Scaling up, characterization of levan and its inhibitory role in carcinogenesis initiation stage'

Honey isolate Bacillus subtilis M was cultivated in shake flasks and in 16-l bioreactor cultures to investigate cell growth, bio-metabolites production kinetics and bioprocess scalability. The respective maximal levan and levansucrase productions of 59.5 g/l and 74.1 U/ml were achieved in bioreactor cultures under pH controlled condition (pH = 7.0) after only 24h. Crude levan (levE) was isolated, characterized and fractionated into F1, F2, and F3 with different molecular weight (21.8, 13.118, 9.53 kDa). H-1 NMR and C-13 NMR spectroscopy proved that LevE and their fractions were mainly beta-(2, 6)-linked levan-type polysaccharide. The cancer chemo-preventive activity indicated that the levE and its fraction 3 were promising inhibitors of cytochrome P-450 1A activity, inducers of glutathione-S-transferase activity in Murine hepatomaHepa1c1c7cells and possessed highest radical scavenging affinity to both ROO center dot and OH center dot. They inhibited the induced-DNA fragmentation. None of the tested samples triggered apoptosis or necrosis in splenocytes, except F2. (c) 2013 Elsevier Ltd. All rights reserved.