Production of molybdenum-coordinating compound by Bacillus thuringiensis

Area of Science:

• Microbiology
• Biochemistry
• Analytical Chemistry

Background:

• Bacillus thuringiensis produces extracellular compounds during growth.
• Iron deficiency can induce specific metabolic pathways in bacteria.
• Molybdenum uptake and metabolism are crucial for various microbial processes.

Purpose of the Study:

• To characterize a novel molybdenum-reactive compound produced by Bacillus thuringiensis.
• To investigate the relationship between L-arginine availability and the production of this compound.
• To develop a method for quantifying the compound and its molybdenum complex.

Main Methods:

• Bacterial culture under iron-deficient conditions.
• Spectrophotometric analysis of the compound and its complex with sodium molybdate.
• Acrylamide gel electrophoresis and Sephadex G-15 gel filtration for molecular weight determination.
• Thin-layer chromatography and amino acid analysis to determine peptide nature.

Main Results:

• A molybdenum-reactive compound, termed chelin, was identified and characterized.
• Chelin production correlated with L-arginine concentration and occurred post-stationary phase.
• Chelin forms a yellow complex with sodium molybdate (molybdo-chelin) with distinct spectral properties.
• Spectrophotometry at 425 nm was established for quantification.
• Molecular weight of chelin estimated at 550 Da, molybdo-chelin at 760 Da.
• Chelin confirmed as a peptide containing threonine, glycine, and alanine.

Conclusions:

• Bacillus thuringiensis synthesizes and secretes a peptide (chelin) that binds molybdenum.
• Chelin production is influenced by nutrient availability (iron and L-arginine).
• The molybdo-chelin complex has unique spectral characteristics enabling its quantification.