Biosurfactants produced by metal-resistant Pseudomonas aeruginosa isolated from Zea mays rhizosphere and compost

Contextualization: Pseudomonas aeruginosa is capable of producing biosurfactants which have many uses in bioremediation and the production of antiviral, antibacterial, antiparasitic, sporicidal and antifungal agents, among others.   Knowledge gap: This study describes the production of mono and di-rhamnolipid biosurfactants by P. aeruginosa strains isolated from Zea mays rhizosphere and composts in the state of Guerrero, Mexico.  Purpose: The overall aims were to investigate biosurfactant, pyocyanin production, and tolerance to heavy metals and antimicrobial activity capacity than biosurfactants produced from P. aeruginosa strains from corn rhizosphere and compost in Mexico. Methodology: Biosurfactant production was determined based hemolysis on blood agar, blue halos in CTAB-Methylene blue agar, drop collapse test and production of foam on PPGAS broth, the emulsion index (IE24) and antibacterial capacity. The strains were identified by sequence of the 16S rDNA gene and their resistance to heavy metals were also evaluated. Results and conclusions: Two strains isolated from Zea mays rhizosphere (PAM8, PAM9) were the best biosurfactant producers and their extracts showed antimicrobial activity against Grampositive and Gramnegative bacteria. PAM8 and PAM9 showed >30% of cellular hydrophobicity to hydrocarbons, and were capable of emulsifying toluene, cyclohexane, petroleum, diesel and oils. All strains showed the same profile of heavy metal tolerance (As5+ >As3+ >Zn2+ >Pb2+ >Fe3+ >Cd2+ >Cu2+ >Cr6+ in concentrations of 20, 10, 10, 6, 4, 4, 2 and 2 mM., respectively). The isolation of biosurfactant-producing and heavy-metal tolerant bacteria from Zea mays rhizosphere and compost in Guerrero demonstrates the capacity for this region to harbor potentially important microbial strains for industrial or bioremediation applications.Contextualización: la Pseudomonas aeruginosa es capaz de producir biosurfactantes que tienen muchos usos en la biorremediación y producción de agentes antivirales, antibacterianos, antiparasitarios, esporicidas y antifúngicos, entre otros. Vacío de conocimiento: este estudio describe la producción de biosurfactantes mono y di-ramnolípidos por cepas de P. aeruginosa aisladas de la rizosfera y compostas de Zea mays en el estado de Guerrero, México. Propósito del estudio: los objetivos generales fueron investigar la producción de biosurfactantes, piocianina y tolerancia a metales pesados y la capacidad de actividad antimicrobiana de los biosurfactantes producidos por cepas de P. aeruginosa aisladas de rizosfera y composta en México. Metodología: Se determinó la producción de biosurfactantes con base en la hemolisis agar sangre, halos azules en agar CTAB-azul de metileno, ensayo de colapso de gotas, producción de espuma en medio PPGAS, índice de emulsión (IE24) y capacidad antibacterial, las cepas se identificaron por la secuencia del gen del 16S y también se evaluó la resistencia a metales pesados. Resultados y conclusiones: Dos cepas aisladas de la rizosfera de Zea mays (PAM8, PAM9) fueron las mejores productoras de biosurfactantes, y sus extractos mostraron actividad antimicrobiana frente a bacterias Grampositivas y Gramnegativas. PAM8 y PAM9 mostraron >30% de hidrofobicidad a hidrocarburos y fueron capaces de emulsionar tolueno, ciclohexano, petróleo, diésel y aceites. Todas las cepas mostraron el mismo perfil de tolerancia a metales pesados (As5+ > As3+ > Zn2+ > Pb2+ > Fe3+ > Cd2+ > Cu2+ > Cr6+ en concentraciones de 20, 10, 10, 6, 4, 4, 2 y 2 mM., respectivamente). El aislamiento de bacterias productoras de biosurfactantes y tolerantes a metales pesados de la rizosfera y composta de Zea mays en Guerrero demuestra que la región alberga cepas microbianas potencialmente importantes para aplicaciones industriales o de biorremediación

Biosurfactants produced by metal-resistant Pseudomonas aeruginosa isolated from Zea mays rhizosphere and compost

Contextualization: Pseudomonas aeruginosa is capable of producing biosurfactants which have many uses in bioremediation and the production of antiviral, antibacterial, antiparasitic, sporicidal and antifungal agents, among others.   Knowledge gap: This study describes the production of mono and di-rhamnolipid biosurfactants by P. aeruginosa strains isolated from Zea mays rhizosphere and composts in the state of Guerrero, Mexico.  Purpose: The overall aims were to investigate biosurfactant, pyocyanin production, and tolerance to heavy metals and antimicrobial activity capacity than biosurfactants produced from P. aeruginosa strains from corn rhizosphere and compost in Mexico. Methodology: Biosurfactant production was determined based hemolysis on blood agar, blue halos in CTAB-Methylene blue agar, drop collapse test and production of foam on PPGAS broth, the emulsion index (IE24) and antibacterial capacity. The strains were identified by sequence of the 16S rDNA gene and their resistance to heavy metals were also evaluated. Results and conclusions: Two strains isolated from Zea mays rhizosphere (PAM8, PAM9) were the best biosurfactant producers and their extracts showed antimicrobial activity against Grampositive and Gramnegative bacteria. PAM8 and PAM9 showed >30% of cellular hydrophobicity to hydrocarbons, and were capable of emulsifying toluene, cyclohexane, petroleum, diesel and oils. All strains showed the same profile of heavy metal tolerance (As5+ >As3+ >Zn2+ >Pb2+ >Fe3+ >Cd2+ >Cu2+ >Cr6+ in concentrations of 20, 10, 10, 6, 4, 4, 2 and 2 mM., respectively). The isolation of biosurfactant-producing and heavy-metal tolerant bacteria from Zea mays rhizosphere and compost in Guerrero demonstrates the capacity for this region to harbor potentially important microbial strains for industrial or bioremediation applications.Contextualización: la Pseudomonas aeruginosa es capaz de producir biosurfactantes que tienen muchos usos en la biorremediación y producción de agentes antivirales, antibacterianos, antiparasitarios, esporicidas y antifúngicos, entre otros. Vacío de conocimiento: este estudio describe la producción de biosurfactantes mono y di-ramnolípidos por cepas de P. aeruginosa aisladas de la rizosfera y compostas de Zea mays en el estado de Guerrero, México. Propósito del estudio: los objetivos generales fueron investigar la producción de biosurfactantes, piocianina y tolerancia a metales pesados y la capacidad de actividad antimicrobiana de los biosurfactantes producidos por cepas de P. aeruginosa aisladas de rizosfera y composta en México. Metodología: Se determinó la producción de biosurfactantes con base en la hemolisis agar sangre, halos azules en agar CTAB-azul de metileno, ensayo de colapso de gotas, producción de espuma en medio PPGAS, índice de emulsión (IE24) y capacidad antibacterial, las cepas se identificaron por la secuencia del gen del 16S y también se evaluó la resistencia a metales pesados. Resultados y conclusiones: Dos cepas aisladas de la rizosfera de Zea mays (PAM8, PAM9) fueron las mejores productoras de biosurfactantes, y sus extractos mostraron actividad antimicrobiana frente a bacterias Grampositivas y Gramnegativas. PAM8 y PAM9 mostraron >30% de hidrofobicidad a hidrocarburos y fueron capaces de emulsionar tolueno, ciclohexano, petróleo, diésel y aceites. Todas las cepas mostraron el mismo perfil de tolerancia a metales pesados (As5+ > As3+ > Zn2+ > Pb2+ > Fe3+ > Cd2+ > Cu2+ > Cr6+ en concentraciones de 20, 10, 10, 6, 4, 4, 2 y 2 mM., respectivamente). El aislamiento de bacterias productoras de biosurfactantes y tolerantes a metales pesados de la rizosfera y composta de Zea mays en Guerrero demuestra que la región alberga cepas microbianas potencialmente importantes para aplicaciones industriales o de biorremediación

Bacterial Community with Plant Growth-Promoting Potential Associated to Pioneer Plants from an Active Mexican Volcanic Complex

Microorganisms in extreme volcanic environments play an important role in the development of plants on newly exposed substrates. In this work, we studied the structure and diversity of a bacterial community associated to Andropogon glomeratus and Cheilanthes aemula at El Chichón volcano. The genetic diversity of the strains was revealed by genomic fingerprints and by 16S rDNA gene sequencing. Furthermore, a metagenomic analysis of the rhizosphere samples was carried out for pioneer plants growing inside and outside the volcano. Multifunctional biochemical tests and plant inoculation assays were evaluated to determine their potential as plant growth-promoting bacteria (PGPB). Through metagenomic analysis, a total of 33 bacterial phyla were identified from A. glomeratus and C. aemula rhizosphere samples collected inside the volcano, and outside the volcano 23 bacterial phyla were identified. For both rhizosphere samples, proteobacteria was the most abundant phylum. With a cultivable approach, 174 bacterial strains were isolated from the rhizosphere and tissue of plants growing outside the volcanic complex. Isolates were classified within the genera Acinetobacter, Arthrobacter, Bacillus, Burkholderia, Cupriavidus, Enterobacter, Klebsiella, Lysinibacillus, Pantoea, Pseudomonas, Serratia, Stenotrophomonas and Pandoraea. The evaluated strains were able to produce indole compounds, solubilize phosphate, synthesize siderophores, showed ACC deaminase and nitrogenase activity, and they had a positive effect on the growth and development of Capsicum chinense. The wide diversity of bacteria associated to pioneer plants at El Chichón volcano with PGPB qualities represent an alternative for the recovery of eroded environments, and they can be used efficiently as biofertilizers for agricultural crops growing under adverse conditions