Diversity and function of the Antarctic krill microorganisms from Euphausia superba

Abstract

The diversity and ecological function of microorganisms associated with Euphausia superba, still remain unknown. This study identified 75 microbial isolates from E. superba, that is 42 fungi and 33 bacteria including eight actinobacteria. And all the isolates showed NaF tolerance in conformity with the nature of the fluoride krill. The maximum concentration was 10%, 3% and 0.5% NaF for actinobacteria, bacteria and fungi, respectively. The results demonstrated that 82.4% bacteria, 81.3% actinobacteria and 12.3% fungi produced antibacterial metabolites against pathogenic bacteria without NaF; the MIC value reached to 3.9 μg/mL. In addition, more than 60% fungi produced cytotoxic metabolites against A549, MCF-7 or K562 cell lines. The presence of NaF led to a reduction in the producing antimicrobial compounds, but stimulated the production of cytotoxic compounds. Furthermore, seven cytotoxic compounds were identified from the metabolites of Penicillium citrinum OUCMDZ4136 under 0.5% NaF, with the IC50 values of 3.6–13.1 μM for MCF-7, 2.2–19.8 μM for A549 and 5.4–15.4 μM for K562, respectively. These results indicated that the krill microbes exert their chemical defense by producing cytotoxic compounds to the mammalians and antibacterial compounds to inhibiting the pathogenic bacteria.

Diversity, Ecological Role and Biotechnological Potential of Antarctic Marine Fungi

“…Nevertheless, the nature and the strength of the relationships between the host and the associated fungi have yet to be fully understood [ 78 ]. Fungal diversity has been investigated in a variety of Antarctic organisms such as sponges, annelids, crustaceans, molluscs, and echinoderms collected in the South Shetland Islands ( Figure 1 ), mainly through culture-dependent approaches [ 54 , 79 , 80 , 81 , 82 , 83 ]. Although culture-based studies allowed isolating and investigating a variety of fungal taxa, molecular tools have allowed the identification of a larger fraction of the fungal diversity provided.…”

Novel Bioactive Penicipyrroether A and Pyrrospirone J from the Marine-Derived Penicillium sp. ZZ380

“…Compound 10 was isolated from a previous culture of ZZ380 in BMPM medium [2]. On the basis of the nuclear magnetic resonance (NMR) data and specific rotation, as well as the comparison with the reported data, eight known compounds were identified as 2,4,5-trimethylresorcinol ( 11 ) [8], stoloniferol B ( 12 ) [9], coniochaetone E ( 13 ) [10], pinselin ( 14 ) [11], quinolactacin A 1 ( 15 ) [12], ergosterol ( 16 ) [13], penicitrinol A ( 17 ) [14] and B ( 18 ) [15]. Their 13 C NMR data are presented in Tables S1 and S2 (Supplementary Materials).…”

New Alkaloids and Polyketides from the Marine Sponge-Derived Fungus Penicillium sp. SCSIO41015

“…Polyketides and alkaloids are two major secondary metabolites from marine-derived fungi, and the same polyketides or alkaloids were often isolated from different fungi. According to the detailed spectroscopic analysis and comparison to the reported literature data, the known compounds ( 4 – 21 ) were identified as quinolactacin B ( 4 ) [10], quinolonimide ( 5 ) [10], quinolonic acid ( 6 ) [10], 4-hydroxy-3-methyl-2(1 H )-quinolinone ( 7 ) [13], sydowinin A ( 8 ) [14], pinselin ( 9 ) [15], β -diversonolic ester ( 10 ) [16], coniochaetone J ( 11 ) [17], dihydrocitrinone ( 12 ) [18], stoloniferol A ( 13 ) [18], 6,8-dihydroxy-3,4,5-trimethylisochroman ( 14 ) [19], moniliphenone ( 15 ) [20], frangula-emodin ( 16 ) [21], methyl-2-(2-acetyl-3,5-dihydroxy-4,6-dimethylphenyl) acetate ( 17 ) [22], phenol A ( 18 ) [23], latifolicinin C ( 19 ) [24], penicitrinone A ( 20 ) [25], and 22-acetylisocyclocitrinol A ( 21 ) [26], respectively.…”