Moorella

Abstract

Moo.rel'la. N.L. fem. n. Moorella in honor of W.E.C. (Ed) Moore, an American bacteriologist, who worked with anaerobes. Firmicutes / “Clostridia” / Thermoanaerobacterales / Thermoanaerobacteraceae / Moorella In early exponential growth phase, cells stain Gram‐positive. However, some species stain negative during the late exponential and stationary growth phases. Straight rods with a tendency to polymorphism under stress conditions such as high glucose or high acetate concentrations. Physiology is obligately anaerobic , thermophilic , and chemolithoautotrophic and / or heterotrophic ; produces acetate as sole or main fermentation product from sugars, C 1 carbon sources, and other substrates. Produces nearly 3 moles of acetate per mole of glucose consumed, which is sometimes called “homoacetogenic” fermentation. While growing on substrates other than hexoses, CO, or CO 2 /H 2 , Moorella species can produce various products. May use nitrate, nitrite or fumarate as electron acceptors. Forms various aromatic compounds via decarboxylation of arylic acids, which are used as CO 2 donors under CO 2 ‐limited conditions. The cell wall contains LL ‐diaminopimelate (DAP). DNA G + C content ( mol %): 53–55. Type species : Moorella thermoacetica (Fontaine, Peterson, McCoy, Johnson and Ritter 1942) Collins, Lawson, Willems, Cordoba, Fernández‐Garayzábal, Garcia, Cai, Hippe and Farrow 1994, 824 VP ( Clostridium thermoaceticum Fontaine, Peterson, McCoy, Johnson and Ritter 1942, 705).

Acetate Production by Moorella thermoacetica via Syngas Fermentation: Effect of Yeast Extract and Syngas Composition

“…More specifically, carboxydotrophic homoacetogen is autotrophic-acetogen-resistant to high CO concentrations. Compared to the other carboxydotrophic homoacetogens commercially available, Moorella thermoacetica is a thermophilic bacterium with a high growth rate for syngas-to-acetate conversion with acetate as a sole product, unlike other carboxydotrophic homoacetogens also synthesizing other organic acids and alcohols [15,16]. Additionally, thermophilic syngas fermentation is preferred due to the low energy requirement for gas cooling and higher fermentation rate than organisms growing under mesophilic conditions [17].…”

“…thermoacetica utilizes CO as both a carbon source and an electron donor for acetate production through WLP [3,16]. In WLP, carbon monoxide dehydrogenase (CODH) catalyzes CO oxidation by releasing 2 mol electrons per 1 mol CO using ferredoxin or NADH as an electron carrier to form CO 2 [15,18,19]. The formed CO 2 is then converted into a methyl group compound in the eastern branch of WLP or reduced back into CO in the western branch of WLP.…”