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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
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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.
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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.
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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.
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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.
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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.

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MATERIALS METHODS
OBSERVATION OF BACTERIAL MORPHOLOGIES The
criteria used for microscopic identification of
prokaryotes include cell shape and grouping,
Gram-stain reaction, and motility.
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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).
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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.
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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.
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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.
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MATERIALS METHODS
Each isolated colony corresponds to an original
microorganism present in the sample of soil used.
Its important to mention here that not all the
microorganisms are cultivable in laboratory
medium.
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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.
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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.
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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.
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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.
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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.
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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.
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