## 4 Discussion  
The preservation of industrial heritage sites for research and educational visits is a recent ethno-touristic activity. These include inactive mines, which are reconditioned, aiming to exhibit and make aware of old mining procedures to extract minerals and how in former times they affected the social and economic life in the region. We explored the old Lousal mine, open to visits, for aerobiological studies. The origin and characterization of airborne microorganisms in subsurface environments represent an important research topic when public access is in consideration. The exclusive features of caves and mines determine the presence of microorganisms inside, acting as selective factor and leading to the adaptation of their metabolism. The isolation of _Pseudomonas_ sp., strain L5B5, and its characterization using both in vitro and in silico analyses delve into the metabolic mechanisms and how this bacterium could interact with the environment. Phylogenetic analyses included strain L5B5 in the fluorescent pseudomonads group, where diverse species, such as the opportunistic pathogen _P. aeruginosa_ and the growth-promoting plant _P. protgens_, are included. rRNA 16S gene sequence related strain L5B5  
Figure 9: Heat map for predicted and expressed virulence genes in _Pseudomonas_ sp., strain L5B5. Prediction of genes involved in virulence factors (**right**), and relation of bacterial pathogens (**left**) which own the same factors, according to the VFDB database. with valid species, such as _P. aloputida_, isolated from rhizosphere of bean plant in Iran [81], _P. juntendi_, a bacterium isolated from sample from a sputum sample of a patient in Japan [82] and the closest relative, _P. piscis_, isolated from the head ulcers of farmed Murray cod in China [83], respectively. However, 16S gene phylogenetic tree grouped strain L5B5 with _P. piscis_ in the same branch, while _P. aloputida_ and _P. juntendi_ were located in a distant branch. This result was endorsed with pairwise genome comparison and phylogenomics, where also three strains of _P. protegens_ CHA0, Cab57 and Pf-5 presented a close relatedness. Therefore, strain L5B5 seemed to share competences with both opportunistic pathogens and growth-promoting pseudomonads. The inhibition of _Bacillus cereus_, _Staphylococcus aureus_, and _Acinetobacter baumanii_ in solid cultures with concentrated filtrates from strain L5B5 was remarkable. Recent studies reported the interaction of _P. aeruginosa_ with _S. aureus_, stimulating the vancomycin susceptibility, and _A. baumannii_, PCN mediating [84, 85]. Strain L5B5 had a high effectivity against all tested fungi, originally isolated from subsurface environments. The presence of fungi in caves and mines is directly related with airborne transport, terrestrial environments, including pathogens and plant endophytic species, and insects [26, 86, 87]. Functional annotations from the assembled genome of strain L5B5 showed a significant abundance of genes involved in biological processes such as stress response, virulence, antibiotic resistance, or nitrogen fixation that could also be linked to similar behaviors in relatives. The prediction of secondary metabolites and gene similarities led to the detection of common mechanisms found in the biocontrol of bacteria, such as the specific antimicrobials pyrrolo nitrin, pyoluterin, and phenazines, as well as the combination of phenazines with the cyclic lipopeptides oramides, as reported [PERSON] et al. [58]. The expression of genes involved in the synthesis of these compounds in SGS condition should be definitive to achieve the inhibition of the tested fungi since the activity of these metabolites have been verified separately [88, 89, 22]. However, the absence of phenazines in liquid-cultured conditions placed siderophores as the most likely factor to inhibit the growth of _S. aureus_ and _B. cereus_, since _E. coli_ has been probed to share in common the same binding site that _P.