Synthesis and characterization of molybdenum dichalcogenides nanoparticles via solution-processed technique for photovoltaic applications
- Authors: Shelter, Chikukwa Evernice
- Date: 2021-02
- Subjects: Nanoparticles , Colloids
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20653 , vital:46417
- Description: Energy generated from non-renewable energy sources has a drawback of prompted outflow of ozone harming substances. These drawbacks of the non-renewable energy have quickened innovative work of renewable power sources, since they have an advantage of the provision of a better, preserved, decent environment that is free from natural contamination and commotion. Photovoltaic devices are prevalent in improving the green energy utilization and defeating the natural concerns yielded from the current most overwhelming energy sources. Herein, the synthesis, characterization, and application of Molybdenum chalcogenide nanoparticles (NP) as alternative sources in the absorber layer of quantum dot solar sensitized cells (QDSSCs) is discussed. The MoS2 NPs were synthesized from the aliphatic and aromatic dithiocarbamate (DTC) ligands and complexes as precursors. The successful synthesis of the DTC ligands and MoDTC complexes was confirmed through characterization with a variety of techniques including 1H and 13C-NMR, Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV-VIS), Thermogravimetric analysis (TGA) and Derivative thermogravimetric (DTG) analysis. The synthesized MoDTC complexes (precursors) were further used in the synthesis of MoS2 nanoparticles. A bottom -up colloidal approach was employed for the synthesis of the MoX2 NPs. The successful synthesis of the NP was confirmed as the results from the diffractive peaks obtained from XRD which were positive and agreed in comparison with the standard. The diffractive peaks were shown in the planes (100), (002), (100) and (105) for MoS2 nanoparticles; (002), (100), (103) and (110) for MoSe2 and (0002), (0004), (103) as well as (0006) for the MoTe2 nanoparticles. The MoSe2 nanoparticles showed the least size of the nanoparticles followed by MoTe2 and lastly MoS2. These results agreed with the results obtained using SEM analysis. For the optical properties of the nanoparticles, UV-VIS and PL were used, the shift of the peaks from the red shift (600 nm) to the blue shift 270-5 nm and 287-9 nm (UV-VIS) confirmed that the nanoparticles were quantum confined. The application of the MoX2 NPs in QDSSCs was done with MoSe2 showing the greatest PCE of 7.86 percent followed by MoTe2 6.93 percent and lastly MoS2 with a PCE of 6.05 percent and 5.47 percent. , Thesis (MSc) (Chemistry) -- University of Fort Hare, 2021
- Full Text:
- Authors: Shelter, Chikukwa Evernice
- Date: 2021-02
- Subjects: Nanoparticles , Colloids
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20653 , vital:46417
- Description: Energy generated from non-renewable energy sources has a drawback of prompted outflow of ozone harming substances. These drawbacks of the non-renewable energy have quickened innovative work of renewable power sources, since they have an advantage of the provision of a better, preserved, decent environment that is free from natural contamination and commotion. Photovoltaic devices are prevalent in improving the green energy utilization and defeating the natural concerns yielded from the current most overwhelming energy sources. Herein, the synthesis, characterization, and application of Molybdenum chalcogenide nanoparticles (NP) as alternative sources in the absorber layer of quantum dot solar sensitized cells (QDSSCs) is discussed. The MoS2 NPs were synthesized from the aliphatic and aromatic dithiocarbamate (DTC) ligands and complexes as precursors. The successful synthesis of the DTC ligands and MoDTC complexes was confirmed through characterization with a variety of techniques including 1H and 13C-NMR, Raman Spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV-VIS), Thermogravimetric analysis (TGA) and Derivative thermogravimetric (DTG) analysis. The synthesized MoDTC complexes (precursors) were further used in the synthesis of MoS2 nanoparticles. A bottom -up colloidal approach was employed for the synthesis of the MoX2 NPs. The successful synthesis of the NP was confirmed as the results from the diffractive peaks obtained from XRD which were positive and agreed in comparison with the standard. The diffractive peaks were shown in the planes (100), (002), (100) and (105) for MoS2 nanoparticles; (002), (100), (103) and (110) for MoSe2 and (0002), (0004), (103) as well as (0006) for the MoTe2 nanoparticles. The MoSe2 nanoparticles showed the least size of the nanoparticles followed by MoTe2 and lastly MoS2. These results agreed with the results obtained using SEM analysis. For the optical properties of the nanoparticles, UV-VIS and PL were used, the shift of the peaks from the red shift (600 nm) to the blue shift 270-5 nm and 287-9 nm (UV-VIS) confirmed that the nanoparticles were quantum confined. The application of the MoX2 NPs in QDSSCs was done with MoSe2 showing the greatest PCE of 7.86 percent followed by MoTe2 6.93 percent and lastly MoS2 with a PCE of 6.05 percent and 5.47 percent. , Thesis (MSc) (Chemistry) -- University of Fort Hare, 2021
- Full Text:
The acoustic niche and conservation status of the recently described Hogsback caco, Cacosternum thorini (Amphibia: Pyxicephalidae), Hogsback, Eastern Cape, South Africa
- Authors: Kom, Nokuthula
- Date: 2021-02
- Subjects: Amphibians
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20429 , vital:45665
- Description: Animals may compete for acoustic space (acoustic niche) in the same way they do for habitat space. The most intense competition involves individuals with the most similar resource requirements (i.e. conspecifics), but if competition is interspecific, then mate recognition must occur both within and between species. The coexistence of the bronze caco (Cacosternum nanum) and the Hogsback caco (C. thorini) in the Tor Doone area of Hogsback could be interpreted as a result of past competition, which drove acoustic partitioning by means of the evolution of specific calls that do not overlap in frequency. Frogs are known to coexist well with other frog species because of their highly specific advertisement calls, which differ even between closely related species. One of the main aims of the project was to record and provide a description of the call of the recently described Hogsback caco, C. thorini. I identified 30 calling males and recorded each for 10 min in February 2016, yielding a total of 235 calls. Summary values for the calls include duration of 40 ± 14 ms, with 16 ± 5 pulses produced at a pulse-rate of 46 ± 21 s-1 and a mean dominant frequency of 4.19 ± 0.58 kHz. The call of C. thorini differs from those of all other cacos, by its incremental structure (increased number of pulses within consecutive units). My second goal was to use playbacks to investigate the preferred habitat of C. thorini and to compare it with that of C. nanum. I conducted experiments to measure the propagation of C. thorini and C. nanum calls in three different habitats (C. thorini habitat, C. nanum habitat, and grassland with no water bodies). Finally, I investigated the effect of drought and flood on the pools used by males as calling sites, using a buried basin to which I added water in 10 litre aliquots. The optimal water level for call propagation in the artificial pools was half-full. Using playbacks, I tested whether the two species responded to each other’s calls. I found that, although the two species call at the same time and each call in response to the other’s calls, they do not recognise heterospecific calls; they simply respond to noise. I found no evidence of acoustic competition between the two species, and in fact, the abundant, dominant species, C. nanum, was rare in the C. thorini preferred habitat. The results of this study may assist efforts to conserve endemic amphibians in the Amatola Mountains. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Authors: Kom, Nokuthula
- Date: 2021-02
- Subjects: Amphibians
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20429 , vital:45665
- Description: Animals may compete for acoustic space (acoustic niche) in the same way they do for habitat space. The most intense competition involves individuals with the most similar resource requirements (i.e. conspecifics), but if competition is interspecific, then mate recognition must occur both within and between species. The coexistence of the bronze caco (Cacosternum nanum) and the Hogsback caco (C. thorini) in the Tor Doone area of Hogsback could be interpreted as a result of past competition, which drove acoustic partitioning by means of the evolution of specific calls that do not overlap in frequency. Frogs are known to coexist well with other frog species because of their highly specific advertisement calls, which differ even between closely related species. One of the main aims of the project was to record and provide a description of the call of the recently described Hogsback caco, C. thorini. I identified 30 calling males and recorded each for 10 min in February 2016, yielding a total of 235 calls. Summary values for the calls include duration of 40 ± 14 ms, with 16 ± 5 pulses produced at a pulse-rate of 46 ± 21 s-1 and a mean dominant frequency of 4.19 ± 0.58 kHz. The call of C. thorini differs from those of all other cacos, by its incremental structure (increased number of pulses within consecutive units). My second goal was to use playbacks to investigate the preferred habitat of C. thorini and to compare it with that of C. nanum. I conducted experiments to measure the propagation of C. thorini and C. nanum calls in three different habitats (C. thorini habitat, C. nanum habitat, and grassland with no water bodies). Finally, I investigated the effect of drought and flood on the pools used by males as calling sites, using a buried basin to which I added water in 10 litre aliquots. The optimal water level for call propagation in the artificial pools was half-full. Using playbacks, I tested whether the two species responded to each other’s calls. I found that, although the two species call at the same time and each call in response to the other’s calls, they do not recognise heterospecific calls; they simply respond to noise. I found no evidence of acoustic competition between the two species, and in fact, the abundant, dominant species, C. nanum, was rare in the C. thorini preferred habitat. The results of this study may assist efforts to conserve endemic amphibians in the Amatola Mountains. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
The optimisation of transportation methods for abalone (Haliotis midae Linnaeus, 1758 (Mollusca: Gastropoda)) larvae
- Authors: Bajaba, Sharone
- Date: 2021-02
- Subjects: Abalone fisheries , Haliotis midae , Abalone culture
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20561 , vital:46124
- Description: Sea ranching has been identified as a viable method for enhancing the natural stock of overexploited abalone (Haliotis midae). Currently, this process involves transporting live juvenile H. midae to the seeding site where they are released onto the reef however this is both costly and logistically problematic. Transportation of abalone larvae is another cost-effective option, as they are cheaper to produce and can be transported at high densities. A suitable larval transport method is required to minimise larval mortalities and stresses that might compromise settlement. A series of simulated experiments were conducted to optimise transportation systems of abalone (Haliotis midae) larvae. First, two potential transportation modes (Wet (W) and Dry (D) transportation) conducted at a cooler (14˚C) and average ambient (18˚C) temperatures with six replicates of each were compared with control treatments (six replicates) that were not subjected to transport, kept in water at 18˚C. Eighty hours post-initial settlement, the 14W treatment had significantly lower settlement (p=0.03) than the other three treatments (14D, 18W, 18D) and the Control. The Dry method was the prefered method to transport larvae as it is logistically simpler to employ. The second experiment investigated the effect of different stocking densities (200, 400 and 800 larvae cm-2) for the Dry method 18˚C over two transit periods (six and twelve hours) on post-transport settlement and post-settlement survival of H. midae larvae. Compared to the control, there was no difference in the number of settled larvae (p=0.368) and larvae still swimming (p=0.835) across all treatments. This suggested that H. midae larvae can be transported for twelve hours at 800 larvae cm-2 without compromising post-transport settlement or survival. This study’s results and recommendations can be used by abalone farms when there is a need to move abalone H. midae larvae between farms or to seeding sites for sea ranching. Furthermore, other researchers can use these results as a benchmark for larval transportation studies of H. midae and other abalone species. , Thesis (MSc) (Zoology) -- University of Fort Hare, 2021
- Full Text:
- Authors: Bajaba, Sharone
- Date: 2021-02
- Subjects: Abalone fisheries , Haliotis midae , Abalone culture
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20561 , vital:46124
- Description: Sea ranching has been identified as a viable method for enhancing the natural stock of overexploited abalone (Haliotis midae). Currently, this process involves transporting live juvenile H. midae to the seeding site where they are released onto the reef however this is both costly and logistically problematic. Transportation of abalone larvae is another cost-effective option, as they are cheaper to produce and can be transported at high densities. A suitable larval transport method is required to minimise larval mortalities and stresses that might compromise settlement. A series of simulated experiments were conducted to optimise transportation systems of abalone (Haliotis midae) larvae. First, two potential transportation modes (Wet (W) and Dry (D) transportation) conducted at a cooler (14˚C) and average ambient (18˚C) temperatures with six replicates of each were compared with control treatments (six replicates) that were not subjected to transport, kept in water at 18˚C. Eighty hours post-initial settlement, the 14W treatment had significantly lower settlement (p=0.03) than the other three treatments (14D, 18W, 18D) and the Control. The Dry method was the prefered method to transport larvae as it is logistically simpler to employ. The second experiment investigated the effect of different stocking densities (200, 400 and 800 larvae cm-2) for the Dry method 18˚C over two transit periods (six and twelve hours) on post-transport settlement and post-settlement survival of H. midae larvae. Compared to the control, there was no difference in the number of settled larvae (p=0.368) and larvae still swimming (p=0.835) across all treatments. This suggested that H. midae larvae can be transported for twelve hours at 800 larvae cm-2 without compromising post-transport settlement or survival. This study’s results and recommendations can be used by abalone farms when there is a need to move abalone H. midae larvae between farms or to seeding sites for sea ranching. Furthermore, other researchers can use these results as a benchmark for larval transportation studies of H. midae and other abalone species. , Thesis (MSc) (Zoology) -- University of Fort Hare, 2021
- Full Text:
The Relationship Between Food Sharing and Social Cohesion among Local Farmers: a case study of Ntafufu Location, Port St Johns Municipality.
- Mphompo, Aphiwe (https://orcid.org/ 0000-0003-0370-8007)
- Authors: Mphompo, Aphiwe (https://orcid.org/ 0000-0003-0370-8007)
- Date: 2021-02
- Subjects: Food supply , Social integration , Food relief
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20981 , vital:46876
- Description: The overall aim of this study was to examine how food sharing at Ntafufu location in Port St Johns (Republic of South Africa), augments social cohesion among local farmers. A mixed-method approach was used for this study. This study used a triangulation research method to measure the correlation between food sharing and social cohesion and to ensure that it is statistically sound, certainly gaining rich data from the study population. Focus groups and questionnaires were used to collect data. The researcher used thematic analysis for qualitative analysis and Statistical Packages for the Social Science (SPSS) for quantitative analysis. The researcher did not include the whole population. The researcher only interviewed selected participants, and these participants were taken from the study population. There were 13 participants for qualitative research and 43 participants for quantitative research totalling 56 participants. The findings revealed that there is a relationship between food sharing and social cohesion. An important finding to emerge in this study is that food sharing alleviates poverty. However, several limitations need to be considered. For instance, witchcraft was mentioned as a challenge for this practice. , Thesis (MSoc) (Anthropology) -- University of Fort Hare, 2021
- Full Text:
- Authors: Mphompo, Aphiwe (https://orcid.org/ 0000-0003-0370-8007)
- Date: 2021-02
- Subjects: Food supply , Social integration , Food relief
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20981 , vital:46876
- Description: The overall aim of this study was to examine how food sharing at Ntafufu location in Port St Johns (Republic of South Africa), augments social cohesion among local farmers. A mixed-method approach was used for this study. This study used a triangulation research method to measure the correlation between food sharing and social cohesion and to ensure that it is statistically sound, certainly gaining rich data from the study population. Focus groups and questionnaires were used to collect data. The researcher used thematic analysis for qualitative analysis and Statistical Packages for the Social Science (SPSS) for quantitative analysis. The researcher did not include the whole population. The researcher only interviewed selected participants, and these participants were taken from the study population. There were 13 participants for qualitative research and 43 participants for quantitative research totalling 56 participants. The findings revealed that there is a relationship between food sharing and social cohesion. An important finding to emerge in this study is that food sharing alleviates poverty. However, several limitations need to be considered. For instance, witchcraft was mentioned as a challenge for this practice. , Thesis (MSoc) (Anthropology) -- University of Fort Hare, 2021
- Full Text:
The term structure of interest rate and expected inflation in South Africa
- Authors: Deve, Richard
- Date: 2021-02
- Subjects: Inflation (Finance) , Rational expectations (Economic theory)| , Inflation (Finance) -- Mathematical models
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/20252 , vital:45639
- Description: One of the questions in the minds of policy-makers, monetary authorities and the government is the nature of South Africa’s yield curve and its ability to predict inflation expectations for this country. This calls for an investigation of the relationship between the term structure of interest rates and expected inflation in South Africa. The study seeks to provide answers to three sequentially structured questions: Is there a long-term relationship between the yield curve and inflation expectations in South Africa? Does interest rate term structure contain information about future inflation movements in an inflation-targeting regime for South Africa? And finally: How useful is the yield spread as a predictor for future inflation in South Africa? To shed light on these questions, monthly data for five core variables covering the period January 2000 to January 2017 was used. In South Africa, a tight monetary policy stance affects economic activity positively. The development of sounder bond markets in developed economies, which enhance economic development, creates predictable monetary policy direction relative to developing economies that are cha-racterised by unstable economic conditions coupled with policy inconsistence. This phenomenon results in less credible central banks, and hence leads to less anchored inflation expectations. However, South Africa has well-anchored inflation expectations and one of the most liquid bond markets in the world, which sets it in an excellent position to compete with developed economies. South Africa’s risk premium and inflation are less volatile than those of other developing countries. This particular study finds that a tight monetary policy stance results in an increase in short-term interest rates, leading consequently to a decline in future inflation expectations, and hence leading to a decrease in long-term interest rates, through which the credibility of the central bank is recognised. The positive marginal effect of the yield spread on inflation expectations suggests that the inflation expectation changes are influenced positively by changes in the yield spread. An observed long-run relationship exists between inflation expectations and the yield spread signals that the yield spread has predictive ability for inflation ex-pectations in South Africa. The forecast inflation mimics realised inflation, which could suggest that the forecast is fairly accurate and valuable in explaining the influence of the inflation targeting regime adopted by the South African Reserve Bank (SARB). On the other hand, inflation expectations are viewed as a lagging indicator. In this line of argument, Mishkin (1990b) mentions that past studies have used the yield curve to extract information about future inflation. This is in line with the findings of the SARB (2016). That study (2016) found that the yield spread is useful for predicting expected future yield over 24 quarters in the South African economy. The study found that the yield curve does have a predictive ability with regard to expected inflation, which is moderate. However, it was found that the repo rate and the current levels of inflation had more predictive power than the yield curve. , Thesis (DPhil) -- Faculty of Management and Commerce, 2021
- Full Text:
- Authors: Deve, Richard
- Date: 2021-02
- Subjects: Inflation (Finance) , Rational expectations (Economic theory)| , Inflation (Finance) -- Mathematical models
- Language: English
- Type: Doctoral theses , text
- Identifier: http://hdl.handle.net/10353/20252 , vital:45639
- Description: One of the questions in the minds of policy-makers, monetary authorities and the government is the nature of South Africa’s yield curve and its ability to predict inflation expectations for this country. This calls for an investigation of the relationship between the term structure of interest rates and expected inflation in South Africa. The study seeks to provide answers to three sequentially structured questions: Is there a long-term relationship between the yield curve and inflation expectations in South Africa? Does interest rate term structure contain information about future inflation movements in an inflation-targeting regime for South Africa? And finally: How useful is the yield spread as a predictor for future inflation in South Africa? To shed light on these questions, monthly data for five core variables covering the period January 2000 to January 2017 was used. In South Africa, a tight monetary policy stance affects economic activity positively. The development of sounder bond markets in developed economies, which enhance economic development, creates predictable monetary policy direction relative to developing economies that are cha-racterised by unstable economic conditions coupled with policy inconsistence. This phenomenon results in less credible central banks, and hence leads to less anchored inflation expectations. However, South Africa has well-anchored inflation expectations and one of the most liquid bond markets in the world, which sets it in an excellent position to compete with developed economies. South Africa’s risk premium and inflation are less volatile than those of other developing countries. This particular study finds that a tight monetary policy stance results in an increase in short-term interest rates, leading consequently to a decline in future inflation expectations, and hence leading to a decrease in long-term interest rates, through which the credibility of the central bank is recognised. The positive marginal effect of the yield spread on inflation expectations suggests that the inflation expectation changes are influenced positively by changes in the yield spread. An observed long-run relationship exists between inflation expectations and the yield spread signals that the yield spread has predictive ability for inflation ex-pectations in South Africa. The forecast inflation mimics realised inflation, which could suggest that the forecast is fairly accurate and valuable in explaining the influence of the inflation targeting regime adopted by the South African Reserve Bank (SARB). On the other hand, inflation expectations are viewed as a lagging indicator. In this line of argument, Mishkin (1990b) mentions that past studies have used the yield curve to extract information about future inflation. This is in line with the findings of the SARB (2016). That study (2016) found that the yield spread is useful for predicting expected future yield over 24 quarters in the South African economy. The study found that the yield curve does have a predictive ability with regard to expected inflation, which is moderate. However, it was found that the repo rate and the current levels of inflation had more predictive power than the yield curve. , Thesis (DPhil) -- Faculty of Management and Commerce, 2021
- Full Text:
Valorization of chicken feather through dekeratinization by keratinolytic Bacillus species to amino acid
- Authors: Matches, Lupho
- Date: 2021-02
- Subjects: Proteolytic enzymes , Poultry -- Processing
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20451 , vital:45667
- Description: The poultry meat processing sector generates chicken feathers as by-products, and they are 90percent keratin in composition. Keratin is an insoluble and structural protein that shows recalcitrance to hydrolysis by classical proteolytic enzymes, including trypsin, pepsin, and papain. Keratinases are a group of proteolytic enzymes endowed with keratin degradation into peptides and amino acids. They are recently gaining traction for their multifaceted potential application in the green industrial space. Hence, keratinolytic bacteria previously isolated from dumpsite were identified using 16S rDNA sequencing. The optimal fermentation conditions were determined for enhanced extracellular keratinase production and chicken feather degradation. Also, the amino acid analysis of the chicken feather hydrolysates was carried out. The biochemical properties of the keratinases were also determined. Based on 16S rDNA sequencing and phylogenetic analysis, the isolates coded as SSN-02 and HSN-03 showed a high percentage of sequence homology with Bacillus spp.; hence, they were identified as Bacillus sp. NFH5 and Bacillus sp. FHNM, respectively. Bacillus sp. NFH5 showed optimal keratinase production of 1149.99 ± 80.99 U/mL after 96 h of incubation time, in optimized fermentation conditions that included pH (4.0), chicken feather (1.5percent, w/v), inoculum size (3percent, v/v) and temperature (30 oC). Similarly, Bacillus sp. FHNM demonstrated the maximum keratinase production of 480 ± 41.14 U/mL 144 h post cultivation, in optimized fermentation conditions with pH (7.0), chicken feather (2.0percent, w/v), inoculum size (3percent, v/v) and temperature (30 oC). For Bacillus sp. NFH5 chicken feather hydrolysate, the amino acids in relatively higher concentration (>1.0g/100g sample) include arginine (1.8), serine (1.16), aspartic acid (1.95), glutamic acid (2.47), proline (1.16) and glycine (1.45). Bacillus sp. FHNM feather hydrolysates, contained (g/100g of sample): arginine (1.9), serine (1.4), aspartic acid (2.5), glutamic acid (2.51), glycine (1.51), proline (1.13), leucine (1.030, histidine (1.25), and lysine (1.06) (g/100g of sample) in high concentration. The keratinases were optimally active at pH 8.0. Bacillus sp. FHNM showed an optimal temperature of 100 oC; while Bacillus sp. NFH5 keratinase displayed optimal activity at 90 oC. EDTA and 1,10-phenanthroline inhibited the keratinases, and the inhibition pattern indicated that they belong to metalloprotease. Keratinase from Bacillus sp. FHNM showed considerable residual activity in the presence of Co²⁺ (93percent), Fe³⁺ (99percent), and K⁺ (94percent). Bacillus sp. NFH5 keratinase retained 92percent, 92percent, 93percent of the original activity against Ba²⁺, Na⁺ and Fe³⁺ treatment. Bacillus sp. FHNM keratinase was remarkably stable after 60 min of detergents treatment with residual activity of 89percent, 96percent, 81percent, 73percent, 96percent, 88percent, 88percent and 98percent for Omo, Surf, Ariel, Sunlight, Prowash, Freshwave, Sky, and Evaklin, respectively. Maq impacted the enzyme stability negatively, with residual activity of 48percent after 60 min of incubation. Additionally, keratinase Bacillus sp. NFH5 retained 68percent, 78percent, 80percent, 84percent, 57percent, 80percent, 98percent, 106percent and 106percent of the original activity against Omo, Surf, Ariel, Sunlight, Maq, Prowash, Freshwave, Sky and Evaklin, respectively. Therefore, these results suggest that Bacillus spp. could be ideal candidates for sustainable production of active keratinases and valorization of the abundantly generated keratinous biomass. The stability displayed by keratinases from Bacillus sp. FHNM and Bacillus sp. NFH5 suggests their promising candidacy for detergent formulation. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Authors: Matches, Lupho
- Date: 2021-02
- Subjects: Proteolytic enzymes , Poultry -- Processing
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20451 , vital:45667
- Description: The poultry meat processing sector generates chicken feathers as by-products, and they are 90percent keratin in composition. Keratin is an insoluble and structural protein that shows recalcitrance to hydrolysis by classical proteolytic enzymes, including trypsin, pepsin, and papain. Keratinases are a group of proteolytic enzymes endowed with keratin degradation into peptides and amino acids. They are recently gaining traction for their multifaceted potential application in the green industrial space. Hence, keratinolytic bacteria previously isolated from dumpsite were identified using 16S rDNA sequencing. The optimal fermentation conditions were determined for enhanced extracellular keratinase production and chicken feather degradation. Also, the amino acid analysis of the chicken feather hydrolysates was carried out. The biochemical properties of the keratinases were also determined. Based on 16S rDNA sequencing and phylogenetic analysis, the isolates coded as SSN-02 and HSN-03 showed a high percentage of sequence homology with Bacillus spp.; hence, they were identified as Bacillus sp. NFH5 and Bacillus sp. FHNM, respectively. Bacillus sp. NFH5 showed optimal keratinase production of 1149.99 ± 80.99 U/mL after 96 h of incubation time, in optimized fermentation conditions that included pH (4.0), chicken feather (1.5percent, w/v), inoculum size (3percent, v/v) and temperature (30 oC). Similarly, Bacillus sp. FHNM demonstrated the maximum keratinase production of 480 ± 41.14 U/mL 144 h post cultivation, in optimized fermentation conditions with pH (7.0), chicken feather (2.0percent, w/v), inoculum size (3percent, v/v) and temperature (30 oC). For Bacillus sp. NFH5 chicken feather hydrolysate, the amino acids in relatively higher concentration (>1.0g/100g sample) include arginine (1.8), serine (1.16), aspartic acid (1.95), glutamic acid (2.47), proline (1.16) and glycine (1.45). Bacillus sp. FHNM feather hydrolysates, contained (g/100g of sample): arginine (1.9), serine (1.4), aspartic acid (2.5), glutamic acid (2.51), glycine (1.51), proline (1.13), leucine (1.030, histidine (1.25), and lysine (1.06) (g/100g of sample) in high concentration. The keratinases were optimally active at pH 8.0. Bacillus sp. FHNM showed an optimal temperature of 100 oC; while Bacillus sp. NFH5 keratinase displayed optimal activity at 90 oC. EDTA and 1,10-phenanthroline inhibited the keratinases, and the inhibition pattern indicated that they belong to metalloprotease. Keratinase from Bacillus sp. FHNM showed considerable residual activity in the presence of Co²⁺ (93percent), Fe³⁺ (99percent), and K⁺ (94percent). Bacillus sp. NFH5 keratinase retained 92percent, 92percent, 93percent of the original activity against Ba²⁺, Na⁺ and Fe³⁺ treatment. Bacillus sp. FHNM keratinase was remarkably stable after 60 min of detergents treatment with residual activity of 89percent, 96percent, 81percent, 73percent, 96percent, 88percent, 88percent and 98percent for Omo, Surf, Ariel, Sunlight, Prowash, Freshwave, Sky, and Evaklin, respectively. Maq impacted the enzyme stability negatively, with residual activity of 48percent after 60 min of incubation. Additionally, keratinase Bacillus sp. NFH5 retained 68percent, 78percent, 80percent, 84percent, 57percent, 80percent, 98percent, 106percent and 106percent of the original activity against Omo, Surf, Ariel, Sunlight, Maq, Prowash, Freshwave, Sky and Evaklin, respectively. Therefore, these results suggest that Bacillus spp. could be ideal candidates for sustainable production of active keratinases and valorization of the abundantly generated keratinous biomass. The stability displayed by keratinases from Bacillus sp. FHNM and Bacillus sp. NFH5 suggests their promising candidacy for detergent formulation. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
Waste keratinous biomass valorization and characterization of keratinases produced by exiguobacteria species
- Authors: Dlume, Tutuka
- Date: 2021-02
- Subjects: Factory and trade waste -- Biodegradation , Bioremediation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20695 , vital:46438
- Description: Keratinous wastes are emanating in a million tons, as by-products, from various agro-industrial processing plants. Consequently, they create a serious solid waste problem in the environment due to poor handling. Microbial keratinases are proteolytic enzymes that effectively participate in keratin-rich biomass hydrolyses such as feathers, nail, hair, hooves, and horns. Therefore, proper management of these wastes via recycling into useful products is ecologically imperative. Biodegradation of keratin-rich biomass has been identified as an economical and environmentally friendly way of transforming these recalcitrant agro wastes into useful products, hence the motivation for this study. Feather degrading bacterial strains previously isolated from a municipal dumpsite and coded as SSB-02 and SSB-03 was identified through 16S rDNA sequencing and phylogenetic analysis. The fermentation conditions for keratinase production were optimized. The protein and amino acids constituents of the hydrolyzed chicken feather were analyzed. The biochemical properties of the keratinase produced were determined. Also, the effect of laundry detergents on the stability of the keratinase was studied. The isolates coded as SSB-02 and SSB-03 showed a high percentage of sequence homology with Exguobacterium spp., hence they were identified as Exiguobacterium sp. FBH5 and Exiguobacterium acetylicum FHBD, respectively. Exiguobacterium sp. FBH5 showed the highest extracellular keratinase production of 934.58 ± 27.27 U/mL at 72 h of incubation; in optimized fermentation conditions that included pH (5.0), temperature (30 oC), and chicken feather (0.5percent, w/v). Similarly, E. acetylicum FHBD displayed optimal keratinase production of 1023.64 ± 25.71 U/mL at 120 h of fermentation and improved fermentation conditions that involved pH (3.0), temperature (35 oC) and chicken feathers (0.5-1.5percent; w/v). The amino acid analysis showed that arginine, aspartic acid and glutamic acid were the most abundant amino acids cleaved from the degradation of chicken feathers by Exiguobacterium sp. FBH5 at a respective concentration of 1.16, 1.28 and 1.45 (g/100g sample). Additionally, hydrolysate that emanated from E. indicum FHBD degradation of feather showed high concentrations of arginine, serine, aspartic acid, glutamic acid, and glycine at the respective concentration (g/100g sample) of 1.2, 1.12, 1.34, 1.58 and 1.29. The keratinases were optimally active at pH and temperature of 8.0 and 50 oC, respectively. EDTA and PMSF did not highly repress keratinolytic proteases' activity, and this inhibitory pattern suggests that they may belong to a mixed protease family. Keratinase from E. acetylicum FHBD was highly stable in the presence of SDS, with 99percent residual activity and displayed variable stability in other chemical agents tested. A similar stability pattern was observed with keratinase from Exiguobacterium sp. FBH5, although the enzyme lost about 40percent of its original activity in the presence of SDS. Evaluation of metal ion stability indicated that E. acetylicum FHBD keratinase was remarkably stable in the presence of Fe3+, Mg2+, Cu2+, Zn2+, and Ba2+, with residual activity of 94percent, 88percent, 89percent, 90percent, and 97percent, respectively. Similarly, Exiguobacterium sp. FBH5 keratinase was considerably stable after treatment with Co2+, K+, and Zn2+ as it displayed a residual activity of 85percent, 84percent and 93percent, respectively. The study of the keratinases stability in laundry detergents showed that E. acetylicum FHBD keratinolytic proteases was activated in the presence of Omo, Surf, Sunlight, and Pro wash after 60 min of pre-incubation compared to 30 min, with residual activity of 94 ± 2.94percent, 91 ± 2.53percent, 95 ± 2.89percent and 87 ± 2.89percent respectively. Likewise, Exiguobacterium sp. FBH5 keratinase activity was promoted after 60 min of incubation compared to 30 min, with a residual enzyme activity of 79percent, 84percent, 101percent, 103percent and 105percent and 106percent for Ariel, Surf, Prowash, Freewave, Sky and Evaklin, respectively. Therefore Exiguobacterium spp., demonstrated excellent keratinolytic potentials that could be exploited for sustainable development of bio-innovative products. The study keratinases' properties suggest their industrial and biotechnological application potentials, especially as bio-additive in the formulation of laundry detergents. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text:
- Authors: Dlume, Tutuka
- Date: 2021-02
- Subjects: Factory and trade waste -- Biodegradation , Bioremediation
- Language: English
- Type: Master's theses , text
- Identifier: http://hdl.handle.net/10353/20695 , vital:46438
- Description: Keratinous wastes are emanating in a million tons, as by-products, from various agro-industrial processing plants. Consequently, they create a serious solid waste problem in the environment due to poor handling. Microbial keratinases are proteolytic enzymes that effectively participate in keratin-rich biomass hydrolyses such as feathers, nail, hair, hooves, and horns. Therefore, proper management of these wastes via recycling into useful products is ecologically imperative. Biodegradation of keratin-rich biomass has been identified as an economical and environmentally friendly way of transforming these recalcitrant agro wastes into useful products, hence the motivation for this study. Feather degrading bacterial strains previously isolated from a municipal dumpsite and coded as SSB-02 and SSB-03 was identified through 16S rDNA sequencing and phylogenetic analysis. The fermentation conditions for keratinase production were optimized. The protein and amino acids constituents of the hydrolyzed chicken feather were analyzed. The biochemical properties of the keratinase produced were determined. Also, the effect of laundry detergents on the stability of the keratinase was studied. The isolates coded as SSB-02 and SSB-03 showed a high percentage of sequence homology with Exguobacterium spp., hence they were identified as Exiguobacterium sp. FBH5 and Exiguobacterium acetylicum FHBD, respectively. Exiguobacterium sp. FBH5 showed the highest extracellular keratinase production of 934.58 ± 27.27 U/mL at 72 h of incubation; in optimized fermentation conditions that included pH (5.0), temperature (30 oC), and chicken feather (0.5percent, w/v). Similarly, E. acetylicum FHBD displayed optimal keratinase production of 1023.64 ± 25.71 U/mL at 120 h of fermentation and improved fermentation conditions that involved pH (3.0), temperature (35 oC) and chicken feathers (0.5-1.5percent; w/v). The amino acid analysis showed that arginine, aspartic acid and glutamic acid were the most abundant amino acids cleaved from the degradation of chicken feathers by Exiguobacterium sp. FBH5 at a respective concentration of 1.16, 1.28 and 1.45 (g/100g sample). Additionally, hydrolysate that emanated from E. indicum FHBD degradation of feather showed high concentrations of arginine, serine, aspartic acid, glutamic acid, and glycine at the respective concentration (g/100g sample) of 1.2, 1.12, 1.34, 1.58 and 1.29. The keratinases were optimally active at pH and temperature of 8.0 and 50 oC, respectively. EDTA and PMSF did not highly repress keratinolytic proteases' activity, and this inhibitory pattern suggests that they may belong to a mixed protease family. Keratinase from E. acetylicum FHBD was highly stable in the presence of SDS, with 99percent residual activity and displayed variable stability in other chemical agents tested. A similar stability pattern was observed with keratinase from Exiguobacterium sp. FBH5, although the enzyme lost about 40percent of its original activity in the presence of SDS. Evaluation of metal ion stability indicated that E. acetylicum FHBD keratinase was remarkably stable in the presence of Fe3+, Mg2+, Cu2+, Zn2+, and Ba2+, with residual activity of 94percent, 88percent, 89percent, 90percent, and 97percent, respectively. Similarly, Exiguobacterium sp. FBH5 keratinase was considerably stable after treatment with Co2+, K+, and Zn2+ as it displayed a residual activity of 85percent, 84percent and 93percent, respectively. The study of the keratinases stability in laundry detergents showed that E. acetylicum FHBD keratinolytic proteases was activated in the presence of Omo, Surf, Sunlight, and Pro wash after 60 min of pre-incubation compared to 30 min, with residual activity of 94 ± 2.94percent, 91 ± 2.53percent, 95 ± 2.89percent and 87 ± 2.89percent respectively. Likewise, Exiguobacterium sp. FBH5 keratinase activity was promoted after 60 min of incubation compared to 30 min, with a residual enzyme activity of 79percent, 84percent, 101percent, 103percent and 105percent and 106percent for Ariel, Surf, Prowash, Freewave, Sky and Evaklin, respectively. Therefore Exiguobacterium spp., demonstrated excellent keratinolytic potentials that could be exploited for sustainable development of bio-innovative products. The study keratinases' properties suggest their industrial and biotechnological application potentials, especially as bio-additive in the formulation of laundry detergents. , Thesis (MSc) -- Faculty of Science and Agriculture, 2021
- Full Text: