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PenaDiaz, A; Navarro, AK; Perez-Guevara, F (2008)

ENDOSPORE DIPICOLINIC ACID DETECTION DURING BACILLUS THURINGIENSIS CULTURE

LETT APPL MICROBIOL 46(2):166-170
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Aims: The aim of this work was to detect Bacillus thuringiensis endospore production during fermentation under conditions hindering endospore detection, i.e. in a complex undefined industrial medium with a high content of solids in suspension.Methods and Results: Bacterial endospore production was measured using the photoluminescence of dipicolinate (DPA) with Tb3+. The high temperature and pressure of a conventional autoclave was used to release DPA from the endospores. The endospore was obtained from B. thuringiensis var. kurstaki HD-73 fermentations in industrial-type media with 25.1 and 54.1 g l(-1) glucose, 4.4 and 35.3 g l(-1) soybean meal, 5.8 g l(-1) yeast extract, 9.2 g l(-1) corn steep solids and mineral salts.Conclusions: In this study, we successfully determined the DPA concentrations during the culture of B. thuringiensis in high-concentration soybean meal media. A good correlation was found between microscope endospore counting and DPA measurements in the cultures.Significance and Impact of the Study: Because of synergy between Cry protein and endospore in B. thuringiensis bioinsecticides formulation, it is important to be able to determine endospore development during B. thuringiensis industrial-type fermentation, in order to ascertain the beginning of sporulation.