Agricultural and Biological Research

Antimicrobial and antioxidant activities of endophytic bacteria associated with medicinal plants

Kasim Muhtari, Inampudi Sailaja*, Beena Kanwar Shekhawat and Sonia Kaura

A lot of bacterial resistance cases towards antibiotics, hearten numerous efforts to obtain new origin of antibiotics. Endophytic bacteria represent potential microbes capable of producing significant bioactive compounds. Psidiium guajava, Mangifera indica, Cassia occidentalis, Calotropis procera and Hibiscus rosa-sinensa have been employed as ingredients of many traditional herbal medicines. The work is aimed to scrutinize the antimicrobial and antioxidant activity of the bacterial endophytes linked with the mentioned medicinal plants. Thirty bacterial colonies were isolated and identified based on physiological and biochemical characteristics shown by the isolates, subsequently, only eight isolates were chosen for this investigation. Antimicrobial activity of the isolates was known via agar well diffusion method. The supernatant of each endophytic culture isolate was plunged on agar well against pathogenic bacteria Escherichia coli and Staphylococcus aureus. Achromobacter xylosoxidans (GL-1), Bacillus megaterium (GB-1), Pseudomonas chlororaphis (CPS-2), Citrobacter koseri (GST-1), Siccibacter colletis (COB-1), Eaerogenes and Coccobacilli (HBL-3) showed antimicrobial activity against Staphylococcus aureus, only Bacillus amyloliquefaciens (GB-3) showed resistance. While isolate Bacillus amyloliquefaciens (GB-3) and E. aerogenes CPF-1 showed antimicrobial activity against Escherichia coli, whereas Achromobacter xylosoxidans (GL-1), Bacillus megaterium (GB-1), Pseudomonas chlororaphis (CPS-2), Siccibacter colletis (COB-1) and Coccobacilli (HBL-3) showed resistance against Escherichia coli respectively. All selected endophytic isolates showed antioxidant activity as observed via scavenging capability toward 2,2-Diphenyl-1-Picrylhydrazyl (DPPH) radical with successive percentage Achromobacter xylosoxidans GL-1 (92.55%), Bacillus megaterium (GB-1) 93.72, Pseudomona schlororaphis (CPS-2) 90.84%, Bacillus amyloliquefaciens (GB-3) 93.50%, Citrobacter koseri (GST-1) 92.76%, Siccibacter colletis (COB-1) 93.18%, E. aerogenes (CPF-1) 90.41% and Coccobacilli (HBL-3) 92.01%.