Production of bioactive compounds with bactericidal and antioxidant potential by endophytic fungus Alternaria alternata AE1 isolated from Azadirachta indica A. Juss.
Production of bioactive compounds with bactericidal and antioxidant potential by endophytic fungus Alternaria alternata AE1 isolated from Azadirachta indica A. Juss.
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DOI：
10.1371/journal.pone.0214744
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发表时间：
2019-04-04
期刊：
影响因子：
3.7
通讯作者：
Mandal, Narayan Chandra
中科院分区：
文献类型：
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作者：
Chatterjee, Sohini;Ghosh, Ranjan;Mandal, Narayan Chandra
为了对抗多药耐药微生物，从植物内生菌中探索天然化合物增加了发现新化合物的机会。从印楝叶中分离到一株产代谢产物的内生真菌AE1。发现代谢物是耐热的，不含蛋白质的，并对革兰氏阳性和革兰氏阴性细菌的数量产生显著的抑制区。经28S rDNA （D1/D2）序列同源性鉴定，AE1为alternnaria alternata。发现麦芽提取物肉汤对分离物最大限度地产生生物活性代谢物有效，并进行了溶剂萃取。AE1乙酸乙酯部分对革兰氏阳性菌和革兰氏阴性菌的MIC值为300 ~ 400 μ g/ml。通过处理中期培养的细菌，检测了EA组分的杀灭方式。扫描电镜研究支持细菌细胞的形态解体。核酸、蛋白质和钾离子（K+）的释放也表明处理后细菌细胞溶解或细胞膜渗漏。此外，所有细菌的EMP途径、TCA循环和糖异生酶活性降低，表明抗菌原理干扰了中心碳水化合物代谢途径。薄层色谱分离和气相色谱分析表明，AE1生产的抗菌化合物数量较多。此外，DPPH自由基和超氧自由基清除实验也表明AE1具有较强的抗氧化能力，IC50值分别为38.0 +/- 1.7 μ g/ml和11.38 +/- 1.2 μ g/ml。基于上述事实，可以得出结论，菌株AE1将是具有药用价值的生物活性化合物的良好来源。
For combating multidrug-resistant microorganisms, exploration of natural compounds from plant endophytes increases the chance of finding novel compounds. An efficient bioactive metabolites producing endophytic fungal strain AE1 was isolated from leaves of Azadirachta indica A. Juss. The metabolites were found to be thermostable, non-proteinacious and produced prominent zones of inhibition against numbers of Gram positive and Gram negative bacteria. Based on 28S rDNA (D1/D2) sequence homology the isolate AE1 was identified as Alternaria alternata. Malt extract broth was found effective for the maximum production of bioactive metabolites by the isolate and was subjected for solvent extraction. The Ethyl acetate (EA) fraction of AE1 showed MIC values of 300-400 mu g/ml against Gram positive and Gram negative bacteria tested. The cidal mode of action of EA fraction was detected by treating bacterial cultures at mid log phase. Scanning electron microscopic study supported morphological disintegration of bacterial cells. Release of nucleic acid, protein and potassium ions (K+) also suggested lysis of bacterial cells or leakage of cell membrane upon treatment. In addition, reduction of the activity of EMP pathway, TCA cycle and gluconeogenic enzymes in all bacteria suggested the interference of antibacterial principles with central carbohydrate metabolic pathways. Thin layer chromatographic separation followed by GCMS analysis of EA fraction suggested numbers of antimicrobial compound production by AE1. In addition, DPPH free radical as well as superoxide radical scavenging assay also suggested strong antioxidant potential of AE1 with an IC50 value of 38.0 +/- 1.7 mu g/ml and 11.38 +/- 1.2 mu g/ml respectively. On the basis of above facts it can be concluded that the strain AE1 will be a good source of bioactive compounds having medicinal importance.