CHARACTERIZATION OF RHIZOBACTERIA ISOLATED FROM TOMATO AND THEIR EFFECT ON TOMATO AND BELL PEPPER GROWTH

Abstract

The use of microbial bio-fertilizers based on plant-growth-promoting rhizobacteria is a biotechnological alternative to improve production of horticultural crops seedlings. In this study, four bacterial strains previously isolated from tomato (Lycopersicum esculentum Mill.) rhizosphere were identified by using 16S rRNA gene sequence analysis and characterized according to their biochemical properties as plant growth promoters, and their effect on seed germination and seedling growth of tomato and bell pepper (Capsicum annuum L.) was also evaluated. The four strains isolated, named MA04, MA06, MA12 and MA17 and belonging to genus Bacillus, were able to produce indole acetic acid (0.9 to 2.3 mg L^-1), to solubilize tricalcium phosphate (18.5 to 34.7 mg L^-1), and posess ACC deaminase activity. Furthermore, MA04, MA06 and MA12 can grow in nitrogen free culture medium (with potential atmospheric nitrogen fixing ability). As far as their effect on tomato seeds, MA04 and MA17 improved germination by 5 and 6 % respectively, while MA06 and MA12 strains increased seedling weight by 17 and 20 %, respectively. On pepper seeds, only MA06 increased germination by 7 %, whereas MA12 and MA17 strains increased biomass by 37 and 16 % respectively. The MA12 strain proved to be the most efficient for improving seedling growth of tomato and bell pepper and could be proposed to produce biofertilizers for both plant species.