- Volume 15, Issue 3, 1956

SUMMARY: Evidence is presented that under the conditions described 11 strains of Actinomyces spp., representing strains described as A. israelii, A. israelii-like or A. naeslundii, require carbon dioxide for anaerobic growth. Some of these strains, under these conditions, are obligate anaerobes to microaerophils, while others appear to be facultative anaerobes. Cultures which are capable of aerobic growth may or may not require carbon dioxide for such growth. Of three strains of Lactobacillus bifidus tested, all required carbon dioxide for anaerobic growth. One avian strain required carbon dioxide to give limited aerobic growth; the remaining strains did hot grow significantly under aerobic conditions. Comparisons of several strains of Actinomyces spp. with L. bifidus indicated that of eleven sugars tested, the sugar of choice for growth of Actinomyces spp. was glucose or maltose, whereas lactose or maltose was preferred by strains of L. bifidus. All strains of each group of organisms were found to be catalase-negative; none liquefied gelatin; all eleven strains of Actinomyces spp. reduced nitrate to nitrite, but none of the bifid strains possessed this ability; production of acetylmethylcarbinol was variable in both groups. All strains of Actinomyces spp. tested formed l (+) lactic acid, although the Tesults suggested that small amounts of d (−) lactic acid were also formed. Fermentation analyses indicated that strains of L. bifidus and Actinomyces spp. form the same products from glucose and carbon dioxide (lactic, acetic, formic and succinic acids). However, strains of Actinomyces spp. form predominantly lactic acid with small amounts of acetic, formic and succinic acids; whereas the strains of L. bifidus form approximately equal amounts of lactic and acetic acids (based on glucose fermented) with trace amounts of succinic and formic acids. Actinomyces strains fermented but 34-59 % of the glucose supplied as compared to the strains of L. bifidus which used from 59 to 89 % of the glucose (1 % glucose medium).

Summary: Indole synthesis from glucose, ammonium chloride and serine by washed suspensions of Escherichia coli 7–4 was inhibited by bacteriostatic concentrations of chloramphenicol and the tetracyclines (Aureomycin, Terramycin, and Achromycin). Indole synthesis was also inhibited by streptomycin but only by concentrations higher than those necessary for bacteriostasis. The inhibition by chloramphenicol and the tetracyclines does not appear to be due to inhibition of adaptive enzyme formation because these antibiotics still inhibited indole synthesis when added to suspensions which were forming indole at maximum rate. Streptomycin, in the same type of test, seemed to inhibit some adaptive process.

Indole synthesis by suspensions of antibiotic-resistant variants of Escherichia coli 7–4 was not inhibited by concentrations of antibiotics which inhibited synthesis by the parent strain. Suspensions of organisms resistant to high concentrations of streptomycin formed at least the same amount of indole in the presence of any concentration of streptomycin tested, as they did in its absence. Streptomycin often stimulated indole synthesis by such organisms. Suspensions of organisms which required streptomycin for growth, after growth in suboptimal concentrations of streptomycin, did not produce appreciable amounts of indole. The addition of streptomycin restored the activity in organisms grown in a liquid defined medium but did not do so with organisms grown on heart infusion agar. Streptomycin-resistant and streptomycin-dependent strains resembled the parent strain in that they utilized malate +pyruvate, or oxalacetate, for indole formation in place of glucose. Strains resistant to various concentrations of chloramphenicol, Aureomycin and Terramycin showed a correlation between the amounts of antibiotic required to inhibit indole synthesis and to inhibit growth in a glucose + tryptophan + inorganic salts medium. The results indicate that some of the antibiotics interfere, either directly or indirectly, with indole synthesis.

Summary: A new Pichia species has been isolated from soil. Its characteristic features are its large cells, the abundant formation of pseudomycelium, an early appearance of a pellicle, and the formation of four-spored asci. The species is nonfermentative and assimilates only glucose, galactose, sucrose and maltose.

SUMMARY: Levansucrase in the corynebacterium studied is apparently an adaptive enzyme. Its optimal formation is dependent on the presence of an inducer (sucrose) and an organic nitrogen source. High nitrogen concentrations increase growth rate and sucrose hydrolysis and significantly decrease levansucrase formation. The pH activity curve of the levansucrase studied is asymmetric and the optimal pH value for its activity is 7·0. These findings suggest that this levansucrase differs from other levansucrases so far described.

SUMMARY: A mutant of Neurospora crassa is shown to have an absolute requirement for riboflavin when grown at 30°, but this requirement is less stringent when the organism is grown at 25°. The Fe, Cu, Zn, Mn and Mo requirements of the mutant, grown at either temperature, are similar to those of the wild type (146) so that it seems unlikely that these metals are involved in the biosynthesis of riboflavin. A study of enzyme patterns in the mutant, grown at 30° and given optimal or deficient concentrations of riboflavin, demonstrated alternative pathways of electron transfer in the fungus. When riboflavin is deficient, the iron enzymes are markedly increased and oxygen is probably the main terminal acceptor of the electrons. At optimal concentrations of riboflavin, the flavoprotein enzymes are produced and nitrate and nitrite reductases are active so that nitrate can act as a terminal acceptor. Iron deficiency is readily produced in the mutant when riboflavin is deficient because of the increased activity of iron enzymes; a molybdenum requirement is greater at optimal riboflavin concentrations because of the enhanced production of molybdo-flavoproteins.

SUMMARY: The morphology, minimal nutritional requirements, and biochemical reactions of the lobster pathogen, Gaffkya homari, and of a tetracoccus found contaminating meat products were compared. The marine and terrestrial cocci were identical by the in vitro methods used. The validity of the genus Gaffkya is discussed. The 4 strains of micrococci herein studied had an unusual nitrogen requirement: all required glutamic acid as nitrogen source; substrates were not utilized in the absence of glutamate.

SUMMARY: Of the 25 group C streptococci examined all but 3 produced a hyaluronidase detectable in a sensitive turbidimetric test. These 3 strains and 6 of the hyaluronidase producers were heavily capsulated on serum glucose agar and in serum + glucose enriched liquid media. The capsules of all strains were readily destroyed by testicular hyaluronidase. In continually neutralized cultures of the capsulated strains hyaluronic acid was detected only transiently during logarithmic growth with the enzyme producers but rose to a high steady concentration with the other 3 strains. Hyaluronidase activity was present throughout the phase of logarithmic growth and beyond, but fell markedly in the 16 hr. following the cessation of logarithmic growth of capsulated strains in neutralized cultures and even more markedly in cultures grown without neutralization. Non-capsulated variants of the 9 capsulated organisms resembled the parent strains in enzyme production. A single passage through mice did not qualitatively influence capsulation, hyaluronic acid or hyaluronidase production by those strains examined.

SUMMARY: The relations between growth rate, generation time distribution and age distribution in growing bacterial cultures are derived. The effect of inheritance on generation time is probably negligible. Some applications to experimental data exemplify the mathematical results. The validity of the principal assumptions is discussed.

Summary: Stable protoplasts may be released from Micrococcus lysodeikticus and Sarcina lutea by digestion of the cell-wall with lysozyme in sucrose or NaCl solutions having an osmotic pressure of some 25 atmospheres, but not in glycerol solutions of the same osmotic pressure. The stability of the protoplasts depends not only upon the depression of the water activity by the solute but upon an osmotic pressure exerted against the protoplast (plasma-) membrane. The permeability of the protoplast membrane to a number of solutes resembles that of the osmotic barrier of intact Staphylococcus aureus.

Summary: Cider sickness is a disorder of sweet low-acid ciders and perries. The causal organism was isolated after anaerobic incubation of the centrifuged deposit from infected cider on a medium which contained apple juice, 1 % (w/v) yeast extract and 10 μg. Actidione/ml., at pH 4·5. The causal organism found was a Gram-negative motile rod for which the name Zymomonas anaerobia var. pomaceae is proposed on the basis of a comparison of its morphology, cultural and biochemical characters with those of Termobacterium mobile Lindner (synonyms: Pseudomonas lindneri, Zymomonas mobile) and Achromobacter anaerobium Shim well (synonym: Saccharomonas anaerobia). It is proposed that the generic name Zymomonas, Kluyver & van Niel (1936) be adopted for the organisms isolated by Lindner (1928) and Shimwell (1937) and the organism described in this paper. The distinctive character which places these three organisms together in a separate genus in the tribe Pseudomonadeae is their ability to ferment glucose to give almost a theoretical yield of ethanol.

Summary: The β-glucosidase activity of 119 strains of yeast was studied with aesculin, arbutin, salicin or cellobiose as substrates. A medium which was sufficient for good growth was in many cases not sufficient to allow the development of β-glucosidase activity. A yeast capable of splitting one β-glucoside did not necessarily hydrolyse another. It is suggested that yeasts may contain different β-glucosidases. There is evidence that, grown under suitable conditions, most yeasts are capable of hydrolysing aesculin.

Summary: A bacteriophage method of classifying strains of Escherichia coli which inhabit the alimentary tract of cattle has been evolved. It was possible to divide the strains into a large number of types by this method. Varying proportions of strains isolated from the faeces of human beings, sheep, pigs and poultry were also typable by the phages employed. This method of phage typing was used to study the origin and behaviour of the E. coli population in the alimentary tract of healthy cows and calves, and of calves suffering from white scours, in one self-contained herd (herd A) and to a lesser extent in twenty-seven other herds. Several types of E. coli were often found in the same faecal specimen in cases of scouring, as well as in healthy calves. Seventy different phage types were found in the faeces of the healthy calves in herd A, many occurring infrequently. Thirty-two different types were discovered in the faeces of the scouring calves in this herd; only one strain of one type was found in scouring calves that was not found also in healthy calves. Two types were found commonly in the calves but rarely in the cows. The examination of strains of E. coli isolated from faeces of cows and calves at daily and weekly intervals indicated that some types usually remained dominant for a week or so and were then gradually succeeded in dominance by other types. In some animals frequent and sudden changes were apparent; in others one type might be the only type isolated from the faeces for a number of weeks continuously. Changes of dominant phage-type commonly occurred in faeces of calves during the time they were suffering from white scours. The mother did not appear to be a frequent source from which a calf acquired its E. coli; the calf pens themselves seemed a more probable source. Exceedingly large numbers of E. coli were found in the faeces of healthy and scouring calves during the first 14 days of life, a period when white scours occurs; very much smaller numbers were found in older animals. Studies on material from the twenty-seven other herds supported the findings in herd A; many phage types of E. coli were found in these herds that had not been found in herd A. The aetiology of calf scours is discussed in the light of these and other observations.

SUMMARY: Cultures of non-motile Salmonella strains treated with phage lysates of motile strains produce in semi-solid agar: (i) swarms, each consisting of a clone of motile bacteria, attributed to complete transduction of motility; (ii) trails, i.e. unbranched linear groups of microcolonies stretching some millimetres from the site of inoculation, attributed to abortive transduction of motility; the latter was thought to result from the importation by phage of a gene conferring motility, which was not replicated but was transmitted, as a supernumerary gene, down one line of descent (unilinearly) to but one of the descendants of the organism which received it, the trail marking the path of the gene-bearing descendants of successive generations.

The present work has led to a modified hypothesis: that the phage-imported non-replieated gene confers on the organism the ability to synthesize motility conferring (MC) particles, which are distributed amongst its non-gene-bearing progeny, which cannot make new ones; that each particle may be unilinearly transmitted for many generations; and that while one MC particle confers motility in broth, several are needed to enable a bacterium to travel in a semi-solid medium.

The main evidence for this hypothesis is provided by pedigrees of bacteria made motile by abortive transduction, isolated by micromanipulation from treated suspensions. All such bacteria produce mainly non-motile offspring. A minority (exceptional or E bacteria) produce clones which after 10–15 generations include 20 to 100 motile descendants; the rest give clones containing only a few (0–12) motile organisms. E bacteria are identified as ones containing the supernumerary gene, the others as ones motile through possession of a few MC particles only.

In each of six extensive pedigrees a single E bacterium was isolated from amongst the 9th-21st generation progeny of the original E parent. None of a large number of other motile bacteria isolated in collateral sublines (and so ex hypothesi not gene-bearing) produced more than 12 motile descendants. These data show that the E character (ability to produce 15 or more motile descendants) is unilineariy transmitted.

Any motile bacteria found amongst the progeny of a non-E bacterium after six or more generations were inferred to be motile through possession of one MC particle each; of many such which were isolated none produced more than one motile descendant; when this in turn was isolated, a single motile organism was sometimes again detected in the clone produced. This shows that there is unilinear transmission of motility (in broth).

Samples of populations of motile bacteria isolated by micro-manipulation from treated suspensions were transferred to semisolid agar, or to individual droplets; the proportion of bacteria which generated trails was about equal to the proportion found to be E. This was to be expected if both characters reflect the presence of the non-replicated gene.

The MC particle is probably a flagellum, or a granule which determines the production of one. The particle presumed to account for the unilinear transmission of the E and trail-forming characters is most economically interpreted as a phage-imported fragment of genetic material which has failed to replace its homologue in the genetic organelle of the recipient organism.

SUMMARY: Two loci which affect the production of penicillin by Penicillium chryso- genum have been identified. Capacity to produce penicillin is suppressed by eight mutant alleles at one of the loci, and a marked decrease of yield accompanied by an effect on conidium colour is produced by one mutant allele at the other locus. The two loci are on different chromosomes. The wild type alleles of the two genes restore penicillin production in the heterokaryotic and heterozygous conditions but not when they are carried in different mycelia in mixed culture. Haploid and diploid strains have been identified among the segregants from a heterozygous diploid.

SUMMARY: Prototrophic recombinant strains were obtained by plating on minimal medium spores from mixed cultures grown on limiting agar, of two strains each with a different double nutritional requirement. Clones showing new associations of properties were isolated on partially supplemented media. Some showed one ‘mutant’ character derived from one of the starting strains and ‘wild’ characters derived from the other; others showed two ‘mutant’ characters, each derived from one of the starting strains.

SUMMARY: A surface antigen preparation obtained from Paramecium aurelia absorbs from a concentrated antiserum approximately 74 % of the total antibody absorbed by the intact animal. An antiserum prepared against this preparation immobilized P. aurelia of the same serotype.

SUMMARY: Evidence is given that potato paracrinkle virus, potato virus S and carnation latent virus are serologically related and should be considered as related virus strains, although they differ considerably in their host range and pathogenicity, and only carnation latent virus is transmissible by aphids. It is suggested that the three have evolved from a common aphid-transmitted ancestor. In addition to the antigens which the three have in common, each has many specific ones, and the two strains from potato are more closely related to one another than to the carnation virus. No plant of the potato variety King Edward was found free from paracrinkle virus, and no Arran Victory plant free from virus S. Minor variants of both paracrinkle virus and of virus S were detected; it is suggested that the variations in severity of symptoms developed when Arran Victory plants are grafted with King Edward scions reflect the various degrees to which different isolates interfere with each other’s multiplication. Most isolates of virus S interfere only slightly with the multiplication of paracrinkle virus.

SUMMARY: A selective medium lor Brucella spp. is described which contains 5-nitrofurfurylmethyl ether, bacitracin, polymyxin and Actidione. Organisms normally encountered in culture from faeces or soil are completely suppressed on the medium while brucellas grow quantitatively within 65 hr. of incubation.

SUMMARY: Thin sections of purified suspensions of Rickettsia burnetii were examined by electron microscopy. The organism possesses a limiting membrane, within which lie a granular region and a dense central body. The configuration of the central body suggests that it may consist of an elongated and irregularly twisted strand.