Siderophore-Producing Bacteria from a Sand Dune Ecosystem and the Effect of Sodium Benzoate on Siderophore Production by a Potential Isolate

Abstract

<jats:p>Bioremediation in natural ecosystems is dependent upon the availability of micronutrients and cofactors, of which iron is one of the essential elements. Under aerobic and alkaline conditions, iron oxidizes to Fe<jats:sup>+3</jats:sup>creating iron deficiency. To acquire this essential growth-limiting nutrient, bacteria produce low-molecular-weight, high-affinity iron chelators termed siderophores. In this study, siderophore-producing bacteria from rhizosphere and nonrhizosphere areas of coastal sand dunes were isolated using a culture-dependent approach and were assigned to 8 different genera with the predominance of<jats:italic>Bacillus</jats:italic>sp. Studies on the ability of these isolates to grow on sodium benzoate revealed that a pigmented bacterial culture TMR2.13 identified as<jats:italic>Pseudomonas aeruginosa</jats:italic>showed growth on mineral salts medium (MSM) with 2% of sodium benzoate and produced a yellowish fluorescent siderophore identified as pyoverdine. This was inhibited above 54 <jats:italic>μ</jats:italic>M of added iron in MSM with glucose without affecting growth, while, in presence of sodium benzoate, siderophore was produced even up to the presence of 108 <jats:italic>μ</jats:italic>M of added iron. Increase in the requirement of iron for metabolism of aromatic compounds in ecosystems where the nutrient deficiencies occur naturally would be one of the regulating factors for the bioremediation process.</jats:p>

Pumping iron to keep fit: modulation of siderophore secretion helps efficient aromatic utilization in Pseudomonas putida KT2440

“…In addition, fine-tuning of siderophore secretion (up-or down-regulation) in response to available carbon sources (aromatic or non-aromatic) provides an additional fitness advantage to P.putida by curtailing unproductive energy expenditure for siderophore secretion where it is not warranted. Our hypothesis can be further supported by two observations: Jin et al (2010) have shown a significant increase in siderophore secretory microbes in iron-limited, phenolic-rich rhizospheric environments, while Gaonkar et al (2012) have shown a significant increase in siderophore secretion in response to sodium benzoate in marine isolates. These observations have indirectly provided a link between siderophore secretion and aromatic utilization.…”

Improved iron acquisition ofAstragalus sinicusunder low iron-availability conditions by soil-borne bacteriaBurkholderia cepacia

“…The siderophore-producing strain of JFW16 was identified via the chrome azurol sulphonate (CAS) assay (Gaonkar et al 2012). …”

Studies on Siderophore and Pigment Produced by an Adhered Bacterial Strain Halobacillus trueperi MXM-16 from the Mangrove Ecosystem of Goa, India

“…Interestingly both pyoverdine and azotobactin are mixed ligand siderophores. Studies have shown that fluorescent pigment pyoverdine from Pseudomonas aeruginosa is one such example that is known to be a powerful scavenger and efficient transporter of Fe(III) [23][24][25]. In the current investigation, the ability of the pigment to chelate iron from the CAS medium was studied.…”