Guy Albagnac

Synthrophomonas sapovorans sp. nov., a new obligately proton reducing anaerobe oxidizing saturated and unsaturated long chain fatty acids

An anaerobic obligately syntrophic fatty acid degrading acetogenic bacterium (Strain OM) was isolated on calcium laurate medium from an oleate enrichment. This organism is a short slightly curved Gram-negative rod which can only use protons as electron acceptor. It ferments all linear saturated fatty acids with 4 to 18 carbon atoms in coculture with a hydrogen-utilizing partner. Some mono- and di-unsaturated long chain fatty acids (oleate, elaidate and linolenate) are also oxidized. Calcium is required for batch cultivation of the syntrophic association on fatty acids with a chain length longer than 8 carbon atoms. In spite of some important morphological and nutritional analogies with Syntrophomonas wolfei, the strain OM must be considered as a different species mainly because of its broader substrate range. The description of strain OM as type strain of a new species, Syntrophomonas sapovorans sp. nov., is proposed.

The influence of raw material characteristics on the storage life of fresh-cut butterhead lettuce

Abstract The physiological characteristics of 5 butterhead lettuce cultivars ( Lactuca sativa L.) were investigated using etiolated leaves. Their storage life under modified and controlled atmospheres was assessed. When prepacked butterhead lettuce was maintained under a low oxygen atmosphere to prevent enzymatic browning, high CO 2 content was the main factor increasing the rate of decay. Shelf life was negatively correlated with respiration rate and susceptibility to CO 2 . Potassium leakage was a good indicator of physiological disorders. High oxygen and low CO 2 enhanced enzymatic browning, while low oxygen and, more significantly, high carbon dioxide enhanced CO 2 injury (brown stain). Maintaining CO 2 concentration within the packs below 5% resulted in an improved preservation of the lettuce leaves. Practical means for obtaining modified atmospheres which were in equilibrium yet were low in both O 2 and CO 2 are discussed.

Soluble sugars and carboxylic acids in ripe apricot fruit as parameters for distinguishing different cultivars

Major sugar and carboxylic acid components in apricot flesh fruits were detected and quantified. Fifty-one genotypes including clones growing in France, Spain, Italy, Greece and USA, belonging to the INRA germ plasm collection has been evaluated. Principal component analysis (PCA) has been performed to study correlation among fruit quality measurements and to interpret relationships between genotypes as a tool for germ plasm characterization. A marked variation in malic and citric acid content has been observed and PCA revealed clusters of apricot genotypes for the malic/citric ratio content. A good correlation between sugar component and refractometer index (r = 0.83) has been detected. The wide range of diversity in malic and citric acid content in apricot germ plasm makes it possible to breed and select genotypes with improved flavour on the basis of superior phenotypes.

Isolation and Characterization of a New Thermophilic Methanosarcina, the Strain CHTI 55

Summary A new thermophilic, acetoclastic methanogen (strain CHTI 55) was isolated from enrichment cultures on sodium acetate from a bench scale digester treating a mixture of solid wastes at 55 °C. Morphologically, the strain has the characteristic appearance of Methanosarcina but it forms very large aggregates and coccoid units which are released from the clumps of organisms in old cultures. The isolate uses acetate, methanol, methylamines but neither H2+CO2 nor formate for growth and methane production. Growth of strain CHTI 55 occured throughout a pH range between 6.5 and 8 and at temperatures ranging from 35 °C to 63 °C. The maximal growth rate on acetate (0.085 h-1) was at pH 6.8 and 57°C. The affinity constant for acetate and cell yield were 9.6 mM and 1.4 g/mol, respectively. The G + C content of DNA was 39.3 mol%.

Isolation and characterization of Desuljobulbus elongatus sp. nov. from a mesophilic industrial digester

Summary From a methanogenic enrichment with propionate as sole carbon source, a new gram negative, propionate degrading sulfate reducer was isolated. The cells of this strain FP are motile rods sometimes slightly curved. The DNA base ratio is 59 mol% guanine plus cytosine. Like Desulfobulbus propionicus strain FP lacked desulfoviridin and its sulfite reductase was identified as desulforubidin. In the presence of sulfate, strain FP oxidises propionate, lactate, pyruvate, ethanol and propanol to acetate. Lactate and pyruvate are fermented to acetate and propionate in the absence of sulfate. Thus, strain FP is nutritionally related to the genus Desulfobulbus. According to its morphology and to whole cell protein patterns, a new species, Desulfobulbus elongatus is proposed.

Characterization of Clostridium thermolacticum sp. nov., a Hydrolytic Thermophilic Anaerobe Producing High Amounts of Lactate

Summary A new species of sporulating thermophilic anaerobes, Clostridium thermolacticum sp. nov., is described. Two strains, TC 21 and TX 41, were isolated from methanogenic enrichment cultures on cellulose and xylan, respectively. Both isolates actively ferment xylan, starch, cellobiose and various sugars with L-lactate as the main end-product. In addition, strain TC 21 weakly ferments cellulose to produce a mixture of ethanol and acetate. Optimum conditions for growth are 60–65°C and pH 7.0–7.2. The DNA type strain C. thermolacticum TX 41 contains 40.9 % mol G + C.

Initial steps of catabolism of trihydroxybenzenes in Pelobacter acidigallici

The initial steps of the anaerobic degradation of trihydroxylated aromatic monomers were investigated in a strain (AG2) isolated on gallic acid and identified as Pelobacter acidigallici. Kinetic studies showed that strain AG2 fermented gallic acid into acetate with a transient accumulation of pyrogallol and phloroglucinol in the medium. In addition phloroglucinol was produced from all other trihydroxylated aromatic monomers and pyrogallol from 2,3,4-trihydroxybenzoate. Although protocatechuate did not support growth of the organism, it was partially decarboxylated by resting cells of strain AG2. Cell free extract of strain AG2 catalysed the oxidation of NADPH in presence of resorcinol, 2,4,6-trihydroxybenzoate and phloroglucinol. However, comparison of activities indicated that the latter was the true physiological electron acceptor. Phloroglucinol and its reduction product dihydrophloroglucinol appeared thus to play a key role in metabolism of trihydroxybenzenes and a unified pathway, involving a decarboxylation of trihydroxybenzoates, a para transhydroxylation of pyrogallol into phloroglucinol and the formation of dihydrophloroglucinol, was proposed.

Modified Atmosphere Packaging of Fresh Beansprouts

Freshly harvested beansprouts displayed a respiration rate of about 1 mmol O 2 kg -1 h -1 at 10°C which was strongly dependent on temperature, a 10-fold increase being observed every 16.5°C (z =16.5°C, ie Q 10 = 4.4). This commodity is also characterised by a high initial microbial load (about 10 7 cells g -1 ). During storage at various temperatures from 1 to 20°C, oxygen uptake rates dramatically increased with time and this phenomenon was well correlated with the development of aerobic microorganisms which reached 10 9 cells g -1 after 2 days at 20°C or 9 days at 1°C. Beansprouts were packaged in films, with permeabilities ranging from 950 to 200 000 ml O 2 m -2 day -1 atm -1 , and stored at 8°C. Due to plant and microbial metabolism, oxygen concentrations decreased steadily within all packs until the onset of plant tissue decay. The latter occurred after 5-6 days with the least permeable films but did not occur within when the film permeability was over 100000 ml O 2 m -2 day -1 atm -1 . However, such films favoured brown discolouration, exudation texture and breakdown. The orientated polypropylene film (OPP) induced anoxic condition within 2 days and favoured anaerobic metabolism and necrosis of the sprouts. In all packages there was a rapid development of aerobic microorganisms and lactic acid bacteria that resulted in the accumulation of acetate and lactate and a decrease in pH. Thus, it clearly appeared that tissue decay was enhanced by microbial activity. At 8°C, 0.24 m 2 of film per kg of sprouts provided the optimal atmosphere composition (ie 5% oxygen and 15% carbon dioxide) when a film permeability of 50000 ml O 2 m -2 day -1 atm -1 was used. These conditions allowed a shelf-life of 4-5 days.

Clostridium neopropionicum sp. nov., a strict anaerobic bacterium fermenting ethanol to propionate through acrylate pathway

Strain X4 was isolated several years ago from an anaerobic mesophilic plant treating vegetable cannery waste waters. It was the first example of propionic fermentation from ethanol. Morphologic and physiologic characterizations of the strain are presented here. This strain is described as type strain of a new species, Clostridium neopropionicum sp. nov. Whole cells of strain X4 ferment [1-13C]ethanol and CO2 to [2-13C]propionate, [1-13C]acetate and [2-13C]propanol, suggesting the absence of a randomizing pathway during the propionate formation. Enzymes involved in this fermentation were assayed in cell-free extracts of cells grown with ethanol as sole substrate. Alcohol dehydrogenase, aldehyde dehydrogenase, phosphate acetyl transferase, acetate kinase, pyruvate synthase, lactate dehydrogenases, and the enzymes of the acrylate pathway were detected at activities sufficient to be involved in ethanol fermentation. The same pathway may be used for the degradation of lactate or acrylate to acetate.

Description of a New Strain of Methanothrix soehngenii and Rejection of Methanothrix concilii as a Synonym of Methanothrix soehngenii

A new mesophilic strain of Methanothrix, strain FE, was highly purified from the sludge of an anaerobic digester after enrichment on sodium acetate and is described. Strain FE was compared with other strains of Methanothrix, Methanothrix soehngenii strain OpfikonT (= DSM 2139T) (T = type strain) and Methanothrix concilii strain GP6T (= DSM 3671T). The differences within the strains were mainly related to their requirement for yeast extract. The three strains were found to be similar in their deoxyribonucleic acid guanine-plus-cytosine contents (50.2 to 52.6 mol%) and showed 100% deoxyribonucleic acid-deoxyribonucleic acid homology. For these reasons we propose to recognize synonymy, reject the name Methanothrix concilii Patel 1985, 35:223, and assign this organism to the species Methanothrix soehngenii Huser, Wuhrmann and Zehnder 1983, 33:439.