Abstract
Readily available inexpensive substrate with high product yield is the key to restoring acetone-butanol-ethanol (ABE) fermentation to economic competitiveness. Lactose-replete cheese whey tends to favor the production of butanol over acetone. In the current study, we investigated the fermentability of milk dust powder with high lactose content, for ABE production by Clostridium acetobutylicum and Clostridium beijerinckii. Both microorganisms produced 7.3 and 5.8 g/L of butanol respectively, with total ABE concentrations of 10.3 and 8.2 g/L, respectively. Compared to fermentation with glucose, fermentation of milk dust powder increased butanol to acetone ratio by 16% and 36% for C. acetobutylicum and C. beijerinckii, respectively. While these results demonstrate the fermentability of milk dust powder, the physico-chemical properties of milk dust powder appeared to limit sugar utilization, growth and ABE production. Further work aimed at improving the texture of milk dust powder-based medium would likely improve lactose utilization and ABE production.
Highlights
Alternative energy-related research currently receives tremendous attention, largely in response to the rising cost of gasoline, and increased depletion of fossil fuel reserves
The physico-chemical characteristics and composition of milk dust powder high performance liquid chromatography (HPLC) analysis showed that the milk dust powder used in this study had lactose content of ~425 g/L (w/v; wet wt.); 8.5-fold higher than cheese whey, which typically has a lactose content of about 50 g/L (Welsh and Veliky 1984)
Microbial cell counts showed that both C. acetobutylicum and C. beijerinckii grew better on glucose than on lactose (Table 2)
Summary
Alternative energy-related research currently receives tremendous attention, largely in response to the rising cost of gasoline, and increased depletion of fossil fuel reserves. Jerusalem artichoke extract (Maddox 1980), cassava starch (Thang et al 2010), cheese whey (Ennis and Maddox 1989; Maddox 1980; Qureshi and Maddox 2005; Stevens et al 1988; Welsh and Veliky 1984), apple pomace (Voget et al 1985) and starch-based packing peanuts (Jesse et al 2002) Among these substrates, cheese whey is the most widely researched for ABE production, mostly due to its abundance, and high biological oxygen demand (BOD), which constitutes a major disposal predicament (Maddox 1980). Lactose metabolism favors butanol production over acetone (Bahl et al 1986; Maddox 1980), an added economic incentive in light of the current impetus for butanol production
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