Results and Discussion
Microbiological analyses for the two collections of ATSW, “Nuove Terme
di Agnano srl”, was performed during the winter and autumn seasons
through two procedures, in order to increase the yield for the
microbiological characterization. The two procedures, filtration and
enrichment, highlighted in both sampling the abundance of bacterial
species belonging mainly to three different phyla: Actinobacteria,
Firmicutes and Proteobacteria with a prevalence of species belonging to
the phylum Firmicutes (Table 2). The filtration procedure determined the
isolation of four bacterial isolates for winter sampling and ten
isolates form autumn sampling, while the enrichment method revealed the
presence in thermal water of sixteen different bacterial species for
winter sampling and eight bacterial species for autumn sampling (Table
3). The analysis showed a difference between the bacterial populations
associated with seasonal changes, highlighting a majority of species
belonging to the genus Staphylococcus , with a prevalence of
Coagulase-negative Staphylococci (ConS) for winter sampling using
enrichment procedure, and the genus Bacillus for autumn sampling,
using both procedures. To underline, the species Pseudomonas
stutzeri and Bacillus subtilis have been isolated from cultures
incubated at 50°C for autumn sampling.
The most represented phylum, Firmicutes, mainly includes gram-positive
species with a genome characterized by a low GC content and includes
several mobile and capable of forming endospores species (Schleifer,
2009). The members of this phylum are abundant in soil and water where
they are involved in the decomposition and recycling of organic matter
(Gibbons and Murray, 1978). However, different genera of phylum
Firmicutes belong to the normal human flora or can be associated with
diseases in humans and animals (Baik et al., 2008). Moreover, some
members of this phylum may have an industrial use for the production of
enzymes or antimicrobial and antifungal activities, such as the speciesLactobacillus plantarum , which is used in the food industry, andBacillus pumilus , which has an antimicrobial activity towardsVibrio spp. and fungicide (Liu et al., 2012) (both isolated
during the autumn sampling by filtration procedure).
Within the phylum Proteobacteria, in particular, in the Gamma
proteobacteria some Pseudomonas spp. like P. luteola andP. stutzeri , could be relevant because they are both involved in
bio-absorption’s mechanisms. P. luteola is involved in
bio-absorption processes of heavy metals such as chromium and aluminum
in acid environments, metal ions often present in industrial waste water
and is also involved in the absorption of copper and nickel as it is a
producer of exopolysaccharide (Ozdemir and Baysal, 2004). Also, the
species P. stutzeri is considered an excellent candidate for the
simultaneous absorption of nitrogen and phosphate in waste water, in
fact it oxidizes ammonia exhibiting the ability of nitrification and
denitrification as well as the ability to degrade organophosphorus
pesticides (Ozdemir et al., 2005).
Among the identified phyla is represented, although to a lesser extent,
the phylum Actinobacteria. To this phylum belong different genera of
Gram positive bacteria present both in terrestrial and aquatic
environments. These microorganisms have a great importance for the human
being since agriculture and forests depend on the contribution of these
bacteria to the processes that take place in the soil. In this
environment, the Actinobacteria grow with characteristics similar to
fungi, forming extensive structures similar to mycelia, favoring the
decomposition of the organic matter of dead organisms so as to provide
the essential elements for plant growth (Servin et al., 2008).
Therefore, the ATSW analyzed is rich in non-pathogenic bacteria that may
play a role in treating various skin disease (Balato et al., 2019). As
ATSW contains live bacteria that could impact the skin’s microbiota, the
water itself is considered to be a probiotic (Zeichner et al., 2018).
Although probiotics have been widely used in the past for the
treatment/prevention of gastrointestinal disorders, a growing number of
evidences has suggested that they can modulate the composition of
microbial community, exerting their healthy effect directly or
indirectly on the skin (Balato et al., 2019; Zeichner et al., 2018).
Moreover, the ATSW is a rich source of minerals. About 31 minerals have
been identified of which 17 are found as major ions (>/=
0,4 mg/l) like chloride, sodium, bicarbonate, sulphate, carbon dioxide,
potassium, silicon, calcium, magnesium, boron, ammonium, bromide,
strontium, litium, fluoride, manganese, arsenic.
Sodium helps to maintain the suppleness of skin due to its water-holding
capacity. Hence it is very useful in dry dermatoses like psoriasis and
ichthyosis. It also helps in desquamation of hyperkeratotic lesions
(Rivaz et al., 2011).
Noteworty, among cations of interest, Mg2+ and
Ca2+ have been recognized for their benefits in skin
barrier recovery (Denda et a., l999). In normal skin, magnesium and
calcium ions were localized with a high concentration in the upper
epidermis (Proksch et al., 2005). After barrier disruption, the
gradients of calcium, magnesium, and potassium in the epidermis
disappeared while the pH was not altered (Denda et a., l999). Loss in
the ion gradient is a signal for an increase in proliferation,
differentiation and lipid synthesis aimed to repair the perturbed
barrier (Lee et al., 1992, Denda et al., 2003). Magnesium is also
essential for cell metabolism. It helps in maturation and
differentiation of keratinocytes. Hence it is very useful in psoriatic
patients who have a low magnesium level in the serum and scales (Rivaz
et al., 2011). Calcium-and magnesium-rich thermal spring waters are
known to improve skin barrier function and accelerate wound healing
(Proksch et al., 2005).
Moreover, the soothing and protective properties of thermal spring
waters in sensitive skin (antioxidant or anti-ageing) are enhanced by
the presence of trace elements such as selenium, strontium (Celerier et
al., 1995). These properties have been demonstrated in many studies
using human keratinocytes, fibroblasts or other response-appropriate
cell lines (Seite et al., 2013; Joly et al., 1998). Furthermore, a
recent study demonstrated the activity of salso-bromo-iodine water on
mucous-secretory disorders, in particular it helped to improve the
relationship between the mucous-protein complexes and the water:
initially, this action was congestive, subsequently, it became an
anti-catarrhal, anti-inflammatory, antiseptic and immunostimulant action
(La Mantia et al., 2018).
The ATWS for its mineral composition and microbial diversity exhibits
both prebiotic and probiotic characteristic, thus it will be analyzed
for its anti-inflammatory and regenerative properties in an in
vitro system.