IMPACT OF ENDOPHYTIC LIPOPEPTIDES USE AGAINST SOME PLANT PATHOGENIC MICROORGANISMS

Abstract

Twelve dissimilar plant associated bacterial colonies were isolated from five different tomato seedlings, the Non Ribosomal Lipopeptides genes were detected by degenerated primers technique in the twelve tomato endophytic isolates, only the long rode bacilli endophytic strains were found to harbour the lipopeptides synthetases genes, these three strains were given laboratory names of (BMG100, BMG101 and BMG102) for further pursuit. Partial sequencing of 16s RNA gene and protein profile analysis for the three bacilli isolates showed that all isolates belonged to Bacillus subtilis. The lipopeptides production by HPLC analysis revealed that all the endophytic isolates from tomato stems had the ability to produce lipopeptides except the third isolate named B. subtilis BMG102 showed no production. different levels of volumetric oxygen transfer coefficient (KLa) were used as cursors for lipopeptides production. The maximum concentration of surfactin type was about 1431, 529 and 437 mg.L-1, the plipastitin (fengycin type ) was 360 198 mg.L-1 and zero while the Mycosubtilin (iturin type) was zero, 228 and 414 mg.L-1 for the strains B. subtilis ATCC21332, BMG100 and BMG101, respectively. Surfactin production is visibly optimal at high oxygen transfer (kLa) and showed more than 0.07 S-1, while the optimum production of the fengycin and iturin could be observed at mild values of O2 transfer (kLa) which equal 0.01 and 0.015 S-1 respectively. The antibacterial - antifungal effects of the three B.subtilis extracts collected during lipopeptides productivity regimes showed inhibition activity against Pseudomonas syringae, Ralstonia solanacearum and Erwinia amylovora, as will as the antifungal activity against Aspergillus niger, Phanerochaete chrysosporium and Alternaria alternata. These results indicate potential use of B.subtilis strains as biocontrol agents, especially when considering commercial implementation. Studies regarding the lipopeptides applications, should also be considered as this will influence the efficacy of the lipopeptides against the target organisms.