The Princeton Guide to Ecology

By Simon A. Levin | Go to book overview

II.12
Ecology of Microbial Populations
Thomas Bell
OUTLINE
1. Introduction
2. Microbial diversity
3. Growth in culture
4. Constraints on growth
5. Multiple resources
6. Multiple populations
7. Outside the laboratory

Laboratory studies of microbial populations have informed many early population models, and there is now an enormous literature describing the dynamics of microbial populations under controlled conditions. This chapter outlines the major developments in the study of microbial populations, from the simplest-case scenario of a single population feeding on a single substrate to situations where there are interactions among multiple populations. Currently, the greatest difficulty is in extrapolating the results of the laboratory studies to understand natural microbial communities.


GLOSSARY

batch/continuous culture. In batch culture, strains are grown for a fixed period (e.g., a few days) before being transferred to fresh medium. In continuous culture, there is a continuous input of nutrients and output of spent medium, resulting in constant environmental conditions. The rate at which nutrients are input (and output) into the microcosm is called the dilution rate. Continuous culture experiments are conducted in a chemostat.

cometabolism. Simultaneous metabolism of two substrates such that the metabolism of one substrate occurs only in the presence of a second substrate.

culturability. The ability to grow strains in the laboratory in pure culture. For example, it is estimated that as few as 1% of bacteria species are culturable. Surveys of microbial communities therefore often rely on culture-independent techniques. For example, it is possible to construct a clone library of amplified DNA sequences to characterize a particular microbial community.

diauxie. Literally “double growth”; diauxie describes the way in which bacterial populations feed on mixtures of substrates (usually sugars). Diauxic growth is characterized by an initial growth phase, followed by a lag where the strain switches from the first to the second substrate, which is in turn followed by a second growth phase as the second substrate is utilized.

microbe. Here defined as an organism that is small (<1 mm) and unicellular. The current discussion is also restricted to free-living microbes (i.e., excluding parasites).

Monod equation. Named after the microbiologist Jacques Monod, the equation describes the relationship between substrate concentration and the growth rate of a microbial population. The form of the equation is equivalent to the Michaelis-Menten equation of enzyme kinetics.

syntrophy. A mutualistic interaction where two strains can utilize a substrate that neither could utilize when the other is absent.

yield. The number of microbial cells produced per unit of substrate.


1. INTRODUCTION

There is a popular conception of the microbial world as an unseen host of germs hiding in unwashed corners, intent on infecting people and crops, contaminating water and food. However, microbial populations are intrinsic to the ecology of animal and plant communities and play a vital role in the flow of nutrients and energy in ecosystems. In aquatic ecosystems, phytoplankton are often the principal source of primary production, thereby controlling the quantity of organic material available to higher trophic levels. Bacteria and fungi control the rate of decomposition in most ecosystems and, therefore, the amount of inorganic matter

-239-

Notes for this page

Add a new note
If you are trying to select text to create highlights or citations, remember that you must now click or tap on the first word, and then click or tap on the last word.
One moment ...
Default project is now your active project.
Project items

Items saved from this book

This book has been saved
Highlights (0)
Some of your highlights are legacy items.

Highlights saved before July 30, 2012 will not be displayed on their respective source pages.

You can easily re-create the highlights by opening the book page or article, selecting the text, and clicking “Highlight.”

Citations (0)
Some of your citations are legacy items.

Any citation created before July 30, 2012 will labeled as a “Cited page.” New citations will be saved as cited passages, pages or articles.

We also added the ability to view new citations from your projects or the book or article where you created them.

Notes (0)
Bookmarks (0)

You have no saved items from this book

Project items include:
  • Saved book/article
  • Highlights
  • Quotes/citations
  • Notes
  • Bookmarks
Notes
Cite this page

Cited page

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

(Einhorn, 1992, p. 25)

(Einhorn 25)

1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited page

Bookmark this page
The Princeton Guide to Ecology
Table of contents

Table of contents

Settings

Settings

Typeface
Text size Smaller Larger Reset View mode
Search within

Search within this book

Look up

Look up a word

  • Dictionary
  • Thesaurus
Please submit a word or phrase above.
Print this page

Print this page

Why can't I print more than one page at a time?

Full screen
/ 810

matching results for page

Cited passage

Style
Citations are available only to our active members.
Sign up now to cite pages or passages in MLA, APA and Chicago citation styles.

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn, 1992, p. 25).

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences." (Einhorn 25)

"Portraying himself as an honest, ordinary person helped Lincoln identify with his audiences."1

1. Lois J. Einhorn, Abraham Lincoln, the Orator: Penetrating the Lincoln Legend (Westport, CT: Greenwood Press, 1992), 25, http://www.questia.com/read/27419298.

Cited passage

Welcome to the new Questia Reader

The Questia Reader has been updated to provide you with an even better online reading experience.  It is now 100% Responsive, which means you can read our books and articles on any sized device you wish.  All of your favorite tools like notes, highlights, and citations are still here, but the way you select text has been updated to be easier to use, especially on touchscreen devices.  Here's how:

1. Click or tap the first word you want to select.
2. Click or tap the last word you want to select.

OK, got it!

Thanks for trying Questia!

Please continue trying out our research tools, but please note, full functionality is available only to our active members.

Your work will be lost once you leave this Web page.

For full access in an ad-free environment, sign up now for a FREE, 1-day trial.

Already a member? Log in now.