Introduction
The Agnano thermal spring water (ATSW), located in the largest thermal basin in Italy with its 72 springs of various nature and characteristics, have been the best expression of this for millennia. Already in the first century. a.C., the Hellenists understood its high curative value, both physical and spiritual, later in the second century. d.C. the Romans began to build structures for the exploitation of these portentous waters. Indeed, with the allocation of the Romans in Flegrea Area began the real thermal activity across the Campi Flegrei. The impressive thermal spa of the Hadrian era (117-138 d.C.) which stands on the south-western side of the Agnano basin, on the slopes of Monte Spina, testifies that thermalism was widespread in Agnano. The benefits of thermal spring water in the treatment of various diseases have been known since ancient times. In fact, thermal spring water has therapeutic functions and can be used in the treatment of various dysfunctions, from respiratory and rheumatic diseases to gynecological and gastrointestinal diseases. Today it is known that thermal spring water acts effectively on various physiological and pathological processes such as: skin regeneration (Liang et al., 2015), cardiovascular diseases (Oyama et al., 2013) and bone diseases (Fioravanti et al., 2011) and most of these beneficial effects depend on the chemical and physical properties of water.
However, all the benefits of thermal spring water, such as improved migration and cell proliferation or anti-inflammatory and regenerative properties, may not be fully explained only by its mineral composition. In this regard, it is known that non-pathogenic bacterial populations play an active role in various processes in the ecological and biological fields (Nicoletti et al., 2015; Zeichner et al., 2018). Maintaining the physiological intestinal well-being is a clear example of how a bacterial microflora is essential for regulating homeostasis, metabolic functions and the immunological response (Sommer et al., 2017).
Sulfurous waters are the most numerous in Italy and the presence of H2S influences immunological response (Valitutti et al., 1990) and have beneficial effects on neurodegenerative disorders, respiratory tract (Keller et al., 2014) and in particular on cardiac functions, as also carbonic waters.
Agnano’s thermal baths belong to the largest volcanic area of the Mediterranean Sea (ca 400 Kmq). It is the only example of thermal spring water extended in urbane area with a huge impact landscape and a great archeological significance. The Agnano thermal spring water (ATSW) is mainly a salso-bromo-iodic-bicarbonate-alkaline-sulphurous water. Thanks to the variability of the temperature and the abundance of mineral elements (sodium chloride, iodine, bromine, calcium, bicarbonate, sulphides), a great number of different disorders can be treated (cardiovascular, gynecological, dermatological and rheumatic).
The aim of the present study is the microbiological characterization of ATSW through the use of two distinct methods in order to determine the total viable bacterial community.