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Nair K, Al-Thani R, Jaoua S. Bacillus thuringiensis strain QBT220 pBtoxis plasmid structural instability enhances δ-endotoxins synthesis and bioinsecticidal activity. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2021; 228:112975. [PMID: 34773843 DOI: 10.1016/j.ecoenv.2021.112975] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2021] [Revised: 10/20/2021] [Accepted: 11/05/2021] [Indexed: 06/13/2023]
Abstract
Bacillus thuringiensis subsp. israelensis (Bti) spherical parasporal crystal contains several insecticidal proteins used as environmentally safe alternative to toxic chemical pesticides. The exploration of a Bti strain isolated from Qatar QBT220 genes encoding the δ-endotoxins responsible of the insecticidal activities revealed the alteration of a 14-kb DNA region including the δ-endotoxins cry10A and cyt1C genes of pBtoxis plasmid. The presence of all the insecticidal genes except cry10A and cyt1C was explained by a structural instability of the plasmid pBtoxis. However, when compared with the Bti reference strains H14 and QBT217 that carry all δ-endotoxins coding genes, it was found that QBT220, has a significantly higher insecticidal activity against the dipteran insect Aedes aegypti larvae despite of the plasmid pBtoxis structural instability due to the alteration of cry10A and cyt1C genes. In addition, QBT220 showed the highest δ-endotoxin synthesis per spore, compared with that of the wildtype strains. These findings confirm that the altered genes cry10A and cyt1C are not mandatory for Bti insecticidal activities and on the other hand show a possible inhibitory effect played by the 2 proteins Cry10A and Cyt1C on the insecticidal activities of the other insecticidal proteins. In addition, the QBT220 increased δ-endotoxins synthesis per cell, makes this strain a good candidate for possible applications in the industrial production of bioinsecticides.
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Affiliation(s)
- Kavita Nair
- Environmental Science Program, Department of Biological & Environmental Sciences, College of Arts & Sciences, Qatar University, 2713, Doha, Qatar
| | - Roda Al-Thani
- Environmental Science Program, Department of Biological & Environmental Sciences, College of Arts & Sciences, Qatar University, 2713, Doha, Qatar
| | - Samir Jaoua
- Environmental Science Program, Department of Biological & Environmental Sciences, College of Arts & Sciences, Qatar University, 2713, Doha, Qatar.
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Borin DB, Castrejón-Arroyo K, Cruz-Nolasco A, Peña-Rico M, Sagrillo MR, Santos RCV, de Baco LS, Pérez-Picaso L, Camacho L, Navarro-Mtz AK. Parasporin A13-2 of Bacillus thuringiensis Isolates from the Papaloapan Region (Mexico) Induce a Cytotoxic Effect by Late Apoptosis against Breast Cancer Cells. Toxins (Basel) 2021; 13:toxins13070476. [PMID: 34357948 PMCID: PMC8309972 DOI: 10.3390/toxins13070476] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 06/30/2021] [Accepted: 07/03/2021] [Indexed: 11/16/2022] Open
Abstract
The protein A13-2 was obtained from Bacillus thuringiensis strains isolated from the Papaloapan watershed region (Oaxaca, Mexico). The cytotoxic activity of parasporal inclusions was studied against breast cancer cell line (MCF-7) and normal cell (human peripheral blood mononuclear cells). The MTT, the formation of reactive species, nitric oxide, free cell DNA, and the type of death cellular were assessed. The protein A13-2 shows the highest cytotoxic activity against MCF-7 (13% cell viability at 6 µg/mL), the extracellular DNA increases, and it shows no stress for reactive species or nitric oxide. Besides, the A13-2 parasporin shows no toxicity to peripheral blood mononuclear cells, and it does not generate changes in nitric oxide levels or free cell DNA. Due to that, the cytotoxic effect of A13-2 was specific for MCF-7, and it does not affect normal cells. According to microscopy and flow cytometry, A13-2 parasporin leads to the death of MCF-7 cells by late apoptosis together with necrosis and without allowing the triggering of the survival mechanisms. When analyzed together, our results show for the first time that the A13-2 protein isolated from Mexican strains of B. thuringiensis preferentially kills MCF- 7 (cancer cells) over HEK 293 and PBMC cell lines (normal cells), thus representing a promising alternative for the treatment of cancer breast.
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Affiliation(s)
- Diego Becker Borin
- Instituto de Biotecnología, Universidad del Papaloapan, Tuxtepec, Oaxaca 68301, Mexico; (D.B.B.); (M.P.-R.)
| | - Karen Castrejón-Arroyo
- División de Estudios de Posgrado, Universidad del Papaloapan, Tuxtepec, Oaxaca 68301, Mexico; (K.C.-A.); (A.C.-N.)
| | - Alain Cruz-Nolasco
- División de Estudios de Posgrado, Universidad del Papaloapan, Tuxtepec, Oaxaca 68301, Mexico; (K.C.-A.); (A.C.-N.)
| | - Miguel Peña-Rico
- Instituto de Biotecnología, Universidad del Papaloapan, Tuxtepec, Oaxaca 68301, Mexico; (D.B.B.); (M.P.-R.)
| | - Michele Rorato Sagrillo
- Graduate Program in Nanoscience, Franciscan University, Santa Maria, Rio Grande do Sul 97010-032, Brazil;
| | - Roberto C. V. Santos
- Oral Microbiology Laboratory, Universidade Federal de Santa Maria, Santa Maria, Rio Grande do Sul 97065-060, Brazil;
| | - Lucas Silva de Baco
- Oncologia, Franciscan University, Santa Maria, Rio Grande do Sul 97015-450, Brazil;
| | - Lemuel Pérez-Picaso
- Instituto de Química Aplicada, Universidad del Papaloapan, Tuxtepec, Oaxaca 68301, Mexico;
| | - Luz Camacho
- Laboratorio de Nutrición Experimental, Instituto Nacional de Pediatría, Ciudad de México 4530, Mexico;
| | - A. Karin Navarro-Mtz
- Instituto de Biotecnología, Universidad del Papaloapan, Tuxtepec, Oaxaca 68301, Mexico; (D.B.B.); (M.P.-R.)
- Correspondence: ; Tel.: +52-28787-59240 (ext. 220); Fax: +52-28787-59240
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