Evaluation of flocculating potentials and charecterization of bioflocculants produced by three bacterial isolates from Algoa Bay, South Africa
- Authors: Okaiyeto, Kunle
- Date: 2016
- Subjects: Flocculation Water -- Purification -- Flocculation Water quality management
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2633 , vital:27947
- Description: 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 percent 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 percent 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 percent (v/v), while 5 percent (v/v) and 3 percent (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 percent 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 percent and 83.2 percent 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 percent 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 percent:11.5 percent (REG-6); 73.7 percent:6.2 percent (MBF-W7) and 76 percent:14 percent (MBF-UFH).
- Full Text:
- Authors: Okaiyeto, Kunle
- Date: 2016
- Subjects: Flocculation Water -- Purification -- Flocculation Water quality management
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/2633 , vital:27947
- Description: 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 percent 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 percent 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 percent (v/v), while 5 percent (v/v) and 3 percent (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 percent 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 percent and 83.2 percent 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 percent 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 percent:11.5 percent (REG-6); 73.7 percent:6.2 percent (MBF-W7) and 76 percent:14 percent (MBF-UFH).
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Exploration of Nahoon beach milieu for lignocellulose degrading bacteria and optimizing fermentation conditions for holocellulase production by selected strains
- Authors: Fatokun, Evelyn
- Date: 2016
- Subjects: Lignocellulose Lignocellulose -- Biodegradation Water -- Purification -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/1529 , vital:27413
- Description: A significant trend in the modern day industrial biotechnology is the utilization and application of renewable resources, and ecofriendly approach to industrial processes and waste management. As a consequence thereof, the biotechnology of holocellulases: cellulase and xylanase and, enzymatic hydrolysis of renewable and abundant lignocellulosic biomass to energy and value added products are rapidly increasing; hence, cost effective enzyme system is imperative. In that context, exploration of microbiota for strains and enzymes with novel industrial properties is vital for efficient and commercially viable enzyme biotechnology. Consequent on the complex characteristics of high salinity, variable pressure, temperature and nutritional conditions, bacterial strains from the marine environment are equipped with enzyme machinery of industrial importance for adaptation and survival. In this study, bacterial strains were isolated form Nahoon beach and optimized for holocellulase production. Three isolates selected for lignocellulolytic potential were identified by 16S ribosomal deoxyribonucleic acid (rDNA) sequence analysis. Isolate FS1k had 98 percent similarity with Streptomyces albidoflavus strain AIH12, was designated as Streptomyces albidoflavus strain SAMRC-UFH5 and deposited in the GenBank with accession number KU171373. Similarly, isolates CS14b and CS22d with respective percentage similarity of 98 and 99 (percent) with Bacillus cereus strains and Streptomyces sp. strain WMMB251 were named Bacillus cereus strain SAMRC-UFH9 and Streptomyces sp. strain SAMRC-UFH6; and were deposited in the GenBank with accession number KX524510 and KU171374 respectively. Optimal pH, temperature and agitation speed for cellulase production by S. albidoflavus strain SAMRC-UFH5, and B. cereus strain SAMRC-UFH9 were 6 and 7; 40 and 30 (°C); and 100 and 150 (rpm) respectively; while xylanase production was optimal at pH, temperature and agitation speed of 8 and 7; 40 and 30 (°C); and 150 and 50 (rpm) respectively. Maximum cellulase activity of 0.26 and 0.061(U/mL) by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 were attained at 60 h respectively, while maximal xylanase activity of 18.54 and 16.6 (U/mL) was produced by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 at 48 h and 60 h respectively. Furthermore, xylanase production by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 was maximally induced by wheat straw and xylan respectively, while cellulase production was best induced by mannose and carboxymethyl cellulose respectively. On the other hand, cellulase and xylanase production by Streptomyces sp. strain SAMRC-UFH6 was optimal at pH, temperature and agitation speed of 7 and 8, 40 °C and 100 rpm, respectively. Highest production of cellulase and xylanase was attained at 84 and 60 h with respective activity of 0.065 and 6.34 (U/mL). In addition, cellulase and xylanase production by the strain was best induced by beechwood xylan. Moreover, xylanase produced by Streptomyces sp. strain SAMRC-UFH6 at optimal conditions was characterized by optimal pH and temperature of 8 and 80-90 °C respectively; retaining over 70 percent activity at pH 5-10 after 1 h and 60 percent of initial activity at 90 °C after 90 min of incubation. In all, optimization improved cellulase and xylanase production yields, being 40 and 95.5, 10.89 and 72.17, and 10 and 115- fold increase by S. albidoflavus strain SAMRC-UFH5, B. cereus strain SAMRC-UFH9 and Streptomyces sp. SAMRC-UFH6 respectively. The results of this study suggest that the marine bacterial strains are resource for holocellulase with industrial applications.
- Full Text:
- Authors: Fatokun, Evelyn
- Date: 2016
- Subjects: Lignocellulose Lignocellulose -- Biodegradation Water -- Purification -- South Africa -- Eastern Cape
- Language: English
- Type: Thesis , Doctoral , DPhil
- Identifier: http://hdl.handle.net/10353/1529 , vital:27413
- Description: A significant trend in the modern day industrial biotechnology is the utilization and application of renewable resources, and ecofriendly approach to industrial processes and waste management. As a consequence thereof, the biotechnology of holocellulases: cellulase and xylanase and, enzymatic hydrolysis of renewable and abundant lignocellulosic biomass to energy and value added products are rapidly increasing; hence, cost effective enzyme system is imperative. In that context, exploration of microbiota for strains and enzymes with novel industrial properties is vital for efficient and commercially viable enzyme biotechnology. Consequent on the complex characteristics of high salinity, variable pressure, temperature and nutritional conditions, bacterial strains from the marine environment are equipped with enzyme machinery of industrial importance for adaptation and survival. In this study, bacterial strains were isolated form Nahoon beach and optimized for holocellulase production. Three isolates selected for lignocellulolytic potential were identified by 16S ribosomal deoxyribonucleic acid (rDNA) sequence analysis. Isolate FS1k had 98 percent similarity with Streptomyces albidoflavus strain AIH12, was designated as Streptomyces albidoflavus strain SAMRC-UFH5 and deposited in the GenBank with accession number KU171373. Similarly, isolates CS14b and CS22d with respective percentage similarity of 98 and 99 (percent) with Bacillus cereus strains and Streptomyces sp. strain WMMB251 were named Bacillus cereus strain SAMRC-UFH9 and Streptomyces sp. strain SAMRC-UFH6; and were deposited in the GenBank with accession number KX524510 and KU171374 respectively. Optimal pH, temperature and agitation speed for cellulase production by S. albidoflavus strain SAMRC-UFH5, and B. cereus strain SAMRC-UFH9 were 6 and 7; 40 and 30 (°C); and 100 and 150 (rpm) respectively; while xylanase production was optimal at pH, temperature and agitation speed of 8 and 7; 40 and 30 (°C); and 150 and 50 (rpm) respectively. Maximum cellulase activity of 0.26 and 0.061(U/mL) by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 were attained at 60 h respectively, while maximal xylanase activity of 18.54 and 16.6 (U/mL) was produced by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 at 48 h and 60 h respectively. Furthermore, xylanase production by S. albidoflavus strain SAMRC-UFH5 and B. cereus strain SAMRC-UFH9 was maximally induced by wheat straw and xylan respectively, while cellulase production was best induced by mannose and carboxymethyl cellulose respectively. On the other hand, cellulase and xylanase production by Streptomyces sp. strain SAMRC-UFH6 was optimal at pH, temperature and agitation speed of 7 and 8, 40 °C and 100 rpm, respectively. Highest production of cellulase and xylanase was attained at 84 and 60 h with respective activity of 0.065 and 6.34 (U/mL). In addition, cellulase and xylanase production by the strain was best induced by beechwood xylan. Moreover, xylanase produced by Streptomyces sp. strain SAMRC-UFH6 at optimal conditions was characterized by optimal pH and temperature of 8 and 80-90 °C respectively; retaining over 70 percent activity at pH 5-10 after 1 h and 60 percent of initial activity at 90 °C after 90 min of incubation. In all, optimization improved cellulase and xylanase production yields, being 40 and 95.5, 10.89 and 72.17, and 10 and 115- fold increase by S. albidoflavus strain SAMRC-UFH5, B. cereus strain SAMRC-UFH9 and Streptomyces sp. SAMRC-UFH6 respectively. The results of this study suggest that the marine bacterial strains are resource for holocellulase with industrial applications.
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