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Table 4 Biofilm formation characteristics of Clostridium acetobutylicum/C. beijerinckii onto various supports

From: Biofilm reactors for industrial bioconversion processes: employing potential of enhanced reaction rates

Support Characteristics
Bonechar C. acetobutylicum culture
- Adsorption is quick
- Biomass layers (biofilms) become visible in 3–4 days time
- Between day 2 and 4, the culture produces polysaccharide in high concentrations (2.04 gL-1 broth as compared to 0.95 gL-1 broth from day 5 to 30)
- Once initial layers appear, biomass accumulation is quick
- Desorption does not occur at high dilution rates
- < than 25% cells were desorbed when adsorbed cell particles were agitated at 200–300 rpm (in shake flasks on shaker) at pH 2.7 for 18–24 h at 30°C
- During initial stages (2–4 days) the culture produced high concentrations of acids (~6–9 gL-1) followed by becoming solventogenic
- During solventogenic stages fluctuations in solvent concentrations were less
Glass beads C. acetobutylicum culture
- Biomass accumulation takes much longer than bone char
- During initial stages (2–4 days) higher amount of polysaccharide production does not occur
- Cells do not stick to the support as firmly as onto bonechar
- Reactor produces <20% solvents as compared to bonechar adsorbed cells
- Reactors are not stable as solvent concentration fluctuates
- Cells can easily be washed off
Glass wool, Polypropylene tow, and stainless steel wire balls C. acetobutylicum culture
- <20% biomass accumulated than in bonechar packed reactor
- Cells do not stick to the support firmly and can be desorbed easily
- Reactors are not stable and poor solventogenesis occurred
Clay brick (Ref. 38) C. beijerinckii culture
- Cells stick firmly as in case of bonechar and reactors were solventogenic