Effect of the volumetric oxygen mass transfer coefficient on producing δ-endotoxins by Bacillus thuringiensis in culture medium based on forage palm. (March 2021)

• Record Type: Journal Article
• Authors: da Silva, Túlio Alexandre Freire; de Freitas, Lívia Santos; da Silva, Larita Veruska José Bezerra; Duarte Neto, José Manoel Wanderley; da Silva, Gilvanda Ribeiro; Maranhão, Liane Maria de Almeida Castro; de Lacerda, Cynthia Araújo; Oliveira, José de Paula; Bezerra, Raquel Pedrosa; Porto, Ana Lúcia Figueiredo
• Is Part Of: Biocatalysis and agricultural biotechnology. Number 32(2021)
• Publication Date: 2021-03
• Subjects: Oxygenation -- Spodoptera frugiperda -- Biological control -- Bioreactor; Agricultural biotechnology -- Periodicals; Enzymes -- Biotechnology -- Periodicals; 660.6
• DOI: 10.1016/j.bcab.2021.101960
• Languages: English
• ISSNs: 1878-8181

Abstract

Abstract: Bacillus thuringiensis is the main commercial source of safe insecticidal toxins. On the industrial scale, oxygenation is the most important variable for enhancing the production of δ-endotoxin by B. thuringiensis and improving its toxicity . Therefore, the parameters of growth kinetics, the formation of spores, the production of δ-endotoxin, and its toxicity against Spodoptera frugiperda were evaluated in batch cultures of B. thuringiensis cultivated in a culture medium based on forage palm with different K L α values. In all conditions, diauxic growth curves were observed due to the change of carbon source. Maximum cell concentration increased when K L α values were raised from 11 to 16 h −1, but biomass productivity was enhanced only when K L a was increased from 11 to 13 h −1 . Due to the diauxic growth, spore production and δ-endotoxin production were observed at two different times. The first peak was generally lower than the second peak. At both peaks, a high concentration of spores was reached using a K L a of 13 h −1, but the highest production of δ-endotoxin and the maximum toxin yield based on spores or substrate were observed in the K L a of 16 h −1 . Therefore, a bioassay against S. frugiperda was performed using δ-endotoxin produced under a K L a of 16 h −1 . Although more δ-endotoxin was produced in the second peak than in the first peak, the highest toxicity was observed with toxins produced in the first peak. These results suggest that the K L α affects the production of δ-endotoxin and that toxicity against S. frugiperda decreases when fermentation time is increased. Graphical abstract: Image 1 Highlights: B. thuringiensis was cultivated at three different K L a conditions. Due to diauxic growth, two peaks of spores and δ-endotoxin production were observed. Spore and δ-endotoxin concentration were higher at the second peak. Maximum toxin and spore were noted at a K L a equal to 13 h −1 and 16 h −1, respectively. δ-endotoxins produced at the first peak has more toxicity to S. frugiperda.