Occurrence of metal and antibiotic resistant Escherichia coli harbouring zntA and copA genes in selected surface water in Ibadan,South-west Nigeria

ABSTRACT

Escherichia coli strains were isolated from surface water collected from three sampling points and cultured on CHROMAgar E. coli. The zinc and copper concentrations of the water samples were determined using Atomic Absorption Spectrophotometer. Colonies of Escherichia coli were subjected to increasing concentration (0.1–1.0 mM) of copper and zinc in the isolation medium. Isolates showing resistance to both metals at 1 mM were identified using conventional methods and by targeting the uidA gene, while PCR amplification of the copA and zntA genes was carried out using specific primers. The selected bacteria were subjected to 10 classes of antibiotics using the Kirby–Bauer disc diffusion technique. Five E. coli showing resistance to copper and zinc and possessing uidA gene were obtained. Of the five isolates, three possessed both zntA and copA genes, while zntA was absent in the remaining two. All the isolates peculiarly showed resistance to ampicillin and doxycycline, while three were multi-drug resistant (MDR).     

Removal of Metal Ions From Wastewater With Roadside Tree Leaves

This paper reports on research related to the removal of heavy metal ions, such as lead, nickel, and zinc from wastewater by using tree leaves. Twelve different kinds of tree leaves were tested at room temperature. The experiments were carried out with 2 g of 40-50 mesh leaves in 200 mL synthetic wastewater containing about 50 mg/L metal ions. The initial pH of the synthetic wastewater was about 5. The experiments showed that the highest removal rates were 96% for lead (Pb ++ ), 61.7% for nickel (Ni ++ ), and 71.3% for zinc (Zn ++ ), compared with 93.9% for lead, 68.5% for nickel, and 72.1% for zinc achieved by activated carbon. Tree leaves appear to beagoodadsorbent for metal ion removal from wastewater.     

An Evaluation of the Efficiency of Commodas Optical Sorting of Gold Waste Rock Dumps

The treating of gold waste rocks in the gold mining industry has grown significantly in the last few years. The operation of a South African gold mining company treating a waste rock dumps with gold content varying between 0.2 to 0.9 g/t with the Commodas optical sorter to minimize the amount of gangue in the waste rock for further treatment was studied. The results obtained showed that the sorting machine has not been operating at the required set targets of 70% gold recovery and <0.1 Au g/t gold waste. The optical sorter was studied to establish the current operating parameters, determine the operating efficiency of the equipment and propose a solution to the deficiencies observed. The studies showed that the highest and second highest gold recovery percents of 71.2 and 61.6% were obtained when the average feed rates were 24.8 and 26 t/hr, while very low recoveries of 2.4 and 3.1% occurred at the feed rates of 46 and 29.5 t/hr; respectively. It was further observed that the waste grade, enrichment ratio and mass pull percent have no clear relationship with the gold recovery percent, while increasing grade of feed improved the concentrate grade. It is therefore proposed that the feed rate should be maintained in the range of 24.8 to 26 t/hr and the process parameters be further studied and adjusted so that gold recovery percents will be fairly proportional to the feed grade and mass pull into the concentrate and inversely proportional to the waste stream grade.     

电子束辐照制备纳米镍

在水溶液中,常温常压下不加入任何催化剂,用电子束加速器辐照作为一种新的方法可成功制备纳米镍。利用X射线衍射(XRD)、透射电子显微镜(TEM)、激光衍射粒度分布仪(LSPSDA)、紫外可见光分光光度计(UV)、样品振荡磁力计(VSM)和差热分析仪(DSC)来分别表征材料的结构、形貌、大小、粒径分布、光学特征、磁学性能以及材料的熔点。TEM图像和LSPSDA分布图证明颗粒大小为39nm,这与XRD实验通过Scherer理论公式计算的结果相一致。     

A spectroscopic study of vanadium in mushroom

Nine different species of mushroom were analysed spectrometrically for their vanadium contents. It was found that some edible species of mushroom, such as Agrocybe and Leutinus, contain vanadium in amounts either comparable with, or higher than, the amounts in some poisonous species. The result suggests that there is no correlation between the vanadium content of the mushroom species examined and their toxicity.