''Streptococcus mitis'' is a

mesophilic A mesophile is an organism that grows best in moderate temperature, neither too hot nor too cold, with an optimum growth range from . The optimum growth temperature for these organisms is 37°C. The term is mainly applied to microorganisms. Org ...

alpha-hemolytic species of ''

Streptococcus ''Streptococcus'' is a genus of gram-positive ' (plural ) or spherical bacteria that belongs to the family Streptococcaceae, within the order Lactobacillales (lactic acid bacteria), in the phylum Bacillota. Cell division in streptococci occu ...

'' that inhabits the oral cavity. It is coccus (spherical shaped), gram-positive, catalase negative, and facultative anaerobe. It was previously classified as ''Streptococcus mitior''. Streptococcus mitis is known to cause several medical conditions one of them being

infective endocarditis Infective endocarditis is an infection of the inner surface of the heart, usually the valves. Signs and symptoms may include fever, small areas of bleeding into the skin, heart murmur, feeling tired, and low red blood cell count. Complication ...

Classification

Members of the Streptococcus genera belong to lactic acid bacteria defined by the formation of lactic acid as an end-product of carbohydrate metabolism. The family ''Streptococcaceae'' is characterized by based upon its 16S rRNA gene sequence analysis within the low (< 50 mol%) G+C branch. There are over 50 species in the genus which are classified by their 16S rRNA sequences.

Habitat

''Streptococcus mitis'' primarily resides in the oral cavity which includes the mouth, nasopharynx, and throat. However, there have also been cases of it in the female genital tract, the gastrointestinal tract, and even in the integumentary system.

Natural genetic transformation

''S. mitis'' is competent for natural genetic transformation. Thus ''S. mitis'' cells are able to take up exogenous DNA and incorporate exogenous sequence information into their genome by

homologous recombination Homologous recombination is a type of genetic recombination in which genetic information is exchanged between two similar or identical molecules of double-stranded or single-stranded nucleic acids (usually DNA as in cellular organisms but may be ...

. These bacteria can employ a predatory fratricidal mechanism for active acquisition of homologous DNA.

Moon Surveyor 3 Probe

Approach

It has been reported that ''Streptococcus mitis'' identified and survived for over two years on the Surveyor 3 probe on the Moon. However, many NASA scientists speculate that this is most probably due to contamination upon return to Earth. The Apollo 12 crew received pieces of Surveyor in 1969, one of these was the TV camera. The probe was then analyzed to consider how the lunar environment affected the material. Surveyor 3 had not been sterilized before its launch because scientists wanted to see if organisms could survive the two and half years on the moon, so looking for surviving organic material was a part of this analysis.

Results

Upon inspection, a group found an amount of ''S. mitis'' inside a piece of foam located inside the camera. Culture plates were made and the identity was later confirmed as ''Streptococcus mitis'' at the US Communicable Disease Center at Atlanta, Georgia. At first, it was speculated that ''S. mitis'' had been picked up from the moon but research later discovered that the residence of the bacteria on the probe had started after the probe returned.

Characteristics of ''Streptococcus mitis''

References

External links

S. mitis subdural empyema
from MedPix
Type strain of ''Streptococcus mitis'' at Bac''Dive'' - the Bacterial Diversity Metadatabase
Streptococcaceae Gram-positive bacteria {{Bacilli-stub