The Antimicrobial Activity Potential of Plant Growth Prompting Lactic Acid Bacteria Against Broad Spectrum of Phytopathogens

Lactic acid bacteria (LAB) have been known as a promising
biocontrol agent against plant pathogens. However,
the reported isolates represented the antagonistic effects
merely against the limited number of bacterial or fungal
phytopathogens. Accordingly, we aimed to screen LAB
isolates possessing inhibitory activities against a broad
spectrum of plant disease causal agents within one of the
most important agricultural areas, Mazandaran, Iran. Additionally,
the plant growth promoting (PGP) properties
were evaluated to introduce the valuable isolates to be
apply in biological practices for reducing the chemicals
consumption.
The LAB were isolated from field and forest soils as well
as livestock manure samples. The in vitro experiments
was performed to assess the antifungal and antibacterial
activities.
Results indicated that the LAB isolates could significantly
(P > 0.05) inhibit the growth of tested bacteria and fungi
in comparison to control. Seven LAB isolates exhibiting
the most antagonistic activity were selected and identified
molecularly as Lactobacillus plantarun (LAB 1, LAB 18,
LAB 19); L. zea (LAB 5, LAB 13); and L. casei (LAB 8,
LAB 6). Moreover, all selected isolates were able to biosynthesis
indole-3-acetic acid (IAA), nitrogen hydroxide
(NH3), and hydrogen cyanide (HCN). The isolates LAB
6, LAB 8, LAB 19 could produce siderophore on chrome
azurol S (CAS) agar and the LAB 6 and LAB 19 were
found to solubilize phosphate on Pikovskaya (PVK) agar
medium.
Hereby, the LAB 19 and LAB 6 had the most antagonistic
activity against all tested pathogens as well as PGP properties.
However, the efficiency of the isolates under field
and greenhouse conditions remain to be determined.

Author(s): Ramtin Vamenani, Ali Pakdin Parizi

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