갈조 다당류 및 다시마 분말의 생물학적 분해 반응을 통한 생리활성물질 및 액체비료로의 활용가능성 평가

Abstract

Worldwide consumption of seaweed has increased steadily due to its bioactive secondary metabolites and health benefits. However, the remaining materials are usually wasted. Fishery wastes, especially from processing process, can cause serious harm to the marine environment such as, bad smell and greatly pollute the environment, producing adverse effect on significant ecosystems. Accordingly, the disposal and reutilization of fishery waste has been essential for preservation of the marine environment and recycling of organic substances. In this study, we isolated six strains, EJ1 to EJ6. Plate assay indicated that each isolate clearly possessed alginate lyase, laminarinase, protease, or/and lipase activity as well. Among them, the best potential strain was EJ1, EJ4, EJ6 for the degradation of brown seaweed component. The isolate clearly showed high degradation ability on alginate laminarin or Laminaria japonica powder with high production of reducing sugars. A TLC analysis of the alginate and laminarin-decomposition products revealed that the biodegradation proceeded by endo-type alginate lyases and exo-type laminarinase. The biodegraded culture broths of alginate by EJ1 and EJ6 exhibited a better radical scavenging activity toward ABTS and hydroxyl radicals and reducing power. The culture supernatants collected during the biodegradation by EJ6 exhibited antimicrobial activity against Staphylococcus aureus. In addition, almost no toxic compounds were found in the culture supernatants collected during the biodegradation of alginate. In a hydroponic culture, kidney beans grown with alginate biodegraded derivatives exhibited better growth than barley. Also, The biodegraded culture broths of Laminaria japonica powder were phytotoxin-free at 1000 dilution ratio and exhibited comparable fertilizing ability with the commercial fertilizer in hydroponic culture with an amino acid content of 1.26 to 8.93 g per 100 g protein, low concentrations of heavy metals, and an N/P/K level of 1.62-2.63%. As a result, the biodegradation was an eco-friendly means to convert seaweed wastes into liquid fertilizer containing various essential nutrients, such as mono-, di-, and oligosaccharides, amino acids, and mineral elements. The results revealed that alginate-derived oligosaccharides by biodegradation can be extensively utilized due to their biological functions, which enhance their value and reutilization of brown seaweed wastes by bioconversion will gain in popularity not only for their potential use in organic and sustainable agriculture but also for helping to protect the environment.