Use of sea water as salts source in starch- and soya bean-based media, for the production of Bacillus thuringiensis bioinsecticides

Spodoptera frugiperda (SMITH, 1797) (Lepidoptera: Noctuidae) affects diverse crops of great economic interest, for instance, it can cause severe yield losses in maize, rice and sorghum. In this study, a selection and characterization of Bacillus thuringiensis (BERLINER, 1911) isolates with a high insecticidal activity against S. frugiperda was performed. Fifty-two crystal-forming B. thuringiensis isolates that were identified from 3384 Bacillus-like colonies were examined and screened by PCR for the presence cry genes (cry1, cry1Aa, cry1Ab, cry1Ac, cry1D, cry2 and cry2Ab). Four isolates that showed high toxicity towards S. frugiperda were shown to harbor cry2 genes. The crystals were analyzed by electron microscopy and showed bipyramidal and cuboidal shapes. Furthermore, these four isolates had lethal concentration (LC 50 ) values of 44.5 ng/cm 2 (SUFT01), 74.0 ng/cm 2 (SUFT02), 89.0 ng/cm 2 (SUFT03) and 108 ng/cm 2 (SUFT 04) to neonate S. frugiperda larvae. An ultrastructural analysis of midgut cells from S. frugiperda incubated with the SUFT01 spore-crystal complex showed disruptions in cellular integrity and in the microvilli of the midgut columnar cells. The isolates characterized in this work are good candidates for the control of S. frugiperda, and could be used for the formulation of new bioinsecticides.

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“…The number of spores and the δ-endotoxin production were determined as described by Ghribi et al (2007).…”

Section: Colony Forming Units (Cfus) and δ-Endotoxin Productionmentioning

confidence: 99%

Selection and characterization of Bacillus thuringiensis isolates with a high insecticidal activity against Spodoptera frugiperda (Lepidoptera: Noctuidae)

et al. 2016

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“…The 250 ml shake fl asks, containing 50 ml of culture medium [11], were incubated for 72 h at 30 °C in a rotary shaker at 200 rev min -1 . The obtained values are the means (±SD) of three determinations of two different experiments.…”

Section: Cultural Conditionsmentioning

confidence: 99%

Experimental design and Bayesian networks for enhancement of delta-endotoxin production by Bacillus thuringiensis

Ennouri

Ayed

Hassen

et al. 2015

Acta Microbiologica et Immunologica Hungarica

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Bacillus thuringiensis (Bt) is a Gram-positive bacterium. The entomopathogenic activity of Bt is related to the existence of the crystal consisting of protoxins, also called delta-endotoxins. In order to optimize and explain the production of delta-endotoxins of Bacillus thuringiensis kurstaki, we studied seven medium components: soybean meal, starch, KH 2 PO 4 , K 2 HPO 4 , FeSO 4 , MnSO 4 , and MgSO 4 and their relationships with the concentration of delta-endotoxins using an experimental design (Plackett-Burman design) and Bayesian networks modelling. The effects of the ingredients of the culture medium on delta-endotoxins production were estimated. The developed model showed that different medium components are important for the Bacillus thuringiensis fermentation. The most important factors infl uenced the production of delta-endotoxins are FeSO 4 , K 2 HPO 4 , starch and soybean meal. Indeed, it was found that soybean meal, K 2 HPO 4 , KH 2 PO 4 and starch also showed positive effect on the delta-endotoxins production. However, FeSO 4 and MnSO 4 expressed opposite effect. The developed model, based on Bayesian techniques, can automatically learn emerging models in data to serve in the prediction of delta-endotoxins concentrations. The constructed model in the present study implies that experimental design (Plackett-Burman design) joined with Bayesian networks method could be used for identifi cation of effect variables on delta-endotoxins variation.

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“…Bt biopesticides are usually composed of spores and crystals protein mixtures, harvested from the production media, readily produced by aerated liquid fermentation. They are easily harvested and have a long shelf life when formulated properly (Ghribi et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Regulation of major cultural components for designing a cost effective medium to increase -endotoxin synthesis by Bacillus thuringiensis

Mourin¹,

Shishir²,

Khan³

et al. 2015

Afr. J. Biotechnol.

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The present study was aimed at designing a cost effective medium for increasing the δ-endotoxin (Cry protein) synthesis by Bacillus thuringiensis (Bt) kurstaki HD-73 and indigenous Bt JSc1 harboring potential cry genes active against Lepidoptera insect orders. In this regard, locally available cheap molasses as carbon source, soybean extract as nitrogen source, sea water as trace elements source, cystine as sporulation/growth factor were considered to design a cost effective medium. Molasses and soybean extract in place of glucose and peptone in glucose-peptone (GP) medium supported 78.85% increase in δ-endotoxin synthesis in shake flask culture. The effect of cystine on endotoxin synthesis was highly pronounced in two media with a range of 80.32 to 110% higher δ-endotoxin under comparable fermentation conditions. While, substituting basal salts with sea water, Btk HD-73 yielded satisfactory and comparable endotoxin (74.3% of yield with basal salts). It was detected that the rapid decrease of endotoxin synthesis in the culture after 24 h was due to the degradation by the endogenous protease, synthesized with the progress of fermentation. This degradation of the endotoxin was much better protected (1.23 mg/ml endotoxin versus 0.312 mg/ml) by adding 4% ammonium sulfate in the optimized medium. The medium thus formulated with molasses, soybean extract, ammonium sulfate, cystine and sea water was then used in 3.0 L bioreactor cultivation for endotoxin synthesis by both Btk HD-73 and Bt JSc1 under 30% saturation of dO 2 through cascade control of agitation and aeration producing a higher yield of δ-endotoxin (2.1 and 2.63 mg/ml, respectively). The present results may successfully be used for large scale production of Bt biopesticide in Bangladesh.

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Use of sea water as salts source in starch- and soya bean-based media, for the production of Bacillus thuringiensis bioinsecticides

Cited by 47 publications

References 14 publications

Selection and characterization of Bacillus thuringiensis isolates with a high insecticidal activity against Spodoptera frugiperda (Lepidoptera: Noctuidae)

Selection and characterization of Bacillus thuringiensis isolates with a high insecticidal activity against Spodoptera frugiperda (Lepidoptera: Noctuidae)

Experimental design and Bayesian networks for enhancement of delta-endotoxin production by Bacillus thuringiensis

Regulation of major cultural components for designing a cost effective medium to increase -endotoxin synthesis by Bacillus thuringiensis

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