChE inhibitory assay, followed by carbofuran, bendiocarb, carbaryl and propoxur with >85% inhibition rate. The results concluded that ChEs extracted from the brain tissue of D. hystrix are applicable to be used as a bioindicator in detecting the presence of carbamates.

Cholinesterase-based biosensor well known as a sensitive method to detect the existence of harmful dissolved compounds in any type of water source, especially the river. This alternative biosensor can be used to determine the level of pollution of the water in a short period of time as well as to evaluate the low cost and simple service. The aim of this study was to exceed the effectiveness of acetylcholinesterase source extracted from the brain tissue of Asian swamp eel; Monopterus albus as a potential environmental biosensor. Purified acetylcholinesterase exposed to a different type of metal ions and mercury showed the highest percentage of inhibition at 62.9% followed by chromium at 59.22% while silver, arsenic, cadmium, cobalt, copper, nickel, zinc and lead at not more than 50% (approximately 37-50%). Metal ions such as mercury, zinc, chromium and copper showed exponential decay type inhibition curves with calculated half maximal inhibitory concentration; IC50 in the ascending sensitivity order 0.005, 0.595, 0.687 and 1.329 mgL-1, respectively. Field trial works exhibited that the acetylcholinesterase was applicable in sensing heavy metals pollution from the river which closed to the industrial and agricultural sites at near real-time and verified using ICP-OES. This study proves the potential use of acetylcholinesterase sourced from M. albus as a biomonitoring tool to assess the contamination level of the river.

Diodon hystrix, commonly known as spot-fin porcupine fish is a salt-water fish belonging to the Diodontidae family. It is widely distributed in Sabah wet market due to its commercial value. This study exploits the effectiveness of Cholinesterase (ChE) obtained from the brain tissue of D. hystrix in detecting carbamates inhibitory activities. Carbamate pesticides known to inhibit ChE and toxic towards living organisms can contaminate the water bodies. By using diethylaminoethanol (DEAE) Sepharose ion exchange chromatography, a total of 40% recovery yield of ChE was obtained with a 165.77 purification fold. Furthermore, the ChE showed a high affinity towards acetylthiocholine iodide (ATC) with an optimum activity at pH 7.45 and temperature ranging from 20 to 40℃. Among five different types of carbamates, methomyl was found to have the highest percentage of inhibition analyzed using ChE inhibitory assay, followed by carbofuran, bendiocarb, carbaryl and propoxur with >85% inhibition rate. The results concluded that ChEs extracted from the brain tissue of D. hystrix are applicable to be used as a bioindicator in detecting the presence of carbamates.

The partially purified enzyme of indigenously isolated Serratia marcescensstrain AQ07 was utilised to develop the best form of cyanide detoxification method that is eco-friendly and cost effective. The present study evaluates the feasibility of the enzyme to degrade high cyanide concentrations and the possible metabolic pathways involved, for which the protein concentration and cyanide detoxification activity were quantified. Bacterial cells grown in cyanide incorporated medium were disrupted by sonication and the resultant cell free extract were tested for metabolic pathway. The cell free extract was precipitated by ammonium sulphate precipitation and partially purified by ion exchange chromatography using DEAE cellulose. The maximum enzyme activity achieved was 2125 µM/min. The partially purified enzyme was found to be able to detoxify 82% of 2 mM KCN in 10 min of incubation and cyanide degradation (or depletion) rate showing a linear increase with increasing enzyme concentration. The effective accruing of ammonia as metabolite illustrated that the detoxification was ensued via the function of cyanide dihydratase. Additional confirmation through SDS-Page showed that the molecular weight of enzyme was assessed to be ~38 kDa, which is tandem with the reported cyanide dihydratases. Hence, the use of enzyme as a substitute to live bacterial cells in detoxification of cyanide illustrates various advantages such as the capacity to withstand and detoxify higher cyanide concentration and total reduction in the total cost of process since nutrient provision is immaterial.

Copper is extensively released into the environment, affecting the natural habitat of surrounding organisms especially the aquatic life. The aim of this study is to explore the different protein expressions on different concentrations of CuSO4. Puntius javanicus liver was used as a tool to investigate the biomarkers and mechanisms of copper toxicity to P. javanicus through proteomic assessment after being exposed with different concentrations of CuSO4 (0, 0.1, 0.3, 0.5, 1.0 and 5.0 mg/L). P. javanicus liver was extracted (TCA-acetone extraction) and electrophoresed (IEF and 2D PAGE). Ten protein spots were found to be significantly different in their expression and subsequently identified via matrix assisted laser desorption/ionization tandem time-of-flight (MALDITOF). Three protein spots were further identified as new alternative biomarkers for copper toxicity namely, zinc finger C4H2 domain-containing protein, insulin gene enhancer protein isl-2a and synaptic vesicle membrane protein VAT-1 homolog-like. The present study could provide an additional understanding on the hepatotoxic mechanisms of copper as well as enhance the development of biomarkers for an efficient monitoring of the contamination level in the environment based on proteomic assessment.

The discharge of industrial effluents into nearby water bodies affects the inhabitants including living organisms. The presence of foreign materials such as heavy metals can be a threat to the ecosystem as they are enormously carcinogenic even though in minute concentration. Hence, an economical and time-efficient preliminary screening test is crucial to be developed for the detection of heavy metals, prior to employment of high technology instruments. In this study, cholinesterase (ChE) from Sabah porcupine fish, Diodon hystrix was purified to test for its potential as an alternative biosensor in detecting metal ions. Few enzymatic parameters including specificity of substrate, temperature and pH were applied to determine its optimal enzymatic activity. ChE enzyme was found to be more sensitive towards the presence of substrate, butyrylthiocholine iodide (BTC), in contrast to acetylthiocholine iodide (ATC) and propionylthiocholine iodide (PTC) with the effective coefficient at 7193, 3680.15 and 2965.26 Vmax/Km, respectively. Moreover, the extracted ChE enzyme showed the optimum activity at pH 9 of 0.1 M Tris-HCl and at 25°C to 30°C range of temperature. When subjected to heavy metals, ChE enzyme was significantly inhibited as the enzyme activity was reduced in the sequence of Hg > Ag > Cr > Cu > Cd > Pb ≥ Zn > As. As a conclusion, the partially purified ChE enzyme proved its sensitivity towards metal ion exposure and can be used as an alternative method in screening the level of contamination in the environment.

Cholinesterase-based biosensor well known as a sensitive method to detect the existence of harmful dissolved compounds in any type of water source, especially the river. This alternative biosensor can be used to determine the level of pollution of the water in a short period of time as well as to evaluate the low cost and simple service. The aim of this study was to exceed the effectiveness of acetylcholinesterase source extracted from the brain tissue of Asian swamp eel; Monopterus albus as a potential environmental biosensor. Purified acetylcholinesterase exposed to a different type of metal ions and mercury showed the highest percentage of inhibition at 62.9% followed by chromium at 59.22% while silver, arsenic, cadmium, cobalt, copper, nickel, zinc and lead at not more than 50% (approximately 37-50%). Metal ions such as mercury, zinc, chromium and copper showed exponential decay type inhibition curves with calculated half maximal inhibitory concentration; IC50 in the ascending sensitivity order 0.005, 0.595, 0.687 and 1.329 mgL-1, respectively. Field trial works exhibited that the acetylcholinesterase was applicable in sensing heavy metals pollution from the river which closed to the industrial and agricultural sites at near real-time and verified using ICP-OES. This study proves the potential use of acetylcholinesterase sourced from M. albus as a biomonitoring tool to assess the contamination level of the river.

Diodon hystrix, commonly known as spot-fin porcupine fish is a salt-water fish belonging to the Diodontidae family. It is widely distributed in Sabah wet market due to its commercial value. This study exploits the effectiveness of Cholinesterase (ChE) obtained from the brain tissue of D. hystrix in detecting carbamates inhibitory activities. Carbamate pesticides known to inhibit ChE and toxic towards living organisms can contaminate the water bodies. By using diethylaminoethanol (DEAE) Sepharose ion exchange chromatography, a total of 40% recovery yield of ChE was obtained with a 165.77 purification fold. Furthermore, the ChE showed a high affinity towards acetylthiocholine iodide (ATC) with an optimum activity at pH 7.45 and temperature ranging from 20 to 40℃. Among five different types of carbamates, methomyl was found to have the highest percentage of inhibition analyzed using ChE inhibitory assay, followed by carbofuran, bendiocarb, carbaryl and propoxur with >85% inhibition rate. The results concluded that ChEs extracted from the brain tissue of D. hystrix are applicable to be used as a bioindicator in detecting the presence of carbamates.

Aim : Cholinesterase (ChE) inhibition and histopathological features of brain tissues of Clarias gariepinus were investigated with a purpose to develop biomarkers for monitoring heavy metals. Methodology : The effects of cadmium toxicity on were assessed by ChE inhibition and characterisation of ChE by affinity chromatography and histological variations in brain tissues were studied by H&E staining under light microscope. Results : The purified enzyme gave 10.58 fold purification with the recovery of 12% with specific activity of 159.729 U-1 mg . The Michaelis-Menten constant (K ) m and V value obtained was 1.985 mM max -1 -1 and 0.4479 µmol min mg , respectively. The enzyme showed the ability to hydrolyse acetylthiocholine iodide (ATC) at a faster rate compared to other two synthetic substrates, propionylcholine iodide (PTC) and butyrylthiocholine iodide (BTC). ChE showed highest activity at 35°C in Tris-HCl pH 7.5. The metal inhibition study also found the maximal inhibitory concentration (IC ) 50 -1 value for cadmium to be 0.6517 mg l . Histological study revealed decrease in the number of cells, degeneration of Purkinje cells, increased aggregation area and cells necrosis. Interpretation : Inhibition of cholinesterase activity and degeneration of Purkinje cells observed in the present study can be used as a tool for further developing a biomarker for detecting heavy metals in the aquatic ecosystems. C. gariepinus

Aim : The cholinesterase (ChE) based inhibition and histopathological studies from fish were investigated and represented in this study to develop as one of the great potential biomarkers for heavy metals monitoring. Methodology : In this study, the histopathological study of gills were observed a under microscope. The capability of ChE extracted from the gills of Clarias gariepinus was assessed for declining Cd. ChE was purified through affinity chromatography and continued with the optimisation and inhibition study (IC50) of cholinesterase. Results : Histopathological study of gills was carried out and several changes such as aneurysm, necrosis and lamella fusion were noted. Purification fold obtained from purified enzyme was 1.15 with 30% a yield specific activity 20.726. The optimum temperature for purified AChE was 35°C along with acetylthiocholine iodide (ATC) as a preferable substrate that had the highest Vmax value of 0.5452 U mg'1 and the lowest Km value of 0.0311 mM. The optimum pH was observed to be 10 of Tris-HCl as a medium. Meanwhile, the IC50 of cadmium was 6.808 mg ľ with R2 value of 0.9532. Interpretation : The result of the study can be used as a tool for further developing a biomarker for the detection of heavy metals in aquatic ecosystems. In addition, the baseline data provided can also be used for designing a kit, which would give rapid and accurate result.

The gill is the site of acid-base balance, ionic regulation, gas exchange, and nitrogenous waste excretion by fish. The physiological, histopathological and enzymatic alterations from Clarias gariepinus gills were examined to assess the effects induced in gill tissues within 96 h exposure to waterborne Al 2 (SO 4 ) 3 with different concentrations (25 to 300 mg/L). The exposure of C. gariepinus to aluminium showed deleterious effects to normal fish behaviours and varying degrees of gill damage when visualised under inverted light microscopy (stained with haematoxylin-eosin), scanning electron microscopy and transmission electron microscopy. The mortality rate was observed increasing with increased Al concentration showing noticeably disrupted lamellae, irregular nucleus shape and increasing area of vacuolation in treated fish gills associated with Al 2 (SO 4 ) 3 exposure concentration. Furthermore, electron microscopic X-ray microanalysis of fish gills exposed to sublethal Al revealed Al accumulated on the surface of the gill lamella. Al toxicity also gave inhibitory effects on cholinesterase (ChE) extracted from the fish gills with 90.0% inhibition at 300 mg/L Al highest concentration exposure (in vivo), whereas the Al metal ion inhibited 50% of ChE activity at 4.12 mg/L (IC 50 ).

The gill is the site of acid-base balance, ionic regulation, gas exchange, and nitrogenous waste excretion by fish. The physiological, histopathological and enzymatic alterations from Clarias gariepinus gills were examined to assess the effects induced in gill tissues within 96 h exposure to waterborne Al 2 (SO 4 ) 3 with different concentrations (25 to 300 mg/L). The exposure of C. gariepinus to aluminium showed deleterious effects to normal fish behaviours and varying degrees of gill damage when visualised under inverted light microscopy (stained with haematoxylin-eosin), scanning electron microscopy and transmission electron microscopy. The mortality rate was observed increasing with increased Al concentration showing noticeably disrupted lamellae, irregular nucleus shape and increasing area of vacuolation in treated fish gills associated with Al 2 (SO 4 ) 3 exposure concentration. Furthermore, electron microscopic X-ray microanalysis of fish gills exposed to sublethal Al revealed Al accumulated on the surface of the gill lamella. Al toxicity also gave inhibitory effects on cholinesterase (ChE) extracted from the fish gills with 90.0% inhibition at 300 mg/L Al highest concentration exposure (in vivo), whereas the Al metal ion inhibited 50% of ChE activity at 4.12 mg/L (IC 50 ).

Aim : Cholinesterase (ChE) inhibition and histopathological features of brain tissues of Clarias gariepinus were investigated with a purpose to develop biomarkers for monitoring heavy metals. Methodology : The effects of cadmium toxicity on were assessed by ChE inhibition and characterisation of ChE by affinity chromatography and histological variations in brain tissues were studied by H&E staining under light microscope. Results : The purified enzyme gave 10.58 fold purification with the recovery of 12% with specific activity of 159.729 U-1 mg . The Michaelis-Menten constant (K ) m and V value obtained was 1.985 mM max -1 -1 and 0.4479 µmol min mg , respectively. The enzyme showed the ability to hydrolyse acetylthiocholine iodide (ATC) at a faster rate compared to other two synthetic substrates, propionylcholine iodide (PTC) and butyrylthiocholine iodide (BTC). ChE showed highest activity at 35°C in Tris-HCl pH 7.5. The metal inhibition study also found the maximal inhibitory concentration (IC ) 50 -1 value for cadmium to be 0.6517 mg l . Histological study revealed decrease in the number of cells, degeneration of Purkinje cells, increased aggregation area and cells necrosis. Interpretation : Inhibition of cholinesterase activity and degeneration of Purkinje cells observed in the present study can be used as a tool for further developing a biomarker for detecting heavy metals in the aquatic ecosystems. C. gariepinus

Aim : The cholinesterase (ChE) based inhibition and histopathological studies from fish were investigated and represented in this study to develop as one of the great potential biomarkers for heavy metals monitoring. Methodology : In this study, the histopathological study of gills were observed a under microscope. The capability of ChE extracted from the gills of Clarias gariepinus was assessed for declining Cd. ChE was purified through affinity chromatography and continued with the optimisation and inhibition study (IC50) of cholinesterase. Results : Histopathological study of gills was carried out and several changes such as aneurysm, necrosis and lamella fusion were noted. Purification fold obtained from purified enzyme was 1.15 with 30% a yield specific activity 20.726. The optimum temperature for purified AChE was 35°C along with acetylthiocholine iodide (ATC) as a preferable substrate that had the highest Vmax value of 0.5452 U mg'1 and the lowest Km value of 0.0311 mM. The optimum pH was observed to be 10 of Tris-HCl as a medium. Meanwhile, the IC50 of cadmium was 6.808 mg ľ with R2 value of 0.9532. Interpretation : The result of the study can be used as a tool for further developing a biomarker for the detection of heavy metals in aquatic ecosystems. In addition, the baseline data provided can also be used for designing a kit, which would give rapid and accurate result.

In Asia, Climbing perch (Anabas testudineus) is commonly found in paddy fields and irrigation systems. Due to its habitat, Climbing perch is exposed to toxic pesticides used in paddy fields such as metaldehyde which is one of the most widely used molluscicide. This study aims to determine the acute toxicity Lethal Concentration50 (LC50) of metaldehyde and its effect on the behaviour and physical changes of the Climbing perch. The fish mortality responses to six different metaldehyde concentrations ranging from 180 to 330 mg/L were investigated. The 96-h LC50 values were determined and analysed using three different analysis methods which is arithmetic, logarithmic and probit graphic. The LC50 values obtained in this study were 239, 234 and 232 mg/L, respectively. After 96-h of exposure to metaldehyde, the fish showed a series of abnormal behavioural response in all cases: imbalance position, and restlessness of movement. The LC50 values show that metaldehyde is moderately toxic to the Climbing perch indicating that metaldehyde is not destructive to Climbing perch. However, long term exposure of aquatic organisms to the metaldehyde means a continuous health risk for the fish population as they are more vulnerable and it is on high risk for human to consume this toxicated fishes.

Copper is a significant trace element necessary for the normal growth and metabolism of living organisms. However, this element may become very dangerous if used beyond its limit, turning into continuous metal compounds with the ability to accumulate in water and cause imbalance to the biological system. Aquaculture activities can also be affected due to the increase in environmental pollution. Copper is observed with the ability to cause some deleterious effects on fish by its toxicity, which can be evaluated from the molecular and structural level of the organism. This is because fish is one of the aquatic organisms that are able to accumulate heavy metals in their tissue. Generally, this accumulation is influenced by several factors namely, metal concentration, time of exposure, ways of metal uptake, environmental condition (water temperature, pH) and intrinsic factors (fish age, size). Different organs of fish show different affinity to copper accumulation. Therefore, this review was conducted with the purpose of investigating the harmful effects of copper on fish as a result of the accumulation of copper in fish organs and the histopathological alteration encountered in fish.

In Asia, Climbing perch (Anabas testudineus) is commonly found in paddy fields and irrigation systems. Due to its habitat, Climbing perch is exposed to toxic pesticides used in paddy fields such as metaldehyde which is one of the most widely used molluscicide. This study aims to determine the acute toxicity Lethal Concentration50 (LC50) of metaldehyde and its effect on the behaviour and physical changes of the Climbing perch. The fish mortality responses to six different metaldehyde concentrations ranging from 180 to 330 mg/L were investigated. The 96-h LC50 values were determined and analysed using three different analysis methods which is arithmetic, logarithmic and probit graphic. The LC50 values obtained in this study were 239, 234 and 232 mg/L, respectively. After 96-h of exposure to metaldehyde, the fish showed a series of abnormal behavioural response in all cases: imbalance position, and restlessness of movement. The LC50 values show that metaldehyde is moderately toxic to the Climbing perch indicating that metaldehyde is not destructive to Climbing perch. However, long term exposure of aquatic organisms to the metaldehyde means a continuous health risk for the fish population as they are more vulnerable and it is on high risk for human to consume this toxicated fishes.

Copper is a significant trace element necessary for the normal growth and metabolism of living organisms. However, this element may become very dangerous if used beyond its limit, turning into continuous metal compounds with the ability to accumulate in water and cause imbalance to the biological system. Aquaculture activities can also be affected due to the increase in environmental pollution. Copper is observed with the ability to cause some deleterious effects on fish by its toxicity, which can be evaluated from the molecular and structural level of the organism. This is because fish is one of the aquatic organisms that are able to accumulate heavy metals in their tissue. Generally, this accumulation is influenced by several factors namely, metal concentration, time of exposure, ways of metal uptake, environmental condition (water temperature, pH) and intrinsic factors (fish age, size). Different organs of fish show different affinity to copper accumulation. Therefore, this review was conducted with the purpose of investigating the harmful effects of copper on fish as a result of the accumulation of copper in fish organs and the histopathological alteration encountered in fish.

The release of pollutants, especially heavy metals, into the aquatic environment is known to have detrimental effects on such an environment and on living organisms including humans when those pollutants are allowed to enter the food chain. The aim of this study is to analyse the damage to Clarias gariepinus’ liver caused by exposure to different concentrations of copper. In the present study, samples of C. gariepinus were exposed to sub-lethal copper sulphate (CuSO4) concentrations (from 0.2 to 20.0 mg/L) for 96 h. Physiological and behavioural alterations were observed with respect to their swimming pattern, mucus secretion and skin colour. Mortality was also observed at high concentrations of copper. Histopathological alterations of the liver were analysed under light, transmission and scanning electron microscopies. The liver of the untreated group showed normal tissue structures, while histopathological abnormalities were observed in the treated fish under light and electron microscopes with increased copper concentrations. Histopathological abnormalities include necrosis, melanomacrophage, hepatic fibrosis and congested blood vessels. In addition, the enzyme activity of liver cholinesterase (ChE) was also found to be affected by copper sulphate, as 100% of cholinesterase activity was inhibited at 20.0 mg/L. Thus, liver enzyme activity and histopathological changes are proven to be alternative sources for biomarkers of metal toxicity.

Acetylcholinesterase (AChE) is usually used as an inhibitive assay for insecticides. A lesser known property of AChE is its inhibition by heavy metals. In this work we evaluate an AChE from brains of striped snakehead (Channa striatus) wastes from aquaculture industry as an inhibitive assay for heavy metals. We discovered that the AChE was inhibited almost completely by Hg2+, Ag2+ and Cu2+ during an initial screening. When tested at various concentrations, the heavy metals exhibited exponential decay type inhibition curves. The calculated IC50 for the heavy metals Hg2+, Ag2+, Pb2+, Cu2+ and Cr6+ were 0.08432, 0.1008, 0.1255, 0.0871, and 0.1771, respectively. The IC50 for these heavy metals are comparable and some are lower than the IC50 values from the cholinesterases from previously studied fish. The assay can be carried out in less than 30 minutes at ambient temperature.

Molybdenum is an emerging pollutant worldwide. The objective of this study is to isolate molybdenum-reducing bacterium with the ability to grow on phenolic compounds (phenol and catechol). The screening process was carried out on a microplate. The bacterium reduced molybdenum in the form of sodium molybdate to molybdenum blue (Mo-blue). The bacterium required a narrow pH range for optimal reduction of molybdenum, i.e. between pH 6.3 and 6.8, with temperature between 34 and 37 oC. Molybdate reduction to Mo-blue was best supported by glucose as the carbon source. However, both phenol and catechol could not support molybdate reduction. Other requirements for molybdate reduction included sodium molybdate concentrations between 15 and 30 mM, and phosphate concentration of 5.0 mM. The bacterium exhibited a Mo-blue absorption spectrum with a shoulder at 700 nm and a maximum peak near the infrared region at 865 nm. The Mo-reducing bacterium was partially identified as Enterobacter sp. strain Saw-2. The capability of this bacterium to grow on toxic phenolic compounds and to detoxify molybdenum made it a significant agent for bioremediation.

Aim: The chdinesterase (ChE) based inhibition studies from fish were investigated and presented here emerged to be one of thegreat potential biomarkersfor heavy metals monitoring. Methodology: In this study, the capability of ChE extracted from the kidney of Lates calcarifer was assessed for of metal. ChE was purified through ammonium sulphate precipitation and ion exchange chromatography. Results: The piffled enzyme gave 12 fold purification with the recovery of 12.17% with specific activity of 2.889 U mgJ. The Michaelis-Menten constant (K) and V,^ value obtained was 0.1426 mM and 0.0217 pmol irin'mg∗1, respectively. The enzyme has the ability to hydrolyse acetytthiocholine iodde (ATC) at a faster rate compared to other two synthetic su bstra tes , propionylthiocholine iodide (PTC) and butyrylthiocholine iodide (BTC). ChE gave highest activity at 20- 30°C in Tris-HO buffer pH 8.0. The results showed that cholinesterase from L. calcarifer kidney was very sensitive to sensitive to copper and lead after being tested argentum, arsenic, cadmium, chromium, copper, cobalt, mercury, nickel, lead and zinc. Interpretation: The effect of heavy metals studied on the activity of ChE differed from each other. The result of the study can be used as a tool for futher developing a biomarker for the detection of heavy metals in aquatic ecosystems. In addition, the information can also be used for designing a kit, that would give a rapid and accurate result.

Recently, the contamination of heavy metals towards the environment especially in aquatic system has drastically increased. Heavy metals are able to transform into persistent metallic compound in which it can be accumulated within the organisms’ body system, disrupting the food chain and eventually threatened the human life. The occurrence of heavy metals spillage in the rivers and lakes are due to the careless disposal of excess heavy metals used for human activities. The accumulation of heavy metals in water system will affect all aquatic organisms especially fish. The toxicity of copper in fish can be determined by several changes in the fish under treatment with heavy metals sub-lethal concentration, LC50 within 96-hours period of acute exposure. Therefore, fish can be considered as a high potential biomarker for monitoring heavy metals pollution in aquatic system. Several selective organs are highly sensitive to the xenobiotic pollution and express changes to the exposure. One of the most potential biomarker is the biochemical biomarker of cholinesterase (ChE) inhibition by heavy metals in fish has been well studied in pollution monitoring recently. Thus, this paper gives an overview of the manipulation of fish as a biomarker of heavy metals through enzymatic reaction which have proven to be very useful in the environmental pollution monitoring.

The environmental toxicants such as copper are known to affect vital organ especially liver. This study examined the effects of copper sulfate (CuSO4) on the liver morphological structure of P. javanicus. The untreated control, 0.1 and 0.3 mg/L CuSO4 treated groups displayed normal polygonal structure of the hepatocyte. However, at the concentrations of 0.5, 1.0 and 5.0 mg/L CuSO4, the hepatostructure was significantly affected, as shown by the increasing number of dilation and congestion of sinusoids, vacuolation, macrophage activities and peliosis. The damage level and HSI value were increased while the number of hepatic nuclei per mm2 was decreased with the increasing of copper concentration. In conclusion, this study shows that the degree of liver damage in P.javanicus is dependent to the dose exposure.

Molybdenum is an emerging pollutant worldwide. The objective of this study is to isolate molybdenum-reducing bacterium with the ability to grow on phenolic compounds (phenol and catechol). The screening process was carried out on a microplate. The bacterium reduced molybdenum in the form of sodium molybdate to molybdenum blue (Mo-blue). The bacterium required a narrow pH range for optimal reduction of molybdenum, i.e. between pH 6.3 and 6.8, with temperature between 34 and 37 oC. Molybdate reduction to Mo-blue was best supported by glucose as the carbon source. However, both phenol and catechol could not support molybdate reduction. Other requirements for molybdate reduction included sodium molybdate concentrations between 15 and 30 mM, and phosphate concentration of 5.0 mM. The bacterium exhibited a Mo-blue absorption spectrum with a shoulder at 700 nm and a maximum peak near the infrared region at 865 nm. The Mo-reducing bacterium was partially identified as Enterobacter sp. strain Saw-2. The capability of this bacterium to grow on toxic phenolic compounds and to detoxify molybdenum made it a significant agent for bioremediation.

Aim: The chdinesterase (ChE) based inhibition studies from fish were investigated and presented here emerged to be one of thegreat potential biomarkersfor heavy metals monitoring. Methodology: In this study, the capability of ChE extracted from the kidney of Lates calcarifer was assessed for of metal. ChE was purified through ammonium sulphate precipitation and ion exchange chromatography. Results: The piffled enzyme gave 12 fold purification with the recovery of 12.17% with specific activity of 2.889 U mgJ. The Michaelis-Menten constant (K) and V,^ value obtained was 0.1426 mM and 0.0217 pmol irin'mg∗1, respectively. The enzyme has the ability to hydrolyse acetytthiocholine iodde (ATC) at a faster rate compared to other two synthetic su bstra tes , propionylthiocholine iodide (PTC) and butyrylthiocholine iodide (BTC). ChE gave highest activity at 20- 30°C in Tris-HO buffer pH 8.0. The results showed that cholinesterase from L. calcarifer kidney was very sensitive to sensitive to copper and lead after being tested argentum, arsenic, cadmium, chromium, copper, cobalt, mercury, nickel, lead and zinc. Interpretation: The effect of heavy metals studied on the activity of ChE differed from each other. The result of the study can be used as a tool for futher developing a biomarker for the detection of heavy metals in aquatic ecosystems. In addition, the information can also be used for designing a kit, that would give a rapid and accurate result.

The release of pollutants, especially heavy metals, into the aquatic environment is known to have detrimental effects on such an environment and on living organisms including humans when those pollutants are allowed to enter the food chain. The aim of this study is to analyse the damage to Clarias gariepinus’ liver caused by exposure to different concentrations of copper. In the present study, samples of C. gariepinus were exposed to sub-lethal copper sulphate (CuSO4) concentrations (from 0.2 to 20.0 mg/L) for 96 h. Physiological and behavioural alterations were observed with respect to their swimming pattern, mucus secretion and skin colour. Mortality was also observed at high concentrations of copper. Histopathological alterations of the liver were analysed under light, transmission and scanning electron microscopies. The liver of the untreated group showed normal tissue structures, while histopathological abnormalities were observed in the treated fish under light and electron microscopes with increased copper concentrations. Histopathological abnormalities include necrosis, melanomacrophage, hepatic fibrosis and congested blood vessels. In addition, the enzyme activity of liver cholinesterase (ChE) was also found to be affected by copper sulphate, as 100% of cholinesterase activity was inhibited at 20.0 mg/L. Thus, liver enzyme activity and histopathological changes are proven to be alternative sources for biomarkers of metal toxicity.

Acetylcholinesterase (AChE) is usually used as an inhibitive assay for insecticides. A lesser known property of AChE is its inhibition by heavy metals. In this work we evaluate an AChE from brains of striped snakehead (Channa striatus) wastes from aquaculture industry as an inhibitive assay for heavy metals. We discovered that the AChE was inhibited almost completely by Hg2+, Ag2+ and Cu2+ during an initial screening. When tested at various concentrations, the heavy metals exhibited exponential decay type inhibition curves. The calculated IC50 for the heavy metals Hg2+, Ag2+, Pb2+, Cu2+ and Cr6+ were 0.08432, 0.1008, 0.1255, 0.0871, and 0.1771, respectively. The IC50 for these heavy metals are comparable and some are lower than the IC50 values from the cholinesterases from previously studied fish. The assay can be carried out in less than 30 minutes at ambient temperature.

Recently, the contamination of heavy metals towards the environment especially in aquatic system has drastically increased. Heavy metals are able to transform into persistent metallic compound in which it can be accumulated within the organisms’ body system, disrupting the food chain and eventually threatened the human life. The occurrence of heavy metals spillage in the rivers and lakes are due to the careless disposal of excess heavy metals used for human activities. The accumulation of heavy metals in water system will affect all aquatic organisms especially fish. The toxicity of copper in fish can be determined by several changes in the fish under treatment with heavy metals sub-lethal concentration, LC50 within 96-hours period of acute exposure. Therefore, fish can be considered as a high potential biomarker for monitoring heavy metals pollution in aquatic system. Several selective organs are highly sensitive to the xenobiotic pollution and express changes to the exposure. One of the most potential biomarker is the biochemical biomarker of cholinesterase (ChE) inhibition by heavy metals in fish has been well studied in pollution monitoring recently. Thus, this paper gives an overview of the manipulation of fish as a biomarker of heavy metals through enzymatic reaction which have proven to be very useful in the environmental pollution monitoring.

The environmental toxicants such as copper are known to affect vital organ especially liver. This study examined the effects of copper sulfate (CuSO4) on the liver morphological structure of P. javanicus. The untreated control, 0.1 and 0.3 mg/L CuSO4 treated groups displayed normal polygonal structure of the hepatocyte. However, at the concentrations of 0.5, 1.0 and 5.0 mg/L CuSO4, the hepatostructure was significantly affected, as shown by the increasing number of dilation and congestion of sinusoids, vacuolation, macrophage activities and peliosis. The damage level and HSI value were increased while the number of hepatic nuclei per mm2 was decreased with the increasing of copper concentration. In conclusion, this study shows that the degree of liver damage in P.javanicus is dependent to the dose exposure.

Bioremediation of pollutants including heavy metals and xenobiotics is an economic and environmentally friendly process. A novel molyb-denum-reducing bacterium with the ability to utilize the pesticide glyphosate as a carbon source is reported. The characterization works were carried out utilizing bacterial resting cells in a microplate format. The bacterium reduces molybdate to Mo-blue optimally between pH 6.3 and 6.8 and at 34oC. Glucose was the best elec-tron donor for supporting molybdate reduction followed by lactose, maltose, melibiose, raffinose, d-mannitol, d-xylose, l-rhamnose, l-arabinose, dulcitol, myo-inositol and glycerol in descending order. Other requirements include a phosphate concentration at 5.0 mM and a molybdate concentration between 20 and 30 mM. The molybdenum blue exhibited an absorption spec-trum resembling a reduced phospho-molybdate. Molybdenum reduction was inhibited by mercury, silver, cadmium and copper at 2 ppm by 45.5, 26.0, 18.5 and 16.3%, respectively. Biochemical analysis identified the bacterium as Klebsiella oxytoca strain Saw-5. To conclude, the capacity of this bacterium to reduce molybdenum into a less toxic form and to grow on glyphosate is novel and makes the bacterium an important instrument for bioremediation of these pollutants.

In a previous study, we isolated Leifsonia sp. strain SIU, a new bacterium from agricultured soil. The bacterium was tested for its ability to degrade caffeine. The isolate was encapsulated in gellan gum and its ability to degrade caffeine was compared with the free cells. The optimal caffeine degradation was attained at a gellan gum concentration of 0.75% (w/v), a bead size of 4 mm diameter, and 250 beads per 100 mL of medium. At a caffeine concentration of 0.1 g/L, immobilised cells of the strain SIU degraded caffeine within 9 h, which is faster when compared to the case of free cells, in which it took 12 h to degrade. The immobilised cells degraded caffeine completely within 39 and 78 h at 0.5 and 1.0 g/L, while the free cells took 72 and 148 h at 0.5 and 1.0 g/L, respectively. At higher caffeine concentrations, immobilised cells exhibited a higher caffeine degradation rate. At concentrations of 1.5 and 2.0 g/L, caffeine-degrading activities of both immobilised and free cells were inhibited. The immobilised cells showed no loss in caffeine-degrading activity after being used repeatedly for nine 24-h cycles. The effect of heavy metals on immobilised cells was also tested. This study showed an increase in caffeine degradation efficiency when the cells were encapsulated in gellan gum.

Climbing Perch or its scientific name, Anabas testudineus is one of the freshwater fish belonging to the family of Anabantidae. It is widely distributed in ponds, swamps and estuaries in Asia. In this study, cholinesterase (ChE) was partially purified from the liver of A. testudineus through ion exchange chromatography. This purification method provided a recovery yield of 5.36% with a purification fold of 6.6. The optimum conditions for ChE assay were identified to be 2.5 mM of butyrylthiocholine iodide (BTC) with pH 8.0 in Tris-HCl buffer at 40°C. Substrate specificity profile also indicated that ChE favours BTC as substrate because it records the highest catalytic efficiency (Vmax/Km). Protein analysis through Native-PAGE showed that ion exchange chromatography is an effective method to partially purify ChE. Metal ion inhibition tests were conducted and mercury (Hg) was found to show the highest inhibition effect (87.30%) whereas lead (Pb) shows the lowest inhibition effect (28.01%). All these findings showed that partially purified ChE from the liver of A. testudineus is suitable to be used as a bioindicator to detect the presence of metal ions.

In a previous study, we isolated Leifsonia sp. strain SIU, a new bacterium from agricultured soil. The bacterium was tested for its ability to degrade caffeine. The isolate was encapsulated in gellan gum and its ability to degrade caffeine was compared with the free cells. The optimal caffeine degradation was attained at a gellan gum concentration of 0.75% (w/v), a bead size of 4 mm diameter, and 250 beads per 100 mL of medium. At a caffeine concentration of 0.1 g/L, immobilised cells of the strain SIU degraded caffeine within 9 h, which is faster when compared to the case of free cells, in which it took 12 h to degrade. The immobilised cells degraded caffeine completely within 39 and 78 h at 0.5 and 1.0 g/L, while the free cells took 72 and 148 h at 0.5 and 1.0 g/L, respectively. At higher caffeine concentrations, immobilised cells exhibited a higher caffeine degradation rate. At concentrations of 1.5 and 2.0 g/L, caffeine-degrading activities of both immobilised and free cells were inhibited. The immobilised cells showed no loss in caffeine-degrading activity after being used repeatedly for nine 24-h cycles. The effect of heavy metals on immobilised cells was also tested. This study showed an increase in caffeine degradation efficiency when the cells were encapsulated in gellan gum.

Inflammation and oxidative stress are believed to contribute to the pathology of several chronic diseases including hypercholesterolemia (elevated levels of cholesterol in blood) and atherosclerosis. HMG-CoA reductase inhibitors of plant origin are needed as synthetic drugs, such as statins, which are known to cause adverse effects on the liver and muscles. Amaranthus viridis (A. viridis) has been used from ancient times for its supposedly medically beneficial properties. In the current study, different parts of A. viridis (leaf, stem, and seed) were evaluated for potential anti-HMG-CoA reductase, antioxidant, and anti-inflammatory activities. The putative HMG-CoA reductase inhibitory activity of A. viridis extracts at different concentrations was determined spectrophotometrically by NADPH oxidation, using HMG-CoA as substrate. A. viridis leaf extract revealed the highest HMG-CoA reductase inhibitory effect at about 71%, with noncompetitive inhibition in Lineweaver-Burk plot analysis. The leaf extract showed good inhibition of hydroperoxides, 2,2-diphenyl-1-picrylhydrazyl (DPPH), nitric oxide (NO), and ferric ion radicals in various concentrations. A. viridis leaf extract was proven to be an effective inhibitor of hyaluronidase, lipoxygenase, and xanthine oxidase enzymes. The experimental data suggest that A. viridis leaf extract is a source of potent antioxidant and anti-inflammatory agent and may modulate cholesterol metabolism by inhibition of HMG-CoA reductase.

Bioremediation of pollutants including heavy metals and xenobiotics is an economic and environmentally friendly process. A novel molybdenum-reducing bacterium with the ability to utilize the pesticide glyphosate as a carbon source is reported. The characterization works were carried out utilizing bacterial resting cells in a microplate format. The bacterium reduces molybdate to Mo-blue optimally between pH 6.3 and 6.8 and at 34oC. Glucose was the best electron donor for supporting molybdate reduction followed by lactose, maltose, melibiose, raffinose, d-mannitol, d-xylose, l-rhamnose, l-arabinose, dulcitol, myo-inositol and glycerol in descending order. Other requirements include a phosphate concentration at 5.0 mM and a molybdate concentration between 20 and 30 mM. The molybdenum blue exhibited an absorption spectrum resembling a reduced phospho-molybdate. Molybdenum reduction was inhibited by mercury, silver, cadmium and copper at 2 ppm by 45.5, 26.0, 18.5 and 16.3%, respectively. Biochemical analysis identified the bacterium as Klebsiella oxytoca strain Saw-5. To conclude, the capacity of this bacterium to reduce molybdenum into a less toxic form and to grow on glyphosate is novel and makes the bacterium an important instrument for bioremediation of these pollutants.

Bioremediation of pollutants including heavy metals and xenobiotics is an economic and environmentally friendly process. A novel molyb-denum-reducing bacterium with the ability to utilize the pesticide glyphosate as a carbon source is reported. The characterization works were carried out utilizing bacterial resting cells in a microplate format. The bacterium reduces molybdate to Mo-blue optimally between pH 6.3 and 6.8 and at 34oC. Glucose was the best elec-tron donor for supporting molybdate reduction followed by lactose, maltose, melibiose, raffinose, d-mannitol, d-xylose, l-rhamnose, l-arabinose, dulcitol, myo-inositol and glycerol in descending order. Other requirements include a phosphate concentration at 5.0 mM and a molybdate concentration between 20 and 30 mM. The molybdenum blue exhibited an absorption spec-trum resembling a reduced phospho-molybdate. Molybdenum reduction was inhibited by mercury, silver, cadmium and copper at 2 ppm by 45.5, 26.0, 18.5 and 16.3%, respectively. Biochemical analysis identified the bacterium as Klebsiella oxytoca strain Saw-5. To conclude, the capacity of this bacterium to reduce molybdenum into a less toxic form and to grow on glyphosate is novel and makes the bacterium an important instrument for bioremediation of these pollutants.

In a previous study, we isolated Leifsonia sp. strain SIU, a new bacterium from agricultured soil. The bacterium was tested for its ability to degrade caffeine. The isolate was encapsulated in gellan gum and its ability to degrade caffeine was compared with the free cells. The optimal caffeine degradation was attained at a gellan gum concentration of 0.75% (w/v), a bead size of 4 mm diameter, and 250 beads per 100 mL of medium. At a caffeine concentration of 0.1 g/L, immobilised cells of the strain SIU degraded caffeine within 9 h, which is faster when compared to the case of free cells, in which it took 12 h to degrade. The immobilised cells degraded caffeine completely within 39 and 78 h at 0.5 and 1.0 g/L, while the free cells took 72 and 148 h at 0.5 and 1.0 g/L, respectively. At higher caffeine concentrations, immobilised cells exhibited a higher caffeine degradation rate. At concentrations of 1.5 and 2.0 g/L, caffeine-degrading activities of both immobilised and free cells were inhibited. The immobilised cells showed no loss in caffeine-degrading activity after being used repeatedly for nine 24-h cycles. The effect of heavy metals on immobilised cells was also tested. This study showed an increase in caffeine degradation efficiency when the cells were encapsulated in gellan gum.

In a previous study, we isolated Leifsonia sp. strain SIU, a new bacterium from agricultured soil. The bacterium was tested for its ability to degrade caffeine. The isolate was encapsulated in gellan gum and its ability to degrade caffeine was compared with the free cells. The optimal caffeine degradation was attained at a gellan gum concentration of 0.75% (w/v), a bead size of 4 mm diameter, and 250 beads per 100 mL of medium. At a caffeine concentration of 0.1 g/L, immobilised cells of the strain SIU degraded caffeine within 9 h, which is faster when compared to the case of free cells, in which it took 12 h to degrade. The immobilised cells degraded caffeine completely within 39 and 78 h at 0.5 and 1.0 g/L, while the free cells took 72 and 148 h at 0.5 and 1.0 g/L, respectively. At higher caffeine concentrations, immobilised cells exhibited a higher caffeine degradation rate. At concentrations of 1.5 and 2.0 g/L, caffeine-degrading activities of both immobilised and free cells were inhibited. The immobilised cells showed no loss in caffeine-degrading activity after being used repeatedly for nine 24-h cycles. The effect of heavy metals on immobilised cells was also tested. This study showed an increase in caffeine degradation efficiency when the cells were encapsulated in gellan gum.

Climbing Perch or its scientific name, Anabas testudineus is one of the freshwater fish belonging to the family of Anabantidae. It is widely distributed in ponds, swamps and estuaries in Asia. In this study, cholinesterase (ChE) was partially purified from the liver of A. testudineus through ion exchange chromatography. This purification method provided a recovery yield of 5.36% with a purification fold of 6.6. The optimum conditions for ChE assay were identified to be 2.5 mM of butyrylthiocholine iodide (BTC) with pH 8.0 in Tris-HCl buffer at 40°C. Substrate specificity profile also indicated that ChE favours BTC as substrate because it records the highest catalytic efficiency (Vmax/Km). Protein analysis through Native-PAGE showed that ion exchange chromatography is an effective method to partially purify ChE. Metal ion inhibition tests were conducted and mercury (Hg) was found to show the highest inhibition effect (87.30%) whereas lead (Pb) shows the lowest inhibition effect (28.01%). All these findings showed that partially purified ChE from the liver of A. testudineus is suitable to be used as a bioindicator to detect the presence of metal ions.