Metabolic Evaluation of Native Bacterial Strains of the Bacillus Genus as a Response to Salt Stress

Objective: To evaluate the main metabolites present under saline stress conditions in two native Bacillus species, by relating the physiological metabolism in root-bacteria association, using metabolomics. Theoretical Framework: The interaction between biological activity and metabolites is a tool for elucidating mechanisms that alleviate physiological stress in plants. Metabolomics allows us to evaluate the correlation of metabolic variables and various interactions between metabolites inside and outside organisms. Method: Two native soil strains were characterized to evaluate metabolite production under saline conditions. Metabolites were quantified by gas chromatography/mass spectrometry, principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA). Cross-validation, predictive capacity, and repeated-measures ANOVA tests were performed. Results and Discussion: The results of PCA and PLS-DA determined that both strains produce similar metabolites and quantities. The strain Bacillus sp. cp-h3 generated 196.84 μg mL-1 of L and D-proline; and 36.1 μg mL-1 of IAA, the second strain Bacillus sp. B1408, 168.8 μg mL-1 of L and D-proline and 28.66 μg mL-1 of IAA. Both metabolites are important during periods of salt stress in bacteria, as well as in plant physiology. Research Implications: The isolation, identification, and metabolomic profiling of reported microbial species validates the use of this technique for routine microbial screening. It is also a useful tool in biotechnological applications such as bioremediation. Originality/Value: A method for introducing strains into an osmotically hostile environment is presented. The viability of reported strains with biotechnological applications is demonstrated.