Godfried D. Vogels

Differential analyses of glyoxylate derivatives

Abstract A differential glyoxylate analysis is given that enables differentiation between allantoin, allantoate, ureidoglycolate, and glyoxylate. The optimal conditions for glyoxylic acid phenylhydrazone formation are studied. At higher phenylhydrazine concentrations the rate of this reaction is limited by the dehydration of glyoxylate. The latter reaction is catalyzed by the presence of bivalent cations and phosphate. The conditions for selective quantitative hydrolysis of the glyoxylate derivatives are described and based upon these data six different methods of analysis are given. The conditions of optimal color formation are studied and some novel properties of the product formed are given. The analysis presented is more accurate, sensitive, and selective than former methods.

A hydrogenosome with a genome

Some anaerobic protozoa and chytridiomycete fungi possess membrane-bound organelles known as hydrogenosomes. Hydrogenosomes are about 1 micrometre in diameter and are so called because they produce molecular hydrogen. It has been postulated that hydrogenosomes evolved from mitochondria by the concomitant loss of their respiration and organellar genomes,, and so far no hydrogenosome has been found that has a genome,. Here we provide evidence for the existence of a hydrogenosomal genome of mitochondrial descent, and show that the anaerobic heterotrichous ciliate Nyctotherus ovalis possesses a new type of nuclear-encoded ‘iron-only’ hydrogenase enzyme.

Symbiosis of methanogenic bacteria and sapropelic protozoa

Fluorescent bacteria were demonstrated to be abundantly spread as single cells throughout the cytoplasm of the giant amoeba Pelomyxa palustris, the sapropelic ciliate Metopus striatus and six other anaerobic protozoa examined. The endosymbionts of P. palustris and M. striatus were identified as methanogenic bacteria on the basis of the presence of the deazaflavin coenzyme F420 and the pterin compound F342. Moreover individuals of P. palustris produced methane over a long period of incubation. The number of methanogenic bacteria was above 1010 cells/ml protozoal cytoplasm. Two types of methanogenic bacteria together with unidentified thick bacteria were found in P. palustris.The physiological background of this endosymbiosis and its functioning in degradation processes in the anoxic environment are discussed.

Association of methanogenic bacteria with ovine rumen ciliates.

1. The frequency of association between methanogenic bacteria and ovine rumen ciliates was studied in the rumen fluid of a fistulated sheep. 2. A period of fasting and flushing of the rumen content with nitrogen resulted in a relatively high association, whereas the intake of food and flushing with hydrogen caused a detachment of the methanogenic bacteria from the ciliates. 3. The changes in the frequency of association can be correlated with the relative attribution to the H2 production by hydrogenogenic bacteria and rumen ciliates.

Degradation of allantoin by Pseudomonas acidovorans

Summary 1. The degradation of allantoin by Pseudomonas acidovorans was investigated. Allantoate, ureidoglycine, ureidoglycolate, glyoxylate and urea are considered to be intermediates in this degradation. Optical specificity of allantoinase (EC 3.5.2.5) and ureidoglycolate amidinohydrolase has been demonstrated for (+)-allantoin and (+)-ureidoglycolate, respectively. The enzyme allantoate amidohydrolase catalyzes the degradation of allantoate. It can be activated by acid-pretreatment and inactivated at pH values of about 6. Inhibition of allantoate amidohydrolase by ureidoglycolate has been demonstrated. 2. Synthesis and properties of ureidoglycolic acid are given. 3. A modified differential glyoxylate analysis is described. It was applied for the quantitative determination of allantoin, allantoate, ureidoglycine, ureidoglycolate and glyoxylate.

Methyltransferases involved in methanol conversion by Methanosarcina barkeri

Abstract2-(Methylthio)ethanesulfonate (CH3S-CoM) is formed as an intermediate in methanogenesis from methanol by cell-free extracts of Methanosarcina barkeri. The enzyme system involved in the methyltransfer from methanol to 2-mercaptoethanesulfonate (HS-CoM) was resolved into two enzyme fractions. One enzyme (methanol: 5-hydroxybenzimidazolylcobamide methyltransferase) appears to be a cobalamin-containing protein, which is oxygen sensitive. The other enzyme (Co-methyl-5-hydroxybenzimidazolylcobamide: HS-CoM methyltransferase) was purified. It is insensitive to oxygen and it transfers also the methylgroup from Co-methyl-5,6-dimethylbenzimidazolylcobamide to HS-CoM.

Isolation and characterization of Methanoplanus endosymbiosus sp. nov., an endosymbiont of the marine sapropelic ciliate Metopus contortus quennerstedt

Epifluorescence microscopy revealed the presence of a methanogenic bacterium as an endosymbiont in the sapropelic marine ciliate Metopus contortus. The in situ methanogenic activity of the symbiont could be demonstrated. The isolated endosymbiont was an irregular, disc-shaped bacterium with a diameter of 1.6–3.4 μm. It had a generation time of 7 or 12 hours on growth on H2/CO2 or formate, respectively. The temperature range for growth was between 16 and 36°C with an optimum at 32°C. The optimal pH range for growth was 6.8 to 7.3. Salts, with an optimum concentration of 0.25 M, and tungsten were required for growth. The mol% G+C was 38.7%. The cell envelope consisted of proteins and a glycoprotein with an apparent molecular weight of 110,000. Morphology, antigenic relationship and the G+C content established the isolate MC1 as a new species of the genus Methanoplanus, and the name Methanoplanus endosymbiosus is proposed.

Psalteriomonas lanterna gen. nov., sp. nov., a free-living amoeboflagellate isolated from freshwater anaerobic sediments

A novel amoeboflagellate, isolated from anoxic sediment samples, is described and named Psalteriomonas lanterna gen. nov., sp. nov. The cells of the flagellate stage show a fourfold rotational symmetry with four nuclei, four ventral grooves and four mastigont systems. Each mastigont has four flagella of equal length. Microtubular roots, striated roots or rhizoplasts and electron-dense structures are associated with their basal bodies. A Golgi apparatus is absent. Organelles surrounded by rough endoplasmic reticulum (RER) are presumably modified mitochondria. Methanogenic endosymbiotic bacteria are closely associated with microbodies and form a central body. Nuclear division shows the characteristics of a closed mitosis. Cells of the amoeboid stage are mononucleated and lack the methanogenic endosymbionts. Reproduction occurs in both stages of the life cycle.

Comparison of growth characteristics of anaerobic fungi isolated from ruminant and non-ruminant herbivores during cultivation in a defined medium.

Anaerobic fungi were isolated from rumen fluid of a domestic sheep (Ovis aries; a ruminant) and from faeces of five non-ruminants: African elephant (Loxodonta africana), black rhinoceros (Diceros bicornis), Indian rhinoceros (Rhinoceros unicornis), Indian elephant (Elephas maximus) and mara (Dolichotis patagonum). The anaerobic fungus isolated from the sheep was a Neocallimastix species and the isolates from non-ruminants were all species similar to Piromyces spp. A defined medium is described which supported growth of all the isolates, and was used to examine growth characteristics of the different strains. For each fungus the lipid phosphate content was determined after growth on cellobiose and the resulting values were used to estimate fungal biomass after growth on solid substrates. The ability of isolates from ruminants and non-ruminants to digest both wheat straw and cellulose was comparable. More than 90% and 60%, respectively, of filter paper cellulose and wheat straw were digested by most strains within 60-78 h. Growth of two fungi, isolated from rumen fluid of a sheep (Neocallimastix strain N1) and from faeces of an Indian rhinoceros (Piromyces strain R1), on cellobiose was studied in detail. Fungal growth yields on cellobiose were 64.1 g (mol substrate)-1 for N1 and 34.2 g mol-1 for R1. The major fermentation products of both strains were formate, lactate, acetate, ethanol and hydrogen.

Corrinoids from Methanosarcina barkeri: Structure of the α-ligand

Abstract 5-Hydroxybenzimidazole is the only base detected in cobamide compounds from methanol-grown Methanosarcina barkeri. 5-Hydroxybenzimidazolylcobamide accounted for about 83 and 90% of the total corrinoids of whole cells and cell-free extracts, respectively. Probably, the rest of the corrinoids are base-less.