Laccase production by selected bacteria species isolated from some aquatic and terrestrial milieu of the Eastern Cape : applications in wastewater treatment
- Authors: Unuofin, John Onolame
- Date: 2018
- Subjects: Laccase Sewage -- Purification -- Biological treatment Water -- Purification
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9626 , vital:34810
- Description: Aromatic pollutants are a diverse group of chemicals which are continuously produced from industrialization, urbanization and sophistication in technological advancement. Pristine water source polluted by these chemicls makes the water unsafe for human consumption, and as well disrupts the trophic structure of the aquatic milieu. Physico-chemical treatment techniques employed so far have been accompanied by major drawbacks which have overriden the relative successes recorded, hence, greener, simpler and more efficient methods of pollutant transformation is imperative. The prospect of enzymatic treatment of pollutants has gradually been receiving growing attention in contemporary times due to the their environmental friendliness and production economic feasiblity. Laccase, a multicopper oxidase has heightened its appeal towards environmental and biotechnological applications due to its broad substrate specificity and its requirement of atmospheric molecular oxygen as a cosubstrate and the discharge of water as the byproduct. Hence, this present study was designed to evaluate the biotechnological potentials of laccases produced by some bacteria species from some aquatic biomes of the Eastern Cape Province, South Africa. The laccase-producing bacteria were isolated from selected environmental samples by selective enrichment using selective aromatic compounds as sole carbon source and subsequently, laccase-screening phenolic substrates. The laccase-producing bacteria were identified by molecular techniques as proteobacteria belonging to the following genera: Achromobacter, Bordetella, Citrobacter, Pseudomonas and Stenotrophomonas. Optimisation of laccase production in a submerged fermentation was by traditional and statistical methods, where four isolates (Hb9c; Achromobacter xylosoxidans HWN16, Hb16c; Bordetella bronchisepta HSO16, Berl11b2; Stenotrophomonas maltophilia BIJ16, Ie1c; Citrobacter freundii LLJ16) were evaluated for the fermentative production of laccase from lignocellulosic agroindustrial residues. Predictions from statistical optimisation showed that weakly acidic conditions (pH 5) and low agitation speed (100 rpm) were required for maximum laccase production from mandarin peelings (0.5 g/200 mL) and NaNO3 (0.25 g/200 mL) in Hb9c, maize stover (0.50 g/200 mL) and NaNO3 (0.050 g/200mL) in Berl11b2 while a lower agitation speed (50 rpm) was required for maximum laccase output from 2.0 g/200 mL maize stover and 0.050 g/200 mL KNO3 in Ie1c. However, 2.50 g/200 mL wheat bran, 0.050 g/200 mL yeast extract and 50 rpm agitiation under acidic conditions (pH3) yielded maximum laccase titres in Hb16c. Further characterisation of Hb9c and Ie1c laccase secretions portrayed their polyextremotolerant capacities. They were active at a broad range of tempertaure (0-90 degreesC); with optima at 70°C (Hb9c) and 60°C (Ie1c), pH (3-11); with optima at pH 6 (Ie1c) and pH 8 (Hb9c), respectively, and were equally thermo- and pH-stable. Their activities were either improved or left unabated by high concentrations of cations, detergents, and chloride. In addition, catalytic activities of Hb9c and Ie1c laccase secretions increased when they were preincubated with 2 – 20 percent of fluoride, a potent inhibitor. Consequently, a molecular perspective depicted the isolates to have multiple homologous laccase encoding genes. The enzymes were successfully immobilised on solid supports comprising gelatin and Na-alginate with a recovery of cca. 85 percent residual activity after 8 cycles of oprertional stability experiments. The immobilised laccases were remarkable in the decolourisation of synthetic dyes, albeit, free forms also elicited satisfactory performances. Ultimately, the application of free laccases in denim bleaching, individually or with a blend of a mediator, ABTS, showed that denim colours could be bleached without the need for chemical bleaching agents. The results obtained suggest the bacteria laccases produced from lignocellulosic wastes may serve as potent degraders of phenolic pollutants in water and, may also contribute to the bioeconomy and promote greener techniques for industrial applications.
- Full Text:
- Authors: Unuofin, John Onolame
- Date: 2018
- Subjects: Laccase Sewage -- Purification -- Biological treatment Water -- Purification
- Language: English
- Type: Thesis , Doctoral , PhD
- Identifier: http://hdl.handle.net/10353/9626 , vital:34810
- Description: Aromatic pollutants are a diverse group of chemicals which are continuously produced from industrialization, urbanization and sophistication in technological advancement. Pristine water source polluted by these chemicls makes the water unsafe for human consumption, and as well disrupts the trophic structure of the aquatic milieu. Physico-chemical treatment techniques employed so far have been accompanied by major drawbacks which have overriden the relative successes recorded, hence, greener, simpler and more efficient methods of pollutant transformation is imperative. The prospect of enzymatic treatment of pollutants has gradually been receiving growing attention in contemporary times due to the their environmental friendliness and production economic feasiblity. Laccase, a multicopper oxidase has heightened its appeal towards environmental and biotechnological applications due to its broad substrate specificity and its requirement of atmospheric molecular oxygen as a cosubstrate and the discharge of water as the byproduct. Hence, this present study was designed to evaluate the biotechnological potentials of laccases produced by some bacteria species from some aquatic biomes of the Eastern Cape Province, South Africa. The laccase-producing bacteria were isolated from selected environmental samples by selective enrichment using selective aromatic compounds as sole carbon source and subsequently, laccase-screening phenolic substrates. The laccase-producing bacteria were identified by molecular techniques as proteobacteria belonging to the following genera: Achromobacter, Bordetella, Citrobacter, Pseudomonas and Stenotrophomonas. Optimisation of laccase production in a submerged fermentation was by traditional and statistical methods, where four isolates (Hb9c; Achromobacter xylosoxidans HWN16, Hb16c; Bordetella bronchisepta HSO16, Berl11b2; Stenotrophomonas maltophilia BIJ16, Ie1c; Citrobacter freundii LLJ16) were evaluated for the fermentative production of laccase from lignocellulosic agroindustrial residues. Predictions from statistical optimisation showed that weakly acidic conditions (pH 5) and low agitation speed (100 rpm) were required for maximum laccase production from mandarin peelings (0.5 g/200 mL) and NaNO3 (0.25 g/200 mL) in Hb9c, maize stover (0.50 g/200 mL) and NaNO3 (0.050 g/200mL) in Berl11b2 while a lower agitation speed (50 rpm) was required for maximum laccase output from 2.0 g/200 mL maize stover and 0.050 g/200 mL KNO3 in Ie1c. However, 2.50 g/200 mL wheat bran, 0.050 g/200 mL yeast extract and 50 rpm agitiation under acidic conditions (pH3) yielded maximum laccase titres in Hb16c. Further characterisation of Hb9c and Ie1c laccase secretions portrayed their polyextremotolerant capacities. They were active at a broad range of tempertaure (0-90 degreesC); with optima at 70°C (Hb9c) and 60°C (Ie1c), pH (3-11); with optima at pH 6 (Ie1c) and pH 8 (Hb9c), respectively, and were equally thermo- and pH-stable. Their activities were either improved or left unabated by high concentrations of cations, detergents, and chloride. In addition, catalytic activities of Hb9c and Ie1c laccase secretions increased when they were preincubated with 2 – 20 percent of fluoride, a potent inhibitor. Consequently, a molecular perspective depicted the isolates to have multiple homologous laccase encoding genes. The enzymes were successfully immobilised on solid supports comprising gelatin and Na-alginate with a recovery of cca. 85 percent residual activity after 8 cycles of oprertional stability experiments. The immobilised laccases were remarkable in the decolourisation of synthetic dyes, albeit, free forms also elicited satisfactory performances. Ultimately, the application of free laccases in denim bleaching, individually or with a blend of a mediator, ABTS, showed that denim colours could be bleached without the need for chemical bleaching agents. The results obtained suggest the bacteria laccases produced from lignocellulosic wastes may serve as potent degraders of phenolic pollutants in water and, may also contribute to the bioeconomy and promote greener techniques for industrial applications.
- Full Text:
Skilled Migrants and Remittances in a Development Context: A Social Value Analysis of Skills and Home Remittances among Zimbabweans living in East London, South Africa
- Authors: Mafuso, Leo Tsakata
- Date: 2018
- Subjects: Migration Emigrant remittances Migrant labor
- Language: English
- Type: Thesis , Doctoral , PhD(Sociology)
- Identifier: http://hdl.handle.net/10353/8840 , vital:33672
- Description: Against the backdrop of a growing orthodoxy that places the issue of home remittances by a country’s emigrant citizens at the centre of national and international development, this study presents a social value analysis of skills and home remittances in the Zimbabwean context. The study unveils the narratives of skilled Zimbabwean citizens living and working in East London, South Africa, with specific regard to the extent to which the revenues gained by the Zimbabwean economy through home remittances offset the skills lost by the same economy through the emigration of its skilled citizens. A mixed-methods approach was adopted, with data drawn from a survey of 158 skilled Zimbabweans, three key informant interviews (with officers of immigration stakeholder organisations) and one focus group discussion. The study found that an overwhelming majority of survey respondents regularly remitted money home, and believed that such remittances helped them to fulfil filial and other familial obligations, besides being vital to the Zimbabwean economy as a whole. They emphasised, however, that the total value of home remittances, though substantial in monetary terms, was miniscule when compared to the skills the country had lost as a result of migration. Respondents expressed the view that home remittances could not substitute for the skills lost by a country and that the proper utilisation of, and compensation for, their skills at home would develop their country faster. The study thus cuts through the dominant discourse on the developmental significance of home remittances and provides insights into the importance of skilled professionals in the Zimbabwean context, and the developmental consequences of seeing them simply as “remitters” of foreign exchange. By privileging the perspectives of skilled migrants, the study highlights how skilled professionals see themselves and their role within the migration-development debate. This therefore was a study of the migration-remittance-development nexus as though the migrant mattered.
- Full Text:
- Authors: Mafuso, Leo Tsakata
- Date: 2018
- Subjects: Migration Emigrant remittances Migrant labor
- Language: English
- Type: Thesis , Doctoral , PhD(Sociology)
- Identifier: http://hdl.handle.net/10353/8840 , vital:33672
- Description: Against the backdrop of a growing orthodoxy that places the issue of home remittances by a country’s emigrant citizens at the centre of national and international development, this study presents a social value analysis of skills and home remittances in the Zimbabwean context. The study unveils the narratives of skilled Zimbabwean citizens living and working in East London, South Africa, with specific regard to the extent to which the revenues gained by the Zimbabwean economy through home remittances offset the skills lost by the same economy through the emigration of its skilled citizens. A mixed-methods approach was adopted, with data drawn from a survey of 158 skilled Zimbabweans, three key informant interviews (with officers of immigration stakeholder organisations) and one focus group discussion. The study found that an overwhelming majority of survey respondents regularly remitted money home, and believed that such remittances helped them to fulfil filial and other familial obligations, besides being vital to the Zimbabwean economy as a whole. They emphasised, however, that the total value of home remittances, though substantial in monetary terms, was miniscule when compared to the skills the country had lost as a result of migration. Respondents expressed the view that home remittances could not substitute for the skills lost by a country and that the proper utilisation of, and compensation for, their skills at home would develop their country faster. The study thus cuts through the dominant discourse on the developmental significance of home remittances and provides insights into the importance of skilled professionals in the Zimbabwean context, and the developmental consequences of seeing them simply as “remitters” of foreign exchange. By privileging the perspectives of skilled migrants, the study highlights how skilled professionals see themselves and their role within the migration-development debate. This therefore was a study of the migration-remittance-development nexus as though the migrant mattered.
- Full Text:
Social work management tasks : the experiences of frontline social workers in the nonprofit organisation sector in Port Elizabeth
- Authors: Perumal, Nevashnee
- Date: 2018
- Subjects: Social service Non-governmental organizations -- Eastern Cape -- Social services
- Language: English
- Type: Thesis , Doctoral , Social Work
- Identifier: http://hdl.handle.net/10353/9756 , vital:34912
- Description: In South Africa, social workers learn how to operationalise the management functions of planning, organising, leading and controlling “on the job” by modelling and following existing managers and/or senior social workers. This points to the use of predictive knowledge, where management decisions are made based on patterns from past experiences, educated guesses and observations, which are limited to individual, personal experiences. For the frontline social worker responding to the dynamic demands of developmental social work, with limited work experience and no formal management training and support, there are several consequences for the Nonprofit Organisation sector and the frontline social worker executing these management tasks. Therefore, this study aimed to gain an understanding of the range of management tasks that frontline social workers undertake in the Nonprofit Organisation sector in operationalising the management functions of planning, organising, leading and controlling. This study employed a descriptive case study design, within the qualitative approach, and was exploratory in nature. In-depth individual interviews were conducted with nineteen frontline social workers from three established Nonprofit Organisations in Port Elizabeth. Qualitative thematic analysis was employed as a data analysis strategy. One focus group was conducted with five middle managers from the same three NPOs. Both phases of data collection were guided by interview themes, which were aligned to the objectives of the study. The major findings indicated that management tasks ranged from workload management, relationship management, information management, human resource management to self-management, and that all these tasks led to frontline social workers developing innovative management strategies as a consequence of undertaking management tasks. Predictive knowledge was magnified as a positive tool as compared to prescriptive knowledge. In light of these findings, it is recommended that organisational support and adjustments are made by the boards of management and directors of the relevant Nonprofit Organisations by specifically providing support to frontline social workers so as to enhance their execution of management tasks. Hence, this study proposes a framework with strategies to support frontline social workers as well as practice guidelines for Nonprofit Organisations’ boards of management and frontline social workers in undertaking their daily management tasks.
- Full Text:
- Authors: Perumal, Nevashnee
- Date: 2018
- Subjects: Social service Non-governmental organizations -- Eastern Cape -- Social services
- Language: English
- Type: Thesis , Doctoral , Social Work
- Identifier: http://hdl.handle.net/10353/9756 , vital:34912
- Description: In South Africa, social workers learn how to operationalise the management functions of planning, organising, leading and controlling “on the job” by modelling and following existing managers and/or senior social workers. This points to the use of predictive knowledge, where management decisions are made based on patterns from past experiences, educated guesses and observations, which are limited to individual, personal experiences. For the frontline social worker responding to the dynamic demands of developmental social work, with limited work experience and no formal management training and support, there are several consequences for the Nonprofit Organisation sector and the frontline social worker executing these management tasks. Therefore, this study aimed to gain an understanding of the range of management tasks that frontline social workers undertake in the Nonprofit Organisation sector in operationalising the management functions of planning, organising, leading and controlling. This study employed a descriptive case study design, within the qualitative approach, and was exploratory in nature. In-depth individual interviews were conducted with nineteen frontline social workers from three established Nonprofit Organisations in Port Elizabeth. Qualitative thematic analysis was employed as a data analysis strategy. One focus group was conducted with five middle managers from the same three NPOs. Both phases of data collection were guided by interview themes, which were aligned to the objectives of the study. The major findings indicated that management tasks ranged from workload management, relationship management, information management, human resource management to self-management, and that all these tasks led to frontline social workers developing innovative management strategies as a consequence of undertaking management tasks. Predictive knowledge was magnified as a positive tool as compared to prescriptive knowledge. In light of these findings, it is recommended that organisational support and adjustments are made by the boards of management and directors of the relevant Nonprofit Organisations by specifically providing support to frontline social workers so as to enhance their execution of management tasks. Hence, this study proposes a framework with strategies to support frontline social workers as well as practice guidelines for Nonprofit Organisations’ boards of management and frontline social workers in undertaking their daily management tasks.
- Full Text:
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