High productivity ethanol fermentation on a mineral medium using a flocculent strain ofZymomonas mobilis

The flocculation of bacteria using cationic synthetic flocculants and chitosan

“…Cells were cultured in 2L baffled flasks at 37°C. 2. mobilis was grown in a semidefined medium ( Baratti et al, 1986 ), comprising ( as g/l ): yeast extract ( Oxoid ), 5, (NH4)2S04 1, KH2PO4 2, MgS04.7H20 0.5 and glucose 100; and a defined medium ( as g/l ): KHzPO4 3.48, N&Cl 2.41, MgS04.7H20 1 , FeS0+7HlO 0.01, calcium pantothenate 0.001, biotin 0.001, sodium citrate 0 .2 1 and glucose 100 ( Lawford and Stevnsborg, 1986 ). 2. mobilis was cultured anaerobically, controlled at pH 5.5 and 30°C in a 2L LH 500 series chemostat fermenter ( D = 0.07 h-l ).…”

“…Experiments aimed at flocculating 2. mobilisby this method, involving the use of chitosan, are currently underway. Since this work commenced, the flocculation of 2. mob&by simultaneous addition of Zetag 87 ( of similar charge density and molecular weight to Zetag 88N ) and titanium hydrous oxide, has been reported ( Ghommidh and Bu'Lock, 1988 ) and their use in ethanolic fermentation was studied, as an alternative to naturally flocculent 2. mobilis ( Baratti et al, 1986 ).…”

Use of wheat bran as a nutritive supplement for the production of ethanol by Zymomonas mobilis

“…When tested under suitable conditions, the per-* Corresponding author. formance of mineral medium was found to be similar to that of media containing yeast extract for ethanol production (Baratti et al 1986). A preliminary estimation of the cost of ethanol production in these media showed a 100-fold reduction of vitamin costs by using calcium pantothenate instead of yeast extract.…”

“…The defined medium (Baratti et al 1986) contained (g/lOO ml): carbohydrate (glucose, sucrose, fructose, or starch hydrolysate), 10; (NH,)2S0, (LR, BDH), 0.1; KH,PO, (LR, BDH), 0.2; MgSO, .7H20 (LR, BDH), 0.05, and yeast extract (HIMEDIA, Bombay, India) 0.5. The medium (200ml; pH 5.5) was bottled in 500ml conical flasks and sterilized at 121°C for 20 min.…”

“…Belaich & Senez (1965) first reported a chemically defined mineral medium and showed that calcium pantothenate could be used to support the growth and ethanol production by Z. mobilis. Since then, several media containing calcium pantothenate have been described for the growth of the organism (Goodman et al 1982;Fein et al 1983a;Nipkow et al 1984;Galani et al 1985;Baratti et al 1986). When tested under suitable conditions, the per-* Corresponding author.…”