Diversity and function of the Antarctic krill microorganisms from Euphausia superba.
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 IC50values 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.
Key Laboratory of Marine Drugs, Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China.|School of Pharmacy, Jining Medical University, Jining 272067, China.
Xiaoqiu
X
Cui
Key Laboratory of Marine Drugs, Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China.
Guoliang
G
Zhu
Key Laboratory of Marine Drugs, Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China.
Haishan
H
Liu
College of Marine Life, Ocean University of China, Qingdao 266003, China.
Guoliang
G
Jiang
Key Laboratory of Marine Drugs, Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China.
Yi
Y
Wang
Key Laboratory of Marine Drugs, Ministry of Education of China, School of Medicine and Pharmacy, Ocean University of China, Qingdao 266003, China.
Weiming
W
Zhu
D000818:Animals; D000864:Antarctic Regions; D000890:Anti-Infective Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects / Q000302:isolation & purification*; D004463:Ecology; D033201:Euphausiacea / Q000382:microbiology*; D005459:Fluorides / Q000494:pharmacology; D005658:Fungi / Q000187:drug effects / Q000302:isolation & purification*; D010710:Phosphates / Q000494:pharmacology
D000890:Anti-Infective Agents; D010710:Phosphates; C012980:fluorophosphate; D005459:Fluorides