Fermentation of Mannitol Extracts From Brown Macro Algae by Thermophilic Clostridia

Abstract

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.

A thermostable mannitol‐1‐phosphate dehydrogenase is required in mannitol metabolism of the thermophilic acetogenic bacterium Thermoanaerobacter kivui

“…is also evident, with 58%–62% sequence identity. As described previously, thermophiles have been described to utilize mannitol (Ji et al ., ; Chades et al ., ), and other thermostable MtlDs are awaiting their biological characterization. For the acetogens, it remains to be elucidated whether more acetogens utilize mannitol, and whether MtlD is important for mannitol oxidation in these species.…”

Biotransformation of organic acids to their corresponding alcohols by Thermoanaerobacter pseudoethanolicus

“…Organisms within the genera of Thermoanaerobacter and Caldanaerobacter have broad metabolic capabilities and are noted for their biotechnological potential such as their highly thermotolerant nature and ability to produce biofuels such as ethanol from a broad range of monosaccharides and branched-chain alcohols from branched-chain amino acids [1][2][3][4][5]. Also, Thermoanaerobacter species have been exploited for their thermostable enzymes such as…”

Enzymatic Saccharification of Laminaria japonica by Cellulase for the Production of Reducing Sugars

“…Table 1 shows the compositions Laminaria spp. [17,[30][31][32][33]. The biomass was washed manually using tap water to remove dirt.…”