Marine Fungi Against Aquaculture Pathogens and Induction of the Activity via Co‐Culture

Abstract

Ethyl acetate extracts from 70 strains of marine-derived fungi, isolated from sponges, were screened against four fish pathogenic bacteria. Sixteen of the fungal isolates exhibited antibacterial activity against at least one pathogen. All the strains showed antibacterial activity against Vagococcus salmoninarum. Three isolates showed strong inhibition against all test pathogens and they may therefore be remarkable as a broadspectrum antimicrobial. Nine isolates showed antibacterial activity against Lactococcus garvieae, six were against Vibrio anguillarum, and four isolates inhibited the growth of Yersinia ruckeri. Co-culture of the fungus with the mix of the pathogen bacteria led to the induction of bioactivity in two isolates. Aspergillus iizukae produced strong and broadspectrum antibacterial activity against pathogens with minimum inhibitory concentrations of 0.8-406 mg mL À1 . The screening results confirmed the sponge associated fungi as a source of environmentally friendly antimicrobials that may contribute the sustainable development of aquaculture. In addition, co-culture technique is a promising strategy to increase antimicrobial activity that can stimulate the production of novel compounds, and increases the antimicrobial activities of marine derived fungi.

From the sea to aquafeed: A perspective overview

“…The natural product ergosta‐4,6,8(14),22‐tetraene‐3‐one obtained from deep sea‐derived fungi Aspergillus penicillioides showed strong inhibitory activity against the pathogenic bacteria Edwardsiella tarda 286 . The fungus Penicillium canescens , isolated from the marine sponge Cacospongia sp., collected from the Aegean Sea Coast of Turkey, revealed activity against Yersinia ruckeri , however, the bioactive compounds were not isolated nor identified 69 . Two chamigrene derived sesquiterpenoids isolated from the red seaweed Laurencia chondrioides , demonstrated antimicrobial bioactivity against Pseudomonas anguilliseptica 298 .…”

“…Moreover, several publications recently demonstrated that marine fungi are a source of antimicrobial compounds for use in aquaculture against fish pathogens. Fungi from sponges have been screened for the production of antimicrobial compounds active against different fish pathogens, that is, Lactococcus garvieae , Vibrio anguillarum , Vibrio harveyi , Yersinia ruckeri and Vagococcus salmoninarum 68–71 . Since bacterial pathogens are a serious threat in aquaculture and the antimicrobial resistance in cultured aquatic animals is at concerning levels, 72 there is an increasing need for new tools and approaches to manage aquaculture sustainably.…”

“…The benefit of mycoprotein production for sustainable feed production lies in their capability to grow in bioreactors with high metabolic rates using different by‐products such as C and N sources 81–84 . Fungal biomasses rich in proteins, can be produced both in submerged 68–72 and in solid‐state fermentation 85,86 of agro‐industrial residues according to circularity assessment criteria that have been outlined in the introduction. This approach has two important advantages: (i) it reduces the production costs; (ii) valorises processing by‐products otherwise treated as waste.…”

“…viridans , suggesting their involvement in the immune responses of this mud crab and possible future use to combat these bacteria 283 . Lactococcus garvieae was efficiently inhibited by an ethyl acetate extract obtained from a marine sponge associated with marine fungus Aspergillus iizukae 69 . Arthrobacter davidanieli , a non‐pathogenic actinobacterium, is used and licensed in Canada as an effective live vaccine against Renibacterium salmoninarum 284 .…”

Potential Antiviral Xanthones from a Coastal Saline Soil Fungus Aspergillus iizukae

“…Aspergillus iizukae is present in various environments, such as leaves of Silybum marianum [ 1 ], sponges [ 2 ], guts of a cricket species Gryllus testaceus [ 3 ], earthworm casts and different kinds of soil [ 4 ]. Recently, Özkaya et al found that the ethyl acetate extract of a sponge-associated A. iizukae showed inhibitory effects against the aquaculture pathogens Lactococcus garvieae and Vagococcus salmoninarum [ 2 ]. Additionally, a novel flavin adenine dinucleotide-dependent glucose dehydrogenase was separated from the culture of A. iizukae , which was capable of catalyzing the oxidation of glucose to glucono-δ-lactone [ 5 ].…”