- Title
- Characterization of bioflocculants produced by consortia of three marine bacteria belonging to the genera bacillus and cobetia previously isolated from the bottom sediment of Algoa Bay in the Eastern Cape Province of South Africa
- Creator
- Ugbenyen, Anthony Moses https://orcid.org/0000-0002-1381-3428
- Subject
- Water -- Purification -- Flocculation
- Subject
- Water quality management
- Subject
- Flocculation
- Date Issued
- 2013
- Date
- 2013
- Type
- Doctoral theses
- Type
- text
- Identifier
- http://hdl.handle.net/10353/24454
- Identifier
- vital:62804
- Description
- The bioflocculant-producing potentials of three marine bacteria isolated from the sediment samples of Algoa Bay in the Eastern Cape Province of South Africa were assessed. Analysis of the partial nucleotide sequence of the 16S rDNA of the bacteria revealed 99 percent, 99 percent, and 98 percent similarity to Cobetia sp. L222, Bacillus sp. A-5A, and Bacillus sp. HXG-C1 respectively and the sequence was deposited in GenBank as Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert (accession number JF799092, JF799093, and HQ537128 respectively). Cultivation condition studies for Cobetia sp. OAUIFE revealed that bioflocculant production was optimal with an inoculum size of 2 percent (v/v), initial pH of 6.0, Mn2+ as the metal ion, and glucose as the carbon source. Metal ions, including Na+, K+, Li+, Ca2+and Mg2+ stimulated bioflocculant production resulting in flocculating activity of above 90 percent. This crude bioflocculant is thermally stable, with about 78 percent of its flocculating activity remaining after heating at 100 oC for 25 min. Analysis of the purified bioflocculant revealed it to be an acidic extracellular polysaccharide. FTIR analysis revealed the presence of methoxyl, hydroxyl, and carboxyl - groups in the compound bioflocculant and SEM micrograph of the bioflocculant revealed a crystal-linear structure. On the other hand, bioflocculant production by Bacillus sp. MAYA was optimal when glucose (95.6 percent flocculating activity) and ammonium nitrate (83.3 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 2 percent (v/v); initial pH 6; and Ca2+ as coagulant aid. Chemical analysis of the purified bioflocculant shows that it is composed of uronic acid, neutral sugar and protein. FTIR analysis also revealed the presence of methoxyl, hydroxyl, carboxyl and amino- groups in this bioflocculant. The bioflocculant is thermostable with about 65.6 percent residual flocculating activity retained after heating the bioflocculant at 100 oC for 25 min. However bioflocculant production by Bacillus sp. Gilbert was optimal when sodium carbonate (95.2 percent flocculating activity) and potassium nitrate (76.6 percent flocculating activity) were used as carbon and nitrogen sources respectively; inoculum size was 3 percent (v/v); initial pH 9; and Al3+ as cation. The crude bioflocculant retained 44.2 percent residual flocculating activity after heating at 100 oC for 15 min. FTIR analysis reveals the presence of hydroxyl, carboxyl and methylene - groups in the compound bioflocculant. SEM micrograph of the bioflocculant revealed an amorphous compound. The consortia of these bacteria strains also produced bioflocculants with high flocculating activities which were highly efficient in removing turbidity and chemical oxygen demand (COD) from brewery wastewater, diary wastewater and river water. The bioflocculants from the consortia seemed better than traditional flocculants such as alum . The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE and Bacillus sp. MAYA showed that this extracellular bioflocculant, composed of 66percent uronic acid and 31percent protein and an optimum flocculation (90 percent) of kaolin suspension, when the dosage concentration was 0.8 mg/ml, under weak alkaline pH of 8, and Ca2+ as a coagulant aid. The bioflocculant is thermally stable, with a high residual flocculating activity of 86.7 percent, 89.3 percent and 87.0 percent after heating at 50 oC, 80 oC and 100 oC for 25 min respectively. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl functional groups. Scanning electron microscopy (SEM) image revealed a crystal-linear spongy-like bioflocculant structure and EDX analysis of the purified bioflocculant showed that the elemental composition in mass proportion of C,N,O,S and P was 6.67:6.23:37.55:0.38:4.42 (percent w/w). However, the characteristics of the bioflocculant produced by the consortium of Cobetia sp OAUIFE and Bacillus sp. Gilbert showed an optimum flocculation (90 percent) of kaolin suspension when the dosage concentration was 0.2 mg/ml, under neutral pH of 7, and Ca2+ as a coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl and carbonyl functional groups. Scanning electron microscopy (SEM) image revealed an amorphous morphology. On the other hand the bioflocculant produced by the consortium of Bacillus sp. MAYA and Bacillus sp. Gilbert showed similar characteristic with the bioflocculant from the consortium of Cobetia sp. OAUIFE and Bacillus sp. Gilbert except for Al3+ being the preferred coagulant aid. The characteristics of the bioflocculant produced by the consortium of Cobetia sp. OAUIFE, Bacillus sp. MAYA and Bacillus sp. Gilbert showed an optimum flocculation (87 percent) of kaolin suspension when the dosage concentration was 1.0 mg/ml. Under strong alkaline pH of 12, flocculating activity reached (95 percent) when Al3+ was the coagulant aid. The FTIR analysis of the bioflocculant indicated the presence of hydroxyl, amino, carbonyl and carboxyl and phosphoryl functional groups. Scanning electron microscopy (SEM) image revealed a flaky amorphous morphological structure. Due to the excellent COD and turbidity removal efficiencies of the bioflocculants produced by the consortia, these make those attractive candidates for use in water and wastewater treatment.
- Description
- Thesis (PhD) -- Faculty of Science and Agriculture, 2013
- Format
- computer
- Format
- online resource
- Format
- application/pdf
- Format
- 1 online resource (148 leaves)
- Format
- Publisher
- University of Fort Hare
- Publisher
- Faculty of Science and Agriculture
- Language
- English
- Rights
- University of Fort Hare
- Rights
- All Rights Reserved
- Rights
- Open Access
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UFH Department of Biochemistry & Microbiology
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