Nadine Cuzin

Bio: Nadine Cuzin is an academic researcher from University of Provence. The author has contributed to research in topics: Fermentation & Desulfovibrio. The author has an hindex of 5, co-authored 6 publications receiving 196 citations.

Methanobacterium congolense sp. nov., from a methanogenic fermentation of cassava peel.

Abstract: Strain CT, a non-motile, mesophilic, hydrogenotrophic, methanogenic bacterium, was isolated from an anaerobic digester used for the treatment of raw cassava-peel waste in Congo. The cells were rods, 0.4-0.5 x 2-10 microm in size, and stained Gram-positive. Hydrogen and carbon dioxide were the only substrates that supported growth and methane production. Methane production, but not growth, occurred with CO2 in the presence of either 2-propanol, 2-butanol or cyclopentanol as hydrogen donors. The temperature range for growth was 25-50 degrees C, the optimum being between 37 and 42 degrees C. The optimum pH for growth was 7.2; consistent growth and methane production were not observed below pH 5.9 or above pH 8.2. The doubling time under optimal growth conditions was 7.5 h. The DNA base composition was 39.5 mol% G+C. On the basis of 16S rRNA gene sequence analysis and phenotypic characteristics, the isolate is proposed as a new species of the genus Methanobacterium, namely Methanobacterium congolense sp. nov. The type strain is strain CT (= DSM 7095T = OCM 779T).

Isolation and characterization of Desulfovibrio burkinensis sp. nov. from an African ricefield, and phylogeny of Desulfovibrio alcoholivorans.

Abstract: A sulfate-reducing bacterium, strain HDvT (T = type strain), was isolated from an anoxic ricefield soil. Cells were Gram-negative, non-sporulating curved rods motile by means of a single polar flagellum. Cytochrome c3 and desulfoviridin were present. In the presence of sulfate, glycerol, 1,2- and 1,3-propanediol, dihydroxyacetone, pyruvate, lactate, fumarate, maleate, malate and succinate were incompletely oxidized mainly to acetate. Sulfite, thiosulfate, elemental sulfur, fumarate, maleate and malate were utilized as alternative electron acceptors. In the absence of added electron acceptors, pyruvate, fumarate, maleate, malate and dihydroxyacetone were fermented. The DNA base composition was 67 mol% G + C. The phylogenetic, phenotypic and physiological characteristics of strain HDvT indicate that it is a new species of the genus Desulfovibrio, for which the name Desulfovibrio burkinensis sp. nov. is proposed; the type strain is HDvT (= DSM 6830T). Phylogenetic analysis confirmed that Desulfovibrio alcoholivorans was a distinct species supporting the previously published phenotypic data.

Reduction of cyanide levels during anaerobic digestion of cassava

Abstract: Summary During the methanogenic fermentation of cassava peel in a plug flow digester, cyanide bound as linamarin in cassava was released as HCN in the fermentation liquor, and then eliminated by the activity of free enzymes and by non-enzymatic reactions. The raw cassava peel contained (1) the enzyme permitting the hydrolysis of linamarin and the liberation of HCN (linamarase), and (2) a cyanide detoxification enzyme (p-cyanoalanine synthase). Cyanide removal was sufficiently fast to maintain a cyanide concentration in the fermentation liquor which was non-inhibitory for the methanogenic microflora.

Anaerobic degradation of 1,2-propanediol by a new Desulfovibrio strain and D. alcoholovorans.

Abstract: A sulfate-reducing bacterium, strain HDv, was isolated from the anoxic soil of a ricefield using lactate as electron donor. Cells were gram-negative, motile, nonsporulating curved rods, with single polar flagella. Substrates were incompletely oxidized to acetate and included glycerol, 1,2-and 1,3-propanediol. Sulfate, sulfite, thiosulfate, elemental sulfur, fumarate, maleate, and malate were utilized as electron acceptors. Pyruvate, fumarate, maleate, malate and dihydroxyacetone were fermented. Desulfoviridin and c-type cytochromes were present. The DNA base composition was 66.6 ± 0.3 mol% G+C. The isolate was identified as a Desulfovibrio sp.; its metabolic properties were somewhat different from those of previously described Desulfovibrio species. Comparative biochemical study of 1,2-propanediol dissimilation by the new isolate and Desulfovibrio alcoholovorans showed that NAD-dependent dehydrogenases play a key role in the catabolism of this substrate. The hypothetical pathways of 1,2-propanediol degradation by Desulfovibrio spp. are presented.

Research letterDetermination of DNA base composition by reversed-phase high-performance liquid chromatography

Abstract: DNA base composition was determined by reversed-phase high-performance liquid chromatography (HPLC). DNA was hydrolysed into nucleosides with nuclease P1 and bacterial alkaline phosphatase. The mixture of nucleosides was applied to HPLC without any further purification. One determination by chromatography needed 2 μg of hydrolysed nucleosides and took only 8 min. The relative standard error of nucleoside analysis was less than 1%. The system described here gives a direct and precise method for determining DNA base composition.

Household Biogas Digesters—A Review

Abstract: This review is a summary of different aspects of the design and operation of small-scale, household, biogas digesters. It covers different digester designs and materials used for construction, important operating parameters such as pH, temperature, substrate, and loading rate, applications of the biogas, the government policies concerning the use of household digesters, and the social and environmental effects of the digesters. Biogas is a value-added product of anaerobic digestion of organic compounds. Biogas production depends on different factors including: pH, temperature, substrate, loading rate, hydraulic retention time (HRT), C/N ratio, and mixing. Household digesters are cheap, easy to handle, and reduce the amount of organic household waste. The size of these digesters varies between 1 and 150 m 3 . The common designs include fixed dome, floating drum, and plug flow type. Biogas and fertilizer obtained at the end of anaerobic digestion could be used for cooking, lighting, and electricity.

Proposal to reclassify the proteobacterial classes Deltaproteobacteria and Oligoflexia, and the phylum Thermodesulfobacteria into four phyla reflecting major functional capabilities

Abstract: The class Deltaproteobacteria comprises an ecologically and metabolically diverse group of bacteria best known for dissimilatory sulphate reduction and predatory behaviour. Although this lineage is the fourth described class of the phylum Proteobacteria, it rarely affiliates with other proteobacterial classes and is frequently not recovered as a monophyletic unit in phylogenetic analyses. Indeed, one branch of the class Deltaproteobacteria encompassing Bdellovibrio-like predators was recently reclassified into a separate proteobacterial class, the Oligoflexia. Here we systematically explore the phylogeny of taxa currently assigned to these classes using 120 conserved single-copy marker genes as well as rRNA genes. The overwhelming majority of markers reject the inclusion of the classes Deltaproteobacteria and Oligoflexia in the phylum Proteobacteria. Instead, the great majority of currently recognized members of the class Deltaproteobacteria are better classified into four novel phylum-level lineages. We propose the names Desulfobacterota phyl. nov. and Myxococcota phyl. nov. for two of these phyla, based on the oldest validly published names in each lineage, and retain the placeholder name SAR324 for the third phylum pending formal description of type material. Members of the class Oligoflexia represent a separate phylum for which we propose the name Bdellovibrionota phyl. nov. based on priority in the literature and general recognition of the genus Bdellovibrio. Desulfobacterota phyl. nov. includes the taxa previously classified in the phylum Thermodesulfobacteria, and these reclassifications imply that the ability of sulphate reduction was vertically inherited in the Thermodesulfobacteria rather than laterally acquired as previously inferred. Our analysis also indicates the independent acquisition of predatory behaviour in the phyla Myxococcota and Bdellovibrionota, which is consistent with their distinct modes of action. This work represents a stable reclassification of one of the most taxonomically challenging areas of the bacterial tree and provides a robust framework for future ecological and systematic studies.

Archaeal habitats — from the extreme to the ordinary

Abstract: The domain Archaea represents a third line of evolutionary descent, separate from Bacteria and Eucarya. Initial studies seemed to limit archaea to various extreme environments. These included habit...