## 3 Results and Discussion
cereus_ of phlorotannin-purified extracts from _Cystoseismic tamariscifolia_ (currently _Ericaria selaginoides_ ([PERSON]) [PERSON] & [PERSON], 2020) was described by [PERSON] et al. (2012) [53]. In addition, the occurrence of five different phenolic structures isolated from the brown algae _Ecklonia kurome_ with antimicrobial activity against _B. cereus_ was described by [PERSON] et al. (2002) [54]. Among them, dieckol and 8.8\({}^{\prime}\)-bieckol exerted the best results (0.54 mmol/mL), followed by phlorofucofuroeckol A (0.66 mmol/mL), eckol (1.08 mmol/mL), and phloroglucinol (>6.35 mmol/mL). Other authors have also described an effect against _B. cereus_ when purified fuoxanthin and fucoidan were tested. [PERSON] et al. (2013) [55] tested concentrations between 10 and 100 mg/mL of fucoxanthin obtained from _Turbinaria triquatra_ via the disk-diffusion method, demonstrating a dose-dependent effect as the size of the inhibition zones increased with the concentration, with values from 1.8 \(\pm\) 0.1 to 6.5 \(\pm\) 0.3 mm. Ethanolic and acetone:methanol extracts performed with other brown algae species, such as _Saccharina japonica_ and _Sargassum horneri_, with fucoxanthin content between 0.41 and 0.48 mg/g as well as 0.71 and 0.77 mg/g, respectively, showed an effect against this target strain, being higher with acetone:methanol extracts [56]. Regarding fucoidans, [PERSON] (2016) [57] also described an enhancement in the inhibition of _Bacillus_ sp. when encapsulated purified fucoidan from _Padina tetrastromatica_ was tested together with a batch of different antibiotics. Research on the action mechanisms of the potential antimicrobial compounds from macroalgae is still scarce, although evidence of interactions at the cell membrane level causing cell disruption has been described for polyphenic compounds, fucoidans, and fucoxanthin [23; 58]. In addition to the interactions of these compounds with the bacterial cell wall, interactions between their functional groups could have occurred. Thus, potential interactions between these compounds together with their polarity differences were assumed to be responsible of the difficulties found in solubilizing the components of the crude extract in a polar dissolution medium. Hence, a specific medium was designed to solubilize the mid-polarity crude extract and fractioning was performed to minimize this issue, which could also explain the improvement in the antimicrobial effect observed with both subfractions discussed below. Although references evaluating the antimicrobial activity of these compounds after purification are limited so far, the evidence described above, together with the fact that there is an occurrence of compounds of this nature in _E. elsaginoides_ crude extract used in this study [27], lead one to consider that the observed antimicrobial effect could not be attributed to a single compound but to an additive, synergic, and/or antagonistic action of compounds of different chemical natures. On the other hand, in the presence of the non-polar subfraction, counts of _B. cereus_ were under the limit of detection (<0.6 log cfu/g) after 2 days in fresh cheese samples with the intermediate and highest concentrations (10 and 20 mg/g), and in 2-4 days in cheese with the lowest concentration (5 mg/g). At the end of the storage time, compared to the control, all the concentrations tested had achieved almost 5 log reduction (4.70 \(\pm\) 0.83 log). The behavior of _B. cereus_ in fresh cheese with the lowest concentration of mid-polar subfraction (10 mg/g) accounted for almost 2 log reduction (1.76 \(\pm\) 1.20 log). At the intermediate concentration applied (25 mg/g), _B. cereus_ counts diminished below the detection limit after 6 days of storage, while, with the highest concentration (50 mg/g), counts were under the limit of detection after 2 days (\(p\) < 0.05). Thus, 4.53 \(\pm\) 1.19 log reduction was observed after 10 days of storage with the intermediate and highest concentrations when compared to control.