- Volume 78, Issue 2, 1973

SUMMARY: galactose was 44 for Lactobacillus plantarum grown aerobically in defined medium containing 1 to 6 μmol galactose/ml. Nevertheless, 93 % of the galactose was converted to acetate, and the Y ATP was 11·3. Yields were not appreciably less if 0·5% acetate or 1·0 10−4 M arsenite was added to the medium, but they were considerably lower if riboflavin was omitted. Lactobacillus plantarum, subsequent to converting low concentrations of hexose to pyruvate by the Embden-Meyerhof-Parnas pathway, can apparently gain, under aerobic conditions, approximately two additional mol ATP/mol hexose by converting most of the pyruvate to acetate. Lipoic acid and coenzyme A were not involved in the production of acetate; riboflavin was involved in the utilization of oxygen as an electron acceptor.

SUMMARY: Bacillus subtilis, grown in media containing amino acids and glucose or other carbohydrates (including glycerol), secreted pyruvate, acetate, acetoin, butanediol, and small quantities of isobutyrate and isovalerate. The enzymes producing acetoin and butanediol were specifically induced by acetate and weakly by propionate. Even when these enzymes were present, acetate accelerated the rate of acetoin production. Since acetoin and butanediol are readily interconverted (via butanediol dehydrogenase), they serve as an oxidation-reduction buffer for NAD/NADH. When carbohydrate was exhausted, acetate and, more slowly, acetoin were oxidized.

Mutants unable to produce acetoin or acetate were blocked in the metabolic path from the carbohydrate to these compounds. Other mutants unable to re-utilize the compounds were either deficient in the necessary enzymes, e.g. of citric acid cycle, or they stopped growth so early that they could not use up the carbohydrate. In particular, a uracil-requiring mutant stopped growth precociously, did not oxidize acids or acetoin, and was unable to sporulate. Addition of uracil restored all these properties to normal. The differences in secretion and re-utilization of metabolites can be employed to classify unidentified sporulation mutants.

SUMMARY: The growth of large quantities of a TRIC agent and the concomitant production of polysaccharide were studied in BHK21 and L cell cultures in suspension. The maximum concentrations of elementary bodies and polysaccharide/culture were attained at about the same time (60 h) after infection in both cell systems. The yield of elementary bodies from a 11 culture was equivalent to the maximum obtained from a total area of 8000 cm2 of BHK21 monolayers. Polysaccharide found in the medium was probably derived from disrupted inclusion bodies. It is postulated that synthesis of the polysaccharide is directed by the TRIC agent but controlled by the host cell.

SUMMARY: The 2-oxogluconate kinase and 2-oxogIuconate 6-phosphate reductase of Pseudomonas aeruginosa were purified approx. 100-fold. The activities of these enzymes, and a 2-oxogluconate transport system, were induced when the organism was grown on glucose, gluconate or 2-oxogluconate but were absent when the organism was grown on glycerol, succinate or citrate. Gluconate dehydrogenase is membrane-bound and acts extracellularly.

SUMMARY: When grown in a medium containing 2 to 4% sucrose, Erwinia carotovora var. atroseptica formed two reducing compounds which accumulated in the culture medium. These compounds had the properties of the disaccharides 6-O-α-d-glucopyranosyl-d-fructofuranose (palatinose, isomaltulose) and 1-O -α-d-glucosyl-fructose.

SUMMARY: Growth of Candida 107 on n-alkanes (C10, C16 or a mixture) completely repressed formation of acetyl-CoA carboxylase and partially repressed the fatty acid synthetase complex. As all fatty acids must then be derived directly from the substrate no matter what its chain length, the yeast must be able to elongate even-chain acids (C10 to C14) and modify, by unknown reactions, odd-chain acids to give even-chain acids. Short-term control of fatty acid biosynthesis appears to be by long-chain (C16 or C18) fatty acyl-CoA esters feedback-inhibiting the activities of both acetyl-CoA carboxylase and fatty acid synthetase. n-Alkanes, n-alcohol, free fatty acids or C12 and C14 acyl-CoA esters, had little or no effects on these enzymes. Extracts from n-alkane-grown yeast inhibited the carboxylase in extracts from glucose-grown yeast, the pattern of inhibition being similar to that observed with hexadecyl-CoA.

SUMMARY: The lipopolysaccharides from fifteen strains of Pseudomonas aeruginosa used for serotyping have been isolated and analysed. They all contained heptose, glucose, rhamnose, glucosamine, galactosamine, 2-keto-3-deoxyoctonic acid and alanine. Many of them contained additional sugars and amino compounds, some of which have been shown to be amino sugars. Their composition and structure suggested the existence of a common region of low molecular weight in all the lipopolysaccharides. They could be classified by their chemistry and that of their degradation products into twelve chemogroups, nine of which contained one serotype and three of which contained two serotypes. All the lipopolysaccharides contained the same fatty acids, 3-OH 10:0, 2-OH 12:0, 3-OH 12:0 and 12:0. The isolated lipopolysaccharides reacted with the homologous Habs type antisera. The serological specificity was limited to the high molecular weight regions thought to correspond to side chains.

SUMMARY: The envelope proteins of Klebsiella aerogenes (syn. Aerobacter aerogenes) grown in glucose-, sulphate-, phosphate-, ammonia-, potassium- and magnesium-limited environments, in chemostats, have been isolated, and compared by SDS-poly-acrylamide gel electrophoresis; marked differences were evident. The envelopes from glucose- and sulphate-limited organisms were examined further: protein content was growth-rate dependent, but sulphate-limited envelopes always contained less protein than glucose-limited envelopes and this protein had a lower sulphur content. The sulphate-limited envelopes contained one major protein component with a molecular weight of 30000 daltons whereas the glucose-limited envelopes contained three main protein components (molecular weights of 46000, 38000 and 28500 daltons).

Selective extraction of membrane proteins with Triton X-100 indicated that both wall and membrane proteins altered in response to changes in the growth environment. Similarly, the soluble proteins of the organisms varied, but the ribo-somal proteins remained almost constant.

SUMMARY: Three phages, isolated from soil samples collected in different localities, produced turbid plaques with a characteristic morphology on Streptomyces coelicolor A3(2). Surviving growth from the plaques was lysogenic: when isolated and purified it was resistant to lysis by the homologous phage and released phage at a low frequency during growth. The three phages were homoimmune. The chromosomal attachment site of one of the prophages, VP5, was mapped in a position between hisE and cysD - that is, in a region devoid of standard markers - on the circular linkage map of the host, by crossing defective lysogens with sensitive strains. The host range of VP5 was restricted; only certain strains belonging to the S. coelicolor (S. violaceoruber) group were attacked. VP5 gave rise to clear-plaque mutants, incapable of lysogenizing the host, at a spontaneous frequency of 10−4, which was increased by u.v. irradiation and by hydroxylamine mutagenesis; the clear-plaque mutants were incapable of lysing strains carrying the wild-type prophage. Electron microscopy showed that VP5 belongs to group B of Bradley’s morphological classification.

SUMMARY: The growth responses of 33 strains of cellulolytic butyrivibrios, isolated from the rumens of sheep fed on low-protein teff hay diets, to various combinations of volatile fatty acids (VFA) have been determined. Propionate alone was generally retardatory to the acetate-utilizing strains whilst acetate was stimulatory. Branched-chain VFA were generally stimulatory to those strains on which propionate had a retardatory effect, and retardatory to those strains on which propionate had no effect. Propionate alone was generally stimulatory to the acetate-producing strains and the effect of acetate and branched-chain VFA was variable. The major nutrient requirements of a few selected acetate-utilizing and acetate-producing strains are presented. A chemically defined medium was formulated which permits as good growth as a rumen-fluid medium for the acetate-utilizing butyrivibrios, Ruminococcus albus and Cillobacterium cellulosolvens.

SUMMARY: Chemotactic behaviour of ten species of motile bacteria from nine different genera toward over 130 compounds was examined using a flat-glass capillary tube technique and microscopical observations on bacteria both individually and in mass. Negative chemotactic behaviour was uniformly exhibited against acidic (pH 1·0 to 3·0) and basic (pH 10·0 to 12·0) stimuli. Benzene, chloroform, acetone and ethanol, whilst not extensively interfering with translational movement, uncoupled tactic responses to gradients of acids or bases. Positive chemotactic behaviour towards a given carbohydrate or amino acid was a relatively constant though rather rare event, governed to some extent by the laboratory conditions imposed. The biological role of negative chemotaxis appears to be one of survival, whereas positive responses may be, in some cases, incidental or useless.

SUMMARY: Cold-sensitive mutants of bacteria are a source of strains defective in the assembly of ribosomes (Guthrie, Nashimoto & Nomura, 1969; Tai, Kessler & Ingraham, 1969). A study of cold-sensitive mutants in Aspergillus nidulans was undertaken in the hope that it would provide ribosomal mutants. Cold-sensitive (cs) mutants were isolated, and when crossed with wild-type the majority of 32 mutants tested segregated as single-gene mutations.

One mutant, cs67, showed non-Mendelian segregation of its cold-sensitive character in such a cross. This paper presents further results demonstrating the extranuclear inheritance of CS67.

SUMMARY: Spores of Clostridium bifermentans are more sensitive to chlorine, added as sodium hypochlorite, than spores of other Clostridia or of Bacillus subtilis (Dye & Mead, 1972). Spores of C. bifermentans or B. subtilis, damaged with chlorine, release dipicolinic acid (Dye & Mead, 1972; Alderton & Halbrook, 1971) and may therefore have increased permeability. We have isolated mutants of C. bifermentans which germinate more slowly than the parent strain, possibly because of reduced permeability to germinants (Wyatt & Waites, 1971). In view of these findings and the frequent use of chlorine as a disinfectant, we examined the effect of hypochlorite on the germination of mutant and parent spores.