Antimicrobial and enzymatic activities of endophytic bacteria isolated from Mentha spicata (MINT)

Aims: This study is to isolate and characterize endophytic bacteria for potential industrial enzymes and antimicrobial activities against some human pathogens. Methodology and results: Mentha spicata, a local medicinal plant, was used to source for endophytes. The roots, stems and leaves of M. spicata were surface-sterilized to isolate the endophytic bacteria. The endophytic bacteria were subsequently characterized based on their 16S rRNA sequences. The endophytic bacteria were screened for both antimicrobial and enzymatic activities. We identified 15 isolates of 4 genus-Pseudomonas (7 species), Bacillus (3 species), Enterobacter (1 species) and Comamonas (1 species) with 97-100 similarity level. Isolates MSS-3 (Pseudomonas putida), MSR-4 (Pseudomonas pictorum), MSS-2 (Bacillus thuringiensis) and MSR-5 (Pseudomonas straminea) showed prominent antimicrobial activities against the pathogens tested with zones of inhibition between 6.3 to 15.3 ? 0.6 mm. All species examined have positive cellulase activities except Comamonas guangdongensis and only isolates of the Bacillus genus, Pseudomonas pictorum and P. argentinensis exhibited amylase activities. Conclusion, significance and impact of study: Our findings revealed potential therapeutic uses of the bioactive compounds of these bacteria endophytes against pathogens. Their enzymatic potential can also be of use in various industries.