This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The microalgal biotechnology industry is expanding rapidly and currently gaining attention due to... more The microalgal biotechnology industry is expanding rapidly and currently gaining attention due to multiple availabilities of high-value products such as pigments, carbohydrates, proteins, nutraceuticals, biopharmaceuticals, and unique oleaginous compounds fractionated by biomass biorefinery. Microalgae are efficient primary producers in the terrestrial and marine biotopes. They are major sources of global oxygen and are gaining topical prominence due to their concomitant role in the phycoremediation of wastewater effluents and biomass production. Despite their minuscule size, microalgae critically contribute to climate change mitigation through carbon fixation and play a major role in bioenergy applications. Furthermore, carotenoids and phycobiliproteins are the main accessory light-harvesting complexes in microalgae and cyanobacteria. The topical biomedical and pharmaceutical applications of microalgae include anticancer, antidiabetic, antiHIV, antimalarial, antimicrobial, inter al...
Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Accli... more Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Acclimatization of freshwater microalgae to hypersaline conditions offers a means to reduce contamination. A freshwater Chlorella species was cultured in a gradient of salinities ranging from 5 to 40‰ and pulse amplitude modulated fluorometry recorded photosynthetic functioning. While the average salinity of seawater is 35‰, optimum acclimatization occurred at 20‰, at which point the growth rate (1.6 µg chl a L −1 d −1) was not significantly different from the control (1.8 µg chl a L −1 d −1). The maximum relative electron transfer rate was lower (9 to 12 µmol m −2 s −1) at 5 to 20‰ as compared to 40‰ (28 µmol m −2 s −1) where no algal growth was recorded. ATP and NADPH were thus shunted towards synthesis of molecules that offset cytoplasmic osmotic stress. Culturing this Chlorella strain in raceway ponds under saline conditions may reduce contamination and improve productivity.
This study investigated the interrelations between hydrogen synthesis and Photosystem I electron ... more This study investigated the interrelations between hydrogen synthesis and Photosystem I electron transport rate in Chlamydomonas reinhardtii. The fluorescence of both photosystems (PS I and PS II) was monitored using a Dual Pulse Amplitude Modulated (PAM) Fluorometer. Hydrogen synthesis was induced by eliminating sulphur from the growth media (TAP-S). Multiple physiological parameters [rETR, Y (I), Y (II), NPQ, α, Fv/Fm and YI:YII] were recorded using the Dual PAM and correlated to hydrogen produced. There was a 66% increase in Photosystem I rETRmax during hydrogen production. A significant direct correlation existed between PS 1 rETRmax and hydrogen evolution values over the ten-day period (r = 0.895, p < 0.01) indicating that PS I can be considered as a driver of H2 production. Significant correlations between rETRmax of PS I and H2 evolution suggest a novel physiological indicator to monitor H2 production during the three critical phases identified in this study.
Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Accli... more Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Acclimatization of freshwater microalgae to hypersaline conditions offers a means to reduce contamination. A freshwater Chlorella species was cultured in a gradient of salinities ranging from 5 to 40‰ and pulse amplitude modulated fluorometry recorded photosynthetic functioning. While the average salinity of seawater is 35‰, optimum acclimatization occurred at 20‰, at which point the growth rate (1.6 µg chl a L −1 d −1) was not significantly different from the control (1.8 µg chl a L −1 d −1). The maximum relative electron transfer rate was lower (9 to 12 µmol m −2 s −1) at 5 to 20‰ as compared to 40‰ (28 µmol m −2 s −1) where no algal growth was recorded. ATP and NADPH were thus shunted towards synthesis of molecules that offset cytoplasmic osmotic stress. Culturing this Chlorella strain in raceway ponds under saline conditions may reduce contamination and improve productivity.
Tissue metal concentrations, filtration and oxygen uptake rates were investigated for Perna perna... more Tissue metal concentrations, filtration and oxygen uptake rates were investigated for Perna perna (Bivalvia: Mollusca) during exposure to Hg , Cu and Zn (50 mgyl for 24 days, and 24 days recovery with no metal). Hg and Cu 2q 2q 2q tissue levels increased with exposure time, reaching maximum levels after 24 days (87.5 mg Hgyg dry mass and 45 mg Cuyg dry mass, respectively). Zn levels peaked after 4 days exposure (to 233 mg Znyg dry mass) and stabilized thereafter. Accumulated metal was rapidly lost from tissues when mussels were returned to uncontaminated seawater, suggesting that tissue concentration data may be of limited use in biomonitoring situations where environmental metals fluctuate to low levels. Filtration rates fell below control rates during Hg exposure, and became elevated again during 2q the recovery period. Cu and Zn exposure had little effect on filtration, but suppressed oxygen uptake. During 2q 2q recovery, oxygen uptake of Cu and Zn exposed mussels was elevated above the controls. Filtration and oxygen 2q 2q uptake rates were not correlated, but rather responded in different ways to metal pollution. While these physiological responses of P. perna may be of limited use in biomonitoring, they could indicate how populations may respond to marine pollution.
PAM fluorometry as a tool to assess microalgal nutrient stress and monitor cellular neutral lipid... more PAM fluorometry as a tool to assess microalgal nutrient stress and monitor cellular neutral lipids. Bioresour Technol
Extremophiles : life under extreme conditions, 2018
Worldwide, cyanobacterial blooms are becoming more frequent, exacerbated by eutrophication, anthr... more Worldwide, cyanobacterial blooms are becoming more frequent, exacerbated by eutrophication, anthropogenic effects, and global climate change. Environmental factors play a direct role in photosynthesis of cyanobacteria and subsequent cellular changes, growth, and bloom dynamics. This study investigated the photosynthetic functioning of a persistent bloom-forming (18 months) cyanobacterium, Cyanothece sp., isolated from Lake St Lucia, South Africa. DUAL-PAM fluorometric methods were used to observe physiological responses in Cyanothece sp. photosystems I and II. Results show that photosystem I activity was maintained under all environmental conditions tested, while photosystem II activity was not observed at all. Out of the environmental factors tested (temperature, salinity, and nitrogen presence), only temperature significantly influenced photosystem I activity. In particular, high temperature (40 °C) facilitated faster electron transport rates, while effects of salinity and nitroge...
The aviation sector relies on petroleum jet fuel because it is the most efficient energy carrier.... more The aviation sector relies on petroleum jet fuel because it is the most efficient energy carrier. Due to environmental and economic concerns a strong demand for alternative fuels is emerging. There is a need for diversification of energy sources from natural resources. These resources must be environmentally friendly and costs effective. Environmental impacts of fossil fuels on global warming and climate change are being a major concern today. Furthermore, the fluctuations of oil prices and need for sustainable fuel supply are the strong drivers for the economies of fuel users. In the aviation sector, Jet fuel from microalgae is one of the alternatives receiving considerable attention; it offers the potential to diversify energy sources. Microalgae species can produce lipids; they do not require high use of land, do not need freshwater, can grow in marine water or wastewater, grow faster in very short period of time, the produced oil is not a threat to food security. Similarly, the effect of climate change and global warming due to the generation of greenhouse gases (GHG) from petroleum jet fuel can be considerably reduced due to low carbon footprint generated by algae based fuels. Therefore, algae based aviation fuels can be considered as an alternative to produce an efficient fuel compared to conventional fuels. Conversely, the key challenge is: many algae species have lower lipid content. Harvesting and drying processes are costly as well as upstream processes to convert microalgae oil into Jet fuel. Although algae biofuels are still small players in the aviation industry, there is a potential for the future. This review analyses some routes to be explored or already explored, their strengths and weaknesses, the current trends and possible conceptual approaches to get aviation fuel from microalgae oil.
Chemistry for Sustainable Development in Africa, 2012
The diminishing petroleum reserves in the world call for sustainable use of cheaply and readily a... more The diminishing petroleum reserves in the world call for sustainable use of cheaply and readily available substrates such as wastewater streams for biomass and lipid production by microalgae. Treated wastewater is rich in macronutrients, such as nitrates and phosphates, and can therefore be used as a substrate for microalgal cultivation in open raceway ponds. The chemistry and composition of treated wastewater is of significance since it is made up of a wide range of compounds that support microalgal growth. The use of raceway pond technology utilizing wastewater streams feed is a new phenomenon that provides much needed phytoremediation of the wastewater as well as facilitating microalgal mass production. Macronutrient utilization by the microalgae justifies the application of treated wastewater as a sustainable raw material for renewable bioenergy production. The operational parameters in the raceway pond such as light intensity, photoperiod, pH, nutrients, salinity, and temperature are carefully optimized for maximal biomass and lipid yield. The biomass and lipid produced using the raceway pond system undergoes downstream processing in order to get the final product. The lipids are converted via transesterification to produce algae biodiesel. Other biologically active compounds and novel phytochemicals can also be derived from microalgae.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
ABSTRACT This study investigated cellular Nicotinamide Adenine Dinucleotide Phosphate (NADPH) flu... more ABSTRACT This study investigated cellular Nicotinamide Adenine Dinucleotide Phosphate (NADPH) fluorescence as a potential indicator of biohydrogen production in Chlamydomonas reinhardtii and a β-NADPH standard. NADPH fluorescence profiles of cultures grown in TAP-S (Tris-acetate phosphate minus sulphur) media, TAP (Tris-acetate phosphate) media and TAP + 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) were subsequently compared. Hydrogen production induced from sulphur depletion was found to correlate directly (r = 0.941) with NADPH over the ten day period. The addition of leachate was used to increase hydrogen yields, and subsequently increased the NADPH concentration by 50%–70%. A direct correlation was observed (r = 0.929) between NADPH and hydrogen when the leachate supplemented media was used. As NADPH is the terminal electron acceptor in the photosynthetic chain, results show that NADPH has a pivotal role in hydrogen production as a carrier molecule. Under sulphur depletion, cellular NADPH fluorescence can be used as an indicator of hydrogen production.
Temporarily open/closed estuaries (TOCEs) account for almost 71% of the total number of South Afr... more Temporarily open/closed estuaries (TOCEs) account for almost 71% of the total number of South African estuarine systems. To date the dynamics of microalgal production and biomass in TOCEs is poorly understood. A survey was therefore conducted in two TOCEs along the KwaZulu-...
This article is an open access article distributed under the terms and conditions of the Creative... more This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY
The microalgal biotechnology industry is expanding rapidly and currently gaining attention due to... more The microalgal biotechnology industry is expanding rapidly and currently gaining attention due to multiple availabilities of high-value products such as pigments, carbohydrates, proteins, nutraceuticals, biopharmaceuticals, and unique oleaginous compounds fractionated by biomass biorefinery. Microalgae are efficient primary producers in the terrestrial and marine biotopes. They are major sources of global oxygen and are gaining topical prominence due to their concomitant role in the phycoremediation of wastewater effluents and biomass production. Despite their minuscule size, microalgae critically contribute to climate change mitigation through carbon fixation and play a major role in bioenergy applications. Furthermore, carotenoids and phycobiliproteins are the main accessory light-harvesting complexes in microalgae and cyanobacteria. The topical biomedical and pharmaceutical applications of microalgae include anticancer, antidiabetic, antiHIV, antimalarial, antimicrobial, inter al...
Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Accli... more Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Acclimatization of freshwater microalgae to hypersaline conditions offers a means to reduce contamination. A freshwater Chlorella species was cultured in a gradient of salinities ranging from 5 to 40‰ and pulse amplitude modulated fluorometry recorded photosynthetic functioning. While the average salinity of seawater is 35‰, optimum acclimatization occurred at 20‰, at which point the growth rate (1.6 µg chl a L −1 d −1) was not significantly different from the control (1.8 µg chl a L −1 d −1). The maximum relative electron transfer rate was lower (9 to 12 µmol m −2 s −1) at 5 to 20‰ as compared to 40‰ (28 µmol m −2 s −1) where no algal growth was recorded. ATP and NADPH were thus shunted towards synthesis of molecules that offset cytoplasmic osmotic stress. Culturing this Chlorella strain in raceway ponds under saline conditions may reduce contamination and improve productivity.
This study investigated the interrelations between hydrogen synthesis and Photosystem I electron ... more This study investigated the interrelations between hydrogen synthesis and Photosystem I electron transport rate in Chlamydomonas reinhardtii. The fluorescence of both photosystems (PS I and PS II) was monitored using a Dual Pulse Amplitude Modulated (PAM) Fluorometer. Hydrogen synthesis was induced by eliminating sulphur from the growth media (TAP-S). Multiple physiological parameters [rETR, Y (I), Y (II), NPQ, α, Fv/Fm and YI:YII] were recorded using the Dual PAM and correlated to hydrogen produced. There was a 66% increase in Photosystem I rETRmax during hydrogen production. A significant direct correlation existed between PS 1 rETRmax and hydrogen evolution values over the ten-day period (r = 0.895, p < 0.01) indicating that PS I can be considered as a driver of H2 production. Significant correlations between rETRmax of PS I and H2 evolution suggest a novel physiological indicator to monitor H2 production during the three critical phases identified in this study.
Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Accli... more Contamination of freshwater raceway ponds impedes the commercial cultivation of microalgae. Acclimatization of freshwater microalgae to hypersaline conditions offers a means to reduce contamination. A freshwater Chlorella species was cultured in a gradient of salinities ranging from 5 to 40‰ and pulse amplitude modulated fluorometry recorded photosynthetic functioning. While the average salinity of seawater is 35‰, optimum acclimatization occurred at 20‰, at which point the growth rate (1.6 µg chl a L −1 d −1) was not significantly different from the control (1.8 µg chl a L −1 d −1). The maximum relative electron transfer rate was lower (9 to 12 µmol m −2 s −1) at 5 to 20‰ as compared to 40‰ (28 µmol m −2 s −1) where no algal growth was recorded. ATP and NADPH were thus shunted towards synthesis of molecules that offset cytoplasmic osmotic stress. Culturing this Chlorella strain in raceway ponds under saline conditions may reduce contamination and improve productivity.
Tissue metal concentrations, filtration and oxygen uptake rates were investigated for Perna perna... more Tissue metal concentrations, filtration and oxygen uptake rates were investigated for Perna perna (Bivalvia: Mollusca) during exposure to Hg , Cu and Zn (50 mgyl for 24 days, and 24 days recovery with no metal). Hg and Cu 2q 2q 2q tissue levels increased with exposure time, reaching maximum levels after 24 days (87.5 mg Hgyg dry mass and 45 mg Cuyg dry mass, respectively). Zn levels peaked after 4 days exposure (to 233 mg Znyg dry mass) and stabilized thereafter. Accumulated metal was rapidly lost from tissues when mussels were returned to uncontaminated seawater, suggesting that tissue concentration data may be of limited use in biomonitoring situations where environmental metals fluctuate to low levels. Filtration rates fell below control rates during Hg exposure, and became elevated again during 2q the recovery period. Cu and Zn exposure had little effect on filtration, but suppressed oxygen uptake. During 2q 2q recovery, oxygen uptake of Cu and Zn exposed mussels was elevated above the controls. Filtration and oxygen 2q 2q uptake rates were not correlated, but rather responded in different ways to metal pollution. While these physiological responses of P. perna may be of limited use in biomonitoring, they could indicate how populations may respond to marine pollution.
PAM fluorometry as a tool to assess microalgal nutrient stress and monitor cellular neutral lipid... more PAM fluorometry as a tool to assess microalgal nutrient stress and monitor cellular neutral lipids. Bioresour Technol
Extremophiles : life under extreme conditions, 2018
Worldwide, cyanobacterial blooms are becoming more frequent, exacerbated by eutrophication, anthr... more Worldwide, cyanobacterial blooms are becoming more frequent, exacerbated by eutrophication, anthropogenic effects, and global climate change. Environmental factors play a direct role in photosynthesis of cyanobacteria and subsequent cellular changes, growth, and bloom dynamics. This study investigated the photosynthetic functioning of a persistent bloom-forming (18 months) cyanobacterium, Cyanothece sp., isolated from Lake St Lucia, South Africa. DUAL-PAM fluorometric methods were used to observe physiological responses in Cyanothece sp. photosystems I and II. Results show that photosystem I activity was maintained under all environmental conditions tested, while photosystem II activity was not observed at all. Out of the environmental factors tested (temperature, salinity, and nitrogen presence), only temperature significantly influenced photosystem I activity. In particular, high temperature (40 °C) facilitated faster electron transport rates, while effects of salinity and nitroge...
The aviation sector relies on petroleum jet fuel because it is the most efficient energy carrier.... more The aviation sector relies on petroleum jet fuel because it is the most efficient energy carrier. Due to environmental and economic concerns a strong demand for alternative fuels is emerging. There is a need for diversification of energy sources from natural resources. These resources must be environmentally friendly and costs effective. Environmental impacts of fossil fuels on global warming and climate change are being a major concern today. Furthermore, the fluctuations of oil prices and need for sustainable fuel supply are the strong drivers for the economies of fuel users. In the aviation sector, Jet fuel from microalgae is one of the alternatives receiving considerable attention; it offers the potential to diversify energy sources. Microalgae species can produce lipids; they do not require high use of land, do not need freshwater, can grow in marine water or wastewater, grow faster in very short period of time, the produced oil is not a threat to food security. Similarly, the effect of climate change and global warming due to the generation of greenhouse gases (GHG) from petroleum jet fuel can be considerably reduced due to low carbon footprint generated by algae based fuels. Therefore, algae based aviation fuels can be considered as an alternative to produce an efficient fuel compared to conventional fuels. Conversely, the key challenge is: many algae species have lower lipid content. Harvesting and drying processes are costly as well as upstream processes to convert microalgae oil into Jet fuel. Although algae biofuels are still small players in the aviation industry, there is a potential for the future. This review analyses some routes to be explored or already explored, their strengths and weaknesses, the current trends and possible conceptual approaches to get aviation fuel from microalgae oil.
Chemistry for Sustainable Development in Africa, 2012
The diminishing petroleum reserves in the world call for sustainable use of cheaply and readily a... more The diminishing petroleum reserves in the world call for sustainable use of cheaply and readily available substrates such as wastewater streams for biomass and lipid production by microalgae. Treated wastewater is rich in macronutrients, such as nitrates and phosphates, and can therefore be used as a substrate for microalgal cultivation in open raceway ponds. The chemistry and composition of treated wastewater is of significance since it is made up of a wide range of compounds that support microalgal growth. The use of raceway pond technology utilizing wastewater streams feed is a new phenomenon that provides much needed phytoremediation of the wastewater as well as facilitating microalgal mass production. Macronutrient utilization by the microalgae justifies the application of treated wastewater as a sustainable raw material for renewable bioenergy production. The operational parameters in the raceway pond such as light intensity, photoperiod, pH, nutrients, salinity, and temperature are carefully optimized for maximal biomass and lipid yield. The biomass and lipid produced using the raceway pond system undergoes downstream processing in order to get the final product. The lipids are converted via transesterification to produce algae biodiesel. Other biologically active compounds and novel phytochemicals can also be derived from microalgae.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this p... more The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein.
ABSTRACT This study investigated cellular Nicotinamide Adenine Dinucleotide Phosphate (NADPH) flu... more ABSTRACT This study investigated cellular Nicotinamide Adenine Dinucleotide Phosphate (NADPH) fluorescence as a potential indicator of biohydrogen production in Chlamydomonas reinhardtii and a β-NADPH standard. NADPH fluorescence profiles of cultures grown in TAP-S (Tris-acetate phosphate minus sulphur) media, TAP (Tris-acetate phosphate) media and TAP + 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) were subsequently compared. Hydrogen production induced from sulphur depletion was found to correlate directly (r = 0.941) with NADPH over the ten day period. The addition of leachate was used to increase hydrogen yields, and subsequently increased the NADPH concentration by 50%–70%. A direct correlation was observed (r = 0.929) between NADPH and hydrogen when the leachate supplemented media was used. As NADPH is the terminal electron acceptor in the photosynthetic chain, results show that NADPH has a pivotal role in hydrogen production as a carrier molecule. Under sulphur depletion, cellular NADPH fluorescence can be used as an indicator of hydrogen production.
Temporarily open/closed estuaries (TOCEs) account for almost 71% of the total number of South Afr... more Temporarily open/closed estuaries (TOCEs) account for almost 71% of the total number of South African estuarine systems. To date the dynamics of microalgal production and biomass in TOCEs is poorly understood. A survey was therefore conducted in two TOCEs along the KwaZulu-...
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