Biotechnological Potential of Rhizospheric Bacillus Strains from Lonquimay, Chile, as Producers of Antimicrobial Biosurfactants

Lamilla, Claudio; Rubilar, Olga; San Martin, Ignacio; Troncoso, David; Rojas, Sebastián; Martínez-Cisterna, Daniel; Cárdenas-Chávez, Diana L.; Diez, María Cristina; Quiroz, Andrés

doi:10.3390/ijms27125401

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Biotechnological Potential of Rhizospheric Bacillus Strains from Lonquimay, Chile, as Producers of Antimicrobial Biosurfactants

by

Claudio Lamilla

^1,2,*

,

Olga Rubilar

^2,3,

Ignacio San Martin

⁴,

David Troncoso

⁵,

Sebastián Rojas

⁶,

Daniel Martínez-Cisterna

²,

Diana L. Cárdenas-Chávez

⁷

,

María Cristina Diez

^2,3

and

Andrés Quiroz

^2,8,*

¹

Scientific and Technological Bioresource Nucleus (BIOREN), Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco 4811230, Chile

²

Centro de Investigación Biotecnológica Aplicada al Medio Ambiente (CIBAMA), Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco 4811230, Chile

³

Departamento de Ingeniería Química, Facultad de Ingeniería y Ciencias, Universidad de La Frontera, Av. Francisco Salazar 01145, Temuco 4780000, Chile

⁴

Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco 4811230, Chile

⁵

Programa de Doctorado en Ciencias de Recursos Naturales, Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco 4811230, Chile

⁶

Programa de Magíster en Ciencias de la Ingeniería Mención Biotecnología, Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco 4811230, Chile

⁷

Tecnologico de Monterrey, School of Engineering and Sciences, Vía Atlixcáyotl 5718, Puebla 72453, México

⁸

Laboratorio de Química Ecológica, Departamento de Ciencias Químicas y Recursos Naturales, Universidad de La Frontera, Av. Francisco Salazar 01145, Casilla 54-D, Temuco 4811230, Chile

^*

Authors to whom correspondence should be addressed.

Int. J. Mol. Sci. 2026, 27(12), 5401; https://doi.org/10.3390/ijms27125401 (registering DOI)

Submission received: 13 April 2026 / Revised: 1 June 2026 / Accepted: 8 June 2026 / Published: 15 June 2026

(This article belongs to the Special Issue Antimicrobial Materials: Molecular Developments and Applications)

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Abstract

Biosurfactants are surface-active microbial molecules with increasing industrial relevance as sustainable alternatives to synthetic surfactants. Among them, lipopeptides produced by Bacillus species, particularly surfactin, exhibit strong interfacial activity and biological functionality. In this study, rhizospheric soils from the La Araucanía region, Chile, were explored as a source of biosurfactant-producing bacteria. Eighteen strains were isolated, and two high-performing strains, Solo 1 and Solo 4, were identified as Bacillus amyloliquefaciens and Bacillus subtilis, respectively. Both strains harbored the srfAA gene and produced surfactin isoforms confirmed by MALDI-TOF MS. Kinetic analysis revealed distinct production profiles, with Solo 1 reaching a maximum of 90 mg L⁻¹ at 24 h, whereas Solo 4 showed continuous production up to 224.4 mg L⁻¹ at 72 h. Both biosurfactants exhibited high emulsification capacity (>80%) and stability across wide ranges of temperature, pH, and salinity. Importantly, cell-free supernatants from both strains showed antibacterial and antibiofilm activity against Staphylococcus aureus, with Solo 4 reaching 81% biofilm inhibition. In addition, surfactin-enriched extracts inhibited the pathogenic bacterium Pseudomonas syringae and the filamentous fungus Fusarium oxysporum, with Solo 4 consistently showing stronger antimicrobial performance. Overall, these findings identify Solo 4 as a promising native Bacillus strain for future development of biosurfactant-based systems aimed at antimicrobial control, biofilm management, agricultural pathogen suppression, surface sanitation, and environmentally compatible biotechnological processes.

Keywords: antibacterial activity; antifungal activity; bacillus; surfactin

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MDPI and ACS Style

Lamilla, C.; Rubilar, O.; San Martin, I.; Troncoso, D.; Rojas, S.; Martínez-Cisterna, D.; Cárdenas-Chávez, D.L.; Diez, M.C.; Quiroz, A. Biotechnological Potential of Rhizospheric Bacillus Strains from Lonquimay, Chile, as Producers of Antimicrobial Biosurfactants. Int. J. Mol. Sci. 2026, 27, 5401. https://doi.org/10.3390/ijms27125401

AMA Style

Lamilla C, Rubilar O, San Martin I, Troncoso D, Rojas S, Martínez-Cisterna D, Cárdenas-Chávez DL, Diez MC, Quiroz A. Biotechnological Potential of Rhizospheric Bacillus Strains from Lonquimay, Chile, as Producers of Antimicrobial Biosurfactants. International Journal of Molecular Sciences. 2026; 27(12):5401. https://doi.org/10.3390/ijms27125401

Chicago/Turabian Style

Lamilla, Claudio, Olga Rubilar, Ignacio San Martin, David Troncoso, Sebastián Rojas, Daniel Martínez-Cisterna, Diana L. Cárdenas-Chávez, María Cristina Diez, and Andrés Quiroz. 2026. "Biotechnological Potential of Rhizospheric Bacillus Strains from Lonquimay, Chile, as Producers of Antimicrobial Biosurfactants" International Journal of Molecular Sciences 27, no. 12: 5401. https://doi.org/10.3390/ijms27125401

APA Style

Lamilla, C., Rubilar, O., San Martin, I., Troncoso, D., Rojas, S., Martínez-Cisterna, D., Cárdenas-Chávez, D. L., Diez, M. C., & Quiroz, A. (2026). Biotechnological Potential of Rhizospheric Bacillus Strains from Lonquimay, Chile, as Producers of Antimicrobial Biosurfactants. International Journal of Molecular Sciences, 27(12), 5401. https://doi.org/10.3390/ijms27125401

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Biotechnological Potential of Rhizospheric Bacillus Strains from Lonquimay, Chile, as Producers of Antimicrobial Biosurfactants

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