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Paper chromatography is very helpful in the identification and comparison of antibiotics, but very few results from the application of this technique have been published so far. The awakening of interest in the search for antibiotics which are active against fungi pathogenic to plants and animals makes the investigator aware of the scant information that is available to help characterize such agents. A knowledge of the Rf values of the known antifungal agents would help advance the search for such therapeutic materials. Often these values, in conjunction with the biological inhibitory activities, are the only criteria by which one can determine whether the unknown agent appears to be a new material. When the Rf data are obtained for shake cultures, one can eliminate many previously described antibiotic-producing organisms from further study, thus allowing more research to be applied to antibiotics which are new and different. The studies reported in this paper should serve as a guide to the identification of some of the known antifungal antibiotics.

Microbiological assay of individual antibiotics in mixtures of antibiotics depends on the use of selective inactivation and/or of test bacteria with differential susceptibility. Controlled experiments revealed that streptomycin in concentrations of 20 and 40 μg/ml did not influence a disk diffusion assay of penicillin with Sarcina lutea (ATCC 9341) as the test organism. In the case of penicillin concentrations less than or equal to 1 IU/ml, addition of 80 μg of streptomycin per ml influenced the penicillin assay significantly. Clinical use of streptomycin resulting in levels above 40 μg/ml usually did not occur; therefore penicillin could be assayed as though streptomycin were not present. We observed additionally that S. lutea was unable to grow on agar plates prepared with semicarbazide hydrochloride.

1. 6-Hydroxykynurenic acid (4,6-dihydroxyquinoline-2-carboxylic acid, 6-HKA) was isolated in crystalline form from both green and cured tobacco leaves. 2. A method for the determination of 6-HKA by paper chromatography and fluorimetry is described. 3. The content of 6-HKA in the flowers, stem and roots of the tobacco plant was much lower than that in the leaf. 4. The 6-HKA content increased throughout leaf development and senescence. 5. 6-HKA was detected in the leaves of plants representing 11 out of 27 families sampled. 6. 6-HKA was found to be devoid of antibacterial and antifungal activity, and was inactive in the Avena-coleoptile and cress-seed-germination tests. 7. The presence of 6-HKA is taken as evidence in plants of the tryptophan-catabolic pathway already known in mammals and micro-organisms.

Acidolin was isolated from skimmilk cultured for 48 hours with Lactobacillus acidophilus (CHR. HANSEN's Laboratory strain 2181). It was extracted from the skimmilk with methanol and acetone and was further concentrated and purified by Sephadex G-25 gel filtration, high voltage electrophoresis, and thin-layer chromatography on silica gel. Ultraviolet, infrared, nuclear magnetic resonance, and mass spectra results are presented for the antibiotic. Acidolin has a low molecular weight (-200), is acidic in nature, possesses a yellow-brown color, and is highly hygroscopic and thermostable. Acidolin exhibits antimicrobial activity against enteropathogenic organisms and sporeformers and only limited activity against lactic-acid bacteria. It is non-toxic to tissue culture cells (H-Ep-2) and is more active against vaccinia than polio virus.

Addition of aromatic acids to the culture medium of Streptomyces caelestis results in the production of antibiotics different from the celestosaminides normally produced by the organism. The new antibiotic produced when 4-aminosalicylic acid was added to the culture medium was isolated and characterized as desalicetin 2'-(4-aminosalicylate). Although biological evaluation of this antibiotic is not complete, its in vitro antibacterial spectrum is identical to that of celesticetin.

SUMMARY: The acetone-extractable antibacterial components of Isochrysis galbana have been resolved by paper-chromatography and bioautography. Two pigmented products with similar antibacterial properties were obtained which were tentatively identified from their absorption spectra as chlorophyll a derivatives, probably pheophytin a and an atypical chlorophyllide a.

Flavomycoin is a polyene antibiotic isolated from the mycelium of Streptomyces roseoflavus ARAI 1951 var. jenensis nov. var. JA 5068 as yellow-green crystals. It shows inhibitive activities against yeasts and fungi as well as protozoa. It is optically active, exhibits an ultraviolet spectrum without fine structure with maxima at 363 nm and 263 nm. Analytical studies indicated that the molecular formula of the antibiotic is C41H68O10 and the molecular weight 721. These results were confirmed by degradation to the parent hydrocarbon and by catalytic hydrogenation. As flavomycoin is different from the related substances mycoticin and flavofungin, it must be considered as a new antibiotic.

Scopafungin (U-29,479) is a crystalline, nonpolyenic antimicrobial agent obtained from the culture broth of Streptomyces hygroscopicus var. enhygrus var. nova UC-2397. Scopafungin inhibits, in vitro, a variety of pathogenic fungi, yeasts, and gram-positive bacteria.

When dl -isoleucine was added to an ammonium nitrate-maltose medium during cultivation of Streptomyces sp. 732, quinomycin B formation was selectively enhanced (from 3 to 70% of the quinomycin mixture) and quinomycin C synthesis was inhibited completely. In addition, two new quinomycins, designated quinomycins D and E, were produced in the presence of isoleucine. These compounds were found to contain N -methylalloisoleucine. In experiments with isoleucine enantiomorphs, it was determined that the order of effectiveness for quinomycin B synthesis was dl -isoleucine > d -isoleucine > l -isoleucine. The extent to which quinomycin B synthesis is enhanced depends upon the concentration and the time of addition of isoleucine to the medium. The effect of dl -isoleucine was reduced to some extent by the addition of l -valine. It is conceivable that amino acids which are precursors of the N -methylamino acids in quinomycin can regulate quinomycin formation.

Two metabolites, active against gram-positive bacteria, have been isolated from a strain of Actinomycetales. The chemical structure of one of the two, named tetrenolin, has been previously described1). The present paper deals with the description of the producing organism, the isolation and properties of the two metabolites.

Lomofungin is a new antimicrobial agent obtained from the culture broth of Streptomyces lomondensis sp. n. UC-5022. Lomofungin is an acidic, olive-yellow, crystalline compound which inhibits, in vitro, a variety of pathogenic fungi, yeasts, and gram-positive and gram-negative bacteria.

Pure cultures of Physarum gyrosum were grown on agar plates with autoclaved Escherichia coli suspensions as the growth medium. Portions of such agar, after growth of the slime mold, contained diffusible materials that inhibited the growth of Bacillus subtilis, B. cereus, E. coli, Staphylococcus aureus , and Pseudomonas aeruginosa . Paper chromatography of extracts of such cultures revealed at least three different active fractions. Preliminary fractionations increased the specific activity by one order of magnitude, probably in part by removal of inactive material and in part by separating active components. The fractionations also demonstrated the multiplicity of the antibiotic activity. Fractions variously obtained always retarded the growth of the bacterial species listed above.

A new antibiotic, cryomycin, was isolated from the culture filtrate of a facultatively psychrophilic streptomycete. As a result of taxonomic studies, it was considered a new subspecies for which the name Streptomyces griseus subsp. psychrophilus, YOSHIDA, TANI and OGATA, is proposed. The type strain is AKU 2881. This organism grows at 0-37°C and produces cryomycin at 0-18°C. Cryomycin is a peptide antibiotic containing a rather large amount of glycine in its molecule. It darkens at 214-217°C with decomposition. This antibiotic is highly active against Gram-positive bacteria in vitro. The LD50 in mice by intravenous injection is 150 mg/kg.

The addition of elemental sulfur to the fermentation of Streptomyces sioyaensis in a soybean meal medium resulted in a three- to fourfold increase of siomycin. Further experiments on the effect of elemental sulfur during fermentation suggest that one of the key steps stimulating siomycin synthesis is the utilization of thiosulfate, which accumulates in the medium as the result of the oxidation of elemental sulfur.

Kitasatoa kauaiensis, a new species of the genus Kitasatoa, belonging to the family Streptoplanaceae, produces 3 kinds of antibiotics in a culture broth. These antibiotics were identified as chloramphenicol, bottromycin and fradicin based on their physico-chemical and biological properties. A new differential bioassay method for chloramphenicol and bottromycin produced in the same culture broth was established.

Two new compounds, pyracrimycins A and B, have been isolated from a Streptomyces species named Streptomyces eridani Coronelli et al. n. sp. The morphological and physiological characteristics of this strain are described in the present paper together with the production and properties of the two metabolites. Pyracrimycin B is biologically inactive whereas pyracrimycin A is active in vitro against both Gram-positive and Gram-negative bacteria.

Streptomyces sioyaensis , which produces the antibiotic siomycin, oxidizes elemental sulfur when added to the culture medium and accumulates thiosulfate in the fermented broth. The accumulated thiosulfate was isolated as the ammonium salt and was identified by melting point, IR spectrum, and paper chromatography. A variety of other streptomycetes also oxidized elemental sulfur and accumulated thiosulfate.

A new antibiotic, designated LL-A491, was isolated by butanol extraction and crystallization from beers of an unidentified streptomycete, Lederle culture A491. LL-A491 was primarily active against gram-positive bacteria and was related to monazomycin. A tentative molecular formula of C 72�2 H 144�8 O 25�1 N for the antibiotic, based on analyses of the crystalline hydrochloride, picrate, and picrolonate salts, is considerably larger than that proposed for monazomycin, from which LL-A491 was not differentiated by paper chromatography. Analysis of the amorphous polyacetate ester suggested 15 to 16 acetylable groups. Upon hydrolysis, LL-A491 liberated ammonia and a reducing sugar which appeared to be mannose. LL-A491 was dextrorotatory, [α] D 25 + 14�, and exhibited only end absorption in the ultraviolet region.

The normal sequence of cell separation in Saccharomyces cerevisiae begins with the formation of a primary septum, presumably consisting of chitin, on which secondary septa are later deposited. In the presence of the antibiotic polyoxin D, a potent inhibitor of chitin synthetase, pairs of abnormal cells of two different types were observed by phase-contrast microscopy: the “exploded pair,” consisting of two lysed cells from which the cytoplasm had been extruded at the cell junction, and the “refringent pair,” consisting of two highly refractile cells joined by a thin bridge. Thus, in both cases the septal region appears to be affected. Observations with the electron microscope showed that the primary chitin septum was not formed in either of these cell types, and as a consequence secondary septa of varying thicknesses were laid down in an abnormal pattern. With [ 3 H]glucose as carbon source the incorporation of tritium into the chitin of abnormal cells was inhibited about 90%, whereas the labeling of mannan was normal and that of glucan somewhat reduced. The effective concentrations of polyoxin D (0.1 to 1 mg/ml) were much greater than those required to inhibit chitin synthesis in vitro. Dimethylsulfoxide and amphotericin B, both known to increase cell permeability, enhanced the action of the antibiotic.

Anticapsin is a new fermentation product which inhibits formation of the hyaluronic acid capsule of Streptococcus pyogenes . Production of this metabolite in a complex medium by S. griseoplanus is enhanced by high levels of carbohydrate. A number of carbon sources support biosynthesis but sucrose is most effective, the optimum level being 150 g/liter. Neither glucose nor fructose, alone or in combination, serves as an equivalent substitute for sucrose. The addition of dibasic potassium phosphate to the medium further increases anticapsin production. Dissolved oxygen levels are important for synthesis and stability of the metabolite. Anticapsular activity diminishes rapidly in previously aerated broths which are held under static conditions. This decrease does not occur in pasteurized broths or unpasteurized filtrates.

A graphic method of predicting antibiotic yields in continuous flow reactors is presented and discussed using the novobiocin fermentation as a model process. Extension to other antibiotic fermentations and steroid bioconversions is emphasized. In the case of the novobiocin fermentation it was concluded that a combination of one growth stage and one or two antibiotic production stages would be the most economic reactor system to conduct such a fermentation on a continuous basis.

A mutant was isolated from Escherichia coli K-12 which showed increased resistance towards phosphonomycin, a new bactericidal antibiotic recently isolated from strains of Streptomyces . Evidence is presented which suggests that this mutant is resistant to lysis by phosphonomycin because of a lower affinity of phosphoenolpyruvate: uridine diphospho- N -acetylglucosamine enolpyruvyl transferase for this antibiotic. This mutant was also found to be temperature-sensitive in growth. At 42 C mutant cells grew poorly, and the rate of incorporation of 3 H-diaminopimelic acid into trichloroacetic acid-insoluble material was also greatly reduced. Genetic studies indicate that the increased resistance toward phosphonomycin and temperature sensitivity in growth of this mutant are probably the consequences of a single mutation.

Sclerothricin is a new strongly basic antibiotic obtained from the culture filtrate of Streptomyces sclerogranulatus SHIMAZU et YONEHARA nov. sp. The antibiotic is active against gram-positive and gram-negative bacteria and some fungi. Sclerothricin (C16H30O8N6) seems to belong to the streptothricin group. It has two N-methyl, a free carboxyl and two N-terminal groups. No carbamoyl group is present.

Isolation, purification and physicochemical properties of the antibiotic complex YA-56, a family of phleomycin-bleomycin group, are described. The antibiotic YA-56 complex was found to be composed mainly of two active components named YA-56 X and Y. These components were clearly differentiated from the reported phleomycins and bleomycins by their physicochemical properties. However, by direct comparison, YA-56 X was found to be identical with zorbamycin reported recently. YA-56 Y was recognized to be a new antibiotic.

The fate of the orally effective antibiotic D-cephaloglycin and its much less active L-enantiomer has been studied in the rat. D-Cephaloglycin-14C is metabolized by two pathways, (1) hydrolysis of the amide linkage to form D-2-phenylglycine-14C and (2) deacetylation to form deacetyl-D-cephaloglycin-14C. D-Cephaloglycin is absorbed from the gastro-intestinal tract at least in part as the intact antibiotic, L-Cephaloglycin-14C is rapidly metabolized to L-2-phenylglycine-14C and its metabolites. In contrast to the results with D-cephaloglycin-14C, no intact L-cephaloglycin-14C or deacetyl-L-cephaloglycin was excreted in the urine of rats.

A nucleotide phosphohydrolase is firmly associated with a purified polyhedral cytoplasmic deoxyvirus, frog virus 3. This adenosine triphosphatase is distinguishable from known mammalian cell adenosine triphosphatases and from adenosine triphosphatase of an unrelated cytoplasmic replicating virus grown in the same host cell. The enzyme activity has a high specificity for adenosine triphosphate; the product of the reaction is adenosine diphosphate. The presence of similar activities in reovirus and poxvirus indicates that adenosine triphosphatase might have a function in the replication of these viruses.

Dianemycin is an antibiotic previously reported to affect cation transport and to be effective in treating coccidiosis in chickens. It is isolated from a fermentation broth of Streptomyces hygroscopicus. The compound was found to be primarily active against gram-positive organisms. The chemical properties of dianemycin indicate a close relationship to monensin and other acidic cation complexing compounds.

We have isolated a temperature-sensitive mutant of S. cerevisiae which has proven useful for the isolation of antibiotic-sensitive strains.

When Streptomyces shoivdoensis (N2-209-56) mycelia were grown in the presence of sodium acetate-2-14C, the radioactive carbon from acetate-2-14C was fairly well incorporated into the showdomycin molecule ; with approximately 14 % of the total radioactivity of the added sodium acetate-2-14C being incorporated during a 10-hour incubation. Although three antibiotic substances were detected in the fermentation broth, the radioactive carbon from acetate-2-14C was incorporated only into showdomycin. The radioactive showdomycin was extracted with methanol from the lyophilized powder of the fermentation broth, re-extracted with n-butanol, and finally purified by chromatography on a silicic acid column. Over 98.1% of the total radioactivity of this preparation was due to the 14C-showdomycin and approximately 0.33 μCi of the preparation corresponded to 1μmole of showdomycin. About 2.8 % of the radioactivity of the added sodium acetate-2-14C was recovered as that of the purified showdomycin-14C.

Osmotically shocked spheroplasts obtained from Pseudomonas schuylkilliensis strain P contained about 54, 32, 28, and 82% of the total cellular protein, ribonucleic acid (RNA), deoxyribonucleic acid (DNA), and phospholipid, respectively. This preparation was capable of incorporating 32 P-orthophosphate into RNA and DNA, 3 H-adenosine or 3 H-uridine into RNA, and 3 H-leucine or 14 C-phenylalanine into protein. These activities were not found in the cytoplasmic fraction which contained most of the glucose-6-phosphate dehydrogenase activity. The synthesis of RNA by intact and disrupted spheroplast preparations was sensitive to actinomycin D, chromomycin A 3 , streptovaricin, rifampin, Lubrol W, Triton X-100, and sodium deoxycholate, whereas RNA synthesis by intact cells was insensitive to these agents. Ethylenediaminetetraacetic acid, porcine pancreatic lipase, the protoplast-bursting factor, high concentrations of salts, and washing the preparation inhibited the synthesis of RNA by disrupted spheroplasts but had little or no effect on intact spheroplasts. Most of the newly synthesized RNA made by disrupted spheroplasts had the characteristics of messenger RNA. The DNA present in this preparation functioned as a template for RNA synthesis; continued protein synthesis was dependent on concomitant RNA synthesis. An unusual feature of the preparation was the finding that the synthesis of macromolecules was completely dependent on oxidative phosphorylation.

The enzyme, l -glutamine d -fructose 6-phosphate amidotransferase (EC 2.6.1.16) of Neurospora crassa , which catalyzes the formation of glucosamine 6-phosphate was shown to be subject to feedback inhibition by uridine diphosphate N -acetyl- d -glucosamine (UDP-GlcNAc). The conclusion is based on the following observations. UDP-GlcNAc, the direct precursor of chitin, did not accumulate in the cell even when its utilization for the synthesis of cell wall chitin was interrupted by the antibiotic polyoxin D, a competitive inhibitor of the chitin synthetase (EC 2.4.1.16). Furthermore, the cellular level of UDP-GlcNAc rose in a short period of time when the amidotransferase was bypassed in vivo by the addition of glucosamine to the growing medium of the fungus. The amidotransferase was purified from N. crassa approximately 85-fold. Kinetic studies showed that UDP-GlcNAc was a potent and specific inhibitor of the amidotransferase, and that it did not alter the Michaelis constant for either l -glutamine or d -fructose 6-phosphate, suggesting that the inhibitor binds at a site on the enzyme distinct from the active site.

The synthesis of peptidoglycan by cell-free membrane and membrane+wall preparations from an autolysin-deficient, β-lactamase-negative mutant of Bacillus licheniformis N.C.T.C. 6346 was studied. The membrane preparation synthesized un-cross-linked polymer, the formation of which was not inhibited by β-lactam antibiotics. Release of d-alanine by the action of d-alanine carboxypeptidase was inhibited variably according to the antibiotic. This inhibition was reversed by neutral hydroxylamine but not by the action of β-lactamases or by washing. Bacitracin inhibited peptidoglycan synthesis, but not the d-alanine carboxypeptidase. Examination of peptidoglycan synthesized in the presence of excess of bacitracin showed that synthesis was not restricted to the addition of one disaccharide-pentapeptide unit at each synthetic site, an average of 2–3 disaccharide-pentapeptide units being added. Peptidoglycan synthesis was three- to four-fold more sensitive to vancomycin than was the release of d-alanine by the action of the carboxypeptidase. Incorporation of newly synthesized peptidoglycan into pre-existing cell wall was studied in membrane+wall preparations. This incorporation was catalysed by a benzylpenicillin- and cephaloridine-sensitive transpeptidase. The concentrations of these antibiotics giving 50% inhibition of incorporation were almost identical with those required to inhibit growth of the bacillus. Inhibition of the transpeptidase was reversed by treatment with β-lactamase or by washing.

The site of action of related mono- and bis-quinaldinium compounds was investigated in Staphylococcus aureus and Bacillus megaterium . The effects of these compounds on cell morphology and on protoplast formation and fragility were studied, and the distribution of C 14 -labeled quinaldinium compound in cell fractions was measured. The latter studies showed that a major part of the quaternary compound penetrates the cell, leaving a very small quantity associated with the cell wall. Similar antibacterial effects were seen with both the mono- and bis-quinaldinium compounds studied, and these effects were comparable with antibacterial properties of known cationic surface-active antibacterial agents.

THE method described by Brieger and Cosslett1 of growing tubercle bacilli on the ‘Formvar’ film of a stainless steel electron microscope grid has been modified for use with liquid media. In this form the method has been found suitable for a study of the action of antibiotics upon growing tubercle bacilli. In order to prevent the fluid medium contaminating the inoculated surfaces, the grids are placed in contact with filter paper which rests on a cotton-wool support in a small dish 5 cm. in diameter and 2 cm. deep. The cotton-wool is kept moist by being thoroughly soaked in the medium. One dish can take up to twenty grids. The grids are inoculated with a drop of bacillary suspension using a fine platinum loop. If the drop does not stay on the surface of the grid, it is assumed that the holes in the ‘Formvar’ film are too large and the grid is discarded. The grids on which the drops remain are considered to be inoculated with similar numbers of bacilli. The dishes are incubated at 37.5° C. and grids removed at various intervals for inspection. Each grid is floated on sterile distilled water to remove any medium adhering to the lower surface, fixed by floating on 5 per cent formalin for 30 min., and washed again to remove any excess fixative. Throughout the procedure care is taken that the inoculated surface of the grid remains undisturbed. This is an essential condition for the study of variations in growth-rate.

SUMMARY: Streptomyces noursei strain 52/152 produced compounds of the cycloheximide series and fungicidin. On the contrary its mutant strain 54/465 did not produce any compound of the cycloheximide series, and as compared with strain 52/152 produced about double the amount of fungicidin. This strain 52/152 was also insensitive to additions to the cultivation medium of fungicidin up to a concentration of 20,000 units/ml. In the strains studied, a direct proportionality was observed between fungicidin production and sensitivity to it. The interrelation of their production is discussed from the viewpoint of a common precursor for fungicidin and cycloheximide (malonyl-coenzyme A).

Of a total of 739 actinomycetes freshly isolated from soil samples from China, 515 (69·7%) were antibiotically active. Their antibiotic spectrum was determined against 14 test micro-organisms, including bacteria, yeasts and fungi, and 386 of them were characterized by paper chromatography using agar blocks, by behaviour on agar plates incorporating ion-exchange resins and by u.v. absorption spectrum (to detect polyene substances). Of these strains, 195 (50·5%) produced a mixture of antibiotics of both polyene and non-polyene type. On the basis of these results the active strains have been classified in various ways.

Antibiotic-resistant enterobacteria, the vast majority of which carried transmissible R factors, were isolated from 81 out of a total of 100 healthy infants. There was surprisingly little correlation between previous antibacterial therapy and the resistant enterobacterial flora.

Out of 200 infections due to Bacteroides fragilis occurring over a period of three years 133 were related to the intestinal tract, 55 to the genitourinary tract, and the remainder were in bedsores and ulcers; 56% occurred in patients undergoing major intestinal surgery.B. fragilis was isolated in pure culture from 56% of the infections. In mixed culture it was most commonly associated with Klebsiella and Enterobacter species. Other anaerobic bacteria were isolated in 9% of the mixed cultures.Altogether 131 (65.5%) of the patients recovered without antibiotic therapy or further surgery, but 59 (29.5%) developed complications and 10 (5%) died. The commonest complication was abscess formation, and the incidence was highest with infections associated with malignancy (44%) and lowest with obstetric infections (5%). The mortality was 5% overall but in the presence of bacteraemia it rose to 33%.Only 43 patients received appropriate chemotherapy. Clindamycin was the most effective antibiotic, having a recovery rate of 78%, but this rate was little better than in untreated patients (65%). The role of prophylactic antibiotic therapy in preventing bacteroides infection remains to be studied.The incidence of the isolation of bacteroides from wound infections after major intestinal surgery rose from 13% in 1970 to 81% in 1973. This increase was due to both the accurate collection and care of specimens while in transit to the laboratory and the use of selective media for the isolation of bacteroides in laboratory culture. The importance of these precautions is emphasized.

Purpuromycin (C26H18O13) is a new antibiotic isolated from the culture broth of Actinoplanes ianthinogenes proposed as a new species on the basis of its morphological, cultural and physiological characteristics. The antibiotic, obtained as purple crystals, belongs to the naphthoquinone group of antibiotics and resulted to be related to rubromycins. The isolation and purification procedures and the chemico-physical properties of the product are reported. Purpuromycin is active in vitro against Gram-positive bacteria at 0.005-0.02μg/ml, at 1-20μg/ml on Gram-negative bacteria and at 0.2-0.5 μg/ml on fungi.

Tobramycin and amikacin are new aminoglycoside antibiotics which resemble gentamicin and kanamycin respectively in pharmacokinetic, toxicological, and some microbiological respects. Minimum inhibitory concentrations for these four antibiotics have been determined against 393 bacterial strains (13 species from eight genera) isolated from clinical materialKanamycin was the least active, 89% of the Pseudomonas aeruginosa strains being resistant. Resistance was also found in 21% of the Klebsiella aerogenes, 16% of the indoleproducing Proteus species, 4% of the E. coli and 3% of the Enterobacter spp. tested. Providenca stuartii strains were often resistant to gentamicin and tobramycin.Apart from these exceptions, however, all the organisms tested were sensitive to all four compounds, gentamicin and tobramycin usually showing the highest intrinsic activity.Amikacin was the most active compound against a selection of strains chosen because of their resistance to one or more of the aminoglycosides. Thus, amikacin represents a significant advance over kanamycin and seems to be superior to gentamicin in terms of its in-vitro properties. This is especially the case in those unusual circumstances when gentamicin-resistant strains are a problem. We suggest that amikacin warrants further investigation since it may prove to be a valuable alternative to gentamicin in the treatment of life-threatening infections.

A new amino acid antibiotic, amiclenomycin is produced by Streptomyces lavendulae subsp. amiclenomycini OKAMI. The chemical structure of amiclenomycin is L-2-amino-4-(4'-amino-2', 5'-cyclohexadienyl)-butyric acid. The antibiotic inhibits growth of mycobacteria and this activity is reversed by biotin and desthiobiotin. α-Methyl-desthiobiotin is coproduced along with amiclenomycin.

relapsed after an interval, but none to date have had a lesion in the same site, although they stated that this had always occurred previously. It remains to be seen to what extent the treatment is curative when it has been applied. Failure in method (inadequate cover of the whole affected area) may explain why some patients derived little benefit from the treat ment, or the virus may have been I.D.U.-resistant. All strains isolated are being examined for this property. All lesions occurred on the face round the mouth, on the lips, and in one instance on the nose.

A new crystalline antimicrobial compound, geldanamycin, has been discovered in the culture nitrates of Streptomyces hygroscopicus var. geldanus var. nova. Geldanamycin is moderately active in vitro against protozoa, bacteria and fungi. It is also active against L-1210 and KB cells growing in culture and against the parasite Syphacia ohlevata, in vivo. The fermentation, assay, chromatography and isolation as well as its biological and chemical properties were investigated. On the basis of its physical and chemical properties, geldanamycin is a complex molecule consisting of an unsaturated moiety attached to a quinone.

RNA was isolated from calf lens polysomes and crude nuclear preparations. Template activity, base composition, sedimentation behaviour, and electrophoretic properties were compared with corresponding RNA fractions from rat liver. 8–9-fold stimulation of amino acid incorporation was obtained in the cell-free test system derived from Escherichia coli. Template activity was widely distributed throughout sucrose density gradients. However, the major activity consistently was found at the bottom of the tubes. All fractions from the gradient revealed a heterogeneous pattern when subjected to polyacrylamide gel electrophoresis. The bottom fraction constistently showed a diffuse pattern instead of discrete bands. Only RNA fractions extracted at 65° and at pH 8.3 showed a G-C content which was significantly different from ribosomal RNA.