Repository logo
 

Research Institutes

Permanent URI for this communityhttp://ir-dev.dut.ac.za/handle/10321/840

Browse

Author: search.filters.author.Kumari, Sheena K.Has files: No

Search Results

Now showing 1 - 5 of 5
  • No Thumbnail Available
    Item
    Phenotypic and genotypic characterisation of an unique indigenous hypersaline unicellular cyanobacterium, Euhalothece sp.nov
    (Elsevier, 2018) Mogany, Trisha; Swalaha, Feroz Mahomed; Allam, Mushal; Mtshali, Phillip Senzo; Ismail, Arshad; Kumari, Sheena K.; Bux, Faizal
    A novel halotolerant species of cyanobacterium of the order Chroococcales was isolated from hypersaline estuary in Kwa-Zulu Natal, South Africa. A comprehensive polyphasic approach viz., cell morphology, pigment com-position and complete genome sequence analysis was conducted to elucidate the taxonomic position of the isolated strain. The blue-green oval to rod-shaped cells were 14–18 μm in size, and contained a high amount of phycocyanin pigments. The strain was moderate thermotolerant/alkalitolerant halophile with the optimum conditions for growth at 35 °C, pH 8.5 and 120 g/l of NaCl. Based on 16S rRNA gene sequence phylogeny, the strain was related to members of the ‘Euhalothece’ subcluster (99%). The whole genome sequence was de-termined, and the annotated genes showed a 90% sequence similarity to the gas-vacuolate, spindle-shaped Dactylococcopsis salina PCC 8305. The size of the genome was determined to be 5,113,178 bp and contained 4332 protein-coding genes and 69 RNA genes with a G + C content of 46.7%. Genes encoding osmoregulation, oxi-dative stress, heat shock, persister cells, and UV-absorbing secondary metabolites, among others, were identified. Based on the phylogenetic analysis of the 16S rRNA gene sequences, physiological data, pigment compositions and genomic data, the strain is considered to represent a novel species of Euhalothece.
  • No Thumbnail Available
    Item
    Evaluation of phytotoxicity effect on selected crops using treated and untreated wastewater from different configurative domestic wastewater plants
    (Taylor and francis Online, 2016) Ravindran, B.; Kumari, Sheena K.; Stenström, Thor-Axel; Bux, Faizal
    This study investigated the phytotoxicity effect of untreated and treated wastewater collected from two different configurations of domestic wastewater treatment plants in South Africa. The phytotoxicity effect on vegetable seed growth was studied in terms of germination index (GI), relative seed germination (RSG) and relative root elongation (RRE) using four commercial crop varieties, viz., tomato (Lycopersicon esculentum), radish (Raphanus sativus), carrot (Daucus carota) and onion (Allium cepa). According to phyototoxicity limits, 80% germination and above is regarded as non-toxic and less than 50% GI is regarded as highly toxic and not suitable for agricultural purposes. In our study, seeds were irrigated with concentrations of 25%, 50%, 75%, 100% of treated effluent (TE) and untreated effluent (UTE). The TE results were best with the highest GI (%) recorded as tomato, 177; carrot, 158.5; onion, 132; and lettuce, 124. The results of this study indicate that TE showed no phytotoxicty effects and recorded above 80% GI. The UTE irrigated crops reached a GI of only 50% and above which is clear evidence of the beneficial effect of waste water treatment. The overall results confirmed that treated wastewater has a beneficial effect on agricultural crops and can be used as a liquid fertilizer.
  • No Thumbnail Available
    Item
    Continuous biohydrogen production from starch wastewater via sequential dark-photo fermentation with emphasize on maghemite nanoparticles
    (Elsevier, 2015) Nasr, Mahmoud; Tawfik, Ahmed; Ookawara, Shinichi; Suzuki, Masaaki; Kumari, Sheena K.; Bux, Faizal
    Hydrogen production from starch wastewater via sequential dark-photo fermentation process was investigated. Two anaerobic baffled reactors (ABRs) were operated in parallel at an OLR of 8.11 ± 0.97 g-COD/L/d, and a HRT of 15 h. ABR-1 and ABR-2 was inoculated with pre-treated sludge and sludge immobilized on maghemite nanoparticles, respectively. Better hydrogen yield of 104.75 ± 12.39 mL-H2/g-COD-removed was achieved in ABR-2 as compared to 66.22 ± 4.88 mL-H2/g-COD-removed in ABR-1. The effluent of ABR-2 was used for further hydrogen production by photo fermentation in ABR-3. An overall hydrogen yield of 166.83 ± 27.79 mL-H2/g-COD-removed was achieved at a total HRT of 30 h. 16S rRNA phylogeny showed that Clostridium and Rhodopseudomonas palustris species were dominant in ABR-1, ABR-2 and ABR-3, respectively.
  • No Thumbnail Available
    Item
    Effect of thermal pre-treatment on inoculum sludge to enhance bio-hydrogen production from alkali hydrolysed rice straw in a mesophilic anaerobic baffled reactor.
    (Taylor & Francis, 2013) Bux, Faizal; Kumari, Sheena K.; Tawfik, Ahmed; El-berry, Haitham
    The effect of thermal pre-treatment on inoculum sludge for continuous H2 production from alkali hydrolysed rice straw using anaerobic baffled reactor (ABR) was investigated. Two reactors, ABR1 and ABR2, were inoculated with untreated and thermally pre-treated sludge, respectively. Both reactors were operated in parallel at a constant hydraulic retention time of 20 h and organic loading rate ranged from 0.5 to 2.16 g COD/L d. The results obtained indicated that ABR2 achieved a better hydrogen conversion rate and hydrogen yield as compared with ABR1. The hydrogen conversion rates were 30% and 24%, while the hydrogen yields were 1.19 and 0.97 mol H2/mol glucose for ABR2 and ABR1, respectively. Similar trend was observed for chemical oxygen demand (COD) and carbohydrate removal, where ABR2 provided a removal efficiency of 53±2.3% for COD and 46±2% for carbohydrate. The microbial community analysis using 16S rRNA phylogeny revealed the presence of different species of bacteria, namely Clostridium, Prevotella, Paludibacter, Ensifer, and Petrimonas within the reactors. Volatile fatty acids generated from ABR1 and ABR2 were mainly in the form of acetate and butyrate and a relatively low fraction of propionate was detected in ABR1. Based on these results, thermal pre-treatment of inoculum sludge is preferable for hydrogen production from hydrolysed rice straw.
  • No Thumbnail Available
    Item
    Phenol degrading ability of Rhodococcus pyrinidivorans and Pseudomonas aeruginosa isolated from activated sludge plants in South Africa
    (Taylor and Francis, 2013-03-13) Kumari, Sheena K.; Bux, Faizal; Chetty, Dereshen; Ramdhani, Nishani
    Phenol, a common constituent in many industrial wastewaters is a major pollutant and has several adverse effects on the environment. The potential of various microorganisms to utilize phenol for their metabolic activity has been observed to be an effective means of remediating this toxic compound from the environment particularly wastewater. Five indigenous bacterial isolates (PD1-PD5) were obtained from phenol bearing industrial wastewater using the mineral salts medium. The isolates were further characterized based on their morphology, biochemical reactions and 16S rRNA phylogeny. The 16S rRNA sequence analysis using universal primers (27f/1492r) revealed that PD1, PD2, PD3 and PD4 were closely related to the actinomycete Rhodococcus pyrinidivorans (99%) and PD5 to Pseudomonas aeruginosa (99%). Growth kinetic patterns and phenol degradation abilities of the two representative isolates (PD1 and PD5) were also evaluated. Both the species were effective in utilizing phenol as the sole carbon source and could tolerate phenol concentrations of up to 500 to 600 mg/L. The ability of these isolates to utilize higher concentrations of phenol as their sole carbon source makes them potential candidates and better competitors in the bioremediation process.