Microbiology for the Analytical Chemist

176 Pages·1996·10.64 MB·English

by  R DART

Microbiology for the
Analytical Chemist

Microbiology for the
Analytical Chemist
R.K. Dart
Lmghborough Universip
THE ROYAL
SOCIETY OF
CH EM I STRY
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ISBN 0-85404-524-4
A catalogue record of this book is available from the British Library
0T he Royal Society of Chemistry 1996
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Preface
The microbiological problem facing analytical chemists is that when a sample is
compromised microbiologically, it is only a matter of time before it is compro-
mised chemically/biochemically. In the case of heavy microbial contamination,
the period of time before a sample becomes compromised chemically, may only
be a few hours.
The majority of problems in analytical chemistry caused by micro-organisms
take the form of four questions. These are:
(a) Is the sample sterile? Technically, sterility is an absolute value, and there
are no degrees of sterility, although as will be seen, this question is not as
straightforward as it seems. The answer to the question should therefore
be either ‘Yes’ or ‘No’. If the answer is ‘Yes’, then there is generally no
further microbiological problem for the analytical chemist. If the answer is
‘NO’,t hen a number of further questions arise.
(b) How many micro-organisms are present?
(c) What sort are they?
(d) What effect do they have on the product/sample?
It is the answers to these four questions which this short book addresses.
It should be appreciated that this is not a comprehensive microbiology text, but
is confined to those micro-organisms of medicinal and industrial importance,
which experience suggests will be found in situations encountered by analytical
chemists. This means that organisms labelled medicinal in the previous sentence,
generally will be those causing food poisoning, whilst those labelled industrial
will, broadly speaking, be those causing spoilage.
V

Contents
Chapter 1 Introduction 1
1 The Microbial Cell 1
1.1 Procaryotic Cells 1
1.2 Eucaryotic Cells 3
1.3 Nomenclature and Taxonomy 3
2 Eucaryotes 6
2.1 Algae 6
2.2 Protozoa 7
2.3 Fungi 7
3 Procaryotes 9
3.1 Eubacteria 9
3.2 Archaebacteria 11
3.3 Culture and Growth 11
4 References and Further Reading 15
Chapter 2 Biodeterioration 16
1 Analytical Samples 16
2 Cosmetics, Toile tries and Pharmaceuticals 16
3 Food 17
4 Specific Food Problems 20
4.1 Cereals 20
4.2 Sugar Products 20
4.3 Alcoholic Drinks 20
4.4 Fruit and Vegetables 20
4.5 Meat 22
4.5.1 Aerobic Spoilage 22
4.5.2 Anaerobic Spoilage 22
5 Wood (Lignocellulose) 22
6 Animal Products (non food) 23
7 Paints 23
8 Rubber and Plastics 23
9 Fuel and Lubricants 23
10 Metals 24
11 Stonework 24
12 Further Reading 24
v11
...
Vlll Contents
Chapter 3 Equipment and Methods 25
1 The Laboratory 25
2 Equipment 25
3 Personal Hygiene 27
4 Methods 27
5 Preparation of Plates 27
6 Isolation of Pure Cultures 28
7 Maintenance of Pure Cultures 29
8 Laboratory Stocks of Bacteria 29
9 Media 30
30 Growth Techniques 30
11 Pipetting 31
12 Autoclaving and Sterile Preparation 32
13 Disposal of Contaminated Material 32
14 References 33
Chapter 4 Microscopy and Staining 34
1 Microscopy 34
2 Staining 37
2.1 Methylene Blue 37
2.2 Gram Stain 37
2.3 Spore Stain 39
2.4 Acid-fast Stain 39
2.5 Lactophenol Stain for Fungi 40
2.6 Other Stains 40
3 References 40
Chapter 5 Microbial Detection and Counting 41
1 Sampling 41
2 Micro-organisms 42
2.1 Essential Organisms 42
2.2 Indicator Organisms 42
2.3 Spoilage Organisms 42
2.4 Pathogens 43
3 Counting 43
4 Cultural Methods 43
4.1 Dilution of Samples 45
4.2 Dip Slides 45
4.3 Pour Plates 45
4.4 Spread Plates 45
4.5 Drop Plate (Miles and Misra) Technique 46
4.6 Automated Plate Counts 47
4.7 Membrane Filtration 47
5 Direct Counting Methods 47
6 Physical and Chemical Methods 48
6.1 Spectrophotometric Methods 48