Browsing by Author "Okaiyeto, Kunle"

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    Evaluation of flocculating potentials and characterization of bioflocculants produced by three bacterial isolates from Algoa bay, South Africa
    (University of Fort Hare, 2016) Okaiyeto, Kunle
    Flocculation has been widely adopted as one of the most effective methods to remove colloidal particles in water or wastewater treatment. Synthetic flocculants are conventionally used because of their high flocculating efficiency and cost-effectiveness. However, they have been reported to have hazardous properties and implicated in some serious health problems including senile dementia and neuro-toxicity, as well as being recalcitrant in the environment. Consequently, efforts are being geared away from the use of synthetic flocculants in water and wastewater treatment. Hence, the need for safe and eco-friendly flocculants has become imperative. Compared with synthetic flocculants, bioflocculants have special advantages such as safety, biodegradability and harmlessness to the environment and humans; attributes which make them potential alternatives in water treatment, downstream as well as fermentation processes. In the current study, the potentials of bacterial isolates recovered from Algoa Bay in the Eastern Cape Province of South Africa for bioflocculant production were investigated. The bacterial isolates were identified by polymerase chain reaction (PCR) as belonging to the Bacillus genus. The analysis of 16S ribosomal deoxyribonucleic acid (rDNA) nucleotide sequence of isolate M72 showed 99% similarity to Bacillus toyonensis strain BCT-7112 and was deposited in the GenBank as Bacillus toyonensis strain AEMREG6 with accession number KP406731. Likewise, the 16S rDNA nucleotide sequences of isolates M69 and M67 showed 98% sequence similarity to Bacillus licheniformis strain W7 and Bacillus algicola strain QD43 respectively; and M67 isolate was subsequently deposited in the GenBank as Bacillus sp. AEMREG7 with accession number KF933697.1. The results of the nutritional requirements and fermentation conditions revealed that optimum inoculum size for REG-6 production was 4% (v/v), while 5% (v/v) and 3% (v/v) were most favourable for MBF-W7 and MBF-UFH production respectively. Glucose was the best carbon source for the production of bioflocculants (REG-6 and MBF-UFH) by Bacillus toyonensis AEMREG6 and Bacillus sp. AEMREG7 respectively, while maltose supported optimum bioflocculant (MBF-W7) production by Bacillus specie. Inorganic nitrogen (NH4NO3) was the favoured nitrogen source for both REG-6 and MBF-W7 production, while mixed nitrogen sources [yeast extract + urea + (NH4)2SO4] supported the maximum production of MBF-UFH. The initial medium pH for REG-6 was 5, while MBF-W7 and MBF-UFH were both maximally produced at the initial pH of 6. After a 96 h cultivation period under optimal culture conditions, 3.2 g of purified REG-6 with a maximum flocculating activity of 77% was recovered from 1 L fermented broth of Bacillus toyonensis AEMREG6. Yields of 3.8 g and 1.6 g pure bioflocculants with the respective highest flocculating activities of 94.9% and 83.2% were also obtained from 1 L, 72 h-fermented broths of Bacillus licheniformis and Bacillus sp. AEMREG7 respectively. Furthermore, all the three bioflocculants (REG-6, MBF-W7 and MBF-UFH), displayed thermal stability within the temperature range of 50 to 100 oC, with strong flocculating activities of over 80% against kaolin suspension over a wide range of pH range (3–11) and relatively low dosage requirements of 0.1-03 mg/ml in the presence of divalent cations in the treatment of kaolin clay suspension and Thyme River waters. Chemical composition analyses of the bioflocculants showed them to be glycoproteins with a predominantly polysaccharide backbones as shown by the following carbohydrate/protein (w/w) ratios: 77.8%:11.5% (REG-6); 73.7%:6.2% (MBF-W7) and 76%:14% (MBF-UFH). Fourier transform infrared spectroscopy (FTIR) revealed the presence of hydroxyl, carboxyl and amide groups which are preferred for effective flocculation. Scanning electron microscopy (SEM) images of the purified bioflocculants showed that they have an irregular, coarse-grained structure connected in netted textures; it also revealed how the bioflocculants connected the scattered kaolin particles firmly together to form bigger flocs which subsequently precipitated out of suspension as a result of gravity. MBF-W7 showed good turbidity removal potential (86.9%) and chemical oxygen demand (COD) reduction efficiency (75.3%) of Thyume River waters. MBF-UFH showed higher flocculating activity for kaolin clay suspension compared to synthetic flocculants (aluminium chloride and iron chloride). The results obtained from this study suggested that the bioflocculants (REG-6, MBF-W7 and MBF-UFH) produced by these bacterial isolates have great potentials to serve as an alternatives to hazardous synthetic flocculants conventionally utilized in various industrial processes including water/wastewater treatment, and stand as attractive candidates for further research and development for industrial-scale application.
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    Production and characterization of a bioflocculant from a consortium of bacteria belonging to the halomonas and micrococcus genera.
    (University of Fort Hare, 2013) Okaiyeto, Kunle
    The physicochemical properties of two bioflocculant producing bacteria; Halomonas sp. Okoh and Micrococcus sp. Leo were investigated. The optimum culture conditions for the individual species were determined. All the growth conditions examined for the individual bacteria were similar. Glucose and ammonium sulphate as sole carbon and nitrogen sources respectively resulted in optimum production of bioflocculant. The flocculating activity of the bioflocculants was stimulated when Al3+ was used as the coagulating aid under acidic medium. The information obtained from individual strains was used to produce a bioflocculant from the consortium of the two bacteria. After purification, the bioflocculant yields from 1L fermentation broths were 1.213 g from Halomonas sp. Okoh, 0.738 g from Micrococcus sp. Leo and 3.51 g from the consortium. The chemical analyses of the purified bioflocculants showed that they were glycoproteins. The thermostability property of the bioflocculants was investigated between 50-100oC and the results revealed that they are heat-stable. Fourier transform infrared revealed the presence of hydroxyl, carboxyl and amino groups in the bioflocculant molecules. Scaning electron microscope (SEM) images showed the structure of each bioflocculant(s) and kaolin clay before and after flocculation. From the results obtained, the idea of using the two strains in consortium for bioflocculant production resulted in an improvement in terms of flocculating activity and yield. The bioflocculants appears to have promise as an alternative to chemical flocculants used in various industrial processes such as wastewater treatment and drinking water purification.