## 2 Results and Discussion
### Antifungal Activity  
The experiment aimed to gain insight into the antifungal activity of two extracts of FD-CB, not to investigate the extracts chemical composition or to identify the compounds responsible for the noted activity. Two solvents of different polarity (H\({}_{2}\)O and dimethyl sulfoxide (DMSO)) were used for the extraction of FD-CB. The antifungal activity of the extracts was determined against the most common and problematic fungal species with regard to regulated and emerging mycotoxin production. The obtained results are given in Table 3. The extracts exhibited a relatively low antifungal effect to most common cereals associated mycotoxicine fungi (_Alternaria alternata_, _Aspergillus flavus_, _Aspergillus ochracaeus_, _Fusarium granimearum_, and _Fusarium verticillioides_), and relatively good antifungal effect (MIC\({}_{50}\) at 50 \(\mu\)g/mL DMSO extract) to fruit associated storage fungi _Penicillium expansum_. When comparing both extracts, there is a significant difference in the antifungal effect suggesting that different components or their concentrations were extracted by two solvents. _Fusarium_ spp. was more susceptible to high concentrations of H\({}_{2}\)O extracts, while _P. expansum_, _A. flavus_, and _Rhizoplus_ spp. were more susceptible to DMSO extracts, although detected MIC\({}_{50}\) concentrations were several orders of magnitude higher compared with the reference standards (_Amphotericin B_, _Itraconazole_, _Posaconazole_, and _Voriconazole_) [50]. On the other hand, increased growth of several fungal species was also noted, and, therefore, a new parameter was added--growth-inducing concentration (GIC\({}_{50}\)). The new parameter also showed at which concentrations the tested extracts induce the growth (based on the optical density at 405 nm) for at least 50% compared with the control. Based on these calculations some of tested extracts on several fungal species did not show inhibitory properties but rather growth inducing properties, while for other fungal strains there was concentration dependent change from MIC\({}_{50}\) to GIC\({}_{50}\). Interestingly, DMSO extract showed the antifungal activity against _Rhizoplus_ spp. at 5000 \(\mu\)g/mL while H\({}_{2}\)O extract at the same concentration showed growth inducing properties. A similar trend was observed for _P. expansum_ where DMSO extract showed excellent antifungal properties, and on the other hand, H\({}_{2}\)O extract exhibited great growth-inducing potential. Both extracts did not show growth-inducing effect against _Fusarium_ spp. _A. ochracaeus_ was only fungi that exhibited susceptibility towards H\({}_{2}\)O extract, and growth-inducing effect towards DMSO extract that was noticeable only when high concentrations were used (5000 \(\mu\)g/mL). _A. flavus_ showed great concentration-dependent response to the usage of FD-CB extracts. While the high amount of DMSOextract exhibited antifungal properties (5000 ug/mL), at low concentrations (5 and 50 ug/mL) DMSO extract showed growth inducing properties. Similarly, H\({}_{2}\)O extract at 5 ug/mL increased the growth of the fungi indicating possible hormetic effect. Further characterization of the active compounds in the extracts is in progress. To the best of the authors' knowledge, this is the first published paper on the antifungal activity of _C. bursa_ against main mycotoxin-producing fungi: _A. alternata, A. flavus, A. ochracues, F. graminearum, F. verticillioides, P. expansum_, and food fermenting _Rhiziolus_ spp. Therefore, it is possible in discussion only to mention previously observed biological activities of other _Codium_ species. Thus, [PERSON] et al. [51] isolated _A. flavus_ from the surface of the edible green algae _C. fragile_ from Korea. The alga induced the growth of _A. flavus_ on its surface, indicating that there is a growth-inducing component. Other published data on _Codium_ spp. showed various levels of bactericidal effects. [PERSON] et al. [15] detected the antimicrobial activity of different extracts of _C. fragile_.