H serotyping
The work presents the results of analyzing the H-serotypes of B.
thuringiensis isolates secluded from the feces of 20 animal species. Of
the 190 isolates, 166 were from 14 mammalian species, 20 were obtained
from 5 reptile species and 4 bird species. The obtained bacterial
populations were assigned to 8 serotypes: H31, H6, H3abc, H7, H4ab/43,
H5ab/21, H8ab, and H9. There were 3 atypical samples in the analyzed
populations, as well as 65 that were not verified. Serotype analysis
showed that H3abc dominated, accounting for 82.0% of the 122 serotyped
isolates, H6 serotype was much less common (8.5%). The remaining 6
serotypes accounted for only up to 1.5% (Fig. 1). The resulting
isolates could be multiples of the same organism.
[Fig. 1 here]
The PCR images of B. thuringiensis serotypes are given in Fig. 2.
[Fig. 2 here]
In the feces of several herbivores, isolates belonging to H3abc were
ubiquitous, accounting for 89% of B. thuringiensis populations.
Examples included the feces of anthropoids and bears.
Arginine hydrolase (ADH) was used as a factor for serotype
identification. Urease reducing enzymes, nitrate reducing enzymes, and
enzymes involved in the degradation of sucrose, mannose, cellobiose, and
salicin were also used. This also includes enzymes involved in the
production of acetyl methyl carbinol (AMC). The latter reaction may be
negative only in some cases. All of the above features were used to
analyze different antigenic subgroups belonging to different serotypes
as well as to analyze a number of isolates that belonged to certain
serotypes. Isolates belonging to the same serotype may have certain
differences. In particular, six isolates of serotype H8ab were similar
in the main characteristics. At the same time, to confirm the hypothesis
of similar main characteristics in one serotype, it is necessary to test
a larger number of samples.