Improved production of bioactive glucosylmannosyl-glycerolipid by sponge-associated Microbacterium species

The marine Microbacterium species HP2 (DSM 12583), isolated from the sponge Halichondria panicea, is able to produce a glucosylmannosyl-glycerolipid when grown on a complex medium with glucose. Optimizing the carbon sources in shake flask experiments has shown that glycerol affords the highest specific glycoglycerolipid production. The product yield approached 300 mg/L or 25 mg/g biomass upon scaling up in a 40-L bioreactor volume. The native diglycosyl-glycerolipid GGL.2 strongly inhibited growth of the tumor cell lines HM02 and Hep G2 (50% inhibition at 0.4 to 3 microg/mL), while the related deacylated compound (GG.2) showed a potent anti-tumor-promoting activity.