Endophytic fungus - Albifimbria verrucaria isolated from Centella asiatica and its antioxidant and antibacterial activities

The present research focuses on the isolation of endophytic fungi from the roots of Centella asiatica and analyzes the antagonistic efficiency of endophytic fungus against bacterial fish pathogens. Agar plug diffusion assay, phytochemical screening, antioxidant activity, agar well diffusion assay and minimum inhibitory and bactericidal concentration were done for the fungal endophytes. Eight endophytic fungi in total were isolated from C.asiatica roots. Among that, CAR1 exhibits maximum antibacterial action in the preliminary screening and it is subjected to an extraction procedure using different polarity solvents to obtain crude extracts. Phytochemical assessment results showed the presence of tannins, saponins, flavonoids, phenol, alkaloids and steroids. In the antioxidant assay, the dichloromethane crude extract exhibited highest radical scavenging effect of 90% at 150 μg/mL concentration. Agar well diffusion assay displayed the highest antagonistic activity against selected bacterial fish pathogens. The maximum inhibition was obtained against V.harveyi (19 mm) at 100 μg/mL concentration and the MIC and MBC values were identified as 25 and 50 μg/mL respectively. The most active (CAR1) isolate was molecularly identified as Albifimbria verrucaria. The results highlighted that the dichloromethane crude extract of the endophytic fungus A.verrucaria has a significant pharmaceutical potential as antibacterial and antioxidant agents.