Anaerobic fermentation of carrageenan waste residue to obtain antifungal activity

Abstract

Anaerobic fermentation of carrageenan residues for the production of antifungal active compounds and their use to inhibit the growth of phytopathogenic bacteria is a novel approach to the utilization of carrageenan residues. In the present study, the treatment of carrageenan residue by anaerobic biofermentation technique showed strong growth inhibitory activity against Fusarium graminearum and Magnaporthe oryzae, which are the typical phytopathogens that reduce the crop yield, with MIC values of 0.0016% (v/v) and 0.00032% (v/v), respectively. The total concentration of polyphenols and flavonoids increased significantly to 20.41 μg/mL and 29.97 μg/mL after anaerobic fermentation. Amino acid metabolic pathway analysis showed that the substances and energy used by colonies to produce antifungal drugs are derived from amino acid metabolism, especially alanine and γ-aminobutyric acid (GABA). The results of redundancy analysis (RDA) indicated that anaerobic fermentation of carrageenan gum residues increased the abundance of specific bacterial groups included Bacillus, Komona, Caproiciproducens, Lactobacillus, Bovibacillus, and SN8, and that the increase in the number of these species favored the production of polyphenols and flavonoids with antifungal activity. This study provides a viable avenue for resource utilization of carrageenan residues.