- Volume 64, Issue 1, 1970

SUMMARY: The preparation, purification and properties of cholera toxin type 2 are described. When the toxin was given to experimental animals it induced a high level of toxin-neutralizing antibodies. Cholera toxoid given to human volunteers induced antibodies consisting of agglutinins, vibriocidal and toxin-neutralizing antibodies. The relevant titres depended on the purity of the antigen administered.

SUMMARY: Twenty-four representative isolates of cellulolytic cocci and ten of cellulolytic rods from the rumens of sheep fed differently supplemented teff hay diets were characterized. Nine of the coccal isolates could be classified as Ruminococcus albus and twelve as R. flavefaciens. Three were classified as a new variety of R. flavefaciens, R. flavefaciens var. lacticus, on the basis of the preponderance of lactic acid among the products of cellulose fermentation. Two of the isolates did not fit into any of these groups. The rods were identified as Butyrivibrio fibrisolvens. Tests for the presumptive identification of cellulolytic bacteria from the rumen are discussed.

SUMMARY: Saprophytic cultures obtained from uredospores of Puccinia graminis f. sp. tritici race 126-anz-6,7 varied. Cultures were placed in two general categories: those which formed macroscopic colonies within 2 weeks of inoculation, and those which formed colonies 4 or more weeks after inoculation. The fast-appearing colonies contained binucleate cells and were the more common; growth ceased by staling or formation of spore-bearing stromata. Slow-appearing colonies were formed at an erratic and low incidence; they were uninucleate, showed much less tendency to stale or form stromata than did fast-appearing colonies, and could be propagated by serial subcultures. Variation of uninucleate colonies during maintenance in axenic culture is described.

SUMMARY: The enzymes involved in the tricarboxylic acid cycle and some other related reactions were measured quantitatively in cell-free extracts from the obligate autotroph Thiobacillus denitrificans grown anaerobically, and in the facultative autotroph Thiobacillus-A 2 grown under various conditions. The presence of an incomplete tricarboxylic acid cycle in T. denitrificans and in Thiobacillus-A 2 (when grown autotrophically on thiosulphate) is described. The cell-free extracts from these two organisms lacked α-ketoglutarate dehydrogenase and succinyl CoA synthetase. The data from Thiobacillus-A 2 grown on succinate, aerobically or anaerobically, and on glutamate aerobically suggest that both the enzymes are repressed during autotrophic growth. Results are further discussed in relation to possible reasons for autotrophy.

SUMMARY: Equations are developed in which the inhibition of cell growth by different levels of a given chemical or environmental agent is expressed by a single straight line. The formulation provides a simple, economic, and consistent way of characterizing different growth inhibitors and evaluating their possible mechanisms of action, e.g. structure-activity relationships.

SUMMARY: Walls of the yeast form of Verticillium albo-atrum showed a granular appearance on the outer surface. The granular components could be extracted by alkali, revealing a fibrillar wall fabric. A region of circularly oriented microfibrils with a minute central ‘orifice’ was commonly found at one of the cell poles and probably represented a bud scar. The material dissolved by alkali was a heteropolysaccharide-protein complex containing mannose, galactose, glucose, glucuronic acid, glucosamine and the common range of amino acids. The alkali-insoluble microfibrillar network was made of a β-linked glucan and chitin. The glucan was digested by endo-β-glucanases yielding glucose, β-1,3-linked glucose oligomers and cellobiose, but no evidence for cellulose was found. Most of the glucan was also soluble in hot acid. The acid-insoluble glucan (hydroglucan) contained β-1,6-links. Acid treatment produced coarse microfibrils resembling those in Saccharomyces cerevisiae walls treated similarly. The hydroglucan was soluble in alkali leaving an insoluble microfibrillar network composed mainly of chitin. A small amount of lipid (2.7 to 3.4%), mostly of the bound type, and traces of phosphate were also found.

SUMMARY: The respiratory electron transport system involved in NADPH (2.0 nmoles/ min./mg.) and NADH (1.0 nmoles/min./mg.) oxidation in the dark that was operative in extracts of light-grown Anabaena variabilis has been examined. NADPH oxidation was inhibited 50% by cyanide (2x10−2m), rotenone (10−4 m); antimycin A, amytal and azide were markedly less inhibitory. NADPH: ferrocytochrome c oxidoreductase, NADPH: menadione oxido-reductase, ferrocytochrome c:oxygen oxidoreductase and succinic dehydrogenase were detected. A phosphorylation (0.4 nmoles/min./mg.), associated with NADPH oxidation, was measured, NADPH could be replaced by NADP and isocitrate. This phosphorylation was absolutely dependent upon oxygen and was inhibited 25% by carbonyl cyanide p-trifluoromethoxy-phenylhydrazone (5 μM).

SUMMARY: The heat evolved by growing Nitrobacter is a measure of its efficiency of free energy utilization which is related to the apparent molar heat of substrate oxidation. The maximum free energy efficiency was about 50 % of a total free energy change of --17.5 kcal./mole. The molar growth yield decreased rapidly with the age from 107 to 3 × 106 organisms/mole substrate. The free energy needed for the synthesis of one Nitrobacter varied from 0.45 nanoca-lories at the onset of growth to 2.9 at later stages. From these values and the bacterial enthalpy content its negentropy content can be calculated.

SUMMARY: Streptomycetes and aerobic bacteria able to utilize cysteic acid and taurine as sole sources of energy, nitrogen and sulphur were isolated from soil materials. None of the isolated fungi did this. The bacterium which was used in most experiments grew on both compounds. The sulphur of the compounds was recovered as sulphate and most of the nitrogen as ammonia after breakdown by growing or pregrown organisms. A significant portion of the nitrogen was assimilated by the growing organisms. Sulphite appeared as a transitory sulphur product. Deamination preceded desulphuration in early periods of incubation; the reactions were brought about by adaptive enzyme systems. Dissimilation of cysteic acid by pregrown organisms was maximum at reactions close to neutrality. During development of pregrown organisms at pH 8.5 and 9.0 appreciable amounts of sulphite were detected. Acid reactions which inhibited development of the cultures were produced during decomposition of taurine.

SUMMARY: DNA binding and competition tests indicate that the species Clostridium botulinum is composed of three groups with only 4 to 18 % DNA homology with each other. One group includes the proteolytic C. botulinum and C. sporogenes strains. The DNA isolated from seven proteolytic C. botulinum a, b, f, and six C. sporogenes strains was 50 to 100% homologous to the C. botulinum a 62 DNA. Clostridium botulinum c and d strains form another group. Clostridium botulinum c8613 and d8625 strains have 38 % homology with the C. botulinum c573 strain. The last group comprises the non-proteo-lytic C. botulinum b, e, and f strains reported previously. All the C. botulinum strains tested were related to only one of the three groups and no intermediate strain was detected.

SUMMARY: Sodium chloride decreased the maximum specific growth rate of Saccharomyces cerevisiae. Chemostat experiments showed this to be largely due to an increased requirement for energy-yielding substrate, apparently linked to maintenance and leading to a decrease in the yield. The increased maintenance requirement is probably concerned with maintaining an intracellular Na+ concentration ten times lower than the extracellular concentration. NaCl caused much higher concentrations of glucose to be required to maintain any particular glucose-uptake rate; it also increased the production of glycerol.

SUMMARY: Wild-type Streptomyces coelicolor a 3(2), and many mutant and recombinant derivatives of it, are of the if (Initial Fertility) type. At an early step in the production of recombinant strains from some of the first derivatives of a3 (2), a variant fertility type arose (nf: Normal Fertility), and subsequently if and nf segregated within the pedigree of stock cultures. if × if crosses are about 100-fold less fertile than nf × nf or if × nf crosses, but the clearest distinction between if and nf is achieved by crossing with a strain of the previously described uf (Ultra-Fertile) type, when the difference in fertility approaches 1000-fold.

The if strains give rise to uf strains with a high spontaneous frequency, and the frequency is increased by ultraviolet or X-irradiation but not appreciably by N-methyl-N'-nitro-N-nitrosoguanidine. nf strains do not give rise to uf variants with a high frequency.

The difference between if and nf is determined by a chromosomal locus near the 9 o'clock position on the linkage map. There is no evidence for the infectious conversion of one type of strain to the other in a mixed culture.

In crosses with an nf strain, both if and uf strains contribute the whole chromosome to the effective merozygotes, and the nf strain contributes the fragment, which obligatorily includes the 9 o'clock region. However, whereas in uf × nf crosses there is obligate inheritance of the 9 o'clock region of the nf genome by all sexually produced progeny, this is not true of if × nf crosses.

SUMMARY: i-Aminopropan-2-ol is a component of vitamin B12 (Cooley, Ellis & Petrow, 1950) possessing the dg-configuration (Wolf, Jones, Valiant & Folkers, 1950). X-Ray crystallography confirmed that the amino alcohol linked the substituted corrin and nucleotide-like ring systems (Hodgkin et al. 1956; Hodgkin, 1958).

The metabolic origin of the nitrogen atom of d-i-aminopropan-2-ol in vitamin B12 was established using [15N]-l-threonine, added to the growth medium of Streptomyces griseus (Krasna, Rosenblum & Sprinson, 1957). It was suggested that the carbon skeleton of the aminopropanol moiety was also derived from threonine by decarboxylation, although this was not investigated. Direct decarboxylation of the amino acid has never been demonstrated, and neither the threonine nor threonine-O-phos-phate analogues of vitamin B12 serve as precursors of cobinamide in either Escherichia coli or Propionibacterium shermanii (Bernhauer & Wagner, 1961, 1962). The discovery of l-threonine dehydrogenase (Neuberger & Tait, 1960, 1962) and d-i-aminopropan-2-ol dehydrogenase activity (Turner, 1966; Dekker & Swain, 1968; Lowe & Turner, 1968) revived interest in the possibility that the free amino alcohol, formed from l-threonine via aminoacetone, served as a precursor. The roles of l-threonine and d-i-aminopropan-2-ol in vitamin B12 biosynthesis by a Streptomyces strain were therefore investigated using 14C-labelled compounds.

SUMMARY: Large, Gram-negative, anaerobic cocci (LC) fermenting lactate were first isolated by enrichment culture from the sheep rumen (Elsden, Volcani, Gilchrist & Lewis, 1956). High counts (about 109/ml.) were obtained from young calves but not from adult ruminants by Hobson, Mann & Oxford (1958). The cocci were cultured in numbers of 106 to 103/ml. from the rumen of cattle fed high-grain rations and named Peptostreptococcus elsdenii by Gutierrez, Davis, Lindahl & Warwick (1959). They can be important fermenters of lactate in the rumen and are associated with amylolytic lactate producers such as Streptococcus bovis when large amounts of starch are consumed by ruminants. The production of propionic acid by P. elsdenii via the acrylate pathway (Ladd, 1959) has attracted the particular interest of biochemists and nutritionists. The types of bacteria active in the rumen are not found only in this organ (Giesecke, 1970), and recent experiments indicate that P. elsdenii is also a prominent lactate fermenter in the large intestine of pigs fed on diets containing potatoes.