Dictionary » F » Facultative




(1) Not compulsory; not restricting.

(2) Of, or relating to, mental faculty.

(biology) Capable of existing to more than one set of (environmental) conditions or by assuming various behaviors.


For example, facultative bacteria can thrive in both aerobic and anaerobic environments.

Word origin: NL facultātīvus.
Related forms: facultatively (adjective).

Compare: obligate (biology).

Related terms:

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Help with unknown

... flexneri Shigella sonnei Proteus vulgaris Proteus mirabilis Here are the test results I ran for my unknown: It is a Gram-negative bacillus facultative anaerobe Motility + Citrate + MR - (Unsure of the MRVP results, so not using it as a reliable test) VP - Sulfur - Indole - Catalase + Oxidase/Kovac's ...

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by kayleighat
Sun Oct 20, 2013 2:43 am
Forum: Microbiology
Topic: Help with unknown
Replies: 0
Views: 3951

Help! "Unknown Bacteria" I have no idea where to look =T

... a positive gelatin hydrolysis result. I am at a complete loss of which direction to look as far as what my bacteria is. I asked my instructor if a facultative anaerobe could produce oxidase, and she told me "No, due to only certain aerobic bacteria produce cytochrome C." I am hoping you ...

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by stephanie1234
Mon Dec 03, 2012 4:44 am
Forum: Microbiology
Topic: Help! "Unknown Bacteria" I have no idea where to look =T
Replies: 1
Views: 4079

How does pH change during sporulation? - Help

... added/removed. At first I thought maybe it had to do with lactic acid production if the thing is anaerobic...but I think my species is aerobic/facultative (commonly found in soil, actually). So I really doubt it would've produced any acid to result in that change in pH. But this was just a ...

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by keetner
Mon Oct 22, 2012 10:22 pm
Forum: Microbiology
Topic: How does pH change during sporulation? - Help
Replies: 2
Views: 2094

Please Help Identify My Unkown Bacteria!!

... appreciated. Initial Observation: opaque/ off white, slightly clump, slight growth on nutrient agar Presumed Optimum temp: 37C Oxygen Requiremets: Facultative Anerobe Bacillus shape (small rods) gram negative non spore forming not acid fast NEGATIVE for casein, starch hydrolysis Produces acid reaction ...

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by KingsMomi
Tue Jul 31, 2012 3:40 am
Forum: Microbiology
Topic: Please Help Identify My Unkown Bacteria!!
Replies: 2
Views: 5051

Unknown Organism

... is motile 15. LIA Ferments dextrose only, no lysine deaminase* 16. TSI Ferments dextrose, lactose and/or sucrose I am 95% positive it is a facultative anaerobe. The ones marked with a "*" I am not completely sure about... My partner and I had varying opinions. Explanations are ...

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by CheriPeace
Fri Jun 29, 2012 9:08 pm
Forum: Microbiology
Topic: Unknown Organism
Replies: 5
Views: 6023
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