The world of Bacteria II Ordinary Gram Positive Bacteria.

1. The world of Bacteria II:
“Ordinary” Gram-Positive Bacteria
Anil Shrestha
Msc Medical Microbiology

2. 1) Aerobic/ Facultatively Anaerobic
Cocci
• They possess cytochrome.
• They are able to respire with oxygen, i.e., have
an oxidative type of metabolism.
• Some can also obtain energy under anaerobic
conditions by fermentation (have a
fermentative type of metabolism).
Deinococcaceae and Micrococcaceae is the
family for this organism.

3. DEINOCOCCACEAE
• The cocci occur mainly in tetrads or cubical
packets.
• The organisms have an unusually high
resistance high resistance to gamma and
ultraviolet radiation.
• Eg: Deinococcus radiodurans

4. MICROCOCCACEAE
• The cocci occur mainly in clusters, tetrads, or cubical
packets of eight cells.
• The cells donot exhibit any unusal resistance to gamma
and ultraviolet radiation.
The genera included are
Micrococcus:- 1) nonmotile, aerobic, oxidative, catalase
positive.
Planococcus:- 1) motile, aerobic, oxidative, catalase
positive.
Staphylococcus:- nonmotile, facultative anaerobes,
fermentative, catalase positive.

5. 2) Aerotolerant fermentative cocci
• They do not possess cytochromes.
• They have only a fermentative type of
metabolism and do not respire; yet they can grow
anaerobically or aerobically.
• The cells are arranged in pairs, chains, or tetrads.
Streptococcus:- arranged in pair or chains, catalase
negative, homofermentative.i.e, the predominant
end product of sugar fermentation is lactic acid.

6. • Lancefield grouping is a method of grouping catalase-negative,
coagulase-negative bacteria based on the carbohydrate
composition of bacterial antigens found on their cell walls.
• Classification
• Group A - Streptococcus pyogenes
• Group B - Streptococcus agalactiae
• Group C - Streptococcus equisimilis, Streptococcus equi,
Streptococcus zooepidemicus, Streptococcus dysgalactiae
• Group D - Enterococci, Streptococcus bovis
• Group E - Streptococcus milleri and mutans
• Group F - Streptococcus anginosus
• Group G - Streptococcus canis and Streptococcus dysgalactiae
• Group H - Streptococcus sanguinis
• Group L - Streptococcus dysgalactiae
• Group M - Streptococcus fryi sp. nov
• Group N - Lactococcus lactis
• Group R&S - Streptococcus suis
• other Streptococcus species are classified as 'non-Lancefield
Streptococci'

7. • Though there are many groups of
streptococcus, only five are known to
commonly cause disease in immune-
competent human beings: Group A, Group B,
both members of Group D, and two groups
that lack the Lancefield carbohydrate antigen:
Streptococcus pneumoniae and Viridans
streptococci.

8. Leuconostoc :-
• Cocci are arranged in pairs and chains.
• Catalase negative
• Heterofermentative; produce CO₂ and ethanol or acetic
acid in addition to lactic acid.
Pediococcus :-
• Cocci occur in pairs and tetrads.
• Catalase negative.
• Exhibit homolactic type of fermentation.
Pediococci are saprophytes and are particularly noted for
their ability to form capsular material that causes beer to
become ropy and viscous.

9. 3) Anaerobic Gram Positive Cocci
• These cocci have a fermentative type of
metabolism. Some genera must be supplied
with a fermentable carbohydrate in order to
grow; others can ferment amino acids and do
not require carbohydrates. Lactic acid is not a
major fermentation product. Most genera
form CO₂, H₂, short-chain fatty acids, and in
some cases ethanol or succinic acid.

10. Genus Arrangement of
Cells
Main Sources of
Carbon and Energy
Occurrence
Peptococcus Pairs, clusters,
tetrads, and short
or long chains
Peptone or amino
acids
Human intestine
and respiratory
tract; clinical
specimens
Peptostreptococcus Pairs and short or
long chains
Peptone or amino
acids
Human clinical
specimens
Ruminococcus Pairs and short or
long chains
Carbohydrates Bovine and Ovine
rumen
Coprococcus Pairs and short or
long chains
Carbohydrates Human feces
Sarcina Cubical packets of
eight cells
Carbohydrates Soil; mud; cereal
grains; diseased
human stomachs

11. Endospore-forming Gram-Positive
bacteria

12. Aerobic/Facultatively Anaerobic
Sporeforming Rods and Cocci
Bacillus
• Rod-shaped bacteria.
• Most species are harmless saprophytes occurring in
soil, freshwater, or sea water.
• Many form exocellular enzymes that hydrolyze proteins
or complex polysaccharides, activities that are often
important causes of food spoilage.
• Because of the heat resistance of endospores, Bacillus
species may species may survive milk pasteurization or
inadequate heat treatment during canning of foods.
• Eg:- B. stearothermophilus, B. polymyxa, B.
thuringiensis, B. anthracis

13. Sporosarcina
• Cocci arranged in tetrads or cubical packets of
eight cells
• Widely distributed in fertile soil, where they
play an active role in the decomposition of
urea.

14. Anaerobic spore-forming Rods
• Clostridium :- have fermentative type of
metabolism
– C. botulism
– C. tetani
– C. perfringens
– C. thermosaccharolyticum

15. • Desulfotomaculum
– Obtain energy by anaerobic respiration, with
sulfate serving as the terminal electron acceptor
and organic substrates such as lactic or pyruvic
acid serving as electron donor. Large amounts of
H₂S are formed during growth.

16. Non spore forming Gram-Positive rods
of Regular shapeGenus Morphology and
Motility
Oxygen
Relationship
Catalase test
Lactobacillus Long to very short
rods, often in
chain; usually
motile
Strictly
fermentative
organism, but can
usually tolerate air;
some strains are
anaerobic
Negative
Listeria Very short rods,
often in chains;
motile by
peritrichous
flagella
Aerobic to
microaerophilic
Positive
Erysipelothrix Filament-forming
rods; nonmotile
Aerobic Negative

17. Non sporeforming Gram-positive rods
of irregular shape

18. Aerobic/Facultatively anaerobic
nonfilamentous rods
• Straight to slightly curved rods that exhibit
swellings, club shapes, or other deviations
from a uniform rod shape.
• An aerobic or facultatively anaerobic nature,
being capable of a respiratory type of
metabolism and in some instances also of a
fermentative type of metabolism.
Eg:- Corynebacterium

19. Anerobic nonfilamentous or
filamentous rods
• Actinomyces ( Facultative anaerobes)
• propionibacterium

20. • Mycobacterium
• Nocardia