Microbiology: A Very Short Introduction

Citation

Money, N. P. (2014). Microbiology: A Very Short Introduction. Oxford University Press.

Chapter Summary

The book is number 413 in Oxford's Very Short Introductions series. It has seven chapters in about 120 pages, with bibliographical references and an index. In the publisher's description, it covers the range of the microbial world and the methods used to study it. These run from traditional microscopy and laboratory culture to DNA sequencing, genomic analysis and genetic manipulation. The book then shows how advances in microbiology have affected medicine, agriculture and biotechnology. The author is a mycologist, a professor of botany at Miami University in Ohio, and has written several popular books about fungi and other microorganisms.

Chapter 1: Microbial diversity

The first chapter sets out the three primary groups of microorganisms. Bacteria and archaea are prokaryotes, with their genetic material in a single chromosome. Eukaryotes hold most of their genome in several chromosomes. The chapter explains how bacterial species have been identified: by cell shape and metabolism, by Gram staining, and by RNA and DNA sequences. It gives counts of named bacteria and archaea, and surveys the eukaryotic supergroups, all of which include single-celled organisms and five of which are entirely microbial.

Chapter 2: How microbes operate

This chapter asks what keeps microbial cells alive. Every active cell needs water and an energy source. Water is essential even in very dry or salty habitats, because enzymes only work when hydrated. Energy comes from sunlight for photosynthetic microbes and from chemical sources for others. The chapter then considers how extremes of temperature, acidity and other conditions constrain microbial life, and concludes that microbes thrive almost wherever liquid water exists.

Chapter 3: Microbial genetics and molecular microbiology

Here the focus shifts to genes and genomes. The chapter explains that cell structures and metabolism are specified by genes encoded in double-stranded DNA. It describes how automated sequencing produced thousands of microbial genomes, and how genome size varies, with the largest prokaryote genomes overlapping the smallest eukaryotic ones. It also covers the role of mutation in evolution, and contrasts the strictly asexual reproduction of prokaryotes with sexual reproduction in eukaryotic microorganisms.

Chapter 4: Viruses

The viruses chapter looks beyond human disease. Viruses control populations of bacteria, archaea and eukaryotes, and by destroying cells they release large quantities of nutrients in water and soil. The chapter explains the classification of viruses into seven groups by genome type and replication mechanism, and how viral genes are expressed using the host cell's machinery.

Chapter 5: Microbiology of human health and disease

Microbiology has been dominated by the study of pathogens since Pasteur, but this chapter gives equal weight to the human microbiome. It describes the microbes of the gut, reproductive tract and respiratory tract: bacteria, viruses, archaea, fungi and other eukaryotes. It argues that most of them are beneficial and only a minority can cause disease.

Chapter 6: Microbial ecology and evolution

This chapter presents microbes as the biochemical foundation of plant and animal life. On land, the topics are nitrogen fixation, the conversion of nitrites to nitrates, phosphorus and trace-element availability, and the recycling of organic matter. In the sea, bacteria and archaea make up most of the biomass, and eukaryotic algae fill the surface waters.

Chapter 7: Microbes in agriculture and biotechnology

The last chapter turns to applied research: improving soil fertility, fighting plant diseases and developing genetically modified crops. Its starting point is that natural soil fertility cannot support intensive agriculture for a growing human population. It also argues that intensive cattle grazing on deforested land is unsustainable.

Key Concepts

Chapters 1–2: Microbial diversity; How microbes operate

• Three domains: bacteria, archaea and eukaryotes. The first two are prokaryotes, and microbial eukaryotes are spread across several supergroups.
• Identification methods: cell shape, metabolism, Gram staining and nucleic-acid sequences.
• Water and energy requirements: active cells need hydrated enzymes and an energy source, which is light or chemical energy.
• Life at extremes: microbes tolerate extreme temperature and acidity, and flourish wherever liquid water is available.

Chapters 3–4: Microbial genetics and molecular microbiology; Viruses

• Genome sequencing: automated methods that made the comparison of thousands of microbial genomes possible.
• Asexual and sexual reproduction: prokaryotes reproduce only asexually, while many eukaryotic microbes also reproduce sexually.
• Viral classification: seven groups of viruses, defined by genome type and replication mechanism.
• Viruses in ecosystems: by killing cells, viruses control microbial populations and release nutrients.

Chapters 5–7: Health and disease; Ecology and evolution; Agriculture and biotechnology

• Human microbiome: the communities of microbes living in the body, mostly beneficial.
• Nutrient cycling: microbial redox chemistry that fertilises soil and recycles organic matter.
• Marine microbes: bacteria and archaea form most ocean biomass and drive marine food webs.
• Applied microbiology: soil amendment, control of plant disease and genetically modified crops.

Critical Analysis

Strengths

• A broad view of the microbial world. Viruses, fungi and protists receive attention alongside bacteria. The ecology chapter treats microbes as the foundation of terrestrial and marine ecosystems, not chiefly as pathogens. This is a useful corrective for students whose only contact with microbiology has been through medicine.
• Methods as well as organisms. The publisher's description stresses that the book explains how microbes are studied, from microscopy and culture to sequencing and genomics. This matters because modern microbiology depends heavily on detecting organisms that cannot be grown in the laboratory.
• A balanced treatment of health. The health chapter explicitly sets the long focus on pathogens against recent work on the microbiome. It stresses that the majority of microbes in and on the body are beneficial.
• Compact. Seven chapters in about 120 pages can be read in a few sittings, which makes the book a realistic first overview before a long textbook.

Limitations

• Dated numbers. The book was published in 2014. Its figures for species counts, sequenced genomes and the size of the human microbiome reflect that date. For example, the chapter on health quotes a ratio of bacterial to human cells that later work has revised downwards: Sender, Fuchs and Milo (2016) estimated a ratio close to one to one. Genome counts have grown enormously since then.
• No coverage of recent outbreaks. The book predates the COVID-19 pandemic. The virus chapter cannot address the virology and epidemiology that followed.
• Not a course text. As a short general-reader book, it gives no systematic account of microbial metabolism, cell structure, growth or control. It cannot be relied on to prepare for an examination.

Where It Fits in the Course

This is the shortest book on the course list and serves best as orientation. The textbooks on the list cover the same ground at length. The OpenStax Microbiology is a free one-semester textbook that introduces the main microbial groups and then concentrates on infection, immunity and disease by body system. Tortora and colleagues' Microbiology: An Introduction is a full course text with case-based examples, aimed at students including non-majors and those heading for health careers. Brock Biology of Microorganisms is a general microbiology textbook for science majors that gives diversity and ecology as much weight as medicine. Read before Brock, Money's book prepares readers for a textbook of that kind.

At a more specialised level, White, Drummond and Fuqua's The Physiology and Biochemistry of Prokaryotes develops the material of Money's second chapter: how prokaryotic cells obtain energy and respond to their surroundings. Snyder and Champness Molecular Genetics of Bacteria takes up the subject of his third chapter in full.

How to Use This Book

No background beyond school biology is required. The book suits several kinds of reader: students about to start a microbiology course, students in other sciences who need an overview, and general readers.

• Before the course: read the whole book. Chapters 1, 3 and 6 are the most useful preparation, because classification, genomics and microbial ecology are the areas where a first textbook can feel most fragmented.
• During the course: use Chapter 4 alongside the virology unit and Chapter 5 alongside the units on infection and normal flora.
• Optional: Chapter 7 is the most applied chapter. Readers interested in agriculture or biotechnology will want it; others can skip it.
• Check the numbers: treat counts of species, genomes and microbiome cells as figures from around 2014. Compare them with current estimates in an up-to-date textbook.

A useful exercise is to list the organisms and processes named in each chapter, then find where the course textbook covers them in detail.