Isolation, diversity and antimicrobial activity of endophytic bacteria from Piper retrofractum Vahl.

Bacterial endophytes associated with a Thai medicinal plant, Piper retrofractum Vahl, were investigated. Twenty-one isolates of endophytic bacteria were obtained from three different parts (root, leaf and stem) of P. retrofractum. According to amplified ribosomal DNA restriction analysis patterns and 16S rRNA gene sequence, the endophytic bacteria isolated in this study belong to 11 families, 14 genera and more than 18 species, with one uncultured isolate. Several of the bacteria are in the genera Pseudomonas and Bacillus. Two isolates, S-PR6Y and S-PR1Y, show antagonistic properties against methicillin-resistant Staphylococcus aureus (MRSA). A partially purified antibacterial agent from Lysobacter sp. (isolate S-PR6Y) shows remarkable stability to heat and pH. It has the potential for use as an alternative antibacterial agent for the treatment of infection with MRSA. [ABSTRACT FROM AUTHOR]