Aerobic and anaerobic bacteria can be identified by growing them in test tubes of thioglycollate broth: 1: Obligate aerobes need oxygen because they cannot ferment or respire anaerobically. They gather at the top of the tube where the oxygen concentration is highest. 2: Obligate anaerobes are poisoned by oxygen, so they gather at the bottom of the tube where the oxygen concentration is lowest. 3: Facultative anaerobes can grow with or without oxygen because they can metabolise energy aerobically or anaerobically. They gather mostly at the top because aerobic respiration generates more ATP than either fermentation or anaerobic respiration. 4: Microaerophiles need oxygen because they cannot ferment or respire anaerobically. However, they are poisoned by high concentrations of oxygen. They gather in the upper part of the test tube but not the very top. 5: Aerotolerant organisms do not require oxygen as they metabolise energy anaerobically. Unlike obligate anaerobes however, they are not poisoned by oxygen. They can be found evenly spread throughout the test tube.
When obligate aerobes are in a temporarily oxygen-deprived environment, they need survival strategies to avoid death.[8] Under these conditions, Mycobacterium smegmatis can quickly switch between fermentative hydrogen production and hydrogen oxidation with either oxygen or fumarate reduction depending on the availability of electron acceptor.[8] This example is the first time that hydrogen production has been seen in an obligate aerobe.[8] It also confirms the fermentation in a mycobacterium and is evidence that hydrogen plays a role in survival as well as growth.[8]
Problems can also arise in oxygen-rich environments, most commonly attributed to oxidative stress. This occurrence is when there is an imbalance of free radicals and antioxidants in the cells of the organism, largely due to pollution and radiation in the environment. Obligate aerobes survive this phenomenon by using the organism's immune system to correct the imbalance.[9]
^ a b c d ePrescott LM, Harley JP, Klein DA (1996). Microbiology (3rd ed.). Wm. C. Brown Publishers. pp. 130–131. ISBN 0-697-29390-4.
^ a b c d e f"Obligate aerobe - definition from Biology-Online.org." Biology Online. Biology-Online, n.d. Web. 12 Dec 2009. <http://www.biology-online.org/dictionary/Obligate_aerobe>
^Hogg, S. (2005). Essential Microbiology (1st ed.). Wiley. pp. 99–100, 118–148. ISBN 0-471-49754-1.
^WI, Kenneth Todar, Madison. "Nutrition and Growth of Bacteria". textbookofbacteriology.net. Retrieved 2021-04-20.{{cite web}}: CS1 maint: multiple names: authors list (link)
^Levinson, W. (2010). Review of Medical Microbiology and Immunology (11th ed.). McGraw-Hill. pp. 150–157. ISBN 978-0-07-174268-9.
^Ryan KJ; Ray CG, eds. (2004). Sherris Medical Microbiology (4th ed.). McGraw Hill. pp. 460–462. ISBN 0-8385-8529-9.
^ a bFischer, Marco; Alderson, Jesse; van Keulen, Geertje; White, Janet; Sawers, R. GaryYR 2010 (2010). "The obligate aerobe Streptomyces coelicolor A3(2) synthesizes three active respiratory nitrate reductases". Microbiology. 156 (10): 3166–3179. doi:10.1099/mic.0.042572-0. ISSN 1465-2080. PMID 20595262.{{cite journal}}: CS1 maint: numeric names: authors list (link)
^ a b c dBerney, Michael; Greening, Chris; Conrad, Ralf; Jacobs, William R.; Cook, Gregory M. (2014-08-05). "An obligately aerobic spirillum fermentative hydrogen production to survive reductive stress during hypoxia". Proceedings of the National Academy of Sciences of the United States of America. 111 (31): 11479–11484. Bibcode:2014PNAS..11111479B. doi:10.1073/pnas.1407034111. ISSN 0027-8424. PMC 4128101. PMID 25049411.
^"What is oxidative stress? Effects on the body and how to reduce". www.medicalnewstoday.com. 2019-04-03. Retrieved 2021-05-08.