COMPOSITION AND ROLE OF EXTRACELLULAR POLYMERS IN METHANOGENIC GRANULES

Methanobacterium formicicum and Methanosarcina mazeii are two prevalen t species isolated from an anaerobic granular consortium grown on a fa tty acid mixture. The extracellular polysaccharides (EPS) were extract ed from Methanobacterium formicicum and Methanosarcina mazeii and from the methanogenic granules to examine their role in granular developme nt, The EPS made up approximately 20 to 14% of the extracellular polym er extracted from the granules, Methanobacterium formicicum, and Metha nosarcina mazeii. The EPS produced by Methanobacterium formicicum was composed mainly of rhamnose, mannose, galactose, glucose, and amino su gars, while that produced by Methanosarcina mazeii contained ribose, g alactose, glucose, and glucosamine. The same sugars were also present in the EPS produced by the granules, These results indicate that the t wo methanogens, especially Methanobacterium formicicum, contributed si gnificantly to the production of the extracellular polymer of the anae robic granules, Growth temperature, substrates (formate and H-2-CO2), and the key nutrients (nitrogen and phosphate concentrations) affected polymer production by Methanobacterium formicicum.