Isolation and characterization of an active mannanase-producing anaerobic bacterium, Clostridium tertiumKT-5A, from lotus soil

Of 10 strains of mannanase-producing anaerobicbacteria isolated from soils and methanogenic sludges, Clostridium tertium KT-5A,which was isolated from lotus soil, produced high amounts of extracellular β-1,4-mannanase. The isolate was an aerotolerant anaerobe without quinon systems; the cell growthcultivated with no addition of reducing agents was also stable. High yields of mannanasewere obtained by inducing enzyme production with galactomannan guar gum and beef extract/peptone as carbon and nitrogen sources, respectively. Fermentation endproducts on galactomannan fermentation were formate, acetate, lactate, butyrate, carbondioxide and hydrogen. The extracellular mannanase displayed high activity ongalactomannans of locust bean gum galactose/mannose (G/M) ratio 1:4 and spinogum (G/M 1:3), but weak activity on guar gum galactomannan (G/M 1:2) and konjac glucomannan. As far as is known, this is the first report on the isolation of an activemannanase-producing anaerobic bacterium from natural environments.