International Journal of Botany Studies 173 International Journal of Botany Studies ISSN: 2455-541X; Impact Factor: RJIF 5.12 Received: 08-10-2020; Accepted: 23-10-2020: Published: 11-11-2020 www.botanyjournals.com Volume 5; Issue 6; 2020; Page No. 173-177 Screening some medicinal plants for endophytic fungi and their antibacterial activity against some human pathogens R Anitha 1 , M Sathiyabama 2* 1-2 Department of Botany, School of Life Sciences, Bharathidasan University, Tiruchirappalli, Tamil Nadu, India Abstract The aim of the present study was to screen for antimicrobial activity in endophytic fungi isolated from surface sterilized leaves of some medicinal plants viz., Anisomeles malabarica, Cardiospermum halicacabum, Aristolochia indica, Acacia mangium. Totally 14 isolates were isolated from these plants. Preliminary analysis of fermentation broth of these isolates was tested for antimicrobial activity by agar diffusion method. Seven isolates displayed antimicrobial activity against at least one pathogenic bacterium. From these, one isolate from each plant was selected based on their morphotypes for further analysis. The isolates were identified using morphological/moleulcar methods (ITS) as Alternaria alternata, Alternaria sp., Rhodotorula mucilaginosa and Phyllosticta citricarpa. The crude ethyl acetate extract of A. alternata showed strongest antibacterial activity against the tested bacterial pathogens. These results indicate that A. alternata as a potential source of antimicrobial agent. Keywords: endophytic fungi, its analysis, antimicrobial activity, medicinal plants Introduction In recent years, drug resistance in bacteria is increasing which cause severe health problem throughout the world. Hence, effective antimicrobial agents are in need. Endophytes are microorganisms that live within the healthy plant tissues and do not show any apparent adverse effect on the host [1] They are good sources of novel bioactive products, while they invade millions of unique biological niches that expand in a variety of unusual circumstances. [2] Natural bioactive products produced by endophytic fungi have unique structures [3] However, Endophytic fungi are poorly investigated group of microorganisms that represent an abundant and dependable source of bioactive and chemically novel compounds with potential for exploitation in pharmaceutical industry [4, 5] . A comprehensive study has indicated that 51% of biologically active substances isolated from endophytic fungi were previously unknown [6, 7, 8] Endophytic fungi with antimicrobial activity of natural products can be used for industrial fermentation to produce natural active compounds for mass production at low cost, without pollution [9] In this study we have selected few medicinal plants viz, Anisomeles malabarica (Lamiaceae), Cardiospermum halicacabum (Sapindaceae), Aristolochia indica (Aristolochiaceae), Acacia mangium (Fabaceae) which are used in traditional, ayurvedic, siddha medicine for various treatment including rheumatism, cancer, wound healing, pneumonia etc. Some of these effects might be due to the presence of endophytic fungi harbored in these plants. Therefore, this study aimed to determine the endophytic fungal community present in the medicinal plants and their potential antimicrobial activities against some human pathogens. The potentially useful endophytic fungi were then identified based on the ITS sequence analysis. 2. Materials and Methods 2.1 Sources of Endophytic fungi The leaf samples were collected from apparently healthy plants viz., Aristolochia indica, Acacia mangium, Anisomeles malabarica, Cardiospermum halicacabum from Dindigul district. All the samples were kept in sterile plastic bags and brought back to the laboratory for fungal isolation on the same day. 2.2 Isolation of endophytic fungi The leaf samples were washed in mild detergent and thoroughly washed in running tap water for 10 - 15 min and air dried. The leaves were cut into small segments (2-3 cm) using sterile surgical blades. The segments were further surface sterilized by immersing in 0.5% (v/v) sodium hypochlorite solution for 3-5 minutes, followed by 70% (v/v) ethanol for 1 min. as reported previously. [10] Then they were rinsed in sterile distilled water thrice and allowed to surface dry using sterile blotting paper. The surface sterilized leaf segments were placed upside-down position in petriplate containing potato dextrose agar (PDA) supplemented with chloramphenicol (150mg/l). The plates were incubated at 25°C until the outgrowth of endophytic fungus was discovered. The hyphal tips that emerge from the cut end of leaf segments were transferred to PDA plates without antibiotics. Each fungal isolate was checked for purity and transferred to fresh medium. Stock cultures were stored at 4°C for further study. 2.3 Extraction of bioactive molecules The endophytic fungal isolates were inoculated into 100 ml of Czapek’s dox (CDB) broth and incubated at 25 ± 2°C with 150 rpm for 21 days. The fermentation broths were