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Revista argentina de microbiología

versión impresa ISSN 0325-7541versión On-line ISSN 1851-7617

Rev. argent. microbiol. vol.53 no.4 Ciudad Autónoma de Buenos Aires dic. 2021

 

MICROBIOLOGICAL IMAGE

Argentinean Bacillus thuringiensis strains exhibiting distinct morphology of their parasporal crystals

Cepas argentinas de Bacillusthuringiensis con distinta morfología en sus cristales paraesporales

Cecilia Peralta1 

Diego Herman Sauka1 

Antonela Marozzi1 

Eleodoro E. Del Valle1 

Leopoldo Palma1 

1 Centro de Investigaciones y Transferencia CIT-VM-CONICET, Universidad Nacional de Villa María, Villa María, Córdoba, Argentina. b Instituto Nacional deTecnología Agropecuaria (INTA), Instituto de Microbiología y Zoología Agrícola (IMYZA), Hurlingham, Buenos Aires, Argentina.c Instituto de Investigaciones en Biodiversidad y Medioambiente (INIBIOMA) - CONICET - UNCo, San Martín de los Andes, Neuquén, Argentina.d ICiagro Litoral, Universidad Nacional del Litoral, CONICET Facultad de Ciencias Agrarias, Esperanza, Santa Fe, Argentina

TEXTO COMPLETO

Bacillus thuringiensisis a Gram-positive and sporulated bacterium exhibiting insecticidal activity against a wide range of insects.3During sporulation, this bacterium produces a number of different proteins forming crystalline inclusions adjacent to the spores (parasporal crystals). Among these insecticidal proteins, the most abundant are those commonly known as Cry (Crystal) proteins, which are responsible for exerting a toxic activity (upon ingestion) against insects of different species.5For this reason,B. thuringiensishas proved to be the most efficient and used bioinsecticide to date.2However,Spodoptera cosmioides,Spodoptera eridaniaandAgrotissp. (Lepidoptera) are species that are not yet controlled by some transgenic crops (e.g. Intacta RR2Pro soybean). Thus, in an attempt to enlarge the host spectrum of this bacterium it is necessary to search for novel strains. In this work we show a sporulatedB. thuringiensisBt-UNVM_84 strain exhibiting a number of rare amorphous to spherical crystal combinations, whereas sporulatedB. thuringiensisstrain Bt-UNVM-94 showed quasi symmetric bipyramidal parasporal crystals, by using scanning electron microscopy (SEM) (Fig. 1). Strains Bt-UNVM_84 and Bt-UNVM_94 were isolated from Oncativo (Córdoba, Argentina) and Cululú (Santa Fe, Argentina), respectively. The insecticidal activity of these differentB. thuringiensisstrains is currently under investigation. Each strain was grown in liquid CCY sporulation medium6for ∼48h (150rpm) until no vegetative cells were observed under a light microscope. The presence of parasporal crystals was first determined using Coomassie blue stained slides1(1000×) under a Nikon E100 light microscope and confirmed later by a NikonTi-Eclipse phase contrast microscope (1000×) (data not shown). For the SEM analysis, aliquots of 1ml were centrifuged for 5minutes (16,000g) at room temperature. Each pellet was washed three times with sterile distilled water and fixed with 100μl 4% formaldehyde. Each fixed preparation was then sent to Centro Integral de Microscopía Electrónica (CIME - CONICET - UNT) for SEM examination.

Figure 1: Scanning electron microscopy of parasporal crystals fromBacillus thuringiensisstrains Bt-UNVM_84 and Bt-UNVM_94 (C=crystal, S=spore). (A)B. thuringiensisstrain Bt-UNVM_84 showed combinations of amorphous to spherical parasporal crystals of ∼0.7-0.9μm from two points along the diametral axis. (B)B. thuringiensisstrain Bt-UNVM_94 exhibited quasi symmetric bipyramidal parasporal crystals of ∼1.0-1.2μm from two points along the longitudinal axis. Crystal size was measured using ImageJ.4Parameters used for image acquisition are shown: Mag=magnification (K×=1000×), WD=work distance, Eht=energy high tension, Det=detector type and SE2=secondary electron. (0,52MB). 

Funding

This work was supported by Universidad Nacional de Villa María research grant PIC UNVM 2018-2019.

ACKNOWLEDGMENTS

We thank to Hernán Esquivel, Luciano Martínez from CIME-CONICET-UNT and Vanessa Areco for their technical assistance. We also thank to the Instituto de Investigación of Universidad Nacional de Villa María for contributing to this ongoing research.

REFERENCES

1 Ammons D., J. Rampersad, A. Khan. Usefulness of staining parasporal bodies when screening forBacillus thuringiensis. J InvertebrPathol, 79 (2002), pp. 203-204 [ Links ]

2 G.S. Jouzani, E. Valijanian, R. Sharafi. Bacillus thuringiensis: a successful insecticide with new environmental features and tidings. Appl Microbiol Biotechnol, 101 (2017), pp. 2691-2711. [ Links ]

3 L. Palma. Bacillus thuringiensis-based biopesticides, are they as effective as they should be?. Rev Argent Microbiol, 49 (2017), pp. 119 [ Links ]

4 C.T. Rueden, J. Schindelin, M.C. Hiner, B.E. DeZonia, A.E. Walter, E.T. Arena, K.W. Eliceiri. ImageJ2: ImageJ for the next generation of scientific image data. [ Links ]

BMC Bioinformatics, 18 (2017), pp. 529 [ Links ]

5 D.H. Sauka, G.B. Benintende. Diversity and distribution of lepidopteran-specific toxin genes inBacillus thuringiensisstrains from Argentina. Rev Argent Microbiol, 49 (2017), pp. 273-281 [ Links ]

6 G.S. Stewart, K. Johnstone, E. Hagelberg, D.J. Ellar. Commitment of bacterial spores to germinate. A measure of the trigger reaction. Biochem J, 198 (1981), pp. 101-106 [ Links ]

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