Growth and Polysaccharide Production by Methylocystis parvus OBBP on Methanol

Methylocystis parvus OBBP, an obligate methylotroph originally isolated as a methane-utilizing bacterium, was cultivated on methanol as a sole source of carbon. After adaptation to high methanol levels, this organism grew on methanol with a maximum specific growth rate of 0.65 h. The pH optimum for growth was between 7 and 9, and the temperature optimum was between 30 and 37 degrees C. Methanol concentrations higher than 5% (by weight) were toxic. Formaldehyde, at a concentration greater than 1 mM, inhibited growth. Formate was neither a substrate nor an inhibitor. An extracellular viscous heteropolysaccharide was produced during growth. The maximum production of the total biomass was 14.5 g (dry weight) per liter of broth. The dried biomass contained 22% (wt/wt) crude protein and 62% (wt/wt) polysaccharide. The main components of the polysaccharide were d-glucose (82%) and l-rhamnose (14%).