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Nocardial recombination appears to be controlled by multiple mating factors of unknown characteristics. A single linear linkage group is indicated by studies of the segregation of unselected characters. In this single linkage group are all of the auxotrophic and resistance characters investigated to the present time. Because of the close relationship between the mycobacteria and nocardiae, it seems likely that similar hereditary control exists in the mycobacteria and can be studied by similar means.

The morphological, cultural and physiological characters of strains ofNocardia corallina andNocardia rubra isolated from coconut oil and the alimentary canal of the earthworm are described. Deeply staining granules in the cytoplasm pf theNocardia when grown on Ashby’s nitrogen-free. medium have been reported,N. corallina showed bipolar granules whileN. rubra showed subcentrally situated granules. The observations are substantiated with photomicrographic illustrations. The need for further study of the cytology and nutrition of theNocardia is emphasised.

Studies on the fatty acids of several Nocardia species The free and combined fatty acids from acetone-soluble lipids of N. asteroides, N. brasiliensis, N. lurida and N. rugosa have been studied. Straight-chain saturated acids from C14 to C19 have been found; palmitic acid is the major compound in this series. The branched-chain saturated acids C15, C16 and C17 belong to the iso and anteiso series; iso C18 and 10-methyloctadecanoic acids have been identified. Several unsaturated acids: 9-hexadecenoic, 10-hexadecenoic, 9-heptadecenoic and oleic acids have also been identified.

Respiration studies of N. rubra confirmed earlier qualitative studies on carbohydrate utilization. The inherent high endogenous respiration of the cells was reduced to less than 10% by shaking over...

SUMMARY: A simple method of detecting arabinose by paper chromatography in the cell-walls of aerobic actinomycetes is described. Mycobacteria and Nocardia species are rich in arabinose while saprophytic species of Streptomyces are deficient. Pathogenic Streptomyces species tend to fall between the two extremes but Streptomyces somaliensis is apparently nearly devoid of arabinose.

Forty-five strains of eight different Nocardia species were tested for phenolphthalein sulphatase activity using three different procedures. N. farcinica could readily be differentiated from other Nocardia species as the only one with sulphatase activity. The Lowenstein-Jensen medium technique is simpler and less variable than other methods.

Summary The MICs of fusidic acid and two sulphonamides for nine strains of Nocardia asteroides, two strains of N. caviae and one strain of N. blackwellii were studied by means of a plate-dilution technique. The median value for the MIC of fusidic acid, 2·5 fig per ml, compared very favourably with those of the sulphonamides, and fusidic acid may well have a part to play in the treatment of nocardiosis. We would like to acknowledge the generous supply of fusidic acid by Leo Laboratories Limited, sulphadiazine by May & Baker Limited and sulphamethoxazole by the Wellcome Foundation. We are also very grateful to those mentioned in the text who supplied us with strains of Nocardia. Finally we wish to thank Dr J. C. J. Ives for helpful criticisms and advice.

Nocardia species aromatized 19-hydroxyprogesterone, 3β, 19-dihydroxy-pregn-5-en-20-one 3-acetate and pregn-5-ene-3β, 19, 20β-triol 3-acetate, without cleavage of the side chain, into 3-hydroxy-19-norpregna-1,3,5 (10)-trien-20-one. Septomyxa affinis aromatized the ring A and cleaved the side chain of 19-hydroxyprogesterone to yield estrone. With 19-hydroxypregna-4, 7-diene-3, 20-dione as substrate, the transformation was more complex and many products were formed.

In the last 15 years, several iron-containing metabolites, characterised by a broad absorption band at 420 to 440 mμ, have been isolated from cultures of micro-organisms; these substances have been called „siderochromes“ (1, 2). Many siderochromes show strong biological activity even at very high dilution. Some of them display marked antibiotic activity, and these have been assigned the name „sideromycins“. However, most of the siderochromes that have been isolated act as bacterial growth-factors and are known as „sideramines“. Only a few siderochromes have been found to be biologically inactive. All the sideramines and sideromycins that have so far been isolated are listed in Table 1.

Sixty-nine strains of twelve different Nocardia species were tested for Tween 80 hydrolyzing activity. N. asteroides, N. braziliensis, N. caviae, N. dassonvillei, N. farcinica and N. madurae break down Tween 80, whereas N. corallina, N. pellegrini, N. pelletieri, N. polychromogenes, N. rubra and N. salmonicilor do not.

A complete life cycle study of Nocardia species has not yet been made. One reason for this is that these organisms are difficult to study cytologically because of their small size. Hyphae of actinomycetes are around 1 micron in diameter, although mycelial development may be quite extensive. The problem of variation in actinomycetes (Streptom yces species especially) has received a great deal of attention. So far no one has been able to explain the exact nature of this variation or to study it from a genetical point of view because of the lack of a complete life cycle cytological study. The importance of such studies was recently emphasized by Jones (1954) who said, "The organism must be better understood before we can make any headway in comprehending variability in Streptomyces. First and foremost an intensive cytological study is needed to give whatever direct information modern techniques can reveal on the finer structure of filaments and spores. Researches on developmental morphology will be of almost equal importance as the whole question of a two-phase life cycle must be settled one way or another. If definite nuclei exist, it may be possible to explore their genetical constitution by the production of heterocaryons through hyphal anastomoses". The problem of variation in Nocardia species, closely related to Streptomyces species, has not received much attention due to the relative unimportance of the former to man. Life cycle and cytological studies have similarly been neglected. The author (1950) studied the cytology of Nocardia species by means of lightand electron-microscopy and microchemical tests and discovered the presence of two different particulate structures in the cytoplasm, but was unable to demonstrate their exact nature. In hyphae grown on medium without nitrogen, internal structure became very clear in electron microscopic studies (figs. 63 and 64). Two kinds of particulate structures were present of different natures which alternated in filaments. A positive Feulgen reaction, generally considered to be the sine qua non for proof of nuclei was not demonstrated. The presence of fat, and carbohydrate-like bodies in the cytoplasm was shown, and no particles possessed the solubilities of volutin. Although the presence of nuclei was not proved in these experiments, strong cytological evidence was presented for their occurrence. Morris (1951) studied the cytology

An early case of mycetoma caused by a Nocardia species is described. The lesion, which appeared on the nose, clinically resembled granuloma faciale. Response to oral sulfonamide therapy was prompt and complete. It is emphasized that an initially pustular or crusted lesion evolving into a lesion clinically resembling granuloma faciale should be carefully studied mycologically, since effective therapy of mycetomas is dependent on early and accurate diagnosis.