The abundance and predominant groups of
bacteria, filamentous fungi and yeasts have been studied by
culture-dependent microbiological methods in peat probes
obtained in two Latvian balneotherapy spa sites, Kemeri
and Baldone. Unsterilized peat samples from both the sites
contained 5.7–8.1 log bacterial colony-forming units
(CFU) and 3.0–5.3 log fungal CFU per gram of dry peat.
Isolated species belonged to
Alpha-,
Beta-, and
Gamma- Proteobacteria
,
Actinobacteria
,
Clostridia
,
Bacilli
and
Flavobacteria
as well as to filamentous fungi and yeasts.
The composition of microbial population of the peat from
both sites shared just four micro-organism groups (
Bacillus
mycoides
,
Burkholderia cepacia
,
Streptomyces
spp. and
Trichoderma
spp.) within totally 36 groups identified. No
pathogenic bacteria or fungi and no faecal pollution indicators
were recovered. Decimal reduction doses for microorganisms
in peat samples and radiation sterilization doses
of peat for the gamma and electron beam radiation were
determined. The highest radiation resistance was observed
for
B. mycoides and
Aureobasidium sp. Gamma-sitosterol
was the most abundant hydrophobic organic compound in
both peats according to GC–MS data. All the sterilization
procedures increased concentration of alkanes, alcohols,
and ketones and decreased the amount of fatty acids. Heat
sterilization proved to be more preserving for the peat
sterols than the radiation sterilization. It is concluded that
the heat and radiation sterilization methods induce different
changes of the profile of hydrophobic organic compounds
of balneological peats, what may lead to different therapeutic
effects at their application.
