Myrto-Panagiota Zacharof
“"Scientists investigate that which already is;Engineers create that which has never been.''” Albert Einstein.
Research interests
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InterestsWastewater Treatment, Microbial Biotechnology, Downstream Processing, Anaerobic Digestion, Microbial Biochemistry, Lactic Acid Bacteria, Microbial Cell Culture, Membrane Filtration, Culture Maintenance, Culture Management, Microbial Biofilms, Bioprocess Engineering, Food Processing, Reactors, Filtration, Industrial Microbiology, Membrane Fluidity, Membrane Fusion, Membrane Potentials, Waste Products, Bioreactors, Acetic Acid, Lactic Acid, Fermentation Science, Microbial Kinetics, Mathematical Modeling, High Performance Liquid Chromatography (HPLC), Pharmaceutical
Publications
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Investigation of Shelf Life of Potency and Activity of the Lactobacilli Produced Bacteriocins Through Their Exposure to Various Physicochemical Stress Factors
Probiotics and Antimicrobial Proteins. 06/2012;
Three Lactobacilli strains, Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014, Lactobacillus lactis NCIMB 8586 have been used for the production of bacteriocins. Though, their production phase, their biochemical nature, their mode of activity even their genetic structure have been ... [more] Three Lactobacilli strains, Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014, Lactobacillus lactis NCIMB 8586 have been used for the production of bacteriocins. Though, their production phase, their biochemical nature, their mode of activity even their genetic structure have been widely investigated, there are hardly any studies investigating their potency and activity in depth of time, in other words their shelf life under several physicochemical conditions that may occur during their production in large scale. As such, the effect of several factors influencing the activity and the potency of bacteriocins when produced in large scale was examined as due to bacteriocins peptide nature degradation or denaturation might occur, under extreme physicochemical conditions. During scale-up process, differences between the output data may occur, such as concerning biomass, metabolic by-products and limiting substrate concentrations. These may affect negatively the activity and the potency of the bacteriocins. For investigating these effects and minimizing them, numerous studies were conducted, which were related to the exact phase of the production of these substances, the effect of dilution and temperature changes. These studies could be used in order to minimize the scaling-up effect when decided to produce these peptides in large scale
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Investigation of Shelf life of Potency and Activity of the Lactobacilli produced Bacteriocins through their exposure to various physicochemical stress factors
International Scientific Conference on Bacteriocins and Antimicrobial PeptidesBAMP 2012; 02/2012
Investigation of Shelf life of Potency and Activity of the Lactobacilli produced Bacteriocins through their exposure to various physicochemical stress factors M.P.Zacharof*¹ and R.W. Lovitt² Multidisciplinary Nanotechnology Center, Swansea University, Swansea, SA2 8PP, UK*¹ School of Engineering,... [more] Investigation of Shelf life of Potency and Activity of the Lactobacilli produced Bacteriocins through their exposure to various physicochemical stress factors M.P.Zacharof*¹ and R.W. Lovitt² Multidisciplinary Nanotechnology Center, Swansea University, Swansea, SA2 8PP, UK*¹ School of Engineering, Multidisciplinary Nanotechnology Center, Swansea University, Swansea, SA2 8PP, UK² *¹ Corresponding author: myrtozacharof1981@yahoo.com Tel: +44(0)74135441769 1.1.Introduction Three Lactobacilli strains, Lactobacillus casei NCIMB 11970 Lactobacillus plantarum NCIMB 8014, Lactobacillus lactis NCIMB 8586 have been used for the production of bacteriocins. Though their production phase, their biochemical nature , their mode of activity even their genetic structure have been widely investigated, there are hardly any studies investigating their potency and activity in depth of time, in other words their self life under several physicochemical conditions that may occur during their production in large scale. As such the effect of several factors influencing the activity and the potency of bacteriocins when produced in large scale were examined as due to bacteriocins peptide nature be degradation or denaturation might occur, under extreme physicochemical conditions. During scale up process, differences between the output data may occur, such as concerning biomass, metabolic by products and limiting substrate concentrations. These may affect negatively, the activity and the potency of the bacteriocins. For investigating these effects and minimising them, numerous studies were conducted, which were related to the exact phase of the production of these substances, the effect of dilution and temperature changes. These studies could be used in order to minimise the scaling up effect when decided to produce these peptides in large scale. 1.2. Materials and Methods Nisin solutions of 1000 IU/ml, crude extracts of the fermented media by Lactobacilli and treated supernatants containing bacteriocins were serially diluted. These were tested for potency against the indicator strain L.delbruckii subsp.lactis NCIMB 8117 and their activity was calculated in international units per millilitre (IU/ml) according to the dose response model fabricated. Mechanical stress was applied to the produced bacteriocins and nisin through microfiltration (0.2μm MWCO) and ultrafiltration (30kDa MWCO). Heat tolerance was also tested in a range of temperature of 40, 60, 80 and 100°C for 15, 30, 45, and 60 minutes time interval in each temperature. The stability of the bacteriocins in low temperatures was also tested. The solutions were kept in 4°C for 12, 48, 60, 72, 84 and 96h. 1.3.Results The bacteriostatic effect of the produced bacteriocins and nisin treated with several methods, was strong up to the first 48h, though the target strain started getting in the death phase. The most sensitive bacteriocin is proven to be the one deriving from L.lactis, as it is partially loses its potency when heated in 80°C. These substances were proven to be sensitive when treated with in very high temperatures but are relatively stable. They maintain though their stability and potency even up to 72 h of storage. 1.4. Discussion and Conclusion When concentrated ,the bacteriocins were causing death of the target strain within 48h. They also retained their potency against the target strain for up to 60 h of storage. Treatment though with heat and microfiltration caused partial loss of potency, though the bacteriocin deriving from L.plantarum was proven to be most active. On the whole these substances were stable and there is potential to scale these processes for production knowing that if handled correctly they will not be significant losses.
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Development of a novel growth strategy for propagation and bacteriocin production from selected strains of Lactobacilli
IV International Conference on Enviromental , Industrial and Applied Microbiology BioMicroWorld 2011, Torremolinos, Spain; 01/2011
An innovative growth strategy for propagation and bacteriocin production of Lactobacilli M.P.Zacharof1 and R.W. Lovitt2 Multidisciplinary Nanotechnology Center, Swansea University, Swansea, SA2 8PP, UK¹ School of Engineering, Multidisciplinary Nanotechnology Center, Swansea University, Swansea, S... [more] An innovative growth strategy for propagation and bacteriocin production of Lactobacilli M.P.Zacharof1 and R.W. Lovitt2 Multidisciplinary Nanotechnology Center, Swansea University, Swansea, SA2 8PP, UK¹ School of Engineering, Multidisciplinary Nanotechnology Center, Swansea University, Swansea, SA2 8PP, UK² Lactobacilli belong to the group of Lactic Acid Bacteria (LAB), extensively utilised in the contemporary food industry. These bacteria are mainly used as natural acidifiers, for the inoculation of bulk quantities of milk and vegetables, in order to produce a variety of fermented products. As such, large quantities of their biomass, produced in cost effective enviromentaly friendly nutrient media, are necessary. Furthermore, during their growth, they naturally produce antimicrobial substances, called bacteriocins or lantibiotics. Due to the constantly developing need for natural food preservatives, bacteriocins deriving from Lactobacilli metabolism, function and activity has been extensively investigated. The possibility of producing these substances in mass quantities was investigated through several techniques. Three known bacteriocin producing strains of Lactobacilli, were carefully selected, L.plantarum NCIMB 8014, L.casei NCIMB 11970 and L.lactis NCIMB 8586. They were grown into simple batch cultures without pH control, where their physicochemical needs were determined. Through the determination of the optimum nutritional conditions for their propagation an optimised growth medium occurred. A simple, liquid turbidometric method was developed to test the bacteriocin productivity of these strains, on the developed media. The antimicrobial activity and potency of the bacteriocins produced, were tested against the target strain L.delbruckii subsp.lactis NCIMB 8117. In an effort to facilitate the extraction of bacteriocins from the fermented broths it was decided , to fabricate a nutrient medium , that would contain, low molecular weight nitrogen sources and equally support high production of bacteriocins and large yields of biomass. In order to achieve that, the optimised medium was then filtrated via ultrafiltration membrane modules of 30 and 4 kDa MWCO , in an effort to simplify the medium and facilitate the extraction of the produced substance. The medium’s efficiency in supporting the growth and the bacteriocin production of the bacilli was tested and comparative studies between filtrated and unfiltrated media were done.The filtered medium, containing low molecular weight nutrient sources, was proven to to successfully support growth and bacteriocin production. Keywords: LAB, Bacteriocins, Target strain, Ultrafiltration, Growth rate, DT.
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Lactobacilli : Their Role and Importance in Contemporary Food and Pharmaceutical Industry Past-Present-Future
International Conference on Enviromental , Industrial and Applied Microbiology BioMicroWorld 2011, Torremolinos, Spain; 01/2011
Lactobacilli : Their Role and Importance in Contemporary Food and Pharmaceutical Industry M.P.Zacharof*,1 and R.W. Lovitt2 Multidisciplinary Nanotechnology Center, Swansea University, Swansea, SA2 8PP, UK¹ School of Engineering, Multidisciplinary Nanotechnology Center, Swansea University, Swansea... [more] Lactobacilli : Their Role and Importance in Contemporary Food and Pharmaceutical Industry M.P.Zacharof*,1 and R.W. Lovitt2 Multidisciplinary Nanotechnology Center, Swansea University, Swansea, SA2 8PP, UK¹ School of Engineering, Multidisciplinary Nanotechnology Center, Swansea University, Swansea, SA2 8PP, UK² A review article Biofermentation of otherwise called biotransformation process has been a heavily exploited and vastly researched field of biochemical engineering science. Throughout the the years, especially during the last decades, a great number of of microbial groups has been tested for the production of commonly used chemicals. Due to the forecasted scarcity of petrol, an effort has been done to replace the production of chemicals deriving from petrochemical feedstocks, with fermentation. A group of bacteria that has being widely investigated due to their abilities are Lactic acifd Bacteria (LAB), especially Lactobacilli . These microorganisms have been widely used in today’s food, chemical and pharmaceutical industry. These bacteria have numerous features, which are based on their main ability to ferment complex carbohydrates such as the production of acids, enzymes and natural antimicrobial substances called bacteriocins. Currently, they are principally used as natural acidifiers for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. some of the most important uses of Lactobacilli in the industry will be reviewed. The production of lactic acid and lantibiotics through the usage of modern fermentation technology, shall be highlighted Keywords:Lactobacilly, LAB, fermentation science, biochemical engineering, industry, bacteriocins, lactic acid
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The Production of Bacteriocins from Lactic Acid Bacteria
Swansea University Interdisciplinary Research week 2011 PechaKucha Competition, Swansea University , SURF Room , Fulton House , Swansea, Wales , UK; 01/2011
http://www.swan.ac.uk/research/interdisciplinary-research-week/ http://mrclabsestream.swan.ac.uk/Embed.aspx?id=1009&code=9u~NCxmdHSoDdppzmNlTXSW&wmode=opaque... [more] http://www.swan.ac.uk/research/interdisciplinary-research-week/ http://mrclabsestream.swan.ac.uk/Embed.aspx?id=1009&code=9u~NCxmdHSoDdppzmNlTXSW&wmode=opaque
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Harvesting of intermediates and nutrients from biogas processes
Low Carbon Research Institute (LCRI) Conference in Wales National Museum , Cardiff , Wales. UK, Cardiff, Wales, United Kingdom; 01/2011
http://www.lcri.org.uk/conference_nov_2011.html
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Development of a suitable growth strategy for intensive propagation and lactic acid production of selected strains of Lactobacilli
19th International Congress of Chemical and Process Engineering CHISA 2010 and the 7th European Congress of Chemical Engineering ECCE-7, Prague, Czech Republic; 01/2010
Abstract Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry nowadays. These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β-galactosidase and natural antimicrobial substances called bacterioc... [more] Abstract Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry nowadays. These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β-galactosidase and natural antimicrobial substances called bacteriocins. They are mainly used as a natural acidifier for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. As such, large quantities of their biomass and the end products of their metabolism are necessary. The possibility of producing these substances in mass quantities will be investigated through several techniques. The selected Lactobacilli, L.plantarum NCIMB 8014, L.casei NCIMB 11970, L.lactis NCIMB 8586 and L.delbruckii NCIMB 11778 were grown into simple batch cultures without pH control where their physicochemical needs were determined. Through the determination of the optimum nutritional conditions for the propagation of the Lactobacilli, an optimised medium for growth occurred. The growth efficiency on the medium was tested on a 2L STR reactor operated batch wise with continuous pH control. The optimum pH conditions for the growth of the bacilli were determined as well as parameters such as cellular yield coefficient, substrate and starter inoculum concentration and lactic acid rate and production. The metabolism of the Lactobacilli was determined as homofermentative, mainly producing lactic acid. The efficiency of the optimized medium was evaluated in terms of growth rate and doubling time through the spectrophotometric measurement of cellular biomass. Keywords: LAB, STR, Growth rate, Doubling time, lactic acid, nutrient medium
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Development of an optimised growth strategy for intensive propagation, lactic acid and bacteriocin production of selected strains of Lactobacilli genus
International Journal of Chemical Engineering and Applications, ISSN: 2010-0221. 01/2010; Vol. 1:55-63.
Abstract -Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry nowadays. These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β- galactosidase and natural antimicrobial substances called bacterio... [more] Abstract -Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry nowadays. These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β- galactosidase and natural antimicrobial substances called bacteriocins. They are mainly used as a natural acidifier for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. As such, large quantities of their biomass and the end products of their metabolism are necessary. The possibility of producing these substances in mass quantities will be investigated through several techniques. The selected Lactobacilli, L.plantarum NCIMB 8014, L.casei NCIMB 11970, L.lactis NCIMB 8586 were grown into simple batch cultures without pH control where their physicochemical needs were determined. Through the determination of the optimum nutritional conditions for the propagation of the Lactobacilli, an optimised medium for growth occurred. The optimum pH conditions for the growth of the bacilli were determined as well as parameters such as cellular yield coefficient, substrate and starter inoculum concentration and lactic acid rate and production. The metabolism of the Lactobacilli was determined as homofermentative, mainly producing lactic acid. The efficiency of the medium combining al the optimised parameters, enhancing the productivity biomass and therefore bacteriocins production from the strains, was tested on a 2L STR reactor operated batchwise with continuous pH control. A simple liquid turbidometric method was developed to test the bacteriocin productivity of the selected bacteria. The activity and potency of the bacteriocin produced was tested against L.delbruckii subsp.lactis NCIMB 8117. Index Terms-Doubling time, Growth rate, Lactic acid, Nisin
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Investigation of a suitable growth strategy for optimisation of intensive propagation and lactic acid production of selected strains of Lactobacillus genus
Conference on Chemical Engineering and Applications (CCEA 2010), Singapore; 01/2010
Abstract Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry nowadays. These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β-galactosidase and natural antimicrobial substances called bacterioc... [more] Abstract Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the food industry nowadays. These microorganisms have several distinguishing abilities such as the production of lactic acid, enzymes such as β-galactosidase and natural antimicrobial substances called bacteriocins. They are mainly used as a natural acidifier for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. As such, large quantities of their biomass and the end products of their metabolism are necessary. The possibility of producing these substances in mass quantities will be investigated through several techniques. The selected Lactobacilli, L.plantarum NCIMB 8014, L.casei NCIMB 11970, L.lactis NCIMB 8586 and L.delbruckii NCIMB 11778 were grown into simple batch cultures without pH control where their physicochemical needs were determined. Through the determination of the optimum nutritional conditions for the propagation of the Lactobacilli, an optimised medium for growth occurred. The growth efficiency on the medium was tested on a 2L STR reactor operated batch wise with continuous pH control. The optimum pH conditions for the growth of the bacilli were determined as well as parameters such as cellular yield coefficient, substrate and starter inoculum concentration and lactic acid rate and production. The metabolism of the Lactobacilli was determined as homofermentative, mainly producing lactic acid. The efficiency of the optimized medium was evaluated in terms of growth rate and doubling time through the spectrophotometric measurement of cellular biomass. Keywords: LAB, STR, Growth rate, Doubling time, lactic acid, nutrient medium
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The importance of Lactobacilli in contemporary food and pharmaceutical industry A review article
International Conference on Chemical Engineering and Applications (CCEA 2010), Singapore; 01/2010
Fermentation technology has been a widely researched and exploited field of the science of biotechnology. Through out the recent years the vast majority of microbial groups have been tested for the production of beneficial compounds especially for the replacement of products produced by petrol such ... [more] Fermentation technology has been a widely researched and exploited field of the science of biotechnology. Through out the recent years the vast majority of microbial groups have been tested for the production of beneficial compounds especially for the replacement of products produced by petrol such as lactic acid. A bacterial group that heavily attracts attention due to its products are Lactic Acid Bacteria (LAB) and especially Lactobacilli. Lactobacilli are widely used in the food and pharmaceutical industry nowadays. These microorganisms have several distinguishing features based on their main ability to ferment carbohydrates such as the production of acids, enzymes and natural antimicrobial substances called bacteriocins. They are mainly used as natural acidifiers for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. As such, large quantities of their biomass and the end products of their metabolism are necessary. In this article some of the most important uses of Lactobacilli in the industry will be reviewed. Emphasis will be given in the production of lactic acid, β-galactosidase and lantibiotics through the usage of modern fermentation technology. Keywords: LAB, fermentation technology, food industry, β-galactosidase, lactic acid,
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The Production of Bacteriocins from Lactic Acid Bacteria
01/2010
Degree: Philosophy Doctorate (Ph.D.)
Supervisor: Dr.R.W. Lovitt
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Contemporary Laboratory Methods for Separation and Purification of Organic Macromolecules: A Review Article
International Journal of Chemical and Environmental Engineering. 01/2010; 1(1):56-62.
Nowadays, there are several laboratory methods suitable for separation and purification of a wide range of chemical substances of commercial interest from mixtures. These assays include filtration, precipitation, high precision dynamic light scattering (DLS) and high performance liquid chromatograph... [more] Nowadays, there are several laboratory methods suitable for separation and purification of a wide range of chemical substances of commercial interest from mixtures. These assays include filtration, precipitation, high precision dynamic light scattering (DLS) and high performance liquid chromatography (HPLC). The main advantage of these methods apart of their cost effectiveness is their suitability for separation, sizing and purification of a wide range of organic substances such as proteins, oligo- and polypeptides , enzymes, antibiotics, dyes, lipids, oils and in general non volatile organic compounds produced either by in vitro synthesis or biotechnologically. In this study, a description of these techniques will follow and several examples of their use will be given.
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A novel growth strategy for propagation and bacteriocin production of Lactobacilli
8th World Congress of Chemical Engineering (WCCE8), Montreal, Quebec,Canada; 01/2009
Abstract Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the dairy industry nowadays. The bacteria are used as a natural acidifier for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. As such, large quantit... [more] Abstract Lactobacilli belong to the group of lactic acid bacteria (LAB), widely used in the dairy industry nowadays. The bacteria are used as a natural acidifier for the inoculation of bulk quantities of milk and vegetables in order to produce a variety of fermented products. As such, large quantities of their biomass are necessary. Furthermore they produce natural antimicrobial substances during their growth, called bacteriocins. The possibility of producing these substances in mass quantities will be investigated through several techniques. The selected Lactobacilli, L.plantarum NCIMB 8014, L.casei NCIMB 11970 and L.lactis NCIMB 8586 were grown into simple batch cultures without pH control where their physicochemical needs were determined. Through the determination of the optimum nutritional conditions for the propagation of the Lactobacilli, an optimised medium for growth occurred. The metabolism of the Lactobacilli was determined as homofermentative, mainly producing lactic acid. A simple liquid turbidometric method was developed to test the bacteriocin productivity of the selected bacteria. The efficiency and potency of the bacteriocin produced was tested against L.delbruckii subsp.lactis NCIMB 8117. The optimised medium was further filtrated via membrane modules of 4 and 30 kDa and autoclaved. The medium’s efficiency in supporting the growth and the bacteriocin production of the bacilli was tested and comparative studies between filtrated and unfiltrated media were done. Keywords: LAB, Bacteriocins, Target strain, Ultrafiltration, Nanofiltration, Growth rate, Doubling time
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Intensive Propagation of the lactic acid bacterium Lactococcus Lactis
01/2007
Degree: Master in Philosophy (MPhil)
Supervisor: Dr.R.W.Lovitt
Following (44)
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Martin Richardson
Swansea University -
Dr. Nina S. Dionisiou
Αριστοτέλειο Πανεπιστήμιο Θεσσαλονίκης -
Olajumoke Odejimi
Swansea University -
Jay Siddharth
Novartis Institutes for BioMedical Research -
Harri Pettitt-Wade
University of Windsor
