Isolating and screening bacterial endophytes producing growth regulator Indole-3 - Acetic Acid (IAA) and antifungal compounds against fusarium oxysporum damping-off disease of Pinus merkusii

Abstract

Endophytic microorganisms in plant tissues, which are not harmful to host
plant, could produce bioactive substances such as growth regulators,
antibiotics, folic acid groups... These compounds promote beneficial effects
for the life of the host plants, stimulate the growth of plant, inhibit the growth of pathogens and enhance the resistance of trees. Isolating and screening endophytes from Pinus merkusii, which are capable of synthesizing IAA and antibiotics, is very essential and have both scientific and practical significance. From the 20 branch samples, 36 Strains of bacterial endophytes were isolated, in which 2 strains of endophytes QI1 and QI
24 having high bioactive activities were selected, QI1 was identified as Pseudomonas fluorescens, which had the ability to produce IAA with 11.872 mg/l. Strain QI24 was identified as Bacillus subtilis which produced antifungal metabolies against Fusarium oxysporum causing damping off of pine, inhibition ring diameter after 10 days was 22mm, production of IAA reached 5.312 mg/l. Both strains QI1 and QI 24 are likely to grow in normal condition to produce biofertilizer to stimulate growth and control damping off for pines.