Effect of saccharides on growth, sporulation rate and -endotoxin synthesis of Bacillus thuringiensis

Abstract

Effect of monosaccharides (glucose, fructose and galactose) and disaccharides (sucrose, lactose and maltose) as carbon sources on growth and sporulation rate of Bacillus thuringiensis MPK13 as well as -endotoxin production was investigated using 400 ml shake flasks culture. Substantially high growth and sporulation rate were obtained in cultivation using glucose and sucrose. Fructose, galactose, lactose and maltose were also able to support growth, but failed to enhance high sporulation rate. In general, high sporulation rate was related with high growth rate and high viable cell count (>1.5 x 10 12 cfu/ml). However, the presence of appropriate quantity of glucose was required to trigger -endotoxin formation. The presence of -endotoxin with molecular weight of 130 kD assayed using sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE), was only detected after 48 h of cultivation using 8 g/L glucose as the sole carbon source. Although good growth with high spore production was obtained in cultivation using a mixture of glucose (4 g/L) with other sugars, the spores produced contained no endotoxin. The existence of -endotoxin was also observed in cultivation using a mixture of various sugars (fructose, sucrose, maltose and lactose) with 8 g/L glucose, indicating that high glucose (> 8 g/L) must be present in the culture to trigger -endotoxin formation in the spores of Bacillus thuringiensis MPK13.

Knowledge of the physiology of spore-forming bacteria can explain the origin of spores in the food environment

“…As an example, sporulation of C. perfringens is repressed by high concentrations (>15 mM) of lactose, mannose and sucrose, but is not affected by the presence of galactose and fructose [18]. Conversely, glucose stimulates the sporulation of Clostridium acetobutylicum [19], while for Bacillus thuringiensis, sporulation is more efficient in the presence of glucose (70% sporulation) than in the presence of lactose (30% sporulation) [20].…”

Effect of different fermentation strategies on Bacillus thuringiensis cultivation and its toxicity towards the bagworm, Metisa plana Walker (Lepidoptera: Psychidae)

“…Bacillus thuringiensis MPK13, obtained from the Malaysian Palm Oil Board (MPOB) culture collection, was used in this study (Mazmira et al 2012). This bacterium was isolated from the gut of the dead larvae of bagworm M. plana through several isolation steps.…”

“…The preferred medium for the cultivation of Bt with high sporulation rate and δ-endotoxin production as described earlier (Içygen et al 2002;Mazmira et al 2012) was used in this study. The medium consisted of (NH 4 ) 2 SO 4 , 2.0 g/l; K 2 HPO 4 .3H 2 O, 0.5 g/l; MgSO 4 .7H 2 O, 0.2 g/l; MnSO 4 .4H 2 O, 0.05 g/l; CaCl 2 .2H 2 O, 0.08 g/l; and yeast extract, 2.0 g/l.…”

“…In the cultivation of Bt MPK13, glucose was identified as the most critical nutrient that supports both viable cell growth and also sporulation (Mazmira et al 2012). Reports on the empirical feeding policies have been developed to achieve high cell density culture (Khodair et al 2008).…”

Impact of Strain, pH and Ethanol Concentration on Ethanol Activation Method of Bacillus Spores Using a Single Spore Approach

“…Nutrient Broth (Oxoid, Basingstoke, UK) was used for the propagation of the species. Regarding sporulation media, 1L of sporulating agar medium was prepared by dissolving, 5 g of peptone, 5 g of sodium chloride, 1 g of meat extract, 2 g of yeast extract, 15 g of agar, 0.5 g of dissodic phosphate, 0,1 g of calcium chloride, 0.04g of manganese sulphate and the pH adjusted to 7±0.2 before sterilization at 121°C for 15 min [20]. The medium was poured into sterile Petri dishes.…”