Questions and Answers (16) View all
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Answer added in Wastewater Treatment13 How to separate the volatile fatty acids (VFA) from the anaerobic digestion liquid of sewage sludge?Dear Liu, I do agree with the colleagues above , VFA will not be in significantly high amounts in the digestate , especially if the AD process has be... [more]
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Answer added in Sample Preparation6 How can I publish my scientific research work in scientific journals?Hello Mohammad, I agree with Sally. May I add a few more things to her post . Make sure that the research you are doing is allowed to be published a... [more]
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Answer added in Glucose64 Is it possible to quantify glucose using HPLC with a C18 column and DAD detector?Dear Willy, it is possible , however it is quite difficult to do and possibly offer questionable results.I would agree with Wahib, please do also re... [more]
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Answer added in Protein Purification21 Maximum duration of freezing bacterial cell pelletsHave you used a cryoprotective agent? If yes , they should last up to 6 months at -20 Cand a bout 1 to 1.5 year at -80 C, if not about a month in -20 ... [more]
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Answer added in Microbiology59 What is the difference between bacteriocin and antibiotic?Hello Vignesh Although bacteriocins could be categorised as antibiotics, they are not. The major difference between bacteriocins and antibiotics is t... [more]
Publications (28) View all
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Article: Complex Effluent Streams as a Potential Source of Volatile Fatty Acids
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ABSTRACT: The recovery of volatile fatty acids (VFA), from complex effluent streams deriving from numerous sources has been an area of research interest for more than a century. In the current era, technological and economic development is widely based on the limited global petroleum resources. Regardless the scarcity faced in coal based fuels, VFA are still extensively and in most cases solely, synthesised from petroleum. With the constantly rising awareness of the environmental impact the carbon based economy has created, research has been focused in developing alternative methods of their production. These include fermentation, anaerobic digestion and recovery from discharged chemical and industrial plants effluents. During these processes, the hydrolysis of target solid wastes followed by the microbial conversion of them to biodegradable organic, content results in the production of intermediate VFA, commonly acetate and butyrate. These, are detected at varying concentrations in the effluent streams and mixed liquors of the reactor systems. Their concentration is depending on hydraulic, retention and organic loading rates. Several studies have shown possible environmental and commercial benefits using various techniques for their separation and recovery. Among these, extensively applied has been reactive extraction. Currently, membrane filtration is most prominent as a source separation process in comparison to integral wastewater treatment. VFA reclamation benefits include the formulation of a valorisized waste effluent that can be further processed for the recovery of valuable nutrients, the relief of municipal treatment plants and the recycle and re-use of favorable nutrients and chemicals.Waste and Biomass Valorization 02/2013; -
Article: Modelling and Simulation of Cell Growth Dynamics, Substrate Consumption and Lactic Acid Production Kinetics of Lactococcus lactis
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ABSTRACT: Lactococcus lactis species have been and still are extensively investigated due to their significant commercial importance. Current scientific research focuses on strains utilized in food industry, due to their multiple uses in food and beverages fabrication. Biomass of Lactococcus lactis is of great interest as well as the end products of its metabolism such as lactic acid and nisin. However their production is constantly challenged due to end product inhibition occurring during intensive propagation of the coccus in reactor systems. To successfully predict the behavior of the culture, the approach of combining mathematics with biology, ergo the development of an unstructured mathematical model, was taken. Although Luedeking and Piret is the model that has been extensively used to demonstrate growth in end-product inhibition cultures, its applicability is limited due to its dependance on the specific growth and product coefficients, particularly related to the culturing conditions used. To overcome these hurdles, a combination of the non competitive single product end inhibition Taylor and Hinselwood models was used, with the significance of this model laying in the fact that it offers a feasible alternative to the commonly used model of Luedeking and Piret for describing fermentation kinetics governed by end-product inhibitions. The fitting with the experimental values, in batch mode, was tested in terms of the coefficient of determination (R²), having values 0.97 ~ 0.99 and suggesting a very good fitting with the experimental data. The model was further developed to achieve theoretical predictions of volumetric cell productivity in continuous and fed-batch mode of substrate feed in different culturring systems.Biotechnology and Bioprocess Engineering 02/2013; 18(1):52-64. · 1.28 Impact Factor -
Article: Partially chemically defined liquid medium development for intensive propagation of industrial fermentation lactobacilli strains
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ABSTRACT: An economic liquid growth medium was synthesised for high-rate production of cellular mass, lactic acid and bacteriocin in lactobacilli. Three lactobacilli that are applied extensively in industry—Lactobacillus casei NCIMB 11970, Lactobacillus plantarum NCIMB 8014, Lactobacillus lactis NCIMB 8586—were chosen to test the medium’s efficiency. These bacteria are chemoorganotrophs requiring rich, complex media for optimum growth. Contrary to the current practice of formulating a strain-specific medium, we attempted to prepare a universal broth that would allow easy formulation and optimisation. Man de Rogosa Sharp (MRS) medium, which can support the growth of lactobacilli, was found unsuitable for use in large quantities due to its high cost of preparation and its use of beef extract and peptone from poultry as nitrogen sources, which are not environmentally friendly and have potential health risks. The developed medium supported the growth of all the three bacteria equally, offering good maximum yields and incorporating only the chemical compounds needed, resulting in an improvement in the growth rate of the bacilli of between 50 % and 241 % compared to the same strains grown on MRS. Lactic acid production was between 28.6 and 35.74 g L−1 and bacteriocin production ranged from 110 to 130 IU mL−1.Annals of Microbiology 12/2012; · 0.69 Impact Factor -
Dataset: Proceedings of 2010 International Conference on Chemical Engineering and Applications (CCEA 2010) Singapore, 26-28 February, 2010
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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. -
Dataset: Proceedings of 2010 International Conference on Chemical Engineering and Applications (CCEA 2010) Singapore, 26-28 February, 2010
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ABSTRACT: 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
