Líffræðifélag Íslands - biologia.is
Líffræðiráðstefnan 2019

Erindi/veggspjald / Talk/poster V21

Fermentation of Mannitol from Brown Macro Algae by Thermophilic Clostridia

Höfundar / Authors: Jóhann Örlygsson (1), Eva Maria Ingvadottir, Sean M. Scully (1)

Starfsvettvangur / Affiliations: 1. University of Akureyri

Kynnir / Presenter: Johann Orlygsson

Mannitol is a potentially abundant and low-cost feedstock for the production of bioethanol and other commodity chemicals. Marine macro algae, such as the mannitol-rich brown algae Ascophyllum nodosum and Laminaria digitata, are ubiquitous along Iceland´s coastlines. Recent work undertaken by our group assessed the ability of selected thermophilic anaerobes within Class Clostridia to ferment mannitol and mannitol-containing algal extracts. The type strains of each species within Caldanaerobius, Caldanaerobacter, Caldicellulosiruptor, Thermoanaerobacter, Thermobrachium, and Thermoanaerobacterium, as well as strains isolates from Iceland´s geothermal features, were screened for their ability to utilize mannitol. Mannitol utilization seems to be most common within the genus of Thermoanaerobacter with ethanol yields up to 88% of the theoretical yield. Selected mannitol-degrading Thermoanaerobacter strains were cultivated on mannitol extracts prepared from A. nodosum and L. digitata; T. pseudoethanolicus was kinetically monitored using mannitol from A. nodosum and L. digitata. Mannitol catabolism was much slower than glucose fermentation, potentially due to the problems associated from disposing of the greater reducing equivalence necessitated by using mannitol as a substrate. Studies using 13C1-labled mannitol also revealed that a number of strains produce glycerol as a major fermentation product of mannitol in addition to ethanol, acetate, and lactate.