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Abstract

Continuous cultures of two strains of Clostridium acetobutylicum were stable for over 70 d when grown on glucose/glycerol mixtures. Butanol was the major fermentation end-product, accounting for 43 to 62% (w/w) of total products. Low-grade glycerol [65% (w/v) purity] could replace commercial glycerol [87% (w/v) purity], leading to a similar fermentation pattern: a butanol yield of 0.34 (mol/mol), a butanol productivity of 0.42 g l(-1) h(-1) and a 84% (w/w) glycerol consumption were attained when cultures were grown at pH 6 and D = 0.05 h(-1); butanol accounted for 94% (w/w) of total solvents. These values are among the highest reported in literature for C. acetobutylicum simple chemostats.

Improved n-butanol production by a non-acetone producing Clostridium pasteurianum DSMZ 525 in mixed substrate fermentation

“…The effect of mixed substrate fermentation on n -butanol production appears to be strain dependent. In C. acetobutylicum , n -butanol productivity was much lower in mixed substrate fermentation than on glucose, and a maximum productivity of 0.42 g/L × h compared to 0.9 g/L × h was reported on mixed or mono-substrate fermentation, respectively (Andrade and Vaconcelos 2003). On the other hand, C. pasteurianum strain CH4 produced 13.2 g/L n -butanol with a productivity of 0.19 g/L × h in co-substrate fermentation compared to 11 g/L and 0.14 g/L × h on glycerol (Kao et al 2012).…”

“…Acid production parallels the energy production necessary for cell viability and homeostasis at high n -butanol concentration. This may explain the enhancement of culture stabilities in C. acetobutylicum and prevention of cell degeneration in the mixed substrate fermentation (Andrade and Vaconcelos 2003). Although a number of possible mechanisms may account for this, further work is required to determine the underlying mechanism(s).…”

Towards continuous industrial bioprocessing with solventogenic and acetogenic clostridia: challenges, progress and perspectives

“…Stable continuous fermentation in chemostat was successfully maintained in several publications [ 13 , 23 , 43 , 127 , 307 ]. A commonly referred strain in stable chemostat runs is Clostridium acetobutylicum ATCC 824 [ 9 , 90 , 126 , 127 , 272 ]. For instance, more than 70 days of stable chemostat cultivation of C. acetobutylicum ATCC 824 was achieved at pH 6 and a dilution rate of 0.05 h −1 with a substrate-mixture of glucose and low-grade glycerol [ 9 ].…”

“…Since the main solvents butanol and ethanol are bulk chemicals, the feedstock should be cheap and available in large quantities [ 21 ]. While basic research mainly relies on costly glucose [ 14 , 81 , 204 , 222 ], glycerol and crude glycerol [ 9 , 23 , 86 , 187 ], the historical ABE fermentation process mainly utilizes sugar- and starch-rich first-generation feedstocks such as sugarcane, molasses and maize [ 92 , 103 , 212 ]. Alternative feedstocks offering a high potential are food and agricultural waste [ 2 , 75 , 236 , 237 ], lignocellulosic biomass [ 54 , 117 , 137 , 203 ], and liquid waste streams, for instance of the pulp and paper industry [ 102 ] (see Table 4 ).…”

PROCESS OPTIMISATION OF 1,3-PROPANEDIOL PRODUCTION BY Klebsiella pneumoniae STRAIN

“…Materials that are renewable and biodegradable, e.g. biodiesel could attract considerable public attention (Andrade and Vasconcelos, 2003;Xu et al, 2003). Biodiesel has increasingly been considered in establishing biorefineries; the challenges faced is to handle the surplus amounts of by-product generated, i.e.…”