Georgi Petkov - Academia.edu (original) (raw)
Papers by Georgi Petkov
The yellow-green alga Trachydiscus minutus has been described as a useful new subject for photoau... more The yellow-green alga Trachydiscus minutus has been described as a useful new subject for photoautotrophic biotechnology (Iliev et al., 2010; Lukavský, 2012; Cepák et al., 2013). Several recently reported qualities characterize T. minutus as a microalga appropriate to be cultivated in a photobioreactor, especially in the temperate zone. Indeed, the alga shows satisfactory growth at low light intensity and optimal temperature 26THE ALGA TRACHYDISCUS MINUTUS AIDS PURIFICATION OF BIOGAS TO METHANE
The idea to develop biofuels from algae is not a new one, but prior to 21st century algal propone... more The idea to develop biofuels from algae is not a new one, but prior to 21st century algal proponents did not gain enough fame. However, since 2007 there has been a significant increase of interest in algal biofuels and the prospects of their application in the future has been greatly overhyped. This review deals with different kinds of biofuels – biodiesel, bioethanol, hydrocarbons, biogas and whether algae can be applied in their production. Our conclusion is that while there is some advancement in growing algae and processing of biomass, harnessing biofuels from them is still a daunting task and far from the promised green future.
Algological Studies/Archiv für Hydrobiologie, Supplement Volumes, 1995
Biotechnology & Biotechnological Equipment, 2010
Pure and Applied Biology, 2014
Zeitschrift für Naturforschung C, 2003
Volatile substances of the green microalga Scenedesmus incrassatulus, cultivated in fresh and sal... more Volatile substances of the green microalga Scenedesmus incrassatulus, cultivated in fresh and salt water, were studied. Cultivation in fresh water diversifies volatile secondary metabolites. Hydrocarbons and derivatives of the acetate pathway predominate when algae are grown in salt water; isoprenoids and aromatics are more abundant after fresh water cultivation.
Green microalgae were grown under natural light in a photobioreactor similar to a transparent pla... more Green microalgae were grown under natural light in a photobioreactor similar to a transparent plate absorber. A proper temperature was maintained through the control of evaporation and the minimization of convective heat waste. Carbon dioxide desorption was lower in comparison to its level during cultivation in open or covered ponds. A yield of 1 g/l per day and over 100 g/m 2 projection area was achieved.
The extracellular substances of concomitant bacteria of the green alga Scenedesmus cultures were ... more The extracellular substances of concomitant bacteria of the green alga Scenedesmus cultures were studied, both in fresh and Black Sea water. Pentadecanoic and hydroxypentadecanoic acid dominate amid the lipophilic substances. Lactic and succinic acid and their esters are the main components of the water soluble material. Formation of esters in water medium is a proof of extracellular bacterial esterication
Zeitschrift für Naturforschung C, 2011
Fa-lty acids of twe.lve. species of cyanob.acteria grown under different photoautotrophic conditi... more Fa-lty acids of twe.lve. species of cyanob.acteria grown under different photoautotrophic conditions were studied and their composition was compared with literature data of-uny other species. We have come to the conclusion that the iiplOs of cyanobacteria do not con'tain fattyacids with a chain. _longer than 18 carbon atoms. In oui opinion, omission of an analyticai procedure, i.e. purification.of fatty acid methyl esters before gas chromatography, leads to incorrect interpretation of the results. Absence or presence oflatty acids wis iuggested as a useful taxonomic marker and a proper diagnostic indicator in the commerciil application of cyanobacterial biomass.
Phytochemistry, 1992
ABSTRACT When 0.15 gl−1 of petrol is added to the medium, Spirulina platensis and Chlorelia vulga... more ABSTRACT When 0.15 gl−1 of petrol is added to the medium, Spirulina platensis and Chlorelia vulgaris are killed but Scenedesmus incrassatulus survives. The fatty acid composition of Scenedesmus is unchanged but the amount of sterols is decreased two-fold and their quantitative composition changes.
International Journal of Infectious Diseases, 2008
European Journal of Lipid Science and Technology, 2012
The quantitative production of microalgae oil is often overestimated. The cost of the salts inves... more The quantitative production of microalgae oil is often overestimated. The cost of the salts invested in the production of 1 kg algal diesel approximates the actual price of 1 kg mineral diesel. Total sum of electrical energy expenses for production of biodiesel from microalgae is several-fold higher than the energy income from combustion of the same quantity. The biological value of cultivated microalgae as food is much higher than as fuel. An opinion is shared that money ought to be invested in microalgal biomass production as a food additive, forage, and pharmaceuticals. The aim is to prevent making too hasty steps and investments in microalgal biodiesel.
Botanica Marina, 1998
Lipid content, fatty acids and sterol composition of Cystoseira abies-marina and total fatty acid... more Lipid content, fatty acids and sterol composition of Cystoseira abies-marina and total fatty acids of C. humilis from Gran Canaria were studied. A high content of polyunsaturated fatty acids 16 : 3 and 16: 4 was found. Their content in rnonogalactosyldiacylglycerols is over 90%. Triacylglycerols and phospholípids contain rnainly arachidonic and eicosapentaenoic acids. Reasons for the differences in the composition of fatty acids and sterols of various species of Cystoseira are discussed. Sorne technological approaches are recommended.
Biotechnology & Biotechnological Equipment, 2011
Seeds of Tribulus terrestris L. were sown in transparent plastic leaky boxes, at a depth of 4-5 m... more Seeds of Tribulus terrestris L. were sown in transparent plastic leaky boxes, at a depth of 4-5 mm in sand. The transparent pots were put on plates, where water has been added through the bottom holes and capillary ascending to the surface. The temperature of soil was 20-37 0 C, temperature of air 20-40 0 C. Either the soil microalgae, or preliminary grown microalgal suspension, single added with the water has been thriving at these conditions. At all experiments, the first seeds germinated exactly 3 days after they have been sown. Above 90 % of the seeds germinated to 7-9 day and single of them to 20 day. Inside, on the wall of the pots, green collour appeared due to microalgae and significantly later mosses appeared, too. Having worked with seeds from Pazardzhik a germination of 31 ± 12 % was achieved (74 seeds). Seeds gathered from nature, Black Sea coast, Zarevo, have germinated 7 of 10 in a single experiment. The manner of work is in consistency with a possible breeding of the plant as greenhouse seedlings.
Algological Studies/Archiv für …, 1993
J. BioSci. Biotech.
The yellow-green alga Trachydiscus minutus has not been studied in detail prior to the first deca... more The yellow-green alga Trachydiscus minutus has not been studied in detail prior to the first decade of the 21st century due to the fact it has been easily confused with the algae of the genus Chlorella. It is known that the cells of the algae have a high amount of lipids and proteins and they lack chlorophyll-b. Currently, there is no published data available to describe the effects of herbicides on growth and biochemical composition. The aim of this work is to study the effects of the glyphosate-containing herbicide Roundup and ...
Biochemical Systematics and Ecology, 2007
Fatty acid composition of three species of Chlorella were studied under conditions of photoautotr... more Fatty acid composition of three species of Chlorella were studied under conditions of photoautotrophic and heterotrophic cultivation, nitrogen starvation, and outdoor in a photobioreactor. The composition 14: 0, 16: 0, 16: 1, 16: 2, 16: 3, 18: 0, 18: 1, 18: 2, α-18: 3 ...
The yellow-green alga Trachydiscus minutus has been described as a useful new subject for photoau... more The yellow-green alga Trachydiscus minutus has been described as a useful new subject for photoautotrophic biotechnology (Iliev et al., 2010; Lukavský, 2012; Cepák et al., 2013). Several recently reported qualities characterize T. minutus as a microalga appropriate to be cultivated in a photobioreactor, especially in the temperate zone. Indeed, the alga shows satisfactory growth at low light intensity and optimal temperature 26THE ALGA TRACHYDISCUS MINUTUS AIDS PURIFICATION OF BIOGAS TO METHANE
The idea to develop biofuels from algae is not a new one, but prior to 21st century algal propone... more The idea to develop biofuels from algae is not a new one, but prior to 21st century algal proponents did not gain enough fame. However, since 2007 there has been a significant increase of interest in algal biofuels and the prospects of their application in the future has been greatly overhyped. This review deals with different kinds of biofuels – biodiesel, bioethanol, hydrocarbons, biogas and whether algae can be applied in their production. Our conclusion is that while there is some advancement in growing algae and processing of biomass, harnessing biofuels from them is still a daunting task and far from the promised green future.
Algological Studies/Archiv für Hydrobiologie, Supplement Volumes, 1995
Biotechnology & Biotechnological Equipment, 2010
Pure and Applied Biology, 2014
Zeitschrift für Naturforschung C, 2003
Volatile substances of the green microalga Scenedesmus incrassatulus, cultivated in fresh and sal... more Volatile substances of the green microalga Scenedesmus incrassatulus, cultivated in fresh and salt water, were studied. Cultivation in fresh water diversifies volatile secondary metabolites. Hydrocarbons and derivatives of the acetate pathway predominate when algae are grown in salt water; isoprenoids and aromatics are more abundant after fresh water cultivation.
Green microalgae were grown under natural light in a photobioreactor similar to a transparent pla... more Green microalgae were grown under natural light in a photobioreactor similar to a transparent plate absorber. A proper temperature was maintained through the control of evaporation and the minimization of convective heat waste. Carbon dioxide desorption was lower in comparison to its level during cultivation in open or covered ponds. A yield of 1 g/l per day and over 100 g/m 2 projection area was achieved.
The extracellular substances of concomitant bacteria of the green alga Scenedesmus cultures were ... more The extracellular substances of concomitant bacteria of the green alga Scenedesmus cultures were studied, both in fresh and Black Sea water. Pentadecanoic and hydroxypentadecanoic acid dominate amid the lipophilic substances. Lactic and succinic acid and their esters are the main components of the water soluble material. Formation of esters in water medium is a proof of extracellular bacterial esterication
Zeitschrift für Naturforschung C, 2011
Fa-lty acids of twe.lve. species of cyanob.acteria grown under different photoautotrophic conditi... more Fa-lty acids of twe.lve. species of cyanob.acteria grown under different photoautotrophic conditions were studied and their composition was compared with literature data of-uny other species. We have come to the conclusion that the iiplOs of cyanobacteria do not con'tain fattyacids with a chain. _longer than 18 carbon atoms. In oui opinion, omission of an analyticai procedure, i.e. purification.of fatty acid methyl esters before gas chromatography, leads to incorrect interpretation of the results. Absence or presence oflatty acids wis iuggested as a useful taxonomic marker and a proper diagnostic indicator in the commerciil application of cyanobacterial biomass.
Phytochemistry, 1992
ABSTRACT When 0.15 gl−1 of petrol is added to the medium, Spirulina platensis and Chlorelia vulga... more ABSTRACT When 0.15 gl−1 of petrol is added to the medium, Spirulina platensis and Chlorelia vulgaris are killed but Scenedesmus incrassatulus survives. The fatty acid composition of Scenedesmus is unchanged but the amount of sterols is decreased two-fold and their quantitative composition changes.
International Journal of Infectious Diseases, 2008
European Journal of Lipid Science and Technology, 2012
The quantitative production of microalgae oil is often overestimated. The cost of the salts inves... more The quantitative production of microalgae oil is often overestimated. The cost of the salts invested in the production of 1 kg algal diesel approximates the actual price of 1 kg mineral diesel. Total sum of electrical energy expenses for production of biodiesel from microalgae is several-fold higher than the energy income from combustion of the same quantity. The biological value of cultivated microalgae as food is much higher than as fuel. An opinion is shared that money ought to be invested in microalgal biomass production as a food additive, forage, and pharmaceuticals. The aim is to prevent making too hasty steps and investments in microalgal biodiesel.
Botanica Marina, 1998
Lipid content, fatty acids and sterol composition of Cystoseira abies-marina and total fatty acid... more Lipid content, fatty acids and sterol composition of Cystoseira abies-marina and total fatty acids of C. humilis from Gran Canaria were studied. A high content of polyunsaturated fatty acids 16 : 3 and 16: 4 was found. Their content in rnonogalactosyldiacylglycerols is over 90%. Triacylglycerols and phospholípids contain rnainly arachidonic and eicosapentaenoic acids. Reasons for the differences in the composition of fatty acids and sterols of various species of Cystoseira are discussed. Sorne technological approaches are recommended.
Biotechnology & Biotechnological Equipment, 2011
Seeds of Tribulus terrestris L. were sown in transparent plastic leaky boxes, at a depth of 4-5 m... more Seeds of Tribulus terrestris L. were sown in transparent plastic leaky boxes, at a depth of 4-5 mm in sand. The transparent pots were put on plates, where water has been added through the bottom holes and capillary ascending to the surface. The temperature of soil was 20-37 0 C, temperature of air 20-40 0 C. Either the soil microalgae, or preliminary grown microalgal suspension, single added with the water has been thriving at these conditions. At all experiments, the first seeds germinated exactly 3 days after they have been sown. Above 90 % of the seeds germinated to 7-9 day and single of them to 20 day. Inside, on the wall of the pots, green collour appeared due to microalgae and significantly later mosses appeared, too. Having worked with seeds from Pazardzhik a germination of 31 ± 12 % was achieved (74 seeds). Seeds gathered from nature, Black Sea coast, Zarevo, have germinated 7 of 10 in a single experiment. The manner of work is in consistency with a possible breeding of the plant as greenhouse seedlings.
Algological Studies/Archiv für …, 1993
J. BioSci. Biotech.
The yellow-green alga Trachydiscus minutus has not been studied in detail prior to the first deca... more The yellow-green alga Trachydiscus minutus has not been studied in detail prior to the first decade of the 21st century due to the fact it has been easily confused with the algae of the genus Chlorella. It is known that the cells of the algae have a high amount of lipids and proteins and they lack chlorophyll-b. Currently, there is no published data available to describe the effects of herbicides on growth and biochemical composition. The aim of this work is to study the effects of the glyphosate-containing herbicide Roundup and ...
Biochemical Systematics and Ecology, 2007
Fatty acid composition of three species of Chlorella were studied under conditions of photoautotr... more Fatty acid composition of three species of Chlorella were studied under conditions of photoautotrophic and heterotrophic cultivation, nitrogen starvation, and outdoor in a photobioreactor. The composition 14: 0, 16: 0, 16: 1, 16: 2, 16: 3, 18: 0, 18: 1, 18: 2, α-18: 3 ...