Isolation, Identification, Biocontrol Activity, and Plant Growth Promoting Capability of a Superior Streptomyces tricolor Strain HM10

Abstract

Streptomyces is a genus with known biocontrol activity, producing a broad range of biologically active substances. Our goal was to isolate local Streptomyces species, evaluate their capacity to biocontrol the selected phytopathogens, and promote the plant growth via siderophore and indole acetic acid (IAA) production and phosphate solubilization. Eleven isolates were obtained from local soil samples in Saudi Arabia via the standard serial dilution method and identified morphologically by scanning electron microscope (SEM) and 16S rRNA amplicon sequencing. The biocontrol of phytopathogens was screened against known soil-borne fungi and bacteria. Plant growth promotion capacity was evaluated based on siderophore and IAA production and phosphate solubilization capacity. From eleven isolates obtained, one showed 99.77% homology with the type strain Streptomyces tricolor AS 4.1867, and was designated S. tricolor strain HM10. It showed aerial hyphae in SEM, growth inhibition of ten known phytopathogens in in vitro experiments, and the production of plant growth promoting compounds such as siderophores, IAA, and phosphate solubilization capacity. S. tricolor strain HM10 exhibited high antagonism against the fungi tested (i.e., Colletotrichum gloeosporides with an inhibition zone exceeding 18 mm), whereas the lowest antagonistic effect was against Alternaria solani (an inhibition zone equal to 8 mm). Furthermore, the most efficient siderophore production was recorded to strain HM8, followed by strain HM10 with 64 and 22.56 h/c (halo zone area/colony area), respectively. Concerning IAA production, Streptomyces strain HM10 was the most effective producer with a value of 273.02 μg/ml. An autochthonous strain S. tricolor HM10 should be an important biological agent to control phytopathogens and promote plant growth.

The Purified Siderophore from Streptomyces tricolor HM10 Accelerates Recovery from Iron-Deficiency-Induced Anemia in Rats

“…Consequently, the relative weights of the liver, kidneys, and spleen were linked to growth and body weight gain. Weight gained in the organs might have been due to improved metabolism and increased fat and muscle mass, as observed and indicated [36,39]. Consequently, ARs with an SD or IED injected with 1 µg Kg −1 of Sid had significantly lower relative liver weights than in the AR group, reflecting the improvement in body weight.…”

“…Different synthesized siderophores have been identified, including catecholate-type, hydroxamate-type, carboxylate-type, and mixed-type siderophores, as reviewed by Sah and Singh [52]. The production and isolation of catecholate-type Sid from S. tricolor HM10 were previously established [39]. In the current research, a catechol-type Sid was successfully isolated and purified from the S. tricolor HM10 strain in significant quantities as 25-30 mg Sid L −1 medium under optimal conditions.…”

“…2.1. Siderophore, Detection, Production, and Purification from S. tricolor HM10 S. tricolor HM10 strain (accession: MN527236) was used for siderophore production, as previously established by Rehan et al [39], with minor modifications. For siderophore detection, the Chrome Azurol S (CAS) assay was applied by adding CAS solution prepared according to Schwyn and Neilands [40] to King's B agar medium (composed of peptone, 20.0; K 2 HPO 4 , 1.50; MgSO 4 .7H 2 O, 1.50; agar, 15.0 (g/L), pH 7.2) with a ratio of 1:9.…”

“…The TPC-purified Sid was determined by using Folin-Ciocalteu reagent according to Yawadio Nsimba et al [47], and the TPC content was expressed as milligrams of Gallic acid equivalents (GAE) per gram (mg of GAE g −1 DW). The radical scavenging activity was measured spectrophotometrically based on the bleaching of DPPH radicals in purple solution according to Yawadio Nsimba et al [39], and ABTS (2,2 -azino-bis (3-ethylbenzothiazoline-6-sulphonic acid)) radicals in a dark green solution using the method by Barakat and Rohn [48]. The final results were expressed as millimoles of Trolox Equivalents (TE) per gram (mmol of TE g −1 ).…”

A Salt-Tolerant Streptomyces paradoxus D2-8 from Rhizosphere Soil of Phragmites communis Augments Soybean Tolerance to Soda Saline-Alkali Stress

“…Actinomycetes produce many bioactive compounds and have a great capacity to promote plant growth ( Bhatti et al 2017 ; Rehan et al 2021 ). Nowadays, several commercial biocontrol agents are developed from actinobacteria, such as Actinovate based on Streptomyces lydicus , Mycostop based on Streptomyces griseoviridis , and Rhizovit based on Streptomyces sp.…”