Impact of Diazotrophic Bacteria on Germination and Growth of Tomato, with Bio-control Effect, Isolated from Algerian Soil

Abstract

soils samples were collected from the west region of Bejaia-Algeria in aseptic conditions. The preliminary germination test on tomatos seeds allowed screening of 4 simples from which 40 different colonies were isolated and purified. These last were submitted to in vitro germination test, while 20 strains with an inductor effect on th e germination were selected and tested for the presence of stimulator effect of growth of tomato in vivo. Biochemical (on API 50 CHB/E gallery), and phylogenetic (DNAr 16S sequencing) identification, tests researching characteristics promoting p lant growth (production of IAA (Indol Acetic Acid) phyto- hormone, enzymes, siderophores, free nitrogen fixation, and an an tagonistic test on five phytopathogenic fungi ( Botrytis cinerea; Phytophtora cactorum, phytophtora cinnamomi; Fusarium oxysporum a nd Verticillium dahliae) were applied for the strain showing positive in vivo germination results on tomato.The results of this last test led to select four strains: S11, S6, S15, and S12 that greatly affected tomato growth, with stems length (cm) of 9.212, 9.280, 9.362 and 9.858, respectively, compared to the control (6.400). Biochemical and phylogenic identifications of these strains allowed to affiliate them as following: Arthrobacter agilis(S6), Streptomyces Sp (S11), Bacillus sp13 (S15) and Mycobacterium Sp(S12). The four strains produced several enzymes, high indol acetic acid (phyto- hormone) quantity (mg/l: 38.47 (S11); 86.90 (S6); 93.96 (S12) and 190.23 (S15), siderophores, nitrogen fixing. It also showed an antagonistic activity against the phytopathogenic fungi tested with variable p lant growth inhibition (PGI) %:0-78.51% for Bacillus sp13; 29-74%for Streptomyces sp; 0-72%for Arthrobacter agilis; and 0-69% for Mycobacterium sp. These results prove that the strains are compatible for tomato growth stimulation.