# Unveiling Biological Activities of Marine Fungi: The Effect of Sea Salt
## 4 Discussion
The escalation of antibiotic-resistant infections globally during the last few decades imposes the need to search for new antimicrobial compounds and measures to contain the dispersion of this type of resistance. Therefore, the antibacterial activity exhibited by _A. affinis_ (CMG 70) and _Pen. lusitanum_ (MUM 18.49/CMG 8) against _K. pneumoniae_ and _P. aeruginosa_ suggests that these strains can be potential sources of antibacterial molecules. Additionally, as observed in enzymatic assays, variations between saline and non-saline culture conditions in antibacterial activity were detected, i.e., the presence or absence of salt affected the production of active metabolites. _Penicillium_ species are important producers of antibacterial compounds, but only a few are reported to produce antifungal substances. In this study, both mycelium and culture medium extracts of _Pen. lusitanum_ showed a higher inhibitory effect on the _C. albicans_ strains tested than the cycloheximide control. These results suggest that _Pen. lusitanum_ (MUM 18.49/CMG 8) could be a source of compounds useful in anti-_Candidida_ therapy, but more studies are necessary to confirm this. Moreover, [PERSON] et al. [78] reported the presence of two metabolites of _Pen. simplicissimum_ active against other filamentous fungi and yeasts, such as _C. albicans_ and _Cryptococcus neoformans_. [PERSON] et al. [79; 80] also isolated metabolites from a marine _Penicillium_ sp. able to inhibit the growth of a methicillin-resistant _S. aureus_, _E. coli_, and of _C. albicans_. Currently, candidiasis represents the fourth leading cause of nosocomial infections, and mortality remains highly dependent on the infecting _Candidia_ species [81] and on the immune state of the patient [82]. Over the last two decades, the number of infections caused by non-_C. albicans_ species (including _C. glabrata_, _C. parasilosis_, and _C. tropicalis_, that we used in this study) has increased considerably [83]. Clinical manifestations of candidiasis in humans are diverse and the patients can show several symptoms, such as stomatitis, gastritis, pneumonia, lung empyema,ystitis, meningitis, otitis, vulvovaginitis, and others [81]. Some _Candidia_ strains are resistant to some topical and systemic antifungals used in the management of candidiasis, such as funconazole, benomyl, or cycloheximide [84,85]. We also observed the resistance of _C. albicans_ to cycloheximide, but little is known about the factors involved in the mechanisms of resistance. Resistance to this antimycotic has already been reported in _C. maltosa_ involving the _CYHR_ gene, which confers this resistance, and in _Saccharomyces cerevisiae_ linked to mutations in ribosomal proteins [85]. All crude culture medium extracts of the fungal species tested induced 100% cytotoxicity at 500 mg/mL against a mammalian cell line (Vero cells). We showed that cytotoxicity was concentration dependent, and cell viability was observed only after fungal extract dilution. The data suggest that the fungal extracts were more cytotoxic when species were cultured in the presence of sea salt. _Aspergillus affinis_ and _Pen. lusitanum_, which exhibited effective antibacterial activity were highly cytotoxic. Some studies have already reported the cytotoxicity evaluation in cancer cell lines of compounds produced by fungal marine species, including _Aspergillus_, _Caldosporium_, _Penicillium_, and _Trichoderma_[86, 87, 88]. In fact, marine fungi with the ability to synthesize cytotoxic compounds showed the potential for the treatment of cancer diseases [89]. Further studies using the extracts that did not induce Vero cells mortality are required to evaluate the cytotoxicity on cancer cell lines for cancer research purposes. In the last few years, natural antioxidants have generated considerable interest in medicine and in the food industry. In consequence, attention has been focused on the characterization of the antioxidant properties of medicinal plant extracts, spices, and mushrooms [90].