Determination of mustard seeds endophytic bacterial population and species composition by development of new method

Abstract

Endophytic bacteria (EB) population and species diversity in seed of oilseeds crops remain unexplored. This study was conducted to overcome the difficulty imposed in serial dilution method employed for determination of mustard seed EB. The EB population in centrifuged pellet of per gram surface sterilized seeds (SSS) of 4 mustard varieties ranged from 4.11- 5.16 log Cfu. Addition of known concentrations (20-100 µl) of surfactant (Tween 20) to crushed SSS and water suspension removed the problem of colony development on nutrient agar and by this method EB population ranged 3.08- 3.37 Cfu/ g seed. The method successfully quantified seed EB of peanut (3.60 log Cfu/g) and sunflower (3.93 log Cfu/g). 16S rRNA based identification showed that Bacillus species of phyla Firmicutes were abundant in mustard and will facilitate further studies on seed EB role in mustard crop. Overall, our study provides knowledge and information on bacterial diversity in mature mustard seeds