Leaf extracts of five medicinal ferns, Acrostichum aureum L. (Pteridaceae), Asplenium nidus L. (Aspleniaceae), Blechnum orientale L. (Blechnaceae), Cibotium barometz (L.) J. Sm. (Cyatheaceae) and Dicranopteris linearis (Burm.) underwood var. linearis (Gleicheniaceae), were investigated for their total phenolic content (TPC), and antioxidative, tyrosinase inhibiting and antibacterial activities. The antioxidative activity was measured by assays for radical scavenging against 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric ion reducing power (FRP), beta-carotene bleaching (BCB) and ferrous ion chelating (FIC). The results revealed B. orientale to possess the highest amount of total polyphenols and strongest potential as a natural antioxidative, tyrosinase inhibiting and antibacterial agent as demonstrated by its strong activities in all related bioassays. The other ferns with antioxidative potential were C. barometz and D. linearis. Except for A. aureum, all ferns showed antibacterial activity which may justify their usage in traditional medicines.

The objectives of this study were (1) to assess the bacteriocinogenic potential of bacteria derived mainly from seaweed, but also sand and seawater, (2) to identify at least some of the bacteriocins produced, if any and (3) to determine if they are unique to the marine environment and/or novel. Fifteen Bacillus licheniformis or pumilus isolates with antimicrobial activity against at least one of the indicator bacteria used were recovered. Some, at least, of the antimicrobials produced were bacteriocins, as they were proteinaceous and the producers displayed immunity. Screening with PCR primers for known Bacillus bacteriocins revealed that three seaweed-derived Bacillus licheniformis harbored the bli04127 gene which encodes one of the peptides of the two-peptide lantibiotic lichenicidin. Production of both lichenicidin peptides was then confirmed by mass spectrometry. This is the first definitive proof of bacteriocin production by seaweed-derived bacteria. The authors acknowledge that the bacteriocin produced has previously been discovered and is not unique to the marine environment. However, the other marine isolates likely produce novel bacteriocins, as none harboured genes for known Bacillus bacteriocins.

Six antimicrobial-producing seaweed-derived Bacillus strains were evaluated in vitro as animal probiotics, in comparison to two Bacillus from an EU-authorized animal probiotic product. Antimicrobial activity was demonstrated on solid media against porcine Salmonella and E. coli. The marine isolates were most active against the latter, had better activity than the commercial probiotics and Bacillus pumilus WIT 588 also reduced E. coli counts in broth. All of the marine Bacillus tolerated physiological concentrations of bile, with some as tolerant as one of the probiotics. Spore counts for all isolates remained almost constant during incubation in simulated gastric and ileum juices. All of the marine Bacillus grew anaerobically and the spores of all except one isolate germinated under anaerobic conditions. All were sensitive to a panel of antibiotics and none harbored Bacillus enterotoxin genes but all, except B. pumilus WIT 588, showed some degree of β-hemolysis. However, trypan blue dye exclusion and xCELLigence assays demonstrated a lack of toxicity in comparison to two pathogens; in fact, the commercial probiotics appeared more cytotoxic than the majority of the marine Bacillus. Overall, some of the marine-derived Bacillus, in particular B. pumilus WIT 588, demonstrate potential for use as livestock probiotics.

Olive processing wastewaters (OPW), namely olive mill wastewater (OMW) and table-olive wastewaters (TOW) were evaluated for their antibacterial activity against five Gram-positive and two Gram-negative bacteria using the standard disc diffusion and thin layer chromatography (TLC)-bioautography assays. Disc diffusion screening and bioautography of OMW were compared to the phenolic extracts of table-olive brines. Positive activity against S. aureus was demonstrated. The optimization of chromatographic separation revealed that hexane/acetone in the ratio of 4:6 was the most effective for phenolic compounds separation. A HPLC-MS analysis was performed showing that only two compounds, hydroxytyrosol and tyrosol, were the predominant phenolic compounds in all OPW. The phenolic extract of OMW generated by a semi-modern process showed the highest free radical-scavenging activity (DPPH assay) compared to the other phenolic extracts. It is apparent from the present study that OPW are a rich source of antioxidants suitable for use in food, cosmetic or pharmaceutical applications.