Jump to ContentJump to Main Navigation
Processes in Microbial Ecology$
Users without a subscription are not able to see the full content.

David L. Kirchman

Print publication date: 2018

Print ISBN-13: 9780198789406

Published to Oxford Scholarship Online: August 2018

DOI: 10.1093/oso/9780198789406.001.0001

Show Summary Details
Page of

PRINTED FROM OXFORD SCHOLARSHIP ONLINE (oxford.universitypressscholarship.com). (c) Copyright Oxford University Press, 2021. All Rights Reserved. An individual user may print out a PDF of a single chapter of a monograph in OSO for personal use. date: 27 November 2021

Symbioses and microbes

Symbioses and microbes

(p.258) Chapter 14 Symbioses and microbes
Processes in Microbial Ecology

David L. Kirchman

Oxford University Press

The book ends with a chapter devoted to discussing interactions between microbes and higher plants and animals. Symbiosis is sometimes used to describe all interactions, even negative ones, between organisms in persistent, close contact. This chapter focuses on interactions that benefit both partners (mutualism), or one partner while being neutral to the other (commensalism). Microbes are essential to the health and ecology of vertebrates, including Homo sapiens. Microbial cells outnumber human cells on our bodies, aiding in digestion and warding off pathogens. In consortia similar to the anaerobic food chain of anoxic sediments, microbes are essential in the digestion of plant material by deer, cattle, and sheep. Different types of microbes form symbiotic relationships with insects and help to explain their huge success in the biosphere. Protozoa are crucial for wood-boring insects, symbiotic bacteria in the genus Buchnera provide sugars to host aphids while obtaining essential amino acids in exchange, and fungi thrive in subterranean gardens before being harvested for food by ants. Symbiotic dinoflagellates directly provide organic material to support coral growth in exchange for ammonium and other nutrients. Corals are now threatened worldwide by rising oceanic temperatures, decreasing pH, and other human-caused environmental changes. At hydrothermal vents in some deep oceans, sulfur-oxidizing bacteria fuel an entire ecosystem and endosymbiotic bacteria support the growth of giant tube worms. Higher plants also have many symbiotic relationships with bacteria and fungi. Symbiotic nitrogen-fixing bacteria in legumes and other plants fix more nitrogen than free-living bacteria. Fungi associated with plant roots (“mycorrhizal”) are even more common and potentially provide plants with phosphorus as well as nitrogen. Symbiotic microbes can provide other services to their hosts, such as producing bioluminescence, needed for camouflage against predators. In the case of the bobtail squid, bioluminescence is only turned on when populations of the symbiotic bacteria reach critical levels, determined by a quorum sensing mechanism.

Keywords:   Microbiome, rumen, bioluminescence, quorum sensing, chemosynthesis, endosymbiont, phyllosphere, arbuscular mycorrhizae, fungus-farming, Symbiodinium

Oxford Scholarship Online requires a subscription or purchase to access the full text of books within the service. Public users can however freely search the site and view the abstracts and keywords for each book and chapter.

Please, subscribe or login to access full text content.

If you think you should have access to this title, please contact your librarian.

To troubleshoot, please check our FAQs , and if you can't find the answer there, please contact us .