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 24 h. Crude levan (levE) was isolated, characterized and fractionated into F1, F2, and F3 with different molecular weight (21.8, 13.118, 9.53 kDa). 1H NMR and 13C NMR spectroscopy proved that LevE and their fractions were mainly β-(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 and OH. They inhibited the induced-DNA fragmentation. None of the tested samples triggered apoptosis or necrosis in splenocytes, except F2.