NDLI: Oxygen supply in Bacillus thuringiensis fermentations: bringing new insights on their impact on sporulation and δ-endotoxin production

Content Provider	Springer Nature Link
Author	Boniolo, Fabrízio Siqueira Rodrigues, Raphael Cardoso Prata, Arnaldo Márcio Ramalho López, Maria Luisa Jacinto, Tânia Silveira, Mauricio Moura Berbert Molina, Marília Amorim
Copyright Year	2012
Abstract	The growth kinetics, sporulation, and toxicity of Bacillus thuringiensis var. israelensis were evaluated through the analysis of batch cultures with different dissolved oxygen (DO) profiles. Firstly, DO was maintained constant at 5%, 20%, or 50% throughout fermentation in order to identify the most suitable one to improve the main process parameters. Higher biomass concentration, cell productivity, and cell yield based on glucose were obtained with 50% DO. The higher aeration level also resulted in higher spore counts and markedly improved the toxic activity of the fermentation broth, which was 9-fold greater than that obtained with 5% DO (LC50 of 39 and 329 mg/L, respectively). Subsequently, using a two-stage oxygen supply strategy, DO was kept at 50% during the vegetative and transition phases until the maximum cell concentration was achieved. Then, DO was changed to 0%, 5%, 20%, or 100% throughout sporulation and cell lysis phases. The interruption of oxygen supply strongly reduced the spore production and thoroughly repressed the toxin synthesis. On the contrary, when DO was raised to 100% of saturation, toxic activity increased approximately four times (LC50 of 8.2 mg/L) in comparison with the mean values reached with lower DO levels, even though spore counts were lower than that from the 50% DO assay. When pure oxygen was used instead of normal air, it was possible to obtain 70% of the total biomass concentration achieved in the air assays; however, cultures did not sporulate and the toxin synthesis was consequently suppressed.
Starting Page	625
Ending Page	636
Page Count	12
File Format	PDF
ISSN	01757598
Journal	Applied Microbiology and Biotechnology
Volume Number	94
Issue Number	3
e-ISSN	14320614
Language	English
Publisher	Springer-Verlag
Publisher Date	2012-03-07
Publisher Place	Berlin, Heidelberg
Access Restriction	Subscribed
Subject Keyword	Bacillus thuringiensis var. israelensis Oxygen supply Sporulation Toxic activity Microbial Genetics and Genomics Microbiology Biotechnology
Content Type	Text
Resource Type	Article
Subject	Medicine Applied Microbiology and Biotechnology Biotechnology

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