Prevalence of bacteriocinogenic Rhizobium spp. in mungbean (Vigna radiata)

Abstract

The present work was undertaken to ascertain prevalence of bacteriocinogenic Rhizobium spp. in mungbean (Vigna radiata). Samples of rhizospheric soil and nodules were plated onto CRYEMA medium, selective for Rhizobium spp. From among the isolates obtained only four, designated as-N8, S1, S6, and S13 demonstrated bacteriocin production. Upto 104 AU/ml (Arbitrary Units/ml) of partially purified bacteriocin (PPB) was detected from N8 and S6. PPB obtained from N8 and S13 exhibited antagonism against indicator strain over a wide range of pH. All isolates of PPB were thermo-stable after heating to 90ºC for 5 minutes. N8 exhibited 14.2mm zone of inhibition after heating to 50ºC for 10 min. It decreased by 29.5% to 10mm (80ºC/ 10min). S6 exhibited zone of inhibition of 11mm (50ºC/10min) which decreased by 18.1% to 9mm (80ºC/10min). Dual inoculation of nitrogen fixing Rhizobium with bacteriocin producing Rhizobium can ensure greater benefit than using nitrogen fixer alone.