4. Results

species, given the global warming and related environmental problems. Growing of bacteria indoors is quite sustainable, when compared to growth of plants although Lea argues that

Water released from the wastewater treatment plant (effluent) was obtained from Notwane Sewage Treatment Plant situated in Gaborone, Botswana. It was collected from the sampling site in sterile 250 ml Duran bottles and immediately placed on ice in a cooler box with ice. The samples were taken to the Department of Biological Sciences, North-West University, Mafikeng for analysis. Samples were analyzed within 24 h of sampling. The treatment plant treats

In the study carried out by the author, out of the many bacteria stated in literature, only Pseudomonas aeruginosa isolated from the wastewater sampled during the study was used. The water samples were divided into two parts, one part was sterilized by autoclaving at 121C for 15 min and the other half was left unsterilized. The wastewater samples were treated with Aroclors of polychlorinated biphenyls (PCBs) obtained from SUPELCO Solutions Within™, USA, through Lehlabile Scientific, South Africa. The PCBs were supplied as Aroclors. Aroclor 1242 (Lot No. LB8851), 1248 (Lot No. LB88969), and 1260 (Lot No. LB92109) in 1 ml ampoules at concentration 1000 μg/ml dissolved in isooctane were used in this study.

To each 100 ml wastewater sample in a 250 ml flask, 10 μl of polychlorinated biphenyls Aroclors mixture, herein referred to as PCBs, was added. The sterilized wastewater samples were inoculated with a colony of the 18 h old culture of the test organism, which was identified as Pseudomonas aeruginosa (with accession number from the gene bank of CP 006832 in a study carried out in 2014). Non-sterilized wastewater without bacterial inoculation (Control 1) and sterilized wastewater without inoculation (Control 2) were both treated with PCBs and were the controls. The flasks were wrapped with aluminum foil to exclude light and were incubated at 30C in the dark in a rotary shaker at 150 rpm [46]. A 5 ml was aseptically taken at 24 h intervals from each setup/flask for detection of PCBs using HPLC and spectral changes were checked at 200–800 nm using Cary 300 UV-visible spectrophotometer, for a period of 96 h.

Analysis for PCB using HPLC was carried out as described by Roy et al. with some modifications [46]. A 1 ml was sampled from each setup to check for residual PCB at 24 h interval. The compounds were extracted by adding 10 ml each of dichloromethane and acetone. The mixture was incubated in a rotary shaker for 24 h at 30C. After incubation, the mixture was centrifuged for 10 min at 12,000 rpm at 4C using a Hermle Z326k high speed microcentrifuge, Labortechnik GmbH (LASEC, South Africa). The extra water was pipetted and 4 g

3.2. Biodegradation of PCBs in wastewater by isolate Pseudomonas aeruginosa

propagation is affordable [44].

3. Materials and method

40,000 m3 per day of sewage.

The purity for each Aroclor was not stated.

3.1. Sample collection

144 Wastewater and Water Quality
