Endophytic fungi play a vital role in plant defense system by secreting various antimicrobial agents. To evaluate the antimicrobial activity of the endophytic fungi of the mangrove plant Heritiera fomes (Buch. -Ham), plants were collected from the Sundarbans, Bangladesh. The endophytic fungi were subsequently isolated and identified. Fifty-five endophytic fungi were isolated from the leaves, root, and bark of H. fomes (Buch. -Ham). Genomic DNA was extracted for PCR (polymerase chain reaction) by specific primers to multiply ITS region and sequences were determined. Nucleotide sequence data were submitted to the Genbank and accession number for each fungal strain was obtained. Antimicrobial activity of the ethyl acetate (EtOAc) and methanolic extracts of eleven species from both fermentation and mycelium, respectively, were analyzed by microtiter plate-based antimicrobial assay incorporating resazurin as an indicator of cell growth against two Gram-positive bacteria namely Staphylococcus aureus NCTC 12981 and Micrococcus luteus NCTC 7508, two Gram-negative bacteria namely Escherichia coli NCTC 12241 and Pseudomonas aeruginosa NCTC 12903, and a fungus Candida albicans ATCC 90028. All the endophytic fungal extracts exhibited antimicrobial activities against more than one-tested pathogenic microbial strains. Overall, methanolic extracts showed greater activity than EtOAc extracts. Pseudopestalotiopsis camelliae-sinensis, Pestalotiopsis microspora, and Penicillium copticola were the most active endophytic fungal strains and exhibited strong inhibitory activity against the microorganisms under investigation and their MIC values ranged from 0.0024 to 5.0 mg/mL. Methanolic extracts of both P. camelliae-sinensis and P. microspora showed the highest antibacterial activity (MIC value of 0.0024 mg/mL) against P. aeruginosa NCTC 12903. This study showed that the isolated and identified endophytic fungi from H. fomes (Buch. -Ham) could be potential sources of antimicrobial agents.

中文翻译：

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从孙德尔本斯红树林植物 Heritiera fome (Buch.-Ham) 中分离出的内生真菌的分子鉴定和抗菌活性

内生真菌通过分泌各种抗菌剂在植物防御系统中发挥重要作用。为了评估红树林植物 Heritiera fome (Buch.-Ham) 的内生真菌的抗微生物活性，从孟加拉国的 Sundarbans 收集植物。随后分离并鉴定了内生真菌。从 H. fome (Buch. -Ham) 的叶、根和树皮中分离出 55 种内生真菌。提取基因组DNA用于PCR（聚合酶链反应），通过特异性引物扩增ITS区域并确定序列。将核苷酸序列数据提交给 Genbank，并获得每个真菌菌株的登录号。分别来自发酵和菌丝体的 11 个物种的乙酸乙酯 (EtOAc) 和甲醇提取物的抗菌活性，通过基于微量滴定板的抗菌测定法分析了刃天青作为针对两种革兰氏阳性菌，即金黄色葡萄球菌 NCTC 12981 和藤黄微球菌 NCTC 7508，两种革兰氏阴性菌，即大肠杆菌 NCTC 12241 和铜绿假单胞菌 NC3TC 的细胞生长指标和一种真菌白色念珠菌 ATCC 90028。所有内生真菌提取物都对一种以上的病原微生物菌株表现出抗菌活性。总的来说，甲醇提取物显示出比 EtOAc 提取物更高的活性。Pseudopestalotiopsis camelliae-sinensis、Pestalotiopsis microspora 和Penicillium coopticola 是最活跃的内生真菌菌株，对所研究的微生物表现出很强的抑制活性，其MIC 值范围为0.0024 至5.0 mg/mL。