Physiology and biochemistry of streptomycetes. III. Incorporation of D-glucose-u-14C in paramomycin as indicator of antibiotic biosynthesis by Streptomyces albus var. metamycinus nov. var.]

Paromomycin was isolated from culture filtrates of Streptomyces albus var. metamycinus nov. var. after feeding the growing cultures with D-glucose-u-14C. From the different incorporation rates conclusions concerning different features of the paromomycin biosynthesis (utilization of the carbon source, proportional and disproportional changes of the rates of synthesis) could be drawn. Uptake and metabolism of glucose are discussed.     

Classification of novel soil streptomycetes as Streptomyces aureus sp. nov., Streptomyces laceyi sp. nov. and Streptomyces sanglieri sp. nov

The taxonomic positions of soil isolates known as Streptomyces groups A, B and C were clarified. Comparative 16S rDNA sequence studies indicated that representatives of all three taxa formed distinct phyletic lines within the Streptomyces tree though the group A strains were shown to be related to Streptomyces griseus and associated validly described species. The taxonomic integrity of all three groups was highlighted by DNA:DNA relatedness and ribotype data though the group A strains encompassed a higher degree of genetic variation than the group B and C strains. In light of these and earlier phenotypic data it is proposed that Streptomyces groups A, B and C be given species status as Streptomyces sanglieri sp. nov., Streptomyces aureus sp. nov. and Streptomyces laceyi sp. nov., respectively. This revised version was published online in June 2006 with corrections to the Cover Date.     

Physiology and biochemistry of streptomycetes. VIII. Esterase activity and production of turimycin in cultures of Streptomyces hygroscopicus JA 6599]

Esterase in cell-free extracts of Streptomyces hygroscopicus JA 6599 has a temperature-optimum of 35 degrees C, a pH-optimum with p-nitrophenylacetate as substrate at pH 7.7--8.1, with alpha-naphthylacetate at pH 7--9. Michaelis constants in cell-free extracts: with alpha-naphthylacetate Km = = 0.71 mM, with p-nitrophenylacetate Km = 0.21 mM. Phenylesters were better hydrolyzed than naphthylesters, phenylacetate was best hydrolyzed; beta-naphthylacetate was better hydrolyzed than alpha-naphthylacetate. Among the naphthylesters the ester of propionic acid was hydrolyzed best. Caprylate, stearate, and 0,0-diethyl-0-(p-nitrophenyl)-phosphate inhibit the splitting of alpha-naphthylacetate. A comparison with esterases of other biological origin shows that the enzyme studied can be a carboxylesterase (E.C.3.1.1.1.). In cultures of JA 6599 V13 and JA 6599-6 the change of esterase activity during the fermentation was determined. We found a carrelation between the enzymatic activity and the antibiotic-concentration in the culture medium.     

Biosynthesis of epsilon-rhodomycinone from glucose by Streptomyces C5 and comparison with intermediary metabolism of other polyketide-producing streptomycetes

The catabolism of glucose by Streptomyces C5, a producer of anthracycline antibiotics, was investigated to determine the pathways that supply precursors for anthracycline biosynthesis. Carbons for the biosynthesis of epsilon-rhodomycinone, an anthracycline aglycone, from radiolabelled glucose were derived primarily from the Embden-Meyerhof-Parnas pathway, with a minor contribution from the pentose phosphate pathway. Furthermore, the anthracycline-producing strain, Streptomyces C5, as well as Streptomyces aureofaciens and Streptomyces lividans, strains that produce nonanthracycline polyketide antibiotics, displayed enzyme activities indicative of the Embden-Meyerhof-Parnas and pentose phosphate glycolytic pathways. As determined from labelling patterns, Streptomyces C5 apparently has a complete tricarboxylic acid cycle, but does not have a glyoxylate bypass pathway.     

Biosynthesis,characterization and antimicrobial activity of silver nanoparticles by Streptomyces sp. SS2

In the present study the microbial biosynthesis of silver nanoparticles (AgNPs) by secondary metabolites of Streptomyces sp. SS2 in an eco-friendly approach has been reported. The Streptomyces sp. SS2 was isolated from the soil sediment of Similipal Biosphere Reserve. The identification of this strain was determined by phenotypical characteristics (morphological and biochemical) and molecular characterization method using 16 s rDNA sequencing. The morphological study was also done by high-resolution scanning electron microscopy. The preliminary characterization of biosynthesized silver nanoparticle was carried out using UV–Vis spectrum analysis, which showed an absorption peak at 420 nm corresponding to plasmon absorption of silver. The average size and charge (zeta potential) of the particles were found to be 67.95 ± 18.52 nm and ?17.7 ± 5.30 mV, respectively. The functional groups were identified by FTIR studies and their morphology (round and spherical shape) was determined by scanning electron microscopy. The synthesized AgNPs exhibited excellent antibacterial activity against Escherichia coli (MTCC 1089), Bacillus subtilis (MTCC 7164), Staphylococcus epidermis (MTCC 3615), Vibrio cholerae (MTCC 3904) and Staphylococcus aureus (MTCC 1144). These biotechnological approaches of synthesis of nanoparticles can direct a new path in biomaterial sciences and enrich biomedical applications.     

Genomics of Sponge-Associated Streptomyces spp. Closely Related to Streptomyces albus J1074: Insights into Marine Adaptation and Secondary Metabolite Biosynthesis Potential

A total of 74 actinomycete isolates were cultivated from two marine sponges, Geodia barretti and Phakellia ventilabrum collected at the same spot at the bottom of the Trondheim fjord (Norway). Phylogenetic analyses of sponge-associated actinomycetes based on the 16S rRNA gene sequences demonstrated the presence of species belonging to the genera Streptomyces, Nocardiopsis, Rhodococcus, Pseudonocardia and Micromonospora. Most isolates required sea water for growth, suggesting them being adapted to the marine environment. Phylogenetic analysis of Streptomyces spp. revealed two isolates that originated from different sponges and had 99.7% identity in their 16S rRNA gene sequences, indicating that they represent very closely related strains. Sequencing, annotation, and analyses of the genomes of these Streptomyces isolates demonstrated that they are sister organisms closely related to terrestrial Streptomyces albus J1074. Unlike S. albus J1074, the two sponge streptomycetes grew and differentiated faster on the medium containing sea water. Comparative genomics revealed several genes presumably responsible for partial marine adaptation of these isolates. Genome mining targeted to secondary metabolite biosynthesis gene clusters identified several of those, which were not present in S. albus J1074, and likely to have been retained from a common ancestor, or acquired from other actinomycetes. Certain genes and gene clusters were shown to be differentially acquired or lost, supporting the hypothesis of divergent evolution of the two Streptomyces species in different sponge hosts.     

New antibiotic, parvulomycin, produced by a culture of Actinomyces parvullus var. chromogenes var. nov]

Actinomycete LIA-O784 was isolated from a soil sample. By its morphological and cultural properties the isolate was close to Act. parvullus but differed from it in synthesis of melanoid pygment, thyrosinase, hydrogen sulphide and pronounced antifungal activity. The actinomycete was classified as a new variant and designated as Actinomyces parvullus var. chromogenes var. nov. The culture produced a new polyglycoside antibiotic named parvulomycin. The physico-chemical characteristics of the antibiotic is presented.     

In vivo absorption of 14C-glucose and 14C-glycine by the rat intestine during ochratoxin A toxicosis.

Ochratoxin A was administered orally at a dose level of 6 mg/kg/day for eight weeks to rats. Studies on the intestinal cellular macromolecules, activities of membrane bound enzymes and in vivo absorption of 14C-glucose and 14C-glycine exhibited significant alterations. The observed reduction in the absorption of these nutrients during ochratoxin A toxicosis is corroborated by the changes observed in the levels of cellular macromolecules and the activity of membrane bound enzymes which are involved in the transport system.     

Biosynthesis of Cobalamine,Erythromycin and Chlortetracycline by Streptomyces Species

Attempts were devoted to use Streptomyces aureofaciens and Streptomyces erythreus, the antibiotics producers as sources for the biosynthesis of cobalamine. The constituents of the fermentation medium and the strain play an important role in the biosynthesis of vitamin B₁₂. The same strain produced different amounts of antibiotic and vitamin on the two different constitutive media. The increase of the phosphorus concentration in the fermentation medium—within limits—increased the vitamin B₁₂ biosynthesis. The optimal concentration of phosphorus favourable for the synthesis of cobalamine was inhibitive for the antibiotic production. The phosphorus level in the fermentation medium plays an important role in the metabolism of carbohydrate and consequently on the biosynthesis of antibiotics. Low concentration of 5,6-dimethylbenzimidazole (cobalamine precursor) in the presence of suitable phosphorus induced the microorganism to increase its biosynthetic potentiality for the vitamin B₁₂ production.     

Biosynthesis of antifungal isoflavonoids in Lupinus albus. Enzymatic prenylation of genistein and 2'-hydroxygenistein.

A 45,000g particulate fraction from hypocotyls of Lupinus albus catalyzes the prenylation of genistein 1 and 2′-hydroxygenistein 2 with dimethylallyl pyrophosphate to the antifungal 6-isopentenylgenistein 3 (wighteone) and 6-isopentenyl-2′-hydroxygenistein 4 (luteone), respectively.     

The exocellular beta-lactamase of Streptomyces albus G. Purification, properties and comparison with the exocellular DD-carboxypeptidase.

The exocellular beta-lactamase of Streptomyces albus G has been purified to near protein homogeneity. It consists of one single polypeptide chain of mol.wt. 30 000-31 000, has a rather low isoelectric point (at pH 6.0) and contains less lysine (2.1%) and more half-cystine residues than most beta-lactamases from other Gram-positive bacteria. Penicillins are much better substrates than delta 3-cephalosporins; the catalytic-centre activity of good penicillin substrates is 333-500 s-1. The exocellular, mol.wt. 17 000 DD-carboxypeptidase of S. albus G [previously purified to protein homogeneity; Duez, Frère, Geurts, Ghuysen, Dierickx & Delcambe (1978) Biochem. J. 175, 793-800] behaves as an exceedingly poor beta-lactamase, hydrolysing benzylpenicillin into benzylpenicilloate 5 x 10(-6)-fold less rapidly than does the exocellular beta-lactamase. To all appearances, the beta-lactamase has no bivalent cation requirement whereas, as shown elsewhere [Dideberg, Charlier, Dupont, Vermeire, Frère & Ghuysen (1980) FEBS Lett. 117, 212-214, and Dideberg, Joris, Frère, Ghuysen, Weber, Robaye, Delbrouck & Roelands (1980) FEBS Lett. 117, 215-218], the DD-carboxypeptidase possesses one essential Zn2+ ion per molecule. Peptide 'mapping' and immunological studies suggest that the two Streptomyces enzymes probably have very different structural and mechanistic properties.     

Axenomycins,new anthelmintic,antiprotozoal and antifungal antibiotics,produced by Streptomyces lisandri nov. sp.

From a soil sample a new microorganism was isolated, described and identified as Streptomyces lisandri nov. sp. In submerged fermentation in a suitable culture medium this streptomycete produces three new related compounds, axenomycins A, B and D. Data on the anthelmintic, antiprotozoal and antifungal activities in vitro are reported.