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.

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.