A new approach to isolating siderophore-producing actinobacteria

Abstract

Aims: This study was conducted to investigate the application of 2,2′‐dipyridyl as a new approach to isolating siderophore‐producing actinobacteria. Methods and Results: Isolation of actinobacteria from soil was conducted by a soil dilution plate technique using starch‐casein agar. Iron starvation was fostered by the incorporation of the iron chelator 2,2′‐dipyridyl in the isolation medium. Pretreatment of the samples at an elevated temperature (40°C) ensured that the majority of nonsporulating bacteria were excluded. The survivors of this treatment were largely actinobacteria. Of the viable cultures grown in the presence of 2,2′‐dipyridyl, more than 78–88% (average of three separate studies) were reported to produce siderophore‐like compounds compared to 13–18% (average of three separate studies) when grown on the basic media in the absence of the chelating agent. The most prolific producers as assessed by the chrome azurol sulphate (CAS) assay were further characterized and found to belong to the genus Streptomyces. Conclusions: Selective pressure using 2,2′‐dipyridyl as an iron‐chelating agent in starch‐casein media increased the isolation of siderophore‐producing actinobacteria compared to the unamended medium. Significance and Impact of the Study: The study described represents a new approach to the isolation of siderophore‐producing actinobacteria using a novel procedure that places a selection on cell population based upon the incorporation of a chelating agent in the medium.

Genomic characterization of a new endophyticStreptomyces kebangsaanensisidentifies biosynthetic pathway gene clusters for novel phenazine antibiotic production

“…3 ). The potential of its therapeutic application is reflected by the use of S. pilosus derived Desferrioxamine B, used for the treatment of iron intoxication ( Nakouti, Sihanonth & Hobbs, 2012 ) and Plasmodium falciparum infection ( Miethke & Marahiel, 2007 ). Furthermore, siderophores produced by endophytes have previously been given more attention due to their role in controlling soil borne plant pathogens ( Loper & Buyer, 1991 ).…”

Engineering the Biosynthesis of the Polyketide-Nonribosomal Peptide Collismycin A for Generation of Analogs with Neuroprotective Activity

“…The 2,2 0 -bipyridyls form complexes with several divalent metal ions, especially copper and iron (Nakouti et al, 2012;Nocentini and Barzi, 1996), and it is widely known that, because tumor cells have higher requirements of iron due to their increased proliferation rate, treatment with iron chelators is an interesting approach for cancer treatment (Kovacevic et al, 2011). Chelators not only cause an arrest in DNA synthesis, they can also affect the expression of key molecules involved in cell cycle control and angiogenesis or directly generate oxidative stress through the formation of redox iron complexes (Kovacevic et al, 2011;Richardson, 2005).…”

Role of Phosphate-Solubilizing Actinomycetes in Plant Growth Promotion: Current Perspective

“…On the contrary, the actinobacteria with their ability to (1) sporulate, (2) transform various complex soil nutrients into simple and accessible forms, (3) extensively and efficiently colonize plant roots, (4) manage phytopathogens, and (5) secrete other plant-growth-promoting substances make these organisms as preferred choices for developing potential field bio-inoculants. Actinomycetes are metabolically flexible soil/rhizosphere-colonizing microorganisms Euanorasetr et al 2010;Lei et al 2013) capable of producing a range of compounds of interest, including (1) antifungal compounds which have been found useful in controlling fungal root diseases (Rothrock and Gottlieb 1984;Zucchi et al 2010;Bungonsiri et al 2011;Sreevidya and Gopalakrishnan 2012;Francisco et al 2013) (2) siderophores (Lee et al 2012;Nakouti et al 2012;Najwa et al 2013), ACC deaminase (El-Tarabily 2008), and (3) plant-growth-promoting hormones (Hamdali et al 2008a;Khamna et al 2010). Generally, plant root exudates stimulate growth, proliferation, and rhizosphere colonization of actinomycetes that may act as a strong antagonist to fungal pathogens.…”