Biotransformation of organic acids to their corresponding alcohols by Thermoanaerobacter pseudoethanolicus.

Higher order alcohols, such as 1-butanol and 1-hexanol, have a large number of applications but are currently prepared from non-renewable feedstocks. Here, the ability of Thermoanaerobacter pseudoethanolicus to reduce short-chain fatty acids to their corresponding alcohols using reducing potential generated by glucose catabolism with yields between 21.0 and 61.0%. 13C-labelled acetate, 1-propionate and 1-butyrate demonstrates that exogenously added fatty acids are indeed reduced to their corresponding alcohols. This mode of producing primary alcohols from fatty acids using a thermophilic anaerobe opens the door for the production of such alcohols from low-value materials using an inexpensive source of reducing potential.

Fermentation of Mannitol Extracts From Brown Macro Algae by Thermophilic Clostridia.

Mannitol-containing macro algae biomass, such as Ascophyllum nodosum and Laminaria digitata, are a potential feedstock for the production of biofuels such as bioethanol. The purpose of this work was to evaluate the ability of thermophilic anaerobes within Class Clostridia to ferment mannitol and mannitol-containing algal extracts. Screening of the type strains of six genera, Caldanaerobius, Caldanaerobacter, Caldicellulosiruptor, Thermoanaerobacter, Thermobrachium, and Thermoanaerobacterium) was conducted on 20 mM mannitol and revealed that 11 of 41 strains could utilize mannitol with ethanol being the dominant end-product. Mannitol utilization seems to be most common within the genus of Thermoanaerobacter (7 of 16 strains) with yields up to 88% of the theoretical yield in the case of Thermoanaerobacter pseudoethanolicus. Six selected mannitol-degrading strains (all Thermoanaerobacter species) were grown on mannitol extracts prepared from A. nodosum and L. digitata. Five of the strains produced similar amounts of ethanol as compared with ethanol yields from mannitol only. Finally, T. pseudoethanolicus was kinetically monitored using mannitol and mannitol extracts made from two macro algae species, A. nodosum and L. digitata for end-product formation.

Production of (S)-1,2-propanediol from l-rhamnose using the moderately thermophilic Clostridium strain AK1.

Clostridium strain AK1 was investigated for its capacity of producing 1,2-propanediol from l-rhamnose but not l-fucose. The maximum yields of 1,2-propanediol from rhamnose was 0.81 mol 1,2-PD/mol l-rhamnose. The influence of different initial substrate concentrations as well as the effect of temperature and pH on 1,2-PD production was investigated.

Branched-chain alcohol formation by thermophilic bacteria within the genera of Thermoanaerobacter and Caldanaerobacter.

Fifty-six thermophilic strains including members of Caldanaerobacter, Caldicellulosiruptor, Caloramator, Clostridium, Thermoanaerobacter, and Thermoanaerobacterium, were investigated for branched-chain amino acid degradation in the presence of thiosulfate in batch culture. All of the Thermoanaerobacter and Caldanaerobacter strains (24) degraded the branched-chain amino acids (leucine, isoleucine, and valine) to a mixture of their corresponding branched-chain fatty acids and branched-chain alcohols. Only one Caloramator strain degraded the branched-chain amino acids to the corresponding branched-chain fatty acids. The ratio of branched-chain fatty acid production over branched-chain alcohol production for Thermoanaerobacter was 7.15, 6.61, and 11.53 for leucine, isoleucine, and valine, respectively. These values for Caldanaerobacter were 3.49, 4.13, and 7.31, respectively. This indicates that members within Caldanaerobacter produce proportionally more of the alcohols as compared with Thermoanaerobacter. No species within other genera investigated produced branched-chain alcohols from branched-chain amino acids in the presence of thiosulfate.

Tuneable regioselectivity during the mono-etherification of the 2,3-diol of a mannose derivative.

The paper reports selective mono-etherification of the 2-, and 3-hydroxyl groups of methyl 4,6-O-isopropylidene-α-d-mannopyranoside using tin(II) chloride catalysed reactions of diaryldiazomethanes. By the use of different diazo compounds and the variation of the tin(II) chloride concentration the ether formation can be shifted from over 90% 3-selectivity to over 90% 2-selectivity.