The Production of Streptomycin by Streptomyces bikiniensis

Identification and enhancing production of a novel macrolide compound in engineered Streptomyces peucetius

Streptomyces peucetius produces doxorubicin and daunorubicin, which are important anticancer drugs. In this study, we activate peucemycin, a new antibacterial compound, using an OSMAC strategy. In general, bioactive compounds are produced in a higher amount at room temperature; however, in this study, we have demonstrated that a bioactive novel compound was successfully activated at a low temperature (18 °C) in S. peucetius DM07. Through LC-MS/MS, IR spectroscopy, and NMR analysis, we identified the structure of this compound as a γ-pyrone macrolide. This compound was found to be novel, thus named peucemycin. It is an unusual 14-membered macrocyclic γ-pyrone ring with cyclization. Also, peucemycin exhibits potential antibacterial activity and a suppressive effect on the viability of various cancer cell lines.

Activation of peucemycin in S. peucetius DM07 by the OSMAC strategy.

Discovering potential Streptomyces hormone producers by using disruptants of essential biosynthetic genes as indicator strains

Autoregulators are low-molecular-weight signaling compounds that control the production of many secondary metabolites in actinomycetes and have been referred to as 'Streptomyces hormones'. Here, potential producers of Streptomyces hormones were investigated in 40 Streptomyces and 11 endophytic actinomycetes. Production of γ-butyrolactone-type (IM-2, VB) and butenolide-type (avenolide) Streptomyces hormones was screened using Streptomyces lavendulae FRI-5 (ΔfarX), Streptomyces virginiae (ΔbarX) and Streptomyces avermitilis (Δaco), respectively. In these strains, essential biosynthetic genes for Streptomyces hormones were disrupted, enabling them to respond solely to the externally added hormones. The results showed that 20% of each of the investigated strains produced IM-2 and VB, confirming that γ-butyrolactone-type Streptomyces hormones are the most common in actinomycetes. Unlike the γ-butyrolactone type, butenolide-type Streptomyces hormones have been discovered in recent years, but their distribution has been unclear. Our finding that 24% of actinomycetes (12 of 51 strains) showed avenolide activity revealed for the first time that the butenolide-type Streptomyces hormone is also common in actinomycetes.

Targeting Reactive Carbonyls for Identifying Natural Products and Their Biosynthetic Origins

Natural products (NPs) serve important roles as drug candidates and as tools for chemical biology. However, traditional NP discovery, largely based on bioassay-guided approaches, is biased toward abundant compounds and rediscovery rates are high. Orthogonal methods to facilitate discovery of new NPs are thus needed, and herein we describe an isotope tag-based expansion of reactivity-based NP screening to address these shortcomings. Reactivity-based screening is a directed discovery approach in which a specific reactive handle on the NP is targeted by a chemoselective probe to enable its detection by mass spectrometry. In this study, we have developed an aminooxy-containing probe to guide the discovery of aldehyde- and ketone-containing NPs. To facilitate the detection of labeling events, the probe was dibrominated, imparting a unique isotopic signature to distinguish labeled metabolites from spectral noise. As a proof of concept, the probe was then utilized to screen a collection of bacterial extracts, leading to the identification of a new analogue of antipain, deimino-antipain. The bacterial producer of deimino-antipain was sequenced and the responsible biosynthetic gene cluster was identified by bioinformatic analysis and heterologous expression. These data reveal the previously undetermined genetic basis for a well-known family of aldehyde-containing, peptidic protease inhibitors, including antipain, chymostatin, leupeptin, elastatinal, and microbial alkaline protease inhibitor, which have been widely used for over 40 years.

Production and cytotoxicity of extracellular insoluble and droplets of soluble melanin by Streptomyces lusitanus DMZ-3

A Streptomyces lusitanus DMZ-3 strain with potential to synthesize both insoluble and soluble melanins was detected. Melanins are quite distinguished based on their solubility for varied biotechnological applications. The present investigation reveals the enhanced production of insoluble and soluble melanins in tyrosine medium by a single culture. Streptomyces lusitanus DMZ-3 was characterized by 16S rRNA gene analysis. An enhanced production of 5.29 g/L insoluble melanin was achieved in a submerged bioprocess following response surface methodology. Combined interactive effect of temperature (50°C), pH (8.5), tyrosine (2.0 g/L), and beef extract (0.5 g/L) were found to be critical variables for enhanced production in central composite design analysis. An optimized indigenous slant culture system was an innovative approach for the successful production (264 mg/L) of pure soluble melanin from the droplets formed on the surface of the culture. Both insoluble and soluble melanins were confirmed and characterized by Chemical, reactions, UV, FTIR, and TLC analysis. First time, cytotoxic study of melanin using brine shrimps was reported. Maximum cytotoxic activity of soluble melanin was Lc50-0.40 µg/mL and insoluble melanin was Lc50-0.80 µg/mL.

Carbomycin, a macrolide antibiotic

Carbomycin is produced by Streptomyces halstedii. It was produced in a medium containing the following ingredients (g/l): soybean meal, 30.0; glucose, 22.0; NaCl, 1.0; CaCO3, 5.0; CoCl2 . 6 H2O, 0.005; and lard oil, 4.0. Influence of trace elements on the biosynthesis of carbomycin was recorded. Methods of extraction and purification were given in the review article. Chemical and physical properties of carbomycin were also described. A microbiological assay method for carbomycin determination was described. Biosynthesis of carbomycin was reported. Mechanism of action of carbomycin on micro-organisms was also given in the review article.

AL, Fisher MW, Hans RJ, Pittillo RF, Vogler DK, Weston KS, Ehrlich J. CHALCOMYCIN, A NEW ANTIBIOTIC: BIOLOGICAL STUDIES

Chalcomycin, a new, slightly water-soluble, organic-solvent-soluble, neutral antibiotic containing only carbon, hydrogen, and oxygen was obtained from filtrates of two new strains of Streptomyces bikiniensis. A paper-disk agar-diffusion assay, which employs Sarcina lutea PCI 1001 W as the test organism, has been developed. The sensitivity range of the assay is 1–10 μg chalcomycin/ml. Shaken flask fermentations in a medium containing glucose, yeast hydrolyzate, and meat peptone have produced titers of 200 μg/ml. Chalcomycin is primarily active against Staphylococcus aureus, including isolates resistant to various antibiotics, and Streptococcus pyogenes. In experimental mouse infections with various mouse-virulent strains of S. aureus, a single dose of chalcomycin gave oral ED50 values of 13 to 53 mg/kg and subcutaneous values of 8 to 47 mg/kg. Against S. pyogenes, oral and subcutaneous administration of a single dose gave ED50 values of 88 and 55 mg/kg, respectively. Chalcomycin was well tolerated by mice, rats, dogs, and monkeys.