- Volume 51, Issue 2, 1968

SUMMARY: The microflora of samples of fodder fed to cattle on 41 farms where some cattle suffered respiratory disease was comparable with the microflora of hays, previously reported. Of the 59 samples of fodder examined, 30 from 29 different farms were very mouldy and were comparable with farmer's-lung-type hay in being rich in Micropolyspora faeni and Thermoactinomyces vulgaris. The remaining samples were classified as either good or mouldy in almost equal numbers.

SUMMARY: The growth kinetics of Neurospora in unstirred liquid culture may be accounted for by an exponential and a linear growth phase. If a cubic growth phase exists it is in addition to the exponential and linear phases of growth. A method of measuring the exponential doubling time in unstirred cultures is described which may be usefully applied to fungi which cannot be observed growing exponentially by normal methods. Rate of linear growth is shown to be proportional to the surface area of the culture. Expression of linear growth rates as μg./cm.2/hr would assist in the comparison of data from different laboratories.

SUMMARY: The relationship between various parameters of growth of Neurospora crassa on solid media in tubes is described. These are (a) the relationship between culture weight and linear growth rate on various media; (b) the relationship between ‘lag’ in growth and inoculum size on various media. This latter relationship appears to obey a log law, enabling an inoculum doubling-time to be calculated. Adaptation of the arginine auxotroph arg-I (46004) to diminution of arginine in the medium first occurred by decrease in mycelial weight and then by decrease in linear growth rate. The inoculum doubling-time did not appear to vary systematically with arginine concentration.

SUMMARY: The process of regeneration of Candida utilis and Pichia polymorpha protoplasts obtained by means of an enzyme preparation from Streptomyces violaceus M R and an enzyme preparation from the snail (Helix pomatia) was followed with the electron microscope. A reticular network of fibrils making up a tube or surrounding the regenerating protoplasts was observed. The fibrils are glucan fibrils, and in C. utilis they are packed in groups of 5 or 6. P. polymorpha fibrils occurred singly. The fibrils are the framework for building the new cell wall. The relation between fibrils and plasmalemma particles is discussed.

SUMMARY: The growth of microcolonies of six strains of unicellular blue-green algae was studied by time-lapse photomicrography. The four rod-shaped strains divided regularly in a plane perpendicular to the long axis of the cell; one spherical strain divided successively in two planes, and one in three planes, perpendicular to one another.

Anacystis nidulans and the other rod-shaped blue-green algae studied have a very restricted ability to form chains, four-celled elements being the longest ones observed in slide cultures. They are therefore unicellular organisms, in no way different with respect to development from rod-shaped unicellular bacteria. The recent proposal that A. nidulans is filamentous and should be reclassified in the genus Phormidium is based on a mis-understanding of the nature of unicellularity among procaryotic organisms.

SUMMARY: For the isolation of blue-green algae from soil and fresh water, temperature is a selective factor of major importance. In a nutritionally non-selective mineral medium, which at 25° supported growth of blue-green algae and of many eucaryotic algae, the development of eucaryotic algae was almost completely suppressed by incubation at 35°. Both the number and variety of blue-green algae recoverable at 35° were greater than those recoverable from parallel cultures incubated at 25°. When a combined-nitrogen source was omitted from the enrichment medium, only blue-green algae developed at both 25° and 35°; the microflora consisted exclusively of heterocyst-forming filamentous types, other groups of blue-green algae being eliminated.

SUMMARY: This report shows that some auxotrophic mutants of Escherichia coli can grow on a minimal medium without growth factors when the gas phase is supplemented with carbon dioxide. Mutants which respond to CO2 are called CO2 mutants. The CO2 mutants of E. coli resemble those already known in Neurospora. When the gas phase is not supplemented with CO2 most of the mutants respond to other specific growth factors such as arginine, uracil, adenine, succinate or isoleucine+valine, depending upon the locus of their mutation. One mutant is an obligate CO2 mutant. The CO2 effects shown by these mutants are discussed in relation to the general problem of CO2 effects in micro-organisms.

SUMMARY: Pseudomonas aeruginosa 8602 was grown in continuous culture under steady-state conditions in a carbon-limited medium containing either 20 mM-acetamide or 20 mM-acetamide + 10 mM-succinate. The amidase specific activity was measured at various dilution rates and found to have a sharp peak at a dilution rate of 0.30–0.35 hr−1. Fully constitutive mutants (C 11 and L 9) gave curves for amidase activity with the highest values at very low dilution rates (0.05–0.10 hr−1) and these decreased as the dilution rate increased. A semi-constitutive mutant (C 17) gave a curve intermediate between that of the wild-type strain and the fully constitutive mutant (C 11). Mutants with decreased sensitivity to catabolite repression by succinate gave curves which declined less steeply at the higher dilution rates. Mutant L 9, a fully constitutive mutant with decreased sensitivity to catabolite repression, had higher specific activities than mutant C 11 at the equivalent dilution rates. Mutant L 11, an inducible mutant with decreased catabolite repressibility, had higher amidase specific activities at high dilution rates than the wild-type inducible strain. It is concluded that in continuous culture under steady-state conditions the specific activity of the inducible amidase of P. aeruginosa is determined by the balance between induction and catabolite repression and that catabolite repression is directly related to the growth rate of the culture.

SUMMARY: Three strains of Vibrio were found to agglutinate both guinea-pig and human red cells. The vibrios differed in haemagglutination tests from fim-briated enterobacteria by showing only partial inhibition by mannose and by agglutinating guinea-pig and human red cells equally well. Electron microscopy of the vibrios revealed filamentous appendages which resembled the common fimbriae of Escherichia coli in having average diameters between 6 and 10 mμ and in being more numerous on organisms from liquid media than from solid media. The fimbriae on vibrios also had some characteristics of F fimbriae of enterobacteria. In comparative studies fimbriae which resembled common fimbriae of E. coli were found on Pseudomonas multi-vorans and Aeromonas liquefaciens.

SUMMARY: One hundred and ninety-one coded features of 21 strains of the genera Rhizobium, 18 of Agrobacterium, 11 of Chromobacterium, selected strains of Vibrio cholerae, Flavobacterium, and other representative strains of the families Enterobacteriaceae and Pseudomonadaceae were subjected to Adansonian analysis, with the use of a high-speed computer for the establishment of Similarity (S) and Matching (M) coefficients and for the sorting of the strains into taxonomic clusters. From the frequency of occurrence of features computed for each of the clusters, tables were prepared which provided correlated characteristics suitable for the description of the clusters. Hypothetical median organisms were also computed for each of the clusters and actual strains were selected as neotypes for the new genera, Rhizobium and Phytomyxa. The genus Rhizobium includes the fast-growing rhizobia and the agrobacteria and contains at least four species: R. meliloti, R. legumino-sarum, R. radiobacter, R. rubi. The genus Phytomyxa is reserved for the slow-growing rhizobia which have been placed in the species R. japonicum. Agro-bacterium gypsophilae and A. pseudotsugae are removed from both Rhizobium and Phytomyxa as defined in this study. The lack of significantly high inter-generic relationships amongst the members of the family Rhizobiaceae suggest revaluation of the family structure. From the results obtained here, the genera Rhizobium and Phytomyxa appear more closely related to the members of the Pseudomonadaceae.

SUMMARY: Two sheep were reared together and then kept on a standard diet over a period of 9 months. The rumen of one sheep contained a mixed population of ciliate protozoal species; the other was initially unfaunated, then faunated with Entodinium caudatum and thhn with Entodinium and Polyplastron multivesiculatum. For each sheep diurnal and day-to-day variations in total concentration, and concentration of particular types, of bacteria, in viable counts of bacteria on non-selective and differential media and in concentrations of the different protozoal species, were determined. Measurements were also made of in vitro rates of fermentation, rumen pH and ammonia and volatile fatty-acid concentrations. The presence of protozoa decreased rumen bacterial concentrations and increased ammonia and volatile fatty-acid concentrations. However, these changes were not always completely clear-cut since the protozoa changed the patterns of diurnal variation not only of bacterial numbers but of some metabolic activities and metabolites and also altered the balance of bacterial types. These results are discussed in the context of interactions between bacteria and protozoa and between protozoal species. The main effects of faunation of the rumen seem to be caused by non-selective ingestion of small bacteria by the protozoa.

SUMMARY: Low concentrations of fatty acids with less than 14 carbon atoms were oxidized without a lag phase over a wide range of pH values by mycelium of Penicillium roqueforti. The effect of the fatty acids upon oxygen uptake by a given weight of mycelium, and the nature of the products of oxidation, were dependent upon the concentration and chain length of the fatty acid and the pH value of the system. The C9-C12 fatty acids which showed the greatest inhibitory effect were not oxidized to the corresponding methyl ketone with one less carbon atom in such high yields as the less toxic C6-C8 acids. The C6-C8 fatty acids markedly inhibited endogenous respiration at low pH values but this inhibition was reversed by increasing the pH value. The toxic effect associated with some fatty acids was less pronounced against mycelium which had been previously shaken over an extended period in phosphate buffer. It is suggested that the cellular regulation of fatty acid oxidation and methyl ketone formation involves deacylation of β-oxo acyl thiolester which provides an alternative means of recycling coenzyme A when oxidation of acetyl CoA is impaired.

SUMMARY: The esterase profiles of 9 strains of Mortierella ramanniana grown on glucose and olive-oil media were determined by starch-gel electrophoresis. The enzymes produced on the oil medium were in most instances produced also on the glucose medium, but on the latter some additional esterase components were produced. The esterase patterns of the different strains varied widely; only one esterase was common to all strains grown on glucose medium, and a second esterase was common to all grown on the olive-oil medium. The data available do not suggest that esterase profiles are of taxonomic significance for these fungi.