Biodegradation of some organochlorine and organophosphate pesticides is difficult because of their low solubility in water and, therefore, their low bioavailability. To overcome the hydrophobicity problem and the limited pesticide availability, biosurfactants play a major role. In this study, we evaluated the effect of an extract from Pseudomonas sp. B0406 strain with surfactant properties, on the solubility of two pesticides: endosulfan (ED) and methyl parathion (MP). Such a process was performed in order to increase the aqueous solubility of both pesticides, to increase its availability to microorganisms and to promote their biodegradation. The extract from Pseudomonas sp. B0406 showed a critical micellar concentration of 1.4 g/L and the surface tension at that point was 40.4 mN/m. The preliminary chemical and physical partial characterization of the extract with surfactant properties indicated that it is an anionic glycolipid, which increases the solubility of both pesticides of 0.41 at 0.92 mg/L for ED and of 34.58 at 48.10 mg/L for MP. The results of this study suggest the effectiveness of this extract in improving the solubility of both pesticides ED and MP in water and, therefore, of its potential use to enhance the degradation of these pesticides.

Phosphate-solubilizing bacteria (PSB) transform precipitated inorganic phosphorus into soluble orthophosphates. This study evaluated the efficiency of tricalcium and iron phosphate solubilization in Pikovskaya medium using five bacterial strains (A1, A2, A3, A5, and A6) cultured in acidic and alkaline pH levels. The bacterial strain that proved to be more efficient for P solubilization and was tolerant to pH variations was selected for assessing bacterial growth and P solubilization with glucose and sucrose in the culture medium. The bacterial strains were identified through 16S rRNA gene sequencing as Pseudomonas libanensis A1, Pseudomonas libanensis (A2), Bacillus pumilus (A3), Pseudomonas libanensis (A5), and Bacillus siamensis (A6). These five bacterial strains grew, tolerated pH changes, and solubilized inorganic phosphorus. The bacterial strain A3 solubilized FePO₄ (4 mg L⁻¹) and Ca₃(PO₄)₂ (50 mg L⁻¹). P solubilization was assayed with glucose and sucrose as carbon sources for A3 (Bacillus pumilus MN100586). After four culture days, Ca₃(PO₄)₂ was solubilized, reaching 246 mg L⁻¹ with sucrose in culture media. Using glucose as a carbon source, FePO₄ was solubilized and reached 282 mg L⁻¹ in six culture days. Our findings were: Pseudomonas libanensis, and Bacillus siamensis, as new bacteria, can be reported as P solubilizers with tolerance to acidic or alkaline pH levels. The bacterial strain B. pumilus grew using two sources of inorganic phosphorus and carbon, and it tolerated pH changes. For that reason, it is an ideal candidate for inorganic phosphorus solubilization and future production as a biofertilizer.

In this work, two agro-industrial wastes, namely Waste Cooking Oil (WCO) and Coffee Wastewater (CW) have been used as the carbon source for the production of biosurfactants, due to their low cost and high availability. Biosurfactant-producing bacterial isolates from the Mexican state of Chiapas were used. The selected biosurfactant-producer strains were evaluated in a liquid medium with 2% (v/v) of WCO as the carbon source. The assay was conducted in an Erlenmeyer flask containing 300 mL aliquots of mineral salt media (MSM) + residue and incubated at 100 rpm at room temperature for 96 hours. The biosurfactant produced in the samples reduced the surface tension from 50 to 30-29 mN/m. Strains A and 83 showed the maximum emulsification index at 58-59%. Strain A showed the highest biosurfactant yield with a production of 3.7 g/L in comparison with strains B, 83 and Pseudomonas aeruginosa ATCC27853. Our results suggest that the biosurfactant produced by strain A has great potential in the treatment of wastewater with a high content of fatty acids, and of soils contaminated by pesticides or oil hydrocarbons.