Biochemical limitations of Bacillus thuringiensis based biopesticides production in a wheat bran culture medium

• Published in: Research in microbiology Vol. 174; no. 6; p. 104043
• Main Authors: Barssoum, Rita, Al Kassis, Gabrielle, Nasseredine, Rayan, Saad, Jihane, El Ghoul, Meriem, Abboud, Joanna, Fayad, Nancy, Dupoiron, Stéphanie, Cescut, Julien, Aceves-Lara, César Arturo, Fillaudeau, Luc, Awad, Mireille Kallassy
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01.07.2023; Elsevier
• Subjects: Bacillus thuringiensis; biochemical limitations; elemental composition; fermentable fraction; Life Sciences; Microbiology and Parasitology; wheat bran; wheat bran; biochemical limitations; Bacillus thuringiensis; elemental composition; fermentable fraction; Elemental composition; Fermentable fraction; Biochemical limitations; Wheat bran
• ISSN: 0923-2508; 1769-7123; 0923-2508
• DOI: 10.1016/j.resmic.2023.104043

Bacillus thuringiensis, a gram-positive sporulating bacteria found in the environment, produces, during its sporulation phase, crystals responsible for its insecticidal activity, constituted of an assembly of pore-forming δ-endotoxins. This has led to its use as a biopesticide, an eco-friendly alternative to harmful chemical pesticides. To minimize production cost, one endemic Bacillus thuringiensis sv. kurstaki (Btk) strain Lip, isolated from Lebanese soil, was cultivated in a wheat bran (WB) based medium (IPM-4-Citrus project EC n° 734921). With the aim of studying the biochemical limitations of Btk biopesticide production in a wheat bran based medium, the WB was sieved into different granulometries, heat treated, inoculated with Btk Lip at flask scale, then filtered and separated into an insoluble and a permeate fractions. Several biochemical analyses, ie. bio performances, starch, elemental composition, total nitrogen and ashes, were then conducted on both fractions before and after culture. On a morphological level, two populations were distinguished, the fine starch granules and the coarse lignocellulosic particles. The biochemical analyses showed that both the raw and sieved WB have a similar proteins content (0.115 g/gdm WB), water content (0.116 g/gdm WB) and elemental composition (carbon: 45 %, oxygen: 37 %, nitrogen: 3 %, hydrogen: 6 %, ashes: 5 %). The starch content was 17 %, 14 % and 34 % and the fermentable fraction was estimated to 32.1 %, 36.1 % and 51.1 % respectively for classes 2, 3 and 4. Both the elemental composition and Kjeldahl analyses showed that the nitrogen is the limiting nutrient of the culture.