Anaerobes play an important role in the microbial world. They are classified into different categories based on their oxygen requirement also there are different types of media for their growth. The different types of anaerobes and cultivation media will be discussed in this presentation

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ANAEROBIC BACTERIA TYPES AND ITS
CULTIVATION
PRESENTED BY- Aditi Kar
COURSE- BACTERIOLOGY
(MBT601)
ROLL. No- A0999321017
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CONTENTS
• Introduction
• Types based on O2 requirement
• Types based on other features
• Lab diagnosis
• Cultivation
• References
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What is an anaerobe?
An anaerobe is any organism that does not require molecular
oxygen for growth. It may react negatively or even die if free
oxygen is present. In contrast, an aerobic organism (aerobe) is an
organism that requires an oxygenated environment.
First observation of an anaerobe was
by Antonie van Leeuwenhoek. He
had had cultivated and seen genuine
anaerobic bacteria, which would
happen again only after 200 years,
namely about 1862 by Pasteur.
Word origin: from French
anaérobie, coined in
1863 by Louis Pasteur,
from Greek an-
(“without”) + aer (“air”) +
bios (“life”).
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Classification based on their oxygen requirement
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 AEROBES grow in ambient conditions that are 21% oxygen and 0.3% carbon
dioxide. (Bacillus cereus)
 OBLIGATE AEROBES strictly require oxygen for their growth. (Pseudomonas
aeruginosa)
 MICROAEROPHILIC can grow under reduced oxygen (5-10%) and increased
carbon dioxide (8-10%). (Campylobacter jejuni and Helicobacter pylori)
 FACULTATIVE ANAEROBES are capable of growth under both aerobic and
anaerobic conditions. (Enterobacteriaceae group, Staphylococcus aureus).
 AEROTOLERANT ANAEROBES that are not killed by exposure to oxygen.
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Lab Diagnosis
Anaerobes cause serious infection when they have access to
normally sterile body fluid or deep tissue that is poorly oxygenated.
The second source of anaerobic infection occurs from the
introduction of spores into a normally sterile site.
 Anaerobic infections are most likely to be found in persons who are
immunosuppressed.
 Identified by their colonial and microscopic morphology, growth on
selective media, oxygen tolerance, biochemical characteristics,
susceptibility to antibiotics
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Cultivation
• Anaerobic bacteria culture is a method used to grow anaerobes from
a clinical specimen.
• Cultures should be placed in an environment that is free of oxygen,
at 35°C for at least 48 hours before the plates are examined for
growth.
• Most strict anaerobes require not only the absence of oxygen to
initiate growth, but also a redox potential below -300mV, which can
be only achieved by the supplementation of media with reducing
agents. 9

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ANAEROBIC MEDIA
The media is also contained 1% glucose, 0.1% thioglycolate, 0.1%
ascorbic acid, 0.05% cysteine or red hot iron filings. Before using the
medium is to be boiled in a water bath to expel any dissolved oxygen
and then sealed with sterile liquid paraffin.
• Thioglycolate Broth
a) multi-purpose & enriched differential medium used primarily to
determine the oxygen requirements of microorganisms.
b) It consumes oxygen and permits the growth of obligate anaerobes.
c) The broth produces a range of oxygen concentrations in
the media along with its depth, indicated by a redox
sensitive dye like resazurin that turns pink in the presence of oxygen.
d) Can be used for both aerobes and anaerobes. 10

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Non-selective media
1. Anaerobic blood agar: It is a nonselective the medium for the
isolation of anaerobes and facultative anaerobes.
2. Egg-yolk agar (EYA): Nonselective for determination of
lecithinase and lipase production by clostridia and fusobacteria.
3. Cooked meat broth: Nonselective for the cultivation of anaerobic
organisms; with the addition of glucose, can be used for gas-liquid
chromatography.
4. Peptone-yeast extract glucose broth (PYG): Nonselective for
cultivation of anaerobic bacteria for gas-liquid chromatography.
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Selective and differential media
1. Bacteroides bile esculin agar (BBE): It is selective and differential
for Bacteriodes fragilis group and good for presumptive identification.
2. Laked Kanamycin-vancomycin blood agar (LKV): It is selective
for isolation of Prevotella and Bacteroides spp.
3. Anaerobic phenyl ethyl alcohol agar (PEA): Selective for inhibition
of gram-negative rods and swarming by some clostridia.
4. Cycloserine cefoxitin fructose agar (CCFA): selective for
Clostridium difficile.
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Special Culture Techniques
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Anaerobic jar
Candle jar Gas Pack

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References
• https://www.ncbi.nlm.nih.gov/books/NBK572753/
• https://microbeonline.com/oxygen-requirements-for-
pathogenic-bacteria/
• https://www.slideshare.net/doctorrao/anaerobic-
bacteriology
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