[Phenotypic variation in Actinobacillus actinomycetemcomitans].
OBJECTIVE
To investigate the colony variation in Actinobacillus actinomycetemcomitans (Aa) from rough to smooth and recognize its different morphology during laboratory translations.


METHODS
Primary strains isolated from subgingival plaque of two juvenile periodontitis patients were repeatedly subcultured on agar plates and broth; for broth culture, every generation was translated in broth and on solid medium separately to observe the corresponding morphologies of Aa grow in broth.


RESULTS
Three smooth strains of Aa from the broth culture were obtained. The process was about 7-8 generations: colonies changed from a small and adherence phenotype to a bigger and sediment ones and finally the culture supernatant became turbid; the corresponding morphologies grow on agar exhibiting an adherent, small rough colony phenotype which had a star-shaped internal structure converted gradually to a kind of bigger, opaque, nonadherent, smooth phenotype, then the colony extended out from the margin of the colony and finally converted to a flat, almost parent morphology and the same time the star-like inner structure converted to a simpler and smaller type and finally disappeared. We could not get completely smooth variants of Aa from agar.


CONCLUSIONS
The variation in colony morphology of Aa from rough to smooth is a process, in which the colony was gradually wetter and bigger and at the same time gradually lost the inner structure. During this process three colony morphologies at least can be seen, including rough, opaque smooth and almost translucent smooth.
Wang
Zhe-ling
ZL
Beijing Institute of Dental Research, Beijing Hospital for Stomatology, Capital University of Medical Sciences, Beijing 100050, China.
Maeda
Nobuko
N
Ohshima
Tomoko
T
Takao
Ayako
A
Yang
Sheng-hui
SH
Li
Jin-lu
JL
D016976:Aggregatibacter actinomycetemcomitans / Q000235:genetics* / Q000254:growth & development*; D002455:Cell Division / Q000235:genetics; D002648:Child; D015169:Colony Count, Microbial; D003773:Dental Plaque / Q000382:microbiology; D014644:Genetic Variation; D006801:Humans; D010518:Periodontitis / Q000382:microbiology; D010641:Phenotype; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D013045:Species Specificity
D012336:RNA, Ribosomal, 16S