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. 2021 Sep 19;10(9):2226. doi: 10.3390/foods10092226

Table 2.

Antimicrobial activity of the algal extract samples assessed by using the agar well diffusion and liquid medium methods.

Algal Extract Sample Pathogenic and Opportunistic Bacteria Strains
Escherichia coli Klebsiella pneumonia Salmonella enterica Cronobacter sakazakii Acinetobacter baumani Pseudomona aeruginosa Staphylococcus aureus Staphylococcus haemolyticus Bacillus subtilis Streptococcus mutans
Inhibition zones by using the agar well diffusion, mm
Cla nd nd nd nd nd nd nd nd 12.0 ± 0.3 nd
Furc nd nd nd nd nd nd nd nd 8.0 ± 0.2 nd
Ul nd nd nd nd nd nd nd nd 17.0 ± 0.4 14.2 ± 0.2
Chlo nd nd nd nd nd nd nd nd nd nd
Sp1 nd nd nd nd nd nd nd 28.3 ± 0.7 10.1 ± 0.5 nd
Sp2 nd nd nd nd nd nd nd nd nd nd
Antimicrobial activity of the algal extracts in liquid medium
Concentration of algae extract 10 µL, concentration of pathogen 10 µL
Cla + + + + + + + + + +
Furc + + + + + + + + + +
Ul + + + + + + + + + +
Chlo + + + + + + + + + +
Sp1 + + + + + + + + + +
Sp2 + + + + + + + + + +
Concentration of algae extract 50 µL, concentration of pathogen 10 µL
Cla + + + + + + + + + +
Furc + + + + + + + + + +
Ul + + + + + + + + + +
Chlo + + + + + + + + + +
Sp1 + + + + + + + + + +
Sp2 + + + + + + + + + +
Concentration of algae extract 100 µL, concentration of pathogen 10 µL
Cla + + + + + + + + + +
Furc + + + + + + + + + +
Ul + + + + + + + + + +
Chlo + + + + + + + + + +
Sp1 + + + + + + + + + +
Sp2 + + + + + + + + + +
Concentration of algae extract 500 µL, concentration of pathogen 10 µL
Cla + + + + + + + + + +
Furc + + + + + + + + + +
Ul + + + + + + + + + +
Chlo + + + + + + + + + +
Sp1 + + + + + + + + + +
Sp2 + + + + + + + + + +
Pathogen control
Pathogen + + + + + + + + + +

Interpretation of results: negative (−) means the pathogens did not grow on the selective culture medium; positive (+) means the pathogens grew on the selective culture medium; nd - not determined. Value in brackets is the algae extract concentration in 10 mL of liquid media. Cla, Cladophora rupestris; Ul, Ulva intestinalis; Furc, Furcellaria lumbricalis; Chlo, Chlorella vulgaris; Sp1, Spirulina (Arthrospira platensis) obtained from University of Texas; Sp2, Spirulina (Ltd. “Spila“).