A new alternative local source of acetylcholinesterase (AChE) has been found to be sensitive towards several insecticides. AChE was purified from the brain tissue of Puntius javanicususing affinity chromatography (procainamide hydrochloride coupled with sephacryl 6B) with the total recovery of 40% at 8.48 purification fold. All carbamate (CB) insecticides tested at the concentration of 1 mg/L were capable of lowering AChE activity to less than 30%; Bendiocarp (18.80%), carbaryl (5.96%,), carbofuran (6.12%), methomyl (13.91%) and propoxur (15.851%). The P. javanicus AChE was found to be unaffected by several activated organophosphates (OP) such as acephate and dimethoate, while trichlorfon slightly inhibited the enzyme activity (p<0.05). Chlorpyrifos, diazinon, malathion and parathion lowered AChE activity to 43.02, 40.97, 37.11 and 46.72%, respectively. Pesticides that inhibit AChE activities more than 50% were further tested in different concentrations to determine the half maximal inhibitory concentration (IC50). Carbofuran and carbaryl showed the lowest IC50 value at 0.035 and 0.031 mg/L, respectively, as both showed no significant differences (p<0.05), followed by bendiocarp, propoxur, methomyl, malathion, diazinon, parathion and chlorpyrifos at 0.045, 0.076, 0.090, 0.063, 0.103, 0.151 and 0.202 mg/L, respectively. Based on these results, the sensitivity of AChE from brain P. javanicus brain tissue shows promise as an alternative biosensor for the detection of insecticides contamination.

Heavy metals are sometimes needed for nutrient uptake but only in low concentrations and the nervous system is the most susceptible to be affected. Cholinesterase (ChE) inhibition has been used extensively as a biomarker for heavy metals detection. In this study, the potential of ChE from Lates calcarifer brain as an alternative biosensor for heavy metals is evaluated. There are many Malaysian rivers such as Sungai Juru and Sungai Merbok that are greatly polluted by industrial effluents. Chronic exposure to heavy metals may cause nervous system disorders. Thus, a fast and simple biomonitoring technique will help in alerting government agencies and the public to such a threat. In this study, ChE from the brain of L. calcarifer (Asian seabass) was purified through ammonium sulphate precipitation and ion exchange chromatography. Enzyme recovery was 5.31% with a specific activity of 5.472 U mg-1. The Michaelis-Menten constant (Km) value was 0.3075 mM and a Vmax of 0.0304 ?mol min-1 mg-1. ChE from L. calcarifer brain showed higher affinity to acetylthiocholine iodide (ATC) compared to butyrylcholinesterase (BTC) and propionylcholinesterase iodide (PTC). Maximum activity of ChE was detected when the enzyme was assayed at the temperature of 20-30�C and incubated in Tris-HCl buffer pH 8.0. Silver (Ag), arsenic (As), cadmium (Cd), chromium (Cr) and mercury (Hg) showed more than 50% inhibition amongst the 10 types of heavy metals that have been tested for inhibition study. These results can be used to further develop an alternative way to detect heavy metals that are low cost and give faster results compared to existing biosensor kits.

Phenol pollution often associated with agriculture industries involving pesticides and respiratory inhibitors. Microorganism used for biodegradation of phenols should also be resistant to the pesticides and respiratory inhibitors. In this study, 1 ppm of carbofuran, paraquat dichloride, atrazine, potassium cyanide (KCN), sodium azide (NaN3) and rotenone were used to investigate the ability of Acinetobacter sp. strain AQ5NOL 1 freely suspended and immobilized in gellan gum beads to degrade phenol in the presence of pesticides and respiratory inhibitors. Results from this study showed that the degradation of phenol after 48 hours of incubation by free cells was inhibited by KCN at 47.48%. However, the degradation of phenol after 18 hours incubation by immobilized cells was inhibited by KCN at 52.68%. The lowest concentration of KCN that showed inhibition to phenol degradation was 0.8 ppm. Prolonging the incubation time from 18 hours to 20 hours for KCN has alleviated the inhibition. Other respiratory inhibitors such as carbofuran, paraquat dichloride, atrazine, NaN3 and rotenone showed no effect on phenol-degrading activities and bacterial growth by both free and immobilised cells compared to control (p>0.05). � 2015, Journal of Pure and Applied Microbiology. All rights reserved.

A diesel-degrading bacterium was isolated from a diesel-contaminated site in Selangor, Malaysia. The isolate was tentatively identified as Acinetobacter sp. strain DRY12 based on partial 16S rDNA molecular phylogeny and Biolog® GN microplate panels and Microlog® database. Optimum growth occurred from 3 to 5% diesel and the strain was able to tolerate as high as 8% diesel. The optimal pH that supported growth of the bacterium was between pH 7.5 to 8.0. The isolate exhibited optimal growth in between 30 and 35° C. The best nitrogen source was potassium nitrate (between 0.6 and 0.9% (w/v)) followed by ammonium chloride, sodium nitrite and ammonium sulphate in descending order. An almost complete removal of diesel components was seen from the reduction in hydrocarbon peaks observed using Solid Phase Microextraction Gas Chromatography analysis after 10 days of incubation. The best growth kinetic model to fit experimental data was the Haldane model of substrate inhibiting growth with a correlation coefficient value of 0.97. The maximum growth rate- μmax was 0.039 hr -1 while the saturation constant or half velocity constant Ks and inhibition constant Ki, were 0.387% and 4.46%, respectively. MATH assays showed that 75% of the bacterium was found in the hexadecane phase indicating that the bacterium was hydrophobic. The characteristics of this bacterium make it useful for bioremediation works in the Tropics.

Biodegradation of agricultural wastes, generated annually from poultry farms and slaughterhouses, can solve the pollution problem and at the same time yield valuable degradation products. But these wastes also constitute environmental nuisance, especially in Malaysia where their illegal disposal on heavy metal contaminated soils poses a serious biodegradation issue as feather tends to accumulate heavy metals from the surrounding environment. Further, continuous use of feather wastes as cheap biosorbent material for the removal of heavy metals from effluents has contributed to the rising amount of polluted feathers, which has necessitated the search for heavy metal-tolerant feather degrading strains. Isolation, characterization and application of a novel heavy metal-tolerant feather-degrading bacterium, identified by 16S RNA sequencing as Alcaligenes sp. AQ05-001 in degradation of heavy metal polluted recalcitrant agricultural wastes, have been reported. Physico-cultural conditions influencing its activities were studied using one-factor-at-a-time and a statistical optimisation approach. Complete degradation of 5�g/L feather was achieved with pH 8, 2% inoculum at 27��C and incubation period of 36�h. The medium optimisation after the response surface methodology (RSM) resulted in a 10-fold increase in keratinase production (88.4 U/mL) over the initial 8.85 U/mL when supplemented with 0.5% (w/v) sucrose, 0.15% (w/v) ammonium bicarbonate, 0.3% (w/v) skim milk, and 0.01% (w/v) urea. Under optimum conditions, the bacterium was able to degrade heavy metal polluted feathers completely and produced valuable keratinase and protein-rich hydrolysates. About 83% of the feathers polluted with a mixture of highly toxic metals were degraded with high keratinase activities. The heavy metal tolerance ability of this bacterium can be harnessed not only in keratinase production but also in the bioremediation of heavy metal-polluted feather wastes. � 2016

The characterization of bacterial enzymatic pathways of phenol metabolism is important to better understand phenol biodegradation. Phenol hydroxylase is the first enzyme involved in the oxidative metabolism of phenol, followed by further degradation via either meta- or ortho-pathways. In this study, the first known instance of phenol degradation via the meta-pathway by a member of the genus Acinetobacter (Acinetobacter sp. strain AQ5NOL 1) is reported. Phenol hydroxylase converts phenol to catechol, which is then converted via the meta-pathway to 2-hydroxymuconic semialdehyde by the catechol 2,3-dioxygenase enzyme. Phenol hydroxylase extracted from strain AQ5NOL 1 was fully purified using DEAE-Sepharose�, DEAE-Sephadex�, Q-Sepharose� and Zorbax� Bioseries GF-250 gel filtration and was demonstrated by SDS-PAGE to have a molecular weight of 50�kDa. The phenol hydroxylase was purified to about 210.51 fold. The optimum pH and temperature for enzyme activities are 20��C and 7�7.5, respectively. The apparent Km and Vmax values of phenol hydroxylase with phenol as the substrate were 13.4��M and 2.5��mol�min?1�mg?1, respectively. The enzyme was stable at ?20��C for 36�days. � 2016, Accademia Nazionale dei Lincei.

Gold mining companies are known to use cyanide to extract gold from minerals. The indiscriminate use of cyanide presents a major environmental issue. Serratia marcescens strain AQ07 was found to have cyanide-degrading ability. Optimisation of biodegradation condition was carried out utilising one factor at a time and response surface methodology. Cyanide degradation corresponded with growth rate with a maximum growth rate of 16.14�log�cfu/mL on day 3 of incubation. Glucose and yeast extract are suitable carbon and nitrogen sources. Six parameters including carbon and nitrogen sources, pH, temperature, inoculum size and cyanide concentration were optimised. In line with the central composite design of response surface methodology, cyanide degradation was optimum at glucose concentration 5.5�g/L, yeast extract 0.55�g/L, pH 6, temperature 32.5��C, inoculum size 20�% and cyanide concentration 200�mg/L. It was able to stand cyanide toxicity of up to 700�mg/L, which makes it an important candidate for bioremediation of cyanide. The bacterium was observed to degrade 95.6�% of 200�mg/L KCN under the optimised condition. Bacteria are reported to degrade cyanide into ammonia, formamide or formate and carbon dioxide, which are less toxic by-products. These bacteria illustrate good cyanide degradation potential that can be harnessed in cyanide remediation. � 2016, Accademia Nazionale dei Lincei.

The purpose of this study was to investigate the ability of Acinetobacter sp. strain AQ5NOL 1 immobilised in gellan gum beads to degrade phenol in the presence of heavy metals. Seven different heavy metals, namely, As5+, Cu2+, Cd2+, Ni2+, Cr6+, Pb2+, and Hg2+ at 1 ppm were tested. Results of the study showed that degradation of phenol by free cells was inhibited by Hg2+, Cu2+ and Cr6+ after 48 hours of incubation by 97.91 %, 77.58 % and 75.26 %, respectively. Only Hg2+ and Cr6+ inhibited phenol degradation by immobilised Acinetobacter cells in 18 hours by 67.55 % and 53.19 %. Phenol degradation by immobilised cells was affected when Cr6+ and Hg2+ concentrations exceeded 0.5 and 0.1 ppm, respectively. However, inhibitory effects of heavy metals can be overcome by prolonging the incubation time for immobilised Acinetobacter sp. strain AQ5NOL 1 from 18 hours to 24 and 30 hours for Cr6+ (46.80%) and Hg2+ (21.40%), respectively. � 2017, National Science Foundation. All rights reserved.

Fish are ubiquitous organisms that have many features that designate their potential as a biomarker of heavy metals pollution. Thus, an investigation was done to detect the effect of heavy metals on cholinesterase (ChE) activity from Lates calcarifer organs which were gill and muscle. Ammonium sulphate precipitation was performed along with ion exchange chromatography to purify the enzyme. In the substrate specificity study, ChE from L. calcarifer gills was capable of breaking down acetylthiocholine iodide (ATC) at a faster rate compared to the other two synthetic substrates, which are butyrylthiocholine iodide (BTC) and propionylthiocholine iodide (PTC). In contrast, the muscle ChE has a higher affinity towards PTC. The maximum activity of ChE observed at the temperature ranging from 20 to 30��C in Tris�HCl buffer pH 8. ChE from the two organs of L. calcarifer showed an inhibitive reaction towards heavy metals, but with different effects. ATC from gills showed 50�% inhibition by Cu, Hg and Pb, while PTC from muscle showed 50�% inhibition by Pb. The variation of inhibitory effect that was shown by ChE from L. calcarifer organs can be further studied in designing a biosensor kit that is sensitive towards heavy metal. � 2016, Accademia Nazionale dei Lincei.