Growth of microalgae in spectrum-neutral, volume-distributed light restriction as the baseline of wastewater exploitation

Producing culture media for microalgae from wastewaters may help reduce the culture management and wastewater treatment costs, but concomitant light limitation, nutrient restriction, toxic and growth-promoting effects complicate the preliminary data analysis and their subsequent exploitation. Post-treating the experimental data with a light-centred growth model would warrant the process developer with a powerful tool, but also a difficult one to validate in the absence of an accurate description of the microalgal growth behaviour in a purely radiative (i.e., non toxic) light restriction condition. Furthermore, purely radiative light restriction cannot be obtained by simply adjusting the external irradiance since in this latter case local irradiance and biomass growth cannot be decoupled. Aim of this work is, thus, carrying out an experimental investigation on the influence of purely radiative, chromatically neutral (grey), and volume-distributed light restriction on the observed growth rate of a microalgal culture. Semi-continuous cultures of the microalga Scenedesmus dimorphus (UTEX strain 1237) were realized in a synthetic culture media, with the addition of a non metabolised and non toxic black dye at different dilutions obtaining an array of equally spaced absorbances, ultimately yielding to a tailored light limitation. The cultures were grown in cylindrical and flat panel photobioreactors under artificial light. The experimental results were analysed with a simple (Lambert-Beer + Monod) growth model to investigate the exploitation criteria for wastewaters as culture media for microalgae

Extraction and purification of exopolysaccharides from exhausted Arthrospira platensis (Spirulina) culture systems

Microalgal endo and exopolysaccharides (EPS) are attracting increasing interest for their potential applications in the food, cosmetic and pharmaceutical industries. The standard applications of microbial EPS are as food coatings, emulsifying and gelling agents, flocculants, hydrating agents etc. They present unique biochemical properties that make them interesting from the biotechnological point of view. Their physical-chemical properties are interesting for biomedical applications, since polysaccharides have been demonstrated to possess inhibitory properties against various types of viruses, bacteria and tumors. The purpose of this work is to upgrade the exhausted culture media resulting from the cultivation of the cyanobacterium Arthrospira platensis (Spirulina), in order to extract the exopolysaccharides excreted by the cyanobacterium and test their exploitation potential in a cosmetic context (a body cream). The study results include: defining the composition and the productivity of EPS by the Spirulina culture, developing a suitable application method for the DPPH assay in lipophilic matrices, and evaluation of the antioxidant action of these polymers in the cosmetic field

Potential of choline chloride - based natural deep eutectic solvents (NaDES) in the extraction of microalgal metabolites

In a typical chemical process, the solvents are widely used for the dissolution of the reagents, to favor the kinetics and the thermodynamics of a chemical reaction, for the extraction of products, for the separation of mixtures. However most of the currently used organic solvents are characterized by different properties harmful to human health and the environment. Among the principles of Green Chemistry are that solvents should be innocuous to Man and to the Environment (safer solvents) and that the substances used in a chemical process should be chosen to minimize the potential for chemical accidents (intrinsically safe processes). Biorefining, the biomass Era counterpart of oil refining is most likely going to be extraction-based, and thus heavily solvent-dependent, much as the Oil Era was based on distillation and hence heat-dependent. Ionic Liquids (ILS) and eutectic mixtures exploited as solvents (DES) are two major classes of solvents that are making their way in Green Chemistry and, in particular, in biomass processing research. NaDES ('Natural Deep Eutectic Solvents'), i.e. mixtures formed by natural primary metabolites present in all organisms, such as sugars, polyols, amino acids, organic acids, derivatives of choline, form intermolecular hydrogen bonds and, when mixed in a certain ratio, change their state from solid to liquid forming a eutectic system. The most interesting NaDESs are those in which water is one of a ternary system since the degree of dilution with water modifies such physical properties of the NaDES as the density, the viscosity, and the polarity. By modulating the water content the solvation power can be adjusted to specific needs. In this work, the PCH (1,2-propanediol, choline chloride, water 1:1:1) NaDES was used to treat microalgal biomass and carry out the extraction of cellular components, such as lipids, proteins, carbohydrates and photosynthetic pigments (chlorophylls and carotenoids) from the biomass itself. Three sets of experiments were carried out based on different contact time between biomass and PCH: 24 and 72 hours, with and without pre-treatment with ultrasound. Biomass was shaken together with the PCH solvent in the presence of glass beads to promote the extraction efficiency. The analysis of the extract composition was carried out spectrophotometrically for pigments (chlorophylls and carotenoids), with biochemical assays for proteins and carbohydrates and gravimetrically for the determination of lipids. The results showed the ability of PCH, coupled with the mechanical destruction of cell walls, to solubilize a wide range of polar biomolecules at room temperature

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Table of Contents / Sumári

Development of semi-theoretical light radiation and photosynthetic growth model for the optimal exploitation of wastewaters by microalgae

In the last decade, interest toward the potential application of microalgae has grown considering their potential use in industrial sectors as human nutrition and health, animal feed and biopolymers. Their ability to use light or/and organic carbon as energy source, makes them able to grow in a wide range of conditions. Because of that, the possibility to use alternative nutrients and water sources for their cultivation has been investigated. The microalgal cultivation using wastewaters mixed with synthetic medium might be a good combination that could reduce costs of water, nutrients and wastewater treatment. Anyway, wastewaters are frequently dark colored and contain toxic compounds that could have a negative impact on microalgal light uptake and metabolism. In this study, an experimental first principles hybrid method for the estimation of microalgal growth in non-transparent media was developed as a guide in the choice of the best formulation of wastewater-based culture media for microalgae. To carry out several experimental runs in parallel with different conditions (dilution of the wastewater, different light sources, etc.) a cylindrical bubble column PhotoBioReactor (PBR) was adopted. Its simple geometry allows the analysis of inside light fluxes. A non-metabolizable and non-toxic dye, in condition of purely light-radiative growth limitation, was added to the medium mimicking the reduced transparency of wastewaters. As final step to test the model, culture mediums with wastewater addiction were used for microalgal cultivation, showing their nutritive effects on growth

Seisaku, gijutsu, patonashippu no apurochi ni yoru Nihon no ITS no kenkyu

制度:新 ; 報告番号:甲2925号 ; 学位の種類:博士(国際情報通信学) ; 授与年月日:2009/9/30 ; 早大学位記番号:新515

Methods used to assess drug prescribing and dispensing behaviours in the public and private sectors by non-professional health providers

In most developing countries, self-medication is common. Pharmacies, drug stores and drug shops are important providers of health advice and provision of inexpensive medicines. In assessing drug sellers performance, various methods have been used to collect data from drug sellers and other non professional providers. Some of these methods include exit interviews for patients after purchase of drugs, observations to assess drug sellers/dispensers roles and consumers behaviour, interviews with the drug sellers and nonprofessional providers themselves, use of simulated client approach and use of the patients care indicators such as generic prescribing/dispensing, number of drugs selected from the essential drug list or national drug formulary of the particular country. The above mentioned methods or approaches have been widely applied in most developing countries to assess dispensing and prescribing practices related to diseases like malaria, respiratory infections (pneumonia), diarrhoea and other childhood conditions. Here, the assessment can be done in 3 problem areas, drug sellers (untrained/unlicensed or nonprofessionals), pharmacists or clinicians and other trained health workers) and patients. In most cases it has been found that non-professional providers sell drugs to customers with or without prescriptions. Furthermore, the majority of drug sellers/dispensers prescribe or dispense drugs using brand names. In addition, the most commonly prescribed and dispensed drugs, antimalarials and antibiotics mostly in syrup forms for under-five children or analgesics such as paracetamol and multivitamins. Rarely do non-professional providers and drug sellers advocate oral rehydration salts (ORS), probably because of the low profit margin compared to antibiotic syrups for diarrhoea.Keywords: Self medication, drug sellers, prescribing behaviour, dispensing, nonprofessional heath providersEast and Central African Journal of Pharmaceutical Sciences Vol.14 (2011) 57-6

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