Isolation and phylogenetic assignation of actinomycetes in the marine sediments from the Arctic Ocean

Actinomycetes in five marine sediments collected from the Arctic Ocean atdepths of 43 to 3 050 m were cultivated using a variety of media. A total of 61 actinomycetecolonies with substrate mycelia only were observed, and no colonies with aerial mycelia wereobserved under aerobic conditions at 15℃. From these colonies, 28 were selected to representdifferent morphological types. Denaturing gradient gel electrophoresis (DGGE) was used to check thepurity of isolates and select representatives for subsequent sequencing. Phylogentic analyses basedon nearly full-length 16S ribosomal RNA gene (rDNA) sequences indicated that the actinomycetesisolated were accommodated within genus Rhodococcus of family Nocardiaceae, genus Dietzia of familyDietziaceae, genera Janibacter and Terrabacter of family Instrasporangiaceae and genera Kocuria andA nhrobacter of family Micrococcaceae. One of the strains (P27-24) from the deep-sea sediment atdepth of 3 050 m was found to be identical in 16S rDNA sequence(1474/1474) with theradiation-resistant Kocuria rosea ATCC 187~T isolated from air. More than half of the isolatesshowed the similarities ranging from 99.5% to 99.9% in 16S rDNA sequence to dibenzofran-degrading,butyl 2-ethylhexanoate-hydrolysising and nitrile-metabolizing actinomycetes. All the strainsisolated were psychrotolerant bacteria and grew better on the media prepared with natural seawaterthan on the media prepared with deionized water. Three of them (Dietzia sp. P27-10, Rhodococcus sp.S11-3 and Rhodococcus sp.P11-5) had an obligate growth requirement for salt, confirming that thesestrains are indigenous marine actinomycetes.

Antimethicilin resistance agents from marine actinomycetes from soil sediments of Lagos Lagoon

Objective:To evaluate the isolation of actinomycetes strains with potential for producing antimicrobials with high methicilin resistance capability.Methods:The soil samples were collected from four different locations of Lagos lagoon.The Actinomycetes were isolated from the samples by serial dilution using spread plate method.Isolates were selected based on their cultural characteristics as well as their Gram reaction and phenotypically and molecularly characterized Streptomyces sp.Isolates were inoculated in starch casein and Kuster’s broth media and secondary metabolites were screened for antimicrobial activity against the following microorganisms:methicillin resistant Staphylococcus aureus,Staphylococcus aureus ATCC 29213,Escherichia coli ATCC 29522,Pseudomonas aeruginosa ATCC 27853,Candida albicans,Enterococcus faecalis ATCC 29212.Coagulase-negative staphylococci isolated from HIV patients were also used(Staphylococcus warneri,Staphylococcus xylosus and Staphylococcus epidermidis).The antimicrobial metabolites of the isolates were identified using gas chromatography-mass spectrometer.Results:Extracts from isolates ULS12 and ULS13 showed antimicrobial activity against methicillin resistant Staphylococcus aureus while ULK3 inhibited Candida albicans only.The gas chromatography-mass spectrometer data analysis showed the antibiotic profile of these isolates.Conclusions:The isolates ULS12 and ULS13 were found to display the highest antimicrobial activity against the test organisms and could be a potential source of new antibiotics.

Genetic transformation of marine Actinomycete sp. isolate M048 and expression of a recombinant plasmid carrying the apc gene

Optimal conditions for protoplasts formation of marine Actinomycete sp. isolate M048 were described, dense and disperse mycelia were cultured in SGGP medium, 0.5% glycine, lysozyme exposure （2 mg/cm^3, 37 ℃, 40 min）, and the concentration of sucrose in protoplast buffer was 0.4 mol/dm^3 for keeping the balance of osmotic pressure. Using PEG-mediated pmtoplasts transformarion, the transformation frequency was 89 transformants per microgramme of pIJ702. Meanwhile, an effective transformation procedure was established based on intergeneric conjugation from E. coli ET12567 （pUZS002） using shuttle vectors pPM801, pPM803 and a φC31-derived integration vector pIJ8600 containing onT and attP fragments. Transformation frequencies were 5.30 ×10^-4 ±0.26 ×10^-4 , 8.92 ×10^-4 ±0. 19 ×10^-4 and 6.38 ×10^-5 ±0.41×10^-5 respectively. Further, the heterologous expression of the allophycocyanin gene （apc） in the strain M048 was used to demonstrate this transformation system. SDS - PAGE and Western blot analysis confirmed the expression of recombinant APC （rAPC）.

A New Degraded Sesquiterpene from Marine Actinomycete Streptomyces sp. 0616208

A new degraded sesquiterpene was isolated from the marine actinomycete Streptomyces sp. 0616208. Its structure was elucidated as （1α; 4aα; 5α, 7β, 8aβ）-5, 8a-dimethyl-decahydrona- phthalene-1, 4a, 7-triol on the basis of spectroscopic data.

Bioactive compounds from marine Streptomyces sp. VITPSA as therapeutics

BACKGROUND： Marine actinomycetes are efficient producers of new secondary metabolites that show different biological activities, including antibacterial, antifungal, anticancer, insecticidal, and enzyme inhibition activities. METHODS： The morphological, physiological, and biochemical properties of the strain Streptomyees sp. VITPSA were confirmed by conventional methods. Antibacterial, anti-oxidant, anti-inflammatory, anti-diabetic, and cytotoxic activities of Streptomyces sp. VITPSA extract were determined. The media were optimized for the production of secondary metabolites. Characterization and identification of secondary metabolites were conducted by high-performance liquid chromatography, gas chromatography-mass spectroscopy, and Fourier transform infrared spectroscopy analysis. RESULTS： The strain showed significant antibacterial, anti-oxidant, and cytotoxic activities, moderate anti-inflammatory activity, and no satisfactory anti-diabetic activity. The ethyl acetate extract of Streptomyces sp. VITPSA showed maximum antibacterial activity against two gram-positive and gram-negative bacteria at 0.5 mg/mL. The antioxidant potential of the crude extract exhibited strong reducing power activity at 0.5 mg/mL with 95.1% inhibition. The cytotoxic effect was found to be an ICso of 50 gg/mL on MCF-7 cell lines. Experimental design of optimization by one-factor analysis revealed the most favorable sucrose, yeast extract, pH （7.25）, and temperature （28~C） conditions for the effective production of secondary metabolites. CONCLUSION： This study revealed that Streptomyces sp. VITPSA is an excellent source of secondary metabolites with various bioactivities.