Biotechnological potential of Ulva ohnoi epiphytic bacteria: enzyme production and antimicrobial activities
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Date
2023
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Abstract
Seaweed surfaces harbor diverse epibiotic bacterial communities with functions
related to morphogenesis, host health, and defense. Among seaweed
holobionts, culturable strains can represent innovative sources of bioactive
compounds and enzymes. The global industrial demand for microbial enzymes
is continually growing in order to improve certain manufacturing processes with
new perspectives of industrial exploitation. In this regard, the present study
focuses on the enzymatic production and the antimicrobial activities of
culturable epibiotic bacteria of Ulva from the Tunisian coast. Culturable
associated bacteria were isolated and molecular identification was realized by
16S rRNA gene sequencing. For each strain, eight enzymatic activities were
investigated: amylase, hemolysis, DNase, cellulase, lecithinase, lipase, gelatinase,
and chitinase. The antimicrobial activity of Ulva-associated bacteria was
evaluated against seven pathogenic bacteria, Escherichia coli, Vibrio
anguillarum, Vibrio alginoliticus, Pseudomonas aeruginosa, Aeromonas
hydrophila, Salmonella typhymurium, and Staphylococcus aureus, and one
yeast, Candida albicans. The antibiotic resistance of isolated strains was
determined for 15 commonly used antibiotics. The phylogenetic analysis
revealed that the isolates belonged to Alphaproteobacteria (3) ,
Gammaproteobacteria (5), Actinobacteria (3), and Firmicutes (4) phyllum. The
majority of the isolates (66%) produced simultaneously more than one enzyme.
Hemolysis was produced by 46.6% of isolates, while DNase was produced by
33% of strains. On the other hand, 13% of strains produced lecithinase, gelatinase,
cellulase, and lipase. No chitinase was produced by the isolated bacteria. In
addition, 60% of isolates displayed antimicrobial activity against at least one
pathogenic strain. All Ulva ohnoi-associated bacteria were resistant to at least
seven commonly used antibiotics. These results highlighted the occurrence of
several enzymatic activities within Ulva-associated bacteria that can have
potential uses in the industrial sector.
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Keywords
seaweed-epibiont, enzyme production, antimicrobial activity, bacterial phylogeny, antibiogram, Ulva ohnoi, antibioresistance