Sustainable Exploitation of Posidonia oceanica Sea Balls (Egagropili): A Review

Abstract

Posidonia oceanica (L.) Delile is the main seagrass plant in the Mediterranean basin that forms huge underwater meadows. Its leaves, when decomposed, are transported to the coasts, where they create huge banquettes that protect the beaches from sea erosion. Its roots and rhizome fragments, instead, aggregate into fibrous sea balls, called egagropili, that are shaped and accumulated by the waves along the shoreline. Their presence on the beach is generally disliked by tourists, and, thus, local communities commonly treat them as waste to remove and discard. Posidonia oceanica egagropili might represent a vegetable lignocellulose biomass to be valorized as a renewable substrate to produce added value molecules in biotechnological processes, as bio-absorbents in environmental decontamination, to prepare new bioplastics and biocomposites, or as insulating and reinforcement materials for construction and building. In this review, the structural characteristics, and the biological role of Posidonia oceanica egagropili are described, as well as their applications in different fields as reported in scientific papers published in recent years.

Streptomycetes as Microbial Cell Factories for the Biotechnological Production of Melanin

“…Streptomycetes can degrade lignocellulose biomasses thanks to their multi-enzymatic pools that include different cellulases (endo-, exo-, and betagalactosidases), lignin peroxidases, and/or laccases. For example, recently, egagropili sea balls, derived by the aggregation of roots and rhizomes of the marine seagrass plant Posidonia oceanica that accumulated as wastes along Mediterranean Sea coasts [ 57 ], were explored as raw sources to enhance the extracellular melanin production of Streptomyces roseochromogenes ATCC 13400 [ 23 ]. Different concentrations (1.0, 2.5, and 5.0 g/L) of untreated egagropili powder were supplemented into a culture medium containing glucose, yeast, and malt extracts.…”

Posidonia Spheroids Intercepting Plastic Litter: Implications for Beach Clean-Ups

“…The uses of EGs might also help in the future to sustain the economic growth of all the countries of the Mediterranean Sea. The removed EGs could be used as a renewable substrate to produce bio-absorbents in environmental remediation, as insulation and reinforcing materials for building and construction, as new material to create paper, textiles, or biofuel, and for bioplastic generation for the next generation [79][80][81][82].…”

Biotechnological Production and Characterization of Extracellular Melanin by Streptomyces nashvillensis

“…The concentrations of the produced pigment greatly vary according to the strain, growth settings, and nutritional conditions [ 14 ]. Complex substrates of plant origin, like soy peptone, amylopectin, and even the rhizome fragments and the roots of a marine-origin grass plant, the egagropili of Posidonia oceanica [ 23 ], have been used as nutrients and supplemented in Streptomyces media to enhance melanin production. Also, complex animal-derived substrates, like casein or beef extract, or metal ions, and/or the L-tyrosine as precursor, have been provided in the growth media to better produce the pigment [ 2 , 16 , 19 , 20 , 21 , 22 ].…”