Isolation, Identification, biocontrol activity and plant growth promoting of a superior strain Streptomyces tricolor strain HM10

Abstract

Purpose: Streptomyces are familiar with biocontrol activity and producing a broad range of biologically active substances. Our goal was to isolate a local Streptomyces bacteria that can promote plant growth via siderophore, indole acetic acid (IAA) production and phosphate solubilization and biocontrol the phytopathogens to reduce the heavy usage of chemical fertilizers and fungicides.Methods: The designated strains were isolated from local soil samples in Saudi Arabia via the standard serial dilution method, identified morphologically, by scanning electron microscope (SEM) and 16S rDNA sequencing and screened against many soils borne fungi. Siderophore, IAA production and phosphate solubilization were detected and measured.Results: A strain designated Streptomyces tricolor strain HM10 was isolated and showed aerial hyphae in SEM. Selected isolate showed highly homolog revealed to 99.69 % with the type strain Streptomyces tricolor LMG 20328. In vitro experiments showed a growth inhibition of ten phytopathogenes by strain HM10 fermentation broth and production of plant growth promoting compounds such as siderophore, IAA and solubilize phosphate. S. tricolor strain HM10 exhibited high antagonism effect against tested fungi (i.e. Colletotrichum gloeosporides with inhibition zone exceed 18 mm whereas the lowest effect was against Alternaria solani (8 mm)). Furthermore, the highest siderophore production was recorded to strain HM8 followed by strain HM10 with 64 and 22.56 h/c (halo zone area/colony area). With regard to IAA production, Streptomyces strain HM10 was the highest producer with value 273.02 µg/ml.Conclusion: Streptomyces tricolor HM10 is an important biological agent that can be used to promote plant growth and control of phytopathogen.

An update about plant growth promoting Streptomyces species

“…Triticum aestivum (Wheat) -Increases phosphate solubility -Indoleacetic acid production -Improves the bioavailability of trace elements such as iron and zinc [55] Streptomyces lydicus strain WYEC 108…”

“…Pisum sativum (pea plant) -Nitrogenase activity -Improves assimilation of iron in nodules -Produces chitinolytic enzymes to inhibit pathogens [9] Streptomyces spp. CIMAP-A1 Geranium (Pelargonium) -Produce siderophores -Produce indole-3-acetic acid -Produce secondary metabolites to resist numerous fungi [55] Streptomyces tricolor Strain HM10…”