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Fernández-Novell et al.

A NEW STRATEGY FOR INTRODUCING SECONDARY SCHOOL STUDENTS TO MICROBIOLOGY AND BIOTECHNOLOGY J. M. Fernández-Novell 1 , D. Cifuentes 1 , C. Madrid 2 & J.C. Ferrer 1 1 Department of Biochemistry and Molecular Biology 2 Department of Microbiology. University of Barcelona. Spain

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Fernández-Novell et al.

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  1. A NEW STRATEGY FOR INTRODUCING SECONDARY SCHOOL STUDENTS TO MICROBIOLOGY AND BIOTECHNOLOGY J. M. Fernández-Novell1, D. Cifuentes1, C. Madrid2 & J.C. Ferrer1 1Department of Biochemistry and Molecular Biology 2Department of Microbiology. University of Barcelona. Spain Fernández-Novell et al.

  2. INTRODUCTION In the last 30 years, biotechnology and microbiology have experienced a rapid development. The very large amount of new information gained has many implications, from scientific or economic issues to those related to health or the environment. Fernández-Novell et al.

  3. INTRODUCTION Biotechnology and microbiology are not taught as separate subjects in Spanish secondary schools. Very few concepts in biotechnology and microbiology are covered in biology courses1. As a result, secondary school students frequently do not appreciate the important role of biotechnology and microbiology in our every day lives. Fernández-Novell et al.

  4. INTRODUCTION For more than ten years the Department of Biochemistry and Molecular Biology of the University of Barcelona has been offering the summer course2 “I love biochemistry”, for the most talented secondary school students. The aim of this course is to bring biochemistry, biotechnology and microbiology close to these advanced students. Fernández-Novell et al.

  5. INTRODUCTION Together with the Department of Microbiology at the University of Barcelona we have designed an introductory session specifically oriented to provide them with the opportunity to debate and gain an informed opinion about some key issues in the areas of microbiology and biotechnology. This introductory session is attended by over 100-110 students per year, which are selected from High Secondary Schools from all over Catalonia. Fernández-Novell et al.

  6. MATERIALS & METHODS • In the session, students are presented with: • Several inoculated Petri dishes containing general and selective media. • Microscopy preparations stained with specific reagents. • They are asked to examine them under a magnifying glass and a microscope. From their observations, students are finally, requested to answer a series of questions. Fernández-Novell et al.

  7. MATERIALS & METHODS OBSERVATION OF BACTERIAL MORPHOLOGIES The criteria used for microscopic identification of prokaryotes include cell shape and grouping, Gram-stain reaction, and motility. Fernández-Novell et al.

  8. MATERIALS & METHODS Gram stain3 permits to distinguish two kinds of bacteria depending on their structure. Fixed bacterial cells stain either Gram-positive (purple) or Gram-negative (pink). Fernández-Novell et al.

  9. MATERIALS & METHODS Motility is easily determined by observing living specimens. The motility of bacteria is due to the presence of flagella that can be also observed with special staining techniques. Fernández-Novell et al.

  10. MATERIALS & METHODS TSA (tryptone, soy, agar) is a rich culture medium that permits the general growth of a high range of microorganisms. Since in this kind of medium, each colony corresponds in general to an original microorganism it is adequate for the quantification of the total number of microorganisms in a given sample. Fernández-Novell et al.

  11. MATERIALS & METHODS Saboureaud Dextrose Agar is useful for the isolation and enumeration of fungi4. The low pH of the medium, 5.6 approximately, and the high glucose concentration (40 g/ L), favours the growth of fungi, while discouraging that of bacteria. Fernández-Novell et al.

  12. MATERIALS & METHODS Each isolated colony corresponds to an original microorganism present in the sample of soil used. It’s important to mention here that not all the microorganisms are cultivable in laboratory medium. Fernández-Novell et al.

  13. MATERIALS & METHODS MacConkey Agar is a selective medium for enterobacteria because it contains bile salts that inhibit the growth of other bacteria. Additionally, it contains lactose as carbon source and a pH indicator (neutral red). When a bacteria that can use lactose grows in MacConkey agar, the pH indicator turns red. Fernández-Novell et al.

  14. MATERIALS & METHODS In the MacConkey Agar plate shown, one of the bacteria inoculated is not an enterobacteria, and therefore is not able to grow in this medium. Two of the other three are able to use lactose, producing a red colour, while the fourth one is unable to metabolise lactose. Fernández-Novell et al.

  15. MATERIALS & METHODS In citrate medium, bacteria able to use citrate as carbon source are easily detected due to the presence of an indicator that turns intense blue upon growth. In the plate shown, only one of the bacterial strains inoculated can metabolise citrate. Fernández-Novell et al.

  16. MATERIALS & METHODS Hektoen enteric agar is another selective and differential culture medium adequate for isolation of pathogenic enterobacteria. In this medium, colonies of Salmonella are dark (blue-green), generally with a black centre, while other enterobacteria produce colonies of salmon colour. Fernández-Novell et al.

  17. CONCLUSIONS After the session, students’ opinions were assessed: - Almost all the students qualified it as a helpful experience for their preparation. - Most appreciated the opportunity to perform practical work in a microbiology laboratory. On the basis of our experience, we encourage proposals of this kind with the aim of bridging the gap between the secondary school and the university. Fernández-Novell et al.

  18. REFERENCES 1.- Fernández-Novell, J.M., Cifuentes, D. Ferrer, J.C. and Guinovart, J.J. (2006) Biotechnology, Microbiology and Secondary School. In Modern Multidisciplinary Applied Microbiology. Exploiting Microbes and Their Interactions, Wiley-VCH. 2.- Fernández-Novell, J.M., Gomis, R.R., Cid, E., Barberà, A. & Guinovart, J.J. (2002) Bridging the gap in biochemistry between secondary school and university. Biochem. Mol. Biol. Education 30, No 3, 172-174. 3.- Sancho Valls, J., Baldris Nacente, R., Sánchez Coll, M. (2001) Handbook of microbiological culture media. Barcelona, Scharlau Chemie S.A. 4.- Corry, J.E.L., Curtis, G.D.W., Baird, R.M. (2003) Handbook of culture media for food microbiology, 2on edition, Elsevier. Fernández-Novell et al.

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