In this study, 338 microorganisms, comprising 271 bacteria and 67 fungi, were isolated from sediment samples collected from underexplored Pacific and Caribbean regions of Colombia. Screening trials were conducted on selected strains (n = 276) to assess their tolerance to cadmium (Cd²⁺), lead (Pb²⁺), and zinc (Zn²⁺), leading to the identification of six bacteria capable of withstanding 750 mg·L⁻¹ of each heavy metal ion. Three promising microorganisms, identified as Enterobacter sp. INV PRT213, Pseudomonas sp. INV PRT215, and Stenotrophomonas sp. INV PRT216 were selected for lead removal experiments using LB broth medium supplemented with 400 mg·L⁻¹ Pb²⁺. Among these, Pseudomonas sp. INV PRT215 exhibited significant potential, removing 49% of initial Pb²⁺ after 240 min of exposure (16.7 g wet biomass·L⁻¹, pH 5, 30 °C). Infrared spectra of Pb-exposed biomass showed changes in functional groups, including carbonyl groups of amides, carboxylate, phosphate, hydroxyl, and amine groups, compared to the not-exposed control. These changes suggested interactions between the metal and functional groups in the biomass. The findings of this study highlight the potential of microorganisms derived from coastal marine environments as promising candidates for future applications in bioremediation of polluted environments contaminated with heavy metals.

Biosurfactants are amphiphilic surface-active molecules of microbial origin principally produced by hydrocarbon-degrading bacteria; in addition to the bioremediation properties, they can also present antimicrobial activity. The present study highlights the chemical characterization and the antimicrobial activities of biosurfactants produced by deep-sea marine bacteria from the generaHalomonas,Bacillus,Streptomyces, andPseudomonas. The biosurfactants were extracted and chemically characterized through Chromatography TLC, FT-IR, LC/ESI–MS/MS, and a metabolic analysis was done through molecular networking. Six biosurfactants were identified by dereplication tools from GNPS and some surfactin isoforms were identified by molecular networking. The half-maximal inhibitory concentration (IC₅₀) of biosurfactant fromHalomonassp. INV PRT125 (7.27 mg L⁻¹) andHalomonassp. INV PRT124 (8.92 mg L⁻¹) were most effective against the pathogenic yeastCandida albicansATCC 10231. For Methicillin-resistantStaphylococcus aureusATCC 43300, the biosurfactant fromBacillussp. INV FIR48 was the most effective with IC₅₀values of 25.65 mg L⁻¹and 21.54 mg L⁻¹forC. albicans, without hemolytic effect (< 1%), and non-ecotoxic effect in brine shrimp larvae (Artemia franciscana), with values under 150 mg L⁻¹, being a biosurfactant promising for further study. The extreme environments as deep-sea can be an important source for the isolation of new biosurfactants-producing microorganisms with environmental and pharmaceutical use.

Mercury pollution is a significant environmental issue, primarily resulting from industrial activities, including gold mining extraction. In this study, 333 microorganisms were tested in increasing mercury concentrations, where 158 bacteria and 14 fungi were able to grow and remain viable at concentrations over 5.0 mg/L of mercuric chloride (II). One of the bacterial strains, Stenotrophomonas sp. INV PRT0231, isolated from the mouth of the San Juan River in the Chocó region in Colombia, showed a high mercury resistance level (MIC₉₀ of 27 ± 9 mg/L), with a removal rate of 86.9%, an absorption rate of 1.2%, and a volatilization rate of 85.7% at pH 6.0 and 30.0 °C. The FTIR analysis showed changes in the functional groups, including fatty acid chains and methyl groups, proteins, and lipopolysaccharides associated with the carboxylate group (COO⁻), suggesting an important role of these biomolecules and their associated functional groups as mechanisms employed by the bacterium for mercury detoxification. Our study contributes to the understanding of the mechanisms of mercury biotransformation in microbial environmental isolates to help develop bioremediation strategies to mitigate mercury pollution caused by anthropogenic activities.